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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: تحقیقات مهندسی سازه های آبیاری و زهکشی
- نوع مقاله: Journal Article
- کلمات کلیدی: تبخیر,سلول خورشیدی,الکتریسیته,ذخیره آب,سد انحرافی
- چکیده: ایران سرزمین کم بارش است و با توجه به پیامدهای تغییرات اقلیمی و وجود خشکسالی باید برای رفع کمآبی در کشور از هر طریقی جلوی هدر رفت آب را گرفت. ازآنجاییکه کشور ایران در نواحی پرتابش واقع است مطالعات نشان میدهد که استفاده از تجهیزات خورشیدی در ایران مناسب بوده و میتواند بخشی از انرژی موردنیاز کشور را تأمین نماید. در استان آذربایجان غربی هرساله حجم عظیمی از آبها در اثر تبخیر از دسترس خارج میشود. در این تحقیق کاهش تبخیر از سد انحرافی نوروزلو توسط پنل خورشیدی موردبررسی قرار گرفت. برای این منظور تبخیر واقعی آب دریاچه سد با استفاده از دادههای ایستگاه کلیماتولوژی سدنوروزلو برآورد گردید و با نرمافزار پی وی سیست برآورد میزان بار انرژی خورشیدی در محدوده سد استخراج گردید. درنهایت پروژه ازنظر اقتصادی بررسی و سودآوری آن تحلیل شد. نتایج نشان داد طبق برآوردهای اقتصادی انجامشده، متوسط هزینه برای خودکفایی برق مصرفی 5 روستای اطراف سد حدود 16 میلیارد تومان به دست میآید. با احتساب درآمد حاصل از کاهش تبخیر تولید برق، بازگشت سرمایه این فنّاوری طی 8/37 سال جبران خواهد شد.
- چکیده انگلیسی: Extended Abstract
Introduction
Iran is a land of low rainfall and due to the consequences of climate change and the existence of drought, water loss should be prevented in any way to eliminate water shortage in the country. In the province of West Azerbaijan, a large amount of water is lost every year due to evaporation.
Solar energy is known as free and clean energy and even the main source of other types of energy on the earth. The scarcity of fossil fuel, as well as non-uniform distribution of this kinds of energy source in the work, motivate humans to find other types of energy especially clean and sustainable solar energy. Nowadays, the rising earth population and impacts of fossil fuel on the environment leads to accelerate the construction of solar power stations (Turki and Abedi, 2012). Owing to the location of Iran in suitable latitude and altitude, the country has a sunny and dry climate. Therefore, the significant magnitude of The sun's radiant energy reaches the earth's surface. On the other hand, the hot and dry climate of Iran makes high evaporation of water from reservoirs of dams.
Covering the surface of freshwater reservoirs with physically thin covers could prevent or reduce the evaporation rate of water. Soltani et al., (2015) reported that water evaporation in aquatic environments could be reduced up to 10% in the presence of the planet. Rezzade et al., (2017) informed that scattering of colored floating balls could prevent evaporation rate from medium to small reservoirs up to 71.5%. Based on their results, the white color balls are more effective than the dark colors such as black in control of evaporation under similar conditions. One of the common means to cover the surface of reservoirs large dam in order to reduce evaporation of water is to use solar panels.
Materials and Method
In this study, the reduction of evaporation from the Nowruzlu diversion dam was investigated by using solar panels. This high diversion dam is located in the northwest of Iran, province of West Azerbaijan. The dam is constructed to divert the resealed water from Boukan earth dam to supply agricultural demands left side intake and domestic, industrial and agricultural demands by right side intake. The height of the dam is about 10 meters, the lake area is 0.2 km2, and the volume of water is more than 14 MCM. The object of this method is not only to reduce evaporation from the reservoir of the dam but also to produce clean solar energy for the domestic energy supply. For this purpose, the actual evaporation of the dam lake water was estimated using the data of Noruzlu dam climatology station. With PVsyst software, the amount of solar energy load in the Norozlo dam range was extracted. Finally, the project was economically evaluated and its profitability was analyzed. In this research, we used recorded evaporation data from the local synoptic station located in a dam site based on a standard A class pan. The solar energy potential was estimated by using the photovoltage software PVSYST model. The software provides an effective tool to simulate and calculate the distribution of energies throughout the year in any region on the earth. The output of the software is categorized in three was as follows based on the software documents:
• The total energy production [MWh/y] is essential for the evaluation of the PV system’s profitability.
• The Performance Ratio (PR [%]) describes the quality of the system itself.
• The specific energy [kWh/kWp] is an indicator of production based on the available irradiation (location and orientation).
Results and discussion
The numerical analysis to evaluate installation circumstances for solar panels revealed that, by 36o inclination, 2 kw/m2 energy would be produced. In order to supply domestic requirements of 1000 houses, 2568 m2covering of lake surface will be sufficient. Hence, via the mentioned states, 2Mw electricity will be produced, in another word, the annually produced energy could be more than 730 Mw.
The results showed that according to economic estimates, the average cost for self-sufficiency in electricity consumption in 5 villages (each of them with 200 houses) around the dam is about 37,680 billion Iranian rials (IRR). By calculating the revenue from the reduction of evaporation and electricity generation, the return on investment of this technology will be compensated in 5.7 years.
Keywords: Evaporation, water storage, diversion dam, solar cell, electricity- انتشار مقاله: 02-11-1399
- نویسندگان: میلاد رضائی,حجت احمدی
- مشاهده
- جایگاه : پژوهشی
- مجله: تحقیقات مهندسی سازه های آبیاری و زهکشی
- نوع مقاله: Journal Article
- کلمات کلیدی: واگذاری,شبکههای آبیاری,شرکتهای بهرهبرداری,قوانین آب
- چکیده: ایجاد چارچوب نامناسب پشتیبانی، حمایت ضعیف از سوی سیاستگذاران و جامعه مدنی و واگذاری زودهنگام وظیفه به سازمانهای غیردولتی بدون ایجاد ظرفیت سازمانی از دلایل مکرر شکست در واگذاری طرحهای آبیاری و زهکشی به بخش خصوصی است؛ بنابراین گردآوری مبانی، اصول و معیارهای موجود، اسناد بالادستی، قوانین کشور و برخی تجربیات بینالمللی معطوف به مفاهیم خصوصیسازی و انتقال مدیریت آب در بخش کشاورزی، در تحقیق حاضر مدنظر قرار گرفته است. نتایج نشان داد کلی بودن قوانین و مقررات بدون توجه به تنوع ویژگیهای خاص هر منطقه، فقدان ضمانت اجرایی و عدم پایش و ارزیابی در حین اجرای طرحهای کاهش تصدیگری دولتی از مشکلات عمده اجرای قوانین موجود در این خصوص است. ضمن اینکه با تغییر سیاستهای کشور از دولتمحوری به سمت مشارکت بخش خصوصی و کشاورزان، قوانین جاری در حوزه منابع آب نیز نیازمند بازنگری هستند همچنین مرور تجربیات بینالمللی نشان داد حمایت سیاسی قوی از طرف مقامات دولتی، استفاده از چارچوب قانونی ساده و انعطافپذیر بهصورت تدریجی در موفقیت اصلاحات در قوانین خصوصیسازی اثرگذار است.
