مطالعه آزمایشگاهی عملکرد شیر خودکار کنترل دبی در خطوط انتقال آب

نوع مقاله: مقاله پژوهشی

نویسندگان

گروه علوم و مهندسی آب، دانشکده کشاورزی و منابع طبیعی، دانشگاه بین المللی امام خمینی (ره)، قزوین، ایران

چکیده

هر گونه صرفه جویی در مصرف آب که منجر به استفاده بهینه از ذخایر موجود و توزیع عادلانه آب در بین زمین های زراعی باشد از اهمیت زیادی برخوردار است. انتقال آب با لوله‌های کم‌فشار می‌تواند تا حد زیادی از تلفات بی‌رویه آب جلوگیری کند. در این تحقیق عملکرد نوعی شیرفلکه خودکار تنظیم دبی برای تحویل حجمی آب به صورت آزمایشگاهی مورد بررسی قرار گرفته است. این ابزار بدون استفاده از تمهیدات الکترونیکی و تنها با انجام برخی اقدامات مکانیکی می‌تواند برای تحویل آب به صورت حجمی در خطوط انتقال آب در شبکه‌های کم فشار مورد استفاده قرار گیرد. برای این منظور شیر‌های کنترل 5 و 10 لیتر بر ثانیه به ترتیب در محدوده‌ی فشار کارکرد 1 تا 10 متر و 3 تا 15 متر طراحی و ساخته شدند. با جایگذاری شیرفلکه‌ها در خطوط انتقال آب با انتهای باز و بسته، ضمن ایجاد نوسانات فشار در بالادست و پایین‌دست خط انتقال، عملکرد شیر‌های کنترل دبی در توزیع جریان به صورت آزمایشگاهی مورد بررسی قرار گرفت. نتایج نشان داد که با وقوع نوسانات فشار در نقاط مختلف شبکه‌های انتهای باز و بسته متوسط میانگین دبی عبور یافته از شیر‌های کنترل 5 و 10 لیتر بر ثانیه به ترتیب برابر با 38/5 و 89/9 لیتر بر ثانیه است. این امر نشان می‌دهد که شیر‌ خودکار کنترل دبی قادر است بدون حساسیت نسبت به تغییرات فشار در شبکه‌های انتقال آب کم فشار، دبی تقریباً ثابتی را به بهره‌برداران تحویل دهد.

کلیدواژه‌ها


عنوان مقاله [English]

Experimental study of the performance of a discharge control valve in water pipelines

نویسندگان [English]

  • Narges Mehri
  • Mohammad Bijankhan
Water sciences and Eng. Dep., Faculty of agriculture and natural resources, Imam Khomeini International University, Qazvin, Iran
چکیده [English]

Extended Abstract
Experimental study of discharge control valve for volumetric water delivery in water pipelines

Introduction
Using pipelines instead of open channels for conveying water is getting much important recently. This type of pipe-water transfer, which is associated with a pressure below 15 meters, is known as low-pressure pipelines. Transfer of water through low pressure pipes can greatly prevent unnecessary losses of irrigation water. In this study, the application of a kind of volumetric water delivery structure known as discharge control valve was investigated. This instrument is used without implementing electronic facilities for water delivery in low pressurized pipe networks. For this purpose, two valves of the design discharges of 5 and 10 l/s are fabricated based on the design guidelines available in the literature. Their performances are experimentally tested in closed and open ended irrigation networks. The result showed that the valves of the design discharges of 5 and 10 l/s are not sensitive to pressure fluctuations in low pressurized networks and can deliver water with an almost constant discharge.
Methodology
This study presents an experimental approach of the application of discharge control valve for fairly water distribution in low pressurized irrigation networks. According to Table.1, four scenarios were defined to evaluate the performance of the flow control valves. Therefore, two experimental setups of open and closed ended networks were constructed in hydraulic laboratory of Imam Khomeini Intentional University, IKIU. Flow control valves of the design discharges of 5 and 10 l/s were installed in the water conveyance pipelines. Then, applying pressure changes at either upstream or downstream of the valves their performances were evaluated experimentally.
Table. 1. Scenarios tested in hydraulic laboratory of Imam Khomeini International University
Scenario Type of network
1 The network is an open ended type. Discharge changes in the upstream of the network and the effect of water distribution examined in the downstream of network.
2 The network is an open ended type and discharge/pressure changes in the downstream of network.
3 The network is a closed ended type and discharge/pressure changes in the upstream of network.
4 The network is a closed ended type and discharge/pressure changes in the downstream of network.





Results and Discussion

According to Table.2, it is concluded that the control discharge valves with the design discharge of 5 and 10 l/s can be used successfully to achieve the goal of volumetric water delivery. In all tested scenarios the delivered water deviates less than almost 10% compared to the associated design values. Consequently, an automatic discharge control valve can be implemented in a network to achieve a reasonable water uniformity which is irrespective to both sources and locations of the pressure fluctuations.

Table.2. Error percentage of control discharge valves in all four scenarios
First Scenario Second Scenario
Design discharge (l/s) Operational differential pressure range (m) Average of the observed discharges (l/s) Deviation from the design discharge (l/s) Design discharge (l/s) Operational differential pressure range (m) Average of the observed discharges (l/s) Deviation from the design discharge (l/s)
5 1-10 5.35 7 5 1-10 5.22 4.4
10 3-15 10.11 1.1 10 3-15 10 0
Third Scenario Fourth Scenario
Design discharge (l/s) Operational differential pressure range (m) Average of the observed discharges (l/s) Deviation from the design discharge (l/s) Design discharge (l/s) Operational differential pressure range (m) Average of the observed discharges (l/s) Deviation from the design discharge (l/s)
5 1-10 5.40 8 5 1-10 5.55 11
10 3-15 9.87 -1.3 10 3-15 9.61 -3.9


Conclusions
Fairly water distribution is an important issue in the irrigation section. In this research, the application of a flow control valve is investigated to improve uniform flow distribution in irrigation networks. Discharge control valves were installed in open and closed-ended pipe networks. According to the experimental results, it was found that the discharge control valves of the design discharges of 5 and 10 l/s deliver average discharges of 5.35 and 9.89 l/s respectively. The results indicated that the constructed control valves can be used effectively to deliver an almost constant discharge which is irrespective to the pressure fluctuations.

Keywords: : Discharge control valve, fairly water distribution, Irrigation networks, volumetric water delivery.

کلیدواژه‌ها [English]

  • Discharge control valve
  • fairly water distribution
  • Irrigation networks
  • volumetric water delivery

مقالات آماده انتشار، پذیرفته شده
انتشار آنلاین از تاریخ 19 اسفند 1398
  • تاریخ دریافت: 28 دی 1398
  • تاریخ بازنگری: 18 اسفند 1398
  • تاریخ پذیرش: 19 اسفند 1398