- چکیده انگلیسی: Introduction
Since the 1990 s, a number of countries adopted the transfer policies or irrigation management transfer (IMT), and in some cases, the incentive to reform water laws was provided (Bruns et al., 2005). Making of the investment decisions and water allocation by local and private organizations requires that the water users have confidence in the quantity and time they receive water and this requires the existence of legal transparency. Therefore, water laws should provide a full and indispensable set of rights for use of water (Bayat et al., 2016). In this study, by focusing on the privatization of agricultural water, relevant law clauses were extracted during different periods, and the effectiveness of these rules on management of water resources was analyzed.
Methodology
In this study, the purpose of “law” is all ratification of parliament, official codes, and administrative regulations. Since land containing groundwater resources are usually governed by private management, the focus is on the rules associated with irrigation networks with surface water resources. To implement the study all documents related to water laws, approved by various organizations of the country, included the resolutions and bills of the Islamic Parliament of Iran, national development plans, the resolutions of the Supreme Council for Water, the efforts of the relevant Ministries, and published procedures and executive regulations. Then the material related to the issue of privatizing and reducing the government’s leadership and authority, or common and applicable laws that lacked relevance to privatization issues were extracted from them and, besides international documents in this regard, were analyzed in a descriptive way.
Results and Discussion
Until 1929, water governance issues were solved by the common rule of society in the ownership of wells and qanats. Then, by compiling civil code, water governance was enforced using this law. In 1944, with the approval of the law allowing the establishment of the irrigation agency, the individual aspect of irrigation was limited to traditional water rights and the government supervised all irrigation affairs. In this period, for the first time, public and private institutions were allowed to build and invest in irrigation networks. By approving the establishment of companies to exploit lands downstream of the dams, the exploitation of command area of irrigation networks was given to natural persons and non-governmental individuals. After the Islamic revolution, according to the constitution and the approval of the cabinet of ministers, the government was obliged to dispose of its shares in the operation of irrigation networks by maintaining state ownership of the infrastructure. Nevertheless, the devolution of these private companies only occurred in the ownership of the shares and these companies are still dominated by the government in management, structure and the way of referral. The development plans of the country and the approvals of the supreme council of water have stressed the acceleration of the privatization process and the reduction of government incumbency in water projects, but financial support and the executive program have not been taken into account to meet their goals. The set of criteria for operation and maintenance of irrigation networks was notified to the ministry of power in 2005. However, except for identifying the competence of companies, other parts of it could not be implemented, so it is needed to update these instructions. In the study of international experiences of water reform with the approach of privatization in developed (United States and France) and developing countries (Chile, Mexico, Turkey and India), some cases such as clear and transparent water rights with guarantee the implementation of the rules, financial independence of water custodian, appropriate water pricing, establishing a legal framework for privatization process and conducting regular assessments to evaluate the results of transfer of management is considered as the most important measures in water privatization.
Conclusions
By changing the policy of government from centralization to the participation of the private sector and the stakeholders, the current laws in the field of water resources need to be reviewed. Due to the importance of the subject, in this research, we proceed to aggregation rules and procedures related to this discussion and review the consequences of implementing laws and policies of privatization in irrigation networks. The results showed that although there are laws and regulations to attract private sector capital, the time of implementation of water plans and low investment profits has prevented the private sector investment in this sector. The generality of laws, disregard for restrictions, climatic conditions and political changes in the country (such as change of government), has made the implementation of water development programs less effective. In addition, attracting the full political support at high levels of management and legislation of the country, and the use of simple legal framework with accordance of the capacity of water users, were the main factors in success of pioneer countries in water privatization.- انتشار مقاله: 16-12-1399
- نویسندگان: پوریا نامدار,عاطفه پرورش ریزی
- مشاهده
- جایگاه : پژوهشی
- مجله: تحقیقات مهندسی سازه های آبیاری و زهکشی
- نوع مقاله: Journal Article
- کلمات کلیدی: بهرهوری,نیاز خالص آبیاری,آبیاری قطرهای نواری,راندمان کاربرد
- چکیده: توسعة سامانههای نوین آبیاری یکی از برنامههای وزارت جهاد کشاورزی در چند دهة گذشته بوده است. ارزیابی نقش این سامانهها در افزایش شاخصهای مدیریت مصرف آب در بخش کشاورزی میتواند در سیاستگذاریها و برنامه-ریزیهای آیندة کشور موثر باشد. ازاینرو، این تحقیق با هدف تعیین شاخصهای مدیریت مصرف آب در تولید گوجه-فرنگی در کشور و ارزیابی نقش آبیاری قطرهای نواری در افزایش آنها، انجام شد. حجم آب کاربردی و عملکرد محصول در 176 مزرعه که در قطب های تولید این محصول در فصل زراعی (98-1397) انتخاب و اندازهگیری شد. مقادیر اندازهگیری شده با نیاز خالص آبیاری حاصل از روش فائو پنمن-مانتیث با استفاده از دادههای هواشناسی و همچنین با مقادیر سند ملی آب مقایسه شدند. در ادامه نیز تاثیر روش آبیاری قطرهای نواری) بر حجم آب کاربردی، راندمان کاربرد و بهرهوری فیزیکی آب در مناطق مورد مطالعه بررسی شد. میانگین وزنی حجم آب کاربردی در مناطق مورد مطالعه 7729 مترمکعب بر هکتار بود. بهرهوری آب در مناطق تولید از 33/4 تا 52/9 کیلوگرم بر مترمکعب متغیر بود و متوسط آن 10/7 کیلوگرم بر مترمکعب به دست آمد. میانگین نیاز خالص آبیاری و راندمان کاربرد آب در مزارع مورد مطالعه بهترتیب 674 میلیمتر و 78 درصد بود. کاربرد آبیاری قطرهای نواری نقش موثری در افزایش شاخصهای مدیریت مصرف آب در مقایسه با روش آبیاری سطحی داشتند. آبیاری قطرهای نواری 25 درصد در کاهش آب کاربردی، 10 درصد در افزایش راندمان کاربرد آب در مزرعه و 16 درصد در ارتقای بهرهوری آب موثر بوده است.
- چکیده انگلیسی: The Role of Modern Irrigation Systems on Tomato Applied Irrigation Water Management in Iran
Introduction
Development of modern irrigation systems has been one of the main programs in developing agricultural sector in the past few decades. Assessing the role of these systems in increasing indicators of irrigation water management can play an important role in future national policies and planning. Therefore, this study was conducted with the aim of appraising water consumption management indicators in tomato production in different regions of Iran and evaluating the role of surface drip irrigation systems in increasing these indicators.
Methodology
In this study, a field survey was conducted to measure yield and applied irrigation water of tomato under the farmers’ management in tomato production hubs. Volume of applied water by farmers in 176 farms in Fars, South Kerman, Hormozgan, Bushehr, Khorasan Razavi, Qazvin, Khuzestan, Golestan, Zanjan, Hamedan and Semnan provinces with different conditions of climates, irrigation methods (furrows and drip), salinity of irrigation water and soil; and different tomato cultivars were measured during growing season 2018-2019. The measured applied irrigation water values were compared with the net irrigation requirements estimated by the FAO Penman-Monteith method using meteorological data from the last 10 years, as well as the values of the national water document. Then, the effect of modern irrigation methods (surface drip irrigation) on applied water, application efficiency and physical water productivity was investigated in the study areas. Crop yield was recorded at the end of the growing season and water productivity (WP) was calcucated as the ratio of yield to total applied water (irrigation water and effective rainfall). Analysis of variance was used to investigate the possible difference between yield, applied water and WP among the hubs. Data adequacy was assessed by using the method provided by Sarmad et al. (2001).
Results and Discussion
The results showed that yield, applied irrigation water and WP in tomato production hubs were significantly different at the P ≤ 0.01. The average volume of applied irrigation water by the farmers was 7729 m3/ha. Water productivity in production areas varied from 4.33 to 9.52 kg/m3 and its average was 7.10 kg/m3. The average net irrigation requirement and irrigation application efficiency were 674 mm and 78%, respectively. Irrigation application efficiency obtained from the studied tomato farms was slightly higher than the average irrigation efficiency in Iran reported by Abbasi et al. (2016). Deficit irrigation was occurred in the fields of some areas such as Bushehr, Golestan and Semnan. Tomato planting time (spring or autumn) affected applied irrigation water, yield and WP. The volume of water used in autumn planted farms (5356 m3/ha) was less than spring planted farms (9831 m3/ha). The average yield of tomatoes in spring planted farms (74.3 t/ha) was significantly higher than the yield of fields planted in autumn (46.1 t/ha). However, the average of WP in spring planting farms (7.7 kg/m3) was higher than the productivity of farms planted in autumn (6.6 kg/m3). The application of surface drip irrigation systems in comparison with furrow irrigation resulted in 25% reducing in applied water, 10% increasing the application efficiency and 16% improving in water productivity.
Conclusions
In general, the results of this study provide useful information on applied irrigation water management indicators in tomato production to managers and water decision makers within Iran. Proper development and management of drip irrigation systems for row crops such as tomatoes and autumn planting of tomatoes in warm tomato production hubs is recommended for effective use of autumn rainfall. Also, training and application of methods to improve the performance of surface irrigation (using methods to reduce evaporation and the use of low pressure systems) is recommended to increase irrigation efficiency and reduce applied irrigation water.- انتشار مقاله: 27-06-1399
- نویسندگان: فریبرز عباسی,محمد جلینی,محمد خرمیان,سید ابراهیم دهقانیان,اسماعیل مقبلی دامنه,مهرداد نورورزی,افشین یوسف گمرکچی,مهدی طاهری,اسحق زارع مهرانی,علیرضا کیانی,نادر سلامتی,سیدحسن موسوی فضل,علی قدمی فیروزآبادی,پرویز بیات,ابوالفضل ناصری
- مشاهده
- جایگاه : پژوهشی
- مجله: تحقیقات مهندسی سازه های آبیاری و زهکشی
- نوع مقاله: Journal Article
- کلمات کلیدی: پلیمر جاذب رطوبت,رطوبت قابل استفادۀ گیاه,منحنی مشخصۀ رطوبتی خاک
- چکیده: یکی از مهمترین چالشهای حال و آینده، به ویژه در مناطق خشک جهان، کم آبی است. یکی از روشهای بهبود بهره وری آب و مدیریت بهتر آب مصرفی در بخش کشاورزی، کاربرد مواد جاذب رطوبت است. هدف از تحقیق حاضر ارزیابی اثر کاربرد پلیمر جاذب رطوبت آکواسورس بر پارامترهای فیزیکی و منحنی مشخصۀ رطوبتی سه بافت مختلف خاک است. آکواسورس نسل جدیدی از پلیمرهای جاذب رطوبت بر پایۀ پتاسیم است که زیست تخریب پذیر بوده و فاقد ترکیب مخرب آکریل آمید است. به این منظور، آزمایشهایی به صورت فاکتوریل در قالب طرح کاملاً تصادفی با 3 تکرار اجرا شد که فاکتور اول چهار درصد وزنی از پلیمر جاذب رطوبت (صفر، 5/0، 1 و 2 درصد وزنی پلیمر/خاک) و فاکتور دوم سه بافت مختلف خاک (لوم شنی، لوم رسی و رسی سیلتی) بود. نتایج بررسیها نشان داد که در تمامی بافتهای خاک مورد مطالعه، کاربرد مادۀ جاذب رطوبت و افزایش سطح مورد استفاده، میزان رطوبت را در نقطۀ ظرفیت زراعی و نقطۀ پژمردگی دائم افزایش دادهاست. بیشترین مقدار رطوبت قابل استفاده گیاه در بافتهای لوم شنی، لوم رسی و رسی سیلتی به ترتیب به میزان 8/9، 8/13 و 7/12 درصد حجمی و مربوط به کاربرد 5/0 درصد وزنی مادۀ جاذب رطوبت در این تیمارهاست. کاربرد مقادیر بیشتر سبب کاهش رطوبت قابل استفاده برای گیاه شدهاست. بنابراین، با آنکه پلیمر جاذب رطوبت آکواسورس در جذب آب توانایی خوبی دارد، اما در سطوح بالای استفاده اثر بازدارندگی دارد و قادر به تخلیۀ مطلوب رطوبت نیست.
- چکیده انگلیسی: Introduction
Today, one of the most important challenges of the present and the future, especially in the arid regions of the world, is the issue of water shortage and in some cases the water crisis. One of the ways to improve water productivity and better water management in agricultural sector as the largest consumer of water is the use of super-absorbent materials to improve soil texture, increase soil water retention, reduce erosion and increase germination. The aim of this study is to evaluate the effect of Aquasource superabsorbent polymer on physical parameters and soil-water characteristic curves (SWCC) of different soil textures.
Methodology
Aquasource is a new generation of potassium-based superabsorbent polymers that are biodegradable and free of destructive acrylamide compounds. In order to evaluate the effect of Aquasource hydrogel on hydro-physical properties of soils, some experiments in the form of a completely randomized design with 3 replications was performed. The first factor was different levels of superabsorbent (0, 0.5, 1 and 2% by weight of superabsorbent/soil) and the second factor was three different soil textures (sandy-loam, clay-loam and silty-clay). SWCCs related to all treatments were determined by determining the moisture content of the samples at different pressures (0, 0.3, 0.5, 1, 3, 6, 9 and 15 bars) using a pressure plate device. Then, to obtain the soil moisture characteristic curve parameters in each sample, two softwares RETC (v.6.02) and Rosetta (v. 1.1) were used.
Results and Discussion
The results of variance analysis and mean comparisons based on Duncan's test showed that in all soil textures studied, the application of superabsorbent and the increase Aquasource amounts, increased the moisture contents at the field capacity and permanent wilting point. However, the highest amount of soil available water for plant use in sandy loam, clay loam and silty clay textures was 9.8%, 13.8% and 12.7%, respectively, and they are related to the use of 0.5% w/w of superabsorbent in these treatments (Fig. 1). The use of larger amounts, up to 2%w/w, reduced the soil available water for plant use. This issue can be related to the reducing the interaction of soil particles and polymers with increasing the amount of superabsorbent application in soil. At high levels of superabsorbent consumption, the contact of the hydrogel with the soil particles is reduced, followed by the aggregation of the superabsorbent. This prevents the proper exchange
between the superabsorbent and the surrounding soil, and thus despite the presence of moisture in the soil-superabsorbent system, this moisture cannot be used for the plant, so that in all three soil textures the lowest amount of plant available water belongs to the treatments of 2% w/w of Aquasource.
The results of statistical analysis for estimating the parameters of the soil-water characteristic curve due to the application of different levels of superabsorbent in different soil textures using two software RETC (v.6.02) and Rosetta (v. 1.1) showed that the fit The Van-Genuchten (Moallem) model in RETC software in all treatments has provided a good approximation of the parameters of the soil-water characteristic curve (R2> 0.98). Also, with increasing the amounts of superabsorbent, the accuracy of the model in estimating the parameters decreased to some extent.
Conclusions
Application of Aquasource superabsorbent and increasing the application level of this superabsorbent polymer (from 0 to 2% by weight of superabsorbent/soil) in sandy-loam, clay-loam and silty-clay soil textures caused an increase in the moisture content at field capacity and permanent wilting point. Application of 2% W/W in sandy-loam, clay-loam and silty-clay soil textures increased the moisture content at the field capacity by about 2.4, 1.6 and 1.5 times, respectively, compared to the control treatments of each soil textures. However, the highest amounts of plant available water in all three soil textures were obtained by applying 0.5% W/W (superabsorbent/soil). Application of 0.5% W/W in sandy loam, clay loam and silty clay textures increased the plant available water by about 1.23, 1.19 and 1.12 times compared to the control treatments in each soil textures, respectively. However, the use of larger amounts reduced the plant available water. At low levels of Aquasource application, the interaction between the
superabsorbent polymer and the soil particles in the soil/polymer system facilitates the transfer of moisture stored in the superabsorbent to soil particles. However, increasing the application level of this polymer up to 2% W/W has an inhibitory effect and in this case, the interaction between the polymer and soil particles is reduced, which leads to a lack of proper drainage of moisture from the polymer.
Acknowledgement
The authors would like to thank Agricultural Engineering Research Institute for supporting this research.- انتشار مقاله: 01-03-1400
- نویسندگان: سالومه سپهری صادقیان,نادر عباسی,محمدمهدی نخجوانی
- مشاهده
- جایگاه : پژوهشی
- مجله: تحقیقات مهندسی سازه های آبیاری و زهکشی
- نوع مقاله: Journal Article
- کلمات کلیدی: الگوریتم ژنتیک,انتخاب ویژگی,آبیاری تحتفشار,برآورد هزینه,Eureqa Formulize
- چکیده: این پژوهش با هدف برآورد هزینه پروژه های آبیاری قطره ای در مراحل اولیه طراحی با استفاده از تکنیک برنامه ریزی ژنتیک، با استفاده از دادههای 100 پروژه آبیاری قطره ای انجام شد. ا مهمترین ویژگی ها که بیشترین تاثیر را در هزینه ها داشتند با استفاده از نرمافزار Eureqa و بهره گیری از برنامه ریزی ژنتیک انتخاب شدند. در مرحله آخر مدل های مختلفی در هر بخش برای برآورد هزینه ارائه شده و بر اساس آماره های دقت و پیچیدگی، بهترین مدل در هر بخش معرفی شدند. نتایج آنالیز همبستگی بین متغیرهای مستقل با متغیر وابسته (هزینه هر بخش) نشان داد که در بخش TCP متغیرPP (توان پمپ مورد نیاز)، در بخش TCF متغیر L16mm (طول کل لترال)، در بخش TCI متغیر SR (فاصله ردیف گیاهان) و در بخش TCT متغیر HP (ارتفاع پمپاژ) به ترتیب با ضریب همبستگی (R) برابر با 0/77، 0/64، 0/36 و 0/43 بیشترین مقدار را بین بقیه متغیرها داشته و همگی در سطح اطمینان یک درصد معنیدار شدند. همچنین نتایج مدلسازی هزینه سامانه آبیاری قطره ای نشان داد که در بخش TCP مدلی با معیار ارزیابی R برابر 0/45، MAE (میانگین قدر مطلق خطا) برابر با 27236333 ریال و پیچیدگی 22 بهترین مدل بوده و این معیارهای ارزیابی برای بهترین مدل در بخش TCF برابر 0/85، 21198257 ریال و 13، در بخش TCI برابر0/77، 45483996 ریال و 11، و در بخش TCT این معیارها به ترتیب 0/74، 77220845 ریال و 15 به دست آمد.
- چکیده انگلیسی: Introduction
Allocation of budget to pressurized irrigation projects is supported by the government to manage, saving water resources and increase agricultural production and is considered as the ideal project of the country. Cost-effectiveness and awareness of the cost of an irrigation system is important and necessary for the government. Therefore, estimating the initial and final cost of the project, especially irrigation systems, is one of the project management tools that allow project managers to make more accurate decisions at different stages. Finding a model to identify the important factors affecting the final cost of an irrigation system, as well as formulating it for use throughout the country and regions with different characteristics, is what the present study seeks.
Methodology
The aim of this study was to estimate the cost of drip irrigation projects in the early stages of design using genetic programming technique, using data from 100 drip irrigation projects, in four sections including; cost of pumping station and central control system (TCP), cost of on-farm equipment (TCF), cost of installation and performing on-farm and pumping station (TCI) and total cost (TCT). First, a database containing 39 important and influential variables on the cost of the mentioned sections was prepared and the prices of the projects were updated for the base year of 2019. In the next step, the most important features that had the highest impact on the costs were selected using Eureqa Formulize software and using genetic programming. In the last stage, different models were presented in each section to estimate the cost and the best model in each section was introduced based on the statistics of accuracy and complexity.
Results and Discussion
The results of correlation analysis between independent variables and dependent variable (cost of each section) show that in TCP section PP variable (pump power required), in TCF section L16mm variable (total lateral length), in TCI section SR variable (plant row spacing) and in the TCT section, the HP variable (pumping height) with the correlation coefficient (R) equal to 0.766, 0.638, 0.355 and 0.429, respectively, had the highest value among the other variables and all were significant at the level of one percent confidence. Also, the results of cost modeling for drip irrigation system showed that in the TCP section, a model with an evaluation criterion of R equal to 0.449, MAE (average absolute error value) equal to 27236333 Rials and complexity of 22 was the best model. These evaluation criteria for the best model in the TCF section were equal to 0.848, 21198257 Rials and 13, in the TCI section equal to 0.770, 45483996 Rials and 11, and in the TCT section these criteria were 0.743, 77220845 Rials and 15, respectively.
Conclusions
In this study, the cost estimation of different parts of the drip irrigation system was modeled using genetic programming algorithm, and the obtained results showed that the presented models had excellent accuracies in each part. The results of this study can be a very useful tool for researchers, managers, students, consultants, contractors and those who are concerned in the water industry. By conducting similar research, it is possible to make an economic estimate with a high accuracy before the implementation stage.
Acknowledgement
This article is extracted from the Ph.D. dissertation, the first author of the article. For this purpose, the authors of the article would like to thank the Department of Irrigation and Reclamation Engineering, Faculty of Agriculture Engineering and Technology, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran for their excellent cooperation, providing the necessary facilities for this research and the preparation of relevant articles.
Keywords: Pressurized Irrigation, Cost Estimation, Genetic Algorithm, Feature Selection, Eureqa Formulize.- انتشار مقاله: 30-10-1399
- نویسندگان: مسعود پورغلام آمیجی,عبدالمجید لیاقت,خالد احمدآلی
- مشاهده
- جایگاه : پژوهشی
- مجله: تحقیقات مهندسی سازه های آبیاری و زهکشی
- نوع مقاله: Journal Article
- کلمات کلیدی: آب زیرزمینی,گرادیان هیدرولیکی,پرده آببند,جبهه شوری
- چکیده: یکی از عوامل تهدیدکننده برای منابع آب شیرین، پیشروی آب شور و نفوذ آن به سفرۀ آب زیرزمینی است. برای کنترلاین پدیده، در این پژوهش سه راهکار زهکش حائل زیرزمینی، زهکش حائل روباز و پردۀ آببند با استفاده از مدل واسنجی شده HYDRUS_2Dبررسی و ارزیابی شد. نتایج بررسیها نشان داد محل قرارگیری زهکش روباز و زیرزمینی اثر قابل توجهی روی خروج آب و املاح از مرز هر دو آبخوان شور و شیرین دارد. مشخص شد با تغییر محل زهکش از نزدیکی مخزن آب شور به مخزن آب شیرین، مقدار آب زهکشی شده با زهکش روباز و زیرزمینی به ترتیب 5/6 و 8/5 متر مکعب بر متر کاهش مییابد، و در حالتی که زهکش روباز در فاصلۀ 90 سانتیمتری از مخزن آب شیرین و عمق 5 سانتیمتری از کف قرار داشته باشد، مقدار تبخیر از سطح خاک در کل مدت شبیهسازی بیشتر از مقدار تبخیر در حالت بدون زهکش است و باعث افزایش شوری در محیط بین دو آبخوان میشود. مشاهده شد نصب پردۀ آببند تا عمقهای 55، 65 و 70 سانتیمتر به ترتیب باعث کاهش 6، 15 و 88 درصد ورود جریان آب شور میشود. بهکارگیری روشها استفاده شده در این پژوهش به منظور جلوگیری از پیشروی شوری، جوانب مختلف محیط زیستی در بر دارد و باید با توجه به شرایط هر منطقه و اهمیت آن یکی از راهکارهای موجود انتخاب شود.
- چکیده انگلیسی: Extended Abstract
Investigations and comparison of the ways to prevent saline water advancement in zones with the shallow water table
Introduction
One of the threating factors to freshwater resources is the advancement of saline water and intrusion into the groundwater aquifer. This problem occurs in coastal zones and desert margins and reduces freshwater quality. Evaporation from the soil surface and the water table depth are factors affecting the salinity and salt distribution in the saturated and unsaturated zones. HYDRUS and the accompanying software package provide numerical models used to simulate the movement of water, solute and heat in a porous medium for saturated and unsaturated conditions. According to the existing reports on the ability of the HYDRUS model to simulate moisture and salinity, using it can help decide and consider how to prevent the salinity advancement.
Methodology
In this research, the advance of saline water with a concentration of 20 dS/m and a level of 25 cm towards freshwater with a concentration of 1 dS/m and a level of 10 cm in the domain of 360×70 cm is considered. Different scenarios were examined to prevent the progression of salinity using a validated model. The studied scenarios include inceptor pipe drainage, inceptor open drainage and subsurface barrier which were simulated using the HYDRUS-2D model. The parameter of the equations governing water flow and solute transport were estimated using observed moisture and salinity data and inverse solution tools in the HYDRUS-2D model. pipe and open drainage were considered at three distances of 270,180 and 90 cm from the freshwater reservoir and two depths of 15 and 5 cm from the impermeable layer. The effect of the subsurface dam on preventing the advance of saline water at three depths of 55, 65 and 70 were investigated.
Results and Discussion
Different scenarios of different drainage locations have been simulated to study salinity distribution and water table after 6 months. Regarding the location of the drainage site, three factors are important that have been studied: 1- The amount of water and salt outflow from the drainage 2- Controlling and preventing the advance of salinity 3- Its effect on the entry and exit of water from the freshwater aquifer. The location of surface and subsurface drainage showed different effects on salinity advancement. By changing the location of drainage from A to f the amount of drained water in pipe and open drainage decreased by 5.8 and 6.5 m3/m, respectively. Drainage location also affected actual evaporation from soil surface and salinity accumulation in the soil surface layer. In the cases of drainage where the lowest and highest evaporation from the soil surface occurs respectively, 15% difference was observed. In the case of open drainage at a distance of 90 cm from the freshwater reservoir and a depth of 5 cm from the impermeable layer, the amount of actual evaporation from the soil surface during the whole simulation period is greater than the actual evaporation in non-drained condition and also caused increased salinity between two reservoirs. The subsurface barrier has generally blocked the saline water flow only when it has reached the impermeable layer. The profile of the water table is broken due to very low hydraulic conductivity (about 0.1 m per day) when it reaches the subsurface barrier. The amount of failure and drop of the water table increased with increasing barrier depth.
Conclusions
The salinity distribution parameters in the area between two aquifers, discharged drain from drainage and its concentration and protection of freshwater aquifer are affected and can be considered according to the condition of each location. On the other hand, each of the scenarios has a positive and negative effect on these factors, so according to each sample and specific location, it must be decided how to prevent the progression of salinity (drainage or subsurface barrier) and their location.- انتشار مقاله: 29-10-1399
- نویسندگان: حسین ربانیها,عبدالمجید لیاقت,مسعود سلطانی
- مشاهده
- جایگاه : پژوهشی
- مجله: تحقیقات مهندسی سازه های آبیاری و زهکشی
- نوع مقاله: Journal Article
- کلمات کلیدی: ابزار دقیق,مصرف آب,سامانه پایش,خودکار سازی
- چکیده: امروزه با توجه توسعه روز افزون اجرای سامانههای آبیاری مکانیزه در سطح کشور، در برخی موارد این نوع سامانهها به دلایل فنی و اجتماعی پاسخگوی نیاز بهرهبرداران نبوده و نیاز به توسعه سامانههای آبیاری دارای انعطافپذیری بالا و تغییر نگرش در شیوه بهرهبرداری سامانههای آبیاری مکانیزه بیش از پیش مشهود است. در این راستا استفاده از قابلیتهای سامانههای خودکار و اعمال فرآیندهای کنترلی، در کنار اجرای سامانههای آبیاری تحتفشار امری ضرور مینماید. از میان سیستمهای اتوماسیون مورد استفاده در سامانههای آبیاری تحت فشار، سیستمهای SCADA از آنجایی که دارای ساختار نرمافزاری و سختافزاری متنوعی است میتواند بعنوان ابزار مناسبی بهمنظور افزایش انعطافپذیری، پایش بهنگام عملکرد و مدیریت بهرهور یک سامانههای آبیاری مطرح گردد به نحوی که در طیف وسیعی از شرایط مختلف بهرهبرداری سامانه آبیاری کارایی داشته و منجر به ارتقاء قابلیتهای بهرهبرداری یک سامانههای آبیاری شود. قابلیت و کارایی این سیستمها با توسعه سامانههای آبیاری تجمیعی و الزامات بهره برداری مرتبط با این نوع سامانهها، امروزه بیش از پیش مشهود می باشد. نوشتار ترویجی حاضر با هدف بررسی قابلیتها، مزایا و محدودیتهای سیستم تلهمتری و SCADA در سامانههای آبیاری تحتفشار انجام گرفته تا کارشناسان، بهرهبرداران، کشاورزان و مروجین به بخشی از قابلیتهای اثر بخش این نوع سامانهها آگاهی یافته و بر اساس یک شناخت جامع، تصمیمگیری نمایند.
- چکیده انگلیسی: One of the fastest solutions for optimal water and energy management in irrigation systems is to upgrade the existing position from the level of mechanization of the systems to its own automation. By applying process automation in irrigation systems that mainly involve installation of software and hardware equipment, instruments and software control, allowing optimal management of water and energy consumption and improve the efficiency of irrigation units is provided. With the entry of electronic science into the agricultural sector, in addition to the production of advanced equipment, there has been an increasing use of automated control systems in irrigation systems. This process is called control, automation or self-automation. According to scientific definitions, automation is the same as intelligent systems, including reducing manpower and the resulting error and precise control of the system work cycle. Severe dependence of mechanized systems on manpower to continuously monitor the performance of tools and equipment on the one hand, error due to the wrong action of the operator or delay in taking the necessary action on the other hand Taking measures will reduce productivity in mechanized irrigation systems. It is important to note that in the current approach to the development and operation of irrigation systems, especially pressurized irrigation systems, maximizing net profit over maximum crop production is preferred, so today the use of automation systems such as SCADA and telemetry Operation of irrigation systems is under increasing pressure. Supervisory control systems and data collection (SCADA) refers to large-scale control and measurement systems. SCADA is a control and monitoring system that collects information and then processes it. In other words, SCADA refers to a set of guidelines, standards and processes and is not a pre-complicated version for system control and monitoring. In fact, SCADA is a software package that sits on the executable hardware. In general, SCADA systems include the elements of instrumentation, control equipment, communication equipment, electrical equipment, software packages, central and local control room. Figure 4 shows the general structure of a SCADA system.
It is important to note that a SCADA system is subject to several major problems in addition to the many benefits it can bring to a system. The main problem is that the cost of a telemetry and telecontrol system such as SCADA is high, especially when its equipment is standardized in the system. In many cases, however, the benefits of energy savings, labor, and better utilization justify this high cost. Another limitation of this type of system is the risk of unauthorized access to the control software (whether it is human access or software changes in the control device). Other major limitations of these systems are related telecommunication protocols. These are the language communication protocols used to receive and transmit information over the network. Also, these systems, or any other type of automation system, need specialized people to operate the system, and in general, the more complex the system, the more skilled users are needed. On the other hand, due to the fact that in this system, all changes must be applied dynamically in the network platform, the relevant hardware and software must be designed with high capabilities. Numerous examples of using SCADA in various sectors of industry, water and wastewater facilities and energy management have been implemented throughout the country, and today, despite high costs and some limitations, the use of telemetry-based operation methods and SCADA in the sector Various agricultural, livestock and fisheries have also found their way and their applications in this sector have always been expanding. One of the important applications of SCADA system in the field of agriculture has been the automation of irrigation systems. The first experience of using SCADA systems in the field of agricultural water management has been in the field of irrigation canal management. Over time, the use of this type of system in other sectors of water management and irrigation has developed more and more. SCADA systems used in the field of management of irrigation systems are similar in nature to other sectors such as water and sewage facilities and water transmission lines, but according to the structure of water management in the field and how different factors affect the equipment. Hardware and telecommunication protocols are different.- انتشار مقاله: 25-11-1399
- نویسندگان: افشین یوسف گمرکچی,سید ابو القاسم حقایقی مقدم
- مشاهده
- جایگاه : پژوهشی
- مجله: تحقیقات مهندسی سازه های آبیاری و زهکشی
- نوع مقاله: Journal Article
- کلمات کلیدی: سرریز پلکانی؛ Flow3D؛ مدل آشفتگی RNG و K-&epsilon؛,ملاحظات اقتصادی
- چکیده: در این پژوهش شبیه سازی عددی با نرمافزار Flow3D و بهینهسازی ابعاد هندسی سرریز پلکانی توسط الگوریتم ژنتیک با هدف ارائه طرحی بهینه به منظور کاهش هزینه های احداث سرریز مورد بررسی قرار گرفته است.
برای این منظور ابتدا مدل آزمایشگاهی سرریز پلکانی سد جره در استان خوزستان به منظور حل عددی و صحتسنجی در نرمافزار Flow3D شبیهسازی شده است و سپس برای بهینهسازی ابعاد هندسی از الگوریتم ژنتیک چندهدفه (NSGAII) استفاده گردیده است. در بخش مدلسازی Flow3D بعد از ورود هندسه مدل آزمایشگاهی به نرمافزار و پس از کالیبراسیون مدل، صحتسنجی به کمک مقایسه نتایج سرعت اندازهگیری شده در آزمایشگاه و خروجیهای نرمافزار انجام گرفته است و در مرحله بهینه سازی پنج حالت هندسی برای مدل درنظر گرفته شد. تعداد پلهها از 3 تا 7 پله بهعنوان قیود مسئله به الگوریتم وارد شدند آنالیز نتایج سرعت مدل فیزیکی توسط نرم افزار Flow3D با دو مدل RNG و K-ε به طور جداگانه محسبه گردیدو پس از مشاهده نتایج ، سرعت حاصل از حل عددی با مدل آشفتگی RNG با خطای کمتر از 10 درصد تطابق مناسبی را با سرعت آزمایشگاهی نشان داد. در مرحله بهینه سازی پس از اتمام فرایند بهینه شدن پارامترهای ابعادی برای هر 5 حالت هندسی تعریف شده تعداد پله، عرض پله و ارتفاع پله مشخص گردید. که نتایج بهدست آمده نشاندهنده بهینهشدن ابعاد هندسی مدل آزمایشگاهی میباشد. گزینه نهایی بهینه سازی حالت 4 پله با در نظر گرفتن ملاحظات هیدرولیکی و اقتصادی و با عرض (1:50) 072/0 متر و ارتفاع (1:50) 0065/0 متر انتخاب گردید.- چکیده انگلیسی: Introduction:
Concerning the importance of water saving in Iran, as an arid and semi-arid country, dam construction plays a crucial role in water resources management. Spillways are one of the most important components of a dam. They are different in shape and function. Stepped spillway is one of the most designed and operated ones. Numerical simulation of the stepped spillway of Jare dam using FLOW 3D software and the geometric optimization of the steps' dimension using the multi-objective genetic algorithm is investigated in this research. The idea of using stepped spillways goes back to 3500 years ago (James et al., 2001). The oldest stepped spillway built in Iran has been recorded from 600 years ago. Studying the geometric features of stepped spillways in order to optimize the size and dimension of steps has also been the issue of interest for researchers (Chanson, 1996 and 20021; Pegram et al., 1999; Ferrari, 2010).
Methodology:
An experimental model of Stepped spillway of Jare Dam has been set up first in order to calibrate and verify the numerical model. Flow 3D software is applied for numeric simulation of the spillway and the multi objective genetic algorithm (NSGAII) is implemented to optimize the geometric dimensions. Calibration of the model has done after introducing the experimental models' geometry to FLOW 3D. Comparing the velocity data recorded by the numerical model and the experimental velocity data, the software has been verified.
Turbulence modeling is the construction and use of a mathematical model to predict the effects of turbulence. Turbulence models are simplified constitutive equations that predict the statistical evolution of turbulent flows. K-epsilon (k-ε) turbulence model is a practical model to simulate the mean flow characteristics for turbulent flow conditions. It is a two-equation model which gives a general description of turbulence condition of the ambient flow by means of two transport equations (PDEs). The RNG model was developed using Re-Normalisation Group (RNG) methods to renormalize the Navier-Stokes equations, to monitor the effects of smaller scales of motion especially those of vertex movements. In k-ε model the eddy viscosity is determined from a single turbulence length scale, so the diffusion seen in the calculated turbulence is that which occurs only at the specified scale, although in real physical situations, all scales of motion will contribute to the turbulent diffusion especially those with more curvature streams. RNG turbulent model, as mathematical method that can be utilized to extract turbulence similar to the k- ε, results in a modified form of the epsilon equation. We have implemented both methods to simulate the turbulancd in the flow over the stepped spillway and to compare the effectiveness of both models when flow is dealing with a complicated solid as the Jare Dam spillway.
Five different types have been considered for the geometry of the stepped spillway. Numbers of steps are designated 3 to 7 steps and are earmarked as the algorithm constrains. The variables are then defined and the fitness function of the algorithm is extracted. The multi objective genetic algorithm is then coded in MATLAB. In optimization procedure the geometric features including width, height and the number of steps in each five discussed type are calculated.
Results and Discussion:
Velocity results using two turbulent models, RNG and K-ε, have been calculated separately. The results of the RNG model depict better match in accordance to the physical model's velocity data with less than 10 percent error. In optimization procedure the stepped spillway with 4 steps, 0.072m width (1:5) and 0.0665m height (1:5), is considered as the most optimum choice regarding the economic and hydraulic concerns.
Conclusion:
Flow 3D software simulated the flow over the stepped spillway of Jare Dam quite acceptable. The simulating model depicted the most accuracy using the RNG turbulent model and the multi objective genetic algorithm used (NSGAII) suggested the 4 steps spillway as the most economic and functional choice for Jare stepped spillway.- انتشار مقاله: 23-08-1399
- نویسندگان: محمد هادی فتاحی,علی سینایی
- مشاهده
- جایگاه : پژوهشی
- مجله: تحقیقات مهندسی سازه های آبیاری و زهکشی
- نوع مقاله: Journal Article
- کلمات کلیدی: تنش برشی,عدد فرود,دانهبندی,توان جریان,سیلابدشت
- چکیده: در این تحقیق اثر دانه بندی و تغییرات پارامترهای هیدرولیکی در مقطع سیلابی مرکب (با دشت سیلابی یک طرف کانال اصلی) بررسی شد. دو مدل آزمایشگاهی مقطع مرکب با مدل اول شیب دیواره جانبی سیلاب دشت صفر و در مدل دوم مقدار برابر با50 درصد در نظر گرفته شد. همچنین با هدف بررسی تاثیر شیب طولی بر شستن رسوبات بستر رودخانه، شیب طولی در سه گام0.002، 0.004 و0.006 تغییر داده شد. با هدف بررسی تاثیر قطر متوسط رسوبات بر روند آبشستگی، در طول آزمایش ها از رسوبات ماسه ای با قطر0.9 و 3 میلی متر استفاده شد. با مقایسه تغییرات پارامترهای هیدرولیکی(سرعت، تنش برشی، نسبت عمق کانال اصلی به عمق سیلاب دشت، دبی و عدد فرود) با تغییر دانه بندی رسوب نتایج نشان داد با کاهش اندازه دانه بندی و در شیب عرضی صفر، میزان پارامترهای هیدرولیکی افزایش یافته است. نتایج نشان داد، افزایش شیب طولی و عرضی تاثیر زیادی بر افزایش حجم رسوبات شسته شده در طول کانال دارند و با افزایش این شیبهای طولی و عرضی در کانال، میزان حجم انتقال رسوبات بیشتری اتفاق می افتد. با بررسی تغییرات تنش برشی و توان جریان واحد در مقابل ظرفیت انتقال رسوب نتایج نشان داد که با افزایش شیب طولی و در شیب عرضی 0.5 ظرفیت انتقال رسوب افزایش یافته است.
- چکیده انگلیسی: Study the soil erosion process, sediment transport capacity plays a vital role in the physical description of soil erosion processes. In recent years, researchers examining the sediment transport capacity under different laboratory conditions have shown that hydrodynamic parameters, especially shear stress and unit stream power have a significant effect on sediment transport capacity. Despite the studies, the effects of sediment size on sediment transport are still not well understood and considering that previous studies have been done in direct channel, the effect of longitudinal slope and transverse slope change by changing sediment particle size in composite channel is investigated and not well understood. Therefore, recognizing and investigating the factors affecting this case is of special importance in hydraulic science. One of the influential factors in the hydraulic and hydrodynamic conditions of floodplains is the lateral slope of floodplains. However, qualitative and quantitative study of the parameter requires the presentation of appropriate laboratory research methods. In this study, by aiming at the effect of lateral slope of floodplain on hydraulic and hydrodynamic conditions of flow, as well as the effect of granulation and hydraulic parameters on the amount of sediment output, an experimental design was presented to investigate this parameter. In this study, the effect of granulation and changes in hydraulic parameters in the combined flood section (with flood plain on one side of the main channel) was investigated. Two laboratory models of compound cross-section with the first model of the lateral wall slope of the flood plain zero and in the second model, the value equal to 50% was considered. In addition, in order to investigate the effect of longitudinal slope on the washed sediments, the longitudinal slope was changed in three steps: 0.002, 0.004 and 0.006. In order to investigate the effect of the average diameter of sediments on the scouring process, sandy sediments with a diameter of 0.9 and 3 mm were used during the experiments. By comparing the changes of hydraulic parameters (velocity, shear stress, ratio of main channel depth to depth of plain flood, discharge and Froude number) with changing sediment granulation, the results showed that by reducing the grain size and at zero transverse slope, the amount of hydraulic parameters increased. The results showed that increasing the longitudinal and transverse slope has a great effect on increasing the volume of leached sediments along the channel and by increasing these longitudinal and transverse slopes in the channel, more sediment transfer volume occurs. By examining the changes in shear stress and unit stream power against sediment transfer capacity, the results showed that with increasing the longitudinal slope and in the transverse slope of 0.5, the sediment transfer capacity has increased. As the shear stress increases at different longitudinal and transverse slopes, the sediment transport capacity increases. These findings indicate that the slope has a positive effect on shear stress. The results show that the transverse slope has a significant effect on the increase and change of shear stress with sediment transfer capacity and in the transverse slope of 0.5 and in different longitudinal slopes, increase in sediment transfer capacity is more and washed sediment increased. With increasing depth of flow in main channel to depth of flow in floodplain, more sediment is removed from the flume and the least amount of sediment washed is when the longitudinal slope is equal to 0.002, transverse slope 0.5, and median particle diameter is 3mm, occurring in discharge of 1.6 l/s. As the Froude number increases, the amount of sediment output will increase more when the size of the sediment particle decreases. Also shear stress varies in longitudinal and transverse slopes.
- انتشار مقاله: 14-09-1399
- نویسندگان: عاطفه عرب,حسنا شفائی,کاظم اسماعیلی
- مشاهده
- جایگاه : پژوهشی
- مجله: تحقیقات مهندسی سازه های آبیاری و زهکشی
- نوع مقاله: Journal Article
- کلمات کلیدی: سرعت موج فشاری,اضافه فشار,پاسخ فشاری,خطوط لوله,ضربهقوچ
- چکیده: امروزه لولههای پلیمری بهعلت برتریهای قابلملاحظه فنی و اقتصادی نسبت به سایر لولهها با روند رو به رشدی در سیستمهای آبرسانی عمومی و صنعتی و انتقال فاضلاب در سراسر دنیا استفاده میشوند. این موضوع لزوم شناخت رفتار سازهای و عملکرد هیدرولیکی لولههای پلیمری و تأثیرات خواص ویسکوالاستیک بر نحوه تشکیل و میرایی موج فشار را بیشازپیش ضروری میسازد که سبب ارائه طرحهای بهینه از منظر اقتصادی و فنی خواهد شد. برای بررسی این موضوع از یک مدل آزمایشگاهی خطوط لوله انتقال پلیاتیلن در آزمایشگاه هیدرولیک دانشگاه شهید چمران اهواز استفاده شد. نتایج نشان داد بلافاصله پس از بستن سریع شیر ضربهقوچ، یک پیک فشاری قابل توجه و به دنبال آن یک افت ناگهانی در سیگنال فشار قابلمشاهده است. چنانچه محاسبات بر اساس مدول الاستسیسته ارایه شده توسط کارخانه انجام شود حتی با فرض الاستیک بودن لوله، مقدار اضافه فشار حدود 6/16 تا 65/37 درصد کمتر از مقدار واقعی می باشد. بهدلیل تغییر شکلهای تأخیری دیواره لوله، امواج فشاری بهسرعت میرا شده و با گذشت زمان از شروع جریان گذرا، تأخیر زمانی آن بیشتر میشود.
- چکیده انگلیسی: Experimental analysis of viscoelastic transmission pipe system under transient flow
Introduction
Transient flow in a pressurized pipe system is an intermediate state flow that arises between one constant flow and another. In other words, whenever the flow conditions change from a steady-state due to any deliberate or accidental disturbance, a transient flow is created in the pipeline (Chaudhry, 2014). This phenomenon is one of the most severe cases of damage in pressurized pipelines.
In many previous studies related to transient flow analysis, the pipe wall has been made of metal and concrete materials with elastic mechanical behavior. In recent years, the increasing use of plastic pipes (such as polyethylene and PVC) has led to the development of mechanical models of transient flow, taking into account the viscoelastic behavior of these materials.
In recent years, polymer pipes such as polyethylene and PVC, due to their technical and economic advantages over other pipes such as steel, cast iron, concrete, and asbestos, have increased day by day. This makes the need to understand the structural behavior and hydraulic performance of polymer pipes even more urgent. The modeling method of polymer pipes for transient flows analysis has several fundamental differences from non-polymer pipes. These differences are mainly related to the interaction of fluid fluctuations with the characteristics of pipe wall structures. Polymers generally exhibit viscoelastic mechanical behavior that affects the intensity, formation, and damping of pressure fluctuations in transient currents. In these equations, it is usually assumed that the pipe wall is made of concrete and metal and has a linear elastic behavior. In comparison, polymer pipes have inelastic behavior.
The present study aims to investigate the pressure response of viscoelastic pipeline under transient flow. For this purpose, first, the pressure signal's initial peak and the effects of line packing are investigated. The effect of the transient valve's closing time in different flows on the pressure signal is investigated in the following. Another important issue is the overpressure. In this research, laboratory values of overpressure are compared with the theoretically calculated values.
Methodology
The laboratory model of this research was designed and built in the hydraulic laboratory of the Faculty of Water Engineering, Shahid Chamran University of Ahvaz, to evaluate the response of the viscoelastic pipeline system under transient flow. The pipes are high-density polyethylene (HDPE) (SDR11, PE100, NP16) with a length of 158 meters, an inner diameter of 5.05 cm, and a thickness of 6.5 mm. According to the four stages of waterhammer, if the constant pressure of the pipeline is low, the pressure signal in the third stage, after returning from the tank and reaching the transient flow valve, enters pressures less than the vapor pressure of the fluid, and due to the column separation. This phenomenon reduces the pressure signal capability to detect other system malfunctions. To avoid this problem, a pressurized reservoir was used as the upstream boundary condition at the pipe system's upper boundary.
Results and Discussion
The initial peak pressure due to the effects of friction and fluid inertia and the delayed deformation of the pipe wall is completely weakened in the first period of the pressure wave and does not exist in subsequent periods. The transient flow signal analysis showed that the classical waterhammer equation could not predict the observed maximum transient pressure of fast transient in polyethylene pipe. The calculation of the wave speed in polyethylene pipes based on the modulus of static elasticity is significantly less than that of elasticity's dynamic modulus. As the valve's closing time increases, their maximum pressure peaks and pressure drop gradients decrease, and this peak gradually weakens and disappears. In addition, depending on the time difference between closing the valve, the pressure wave will have a time delay. The results showed that a significant energy drop with phase change in the pressure wave is observed in all measurement locations.
Conclusions
After quickly closing the transient valve, a significant pressure peak is observed, followed by a sudden drop in the pressure signal. At a constant flow, the initial peak pressure decreases with increasing valve closing time. Suppose the calculations are based on the modulus of elasticity provided by the factory. Even if the elastic tube is assumed, the amount of overpressure is 16.6 to 37.65% less than the actual value.This is an important reason to consider polymer pipes' viscoelastic behavior by precision transient flow hydraulic models or to consider the dynamic modulus of elasticity, sometimes up to twice the static modulus of elasticity proposed by manufacturers, in the design phase.- انتشار مقاله: 12-09-1399
- نویسندگان: ایرج رضاپور,محمود شفاعی بجستان,بابک امین نژاد
- مشاهده