Gürol YILDIRIM, Necati AĞIRALİOĞLU

Mikro-sulama sistemi lateral borularının hidrolik tasarımında hesap metotlarının karşılaştırılmalı analizi

Mikro-sulama sisteminin temel unsuru olan lateral borular, sistemin tamamında öngörülen üniformluk seviyesi, basınç yükü değişimi ve toplam sürtünme kaybı kriterlerine bağlı olarak tasarlanabilen hidrolik yapılardır. Hidrolik bakımdan lateraldeki akım, mansap yönünde damlatıcı debisindeki azalmayla birlikte, yere bağlı değişken debi fonksiyonunun geçerli olduğu düzenli boru akımıdır. Mikro-sulama sistemi lateral borularının projelendirilmesinde genellikle takip edilen metot, öngörülen damlatıcı özelliği, lateral boru uzunluğu ve boru çapı için, damlatıcı debileri arasındaki değişimin belirli bir sınır değerini aşmamasını sağlamaktır. Bir başka anlatımla, damlatıcı debileri arasındaki değişimin kabul edilebilir bir üniformluk katsayısını sağlayacak biçimde düzenlenmesidir. Diğer taraftan, lateral boyunca menba ve mansap noktalarındaki başlangıç ve sınır şartları ile belirlenen bir projelendirme aralığı içerisinden, sistemde öngörülen toplam yük kaybı ve üniformluk seviyesi kriterlerini sağlayacak optimum giriş basınç yükü değerinin belirlenmesi lateral hidroliğinin temel problemidir. Zira lateral boyunca enerji çizgisinin değişimi ve çıkış akımı dağılımı, lateral girişindeki basınç yükü değerine bağlı olarak farklı profillerde oluşmaktadır. Çalışmanın ilk kısmında, üniform eğimli ve sabit çaplı bir lateral boru için lateral hidroliğinin temel prensipleri sunulmaktadır. Çalışmanın ikinci kısmında, sabit veya yere bağlı değişken debi yaklaşımlarından hareketle ortaya konan 7 adet hidrolik hesap metodunda, tasarım parametreleri için elde edilen başlıca denklemlere yer verilerek, optimum giriş basınç yükünün belirlenmesinde, sağlanması gereken hidrolik kriterler değerlendirilmektedir. Söz konusu metotların karşılaştırmalı analizi için, farklı eğim koşulları ve damlatıcı karakteristikleri için örnek bir uygulama seçilerek, her bir metottan elde edilen sonuçlar, boyutsuz eğriler halinde karşılaştırılmaktadır.

Comparative analysis of calculation methods in hydraulic design of micro-irrigation laterals

An important objective of any micro-irrigation (drip, trickle) system is a uniform distribution of water delivered through the emitters along the lateral line. Adequate analysis of micro-irrigation laterals is very important for the design and evaluation of micro-irrigation systems. The increasing progress in computer technology has led to the development of numerical methods of hydraulic analysis as the finite-element method, the finite difference method, successive approximations method, and others. Lateral pipes are hydraulic structures whose design is limited by the desired level of uniformity, pressure head variation and total friction loss criteria. Design of this system depends upon a good understanding of lateral hydraulics and emitter characteristics. Hydraulically, flow in the lateral pipe is considered to be a steady, spatially varied flow with decreasing emitter outflow in the downstream direction. With decreasing discharge along the lateral, the energy gradient line decreases. Computation of flow distribution requires knowledge of the variables such as pressure, flow rate, length or internal diameter of the lateral, orifice characteristics, and frictional losses in the system. The hydraulic design of a lateral or a sub-main unit in a micro-irrigation system has been a problem tackled by many authors. In applications of previous analytical approaches for trickle lateral hydraulic computation, the primary solution is based on a discharge that is uniform, although ramifications of the manufacturer’s variability have been modeled based on the derived hydraulic profile. However, significant deviations from accurate numerical solutions in hydraulic analysis could be caused by this basic assumption of constant emitter outflow. Recently, some alternative hydraulic calculation methods with more accurate results were developed based on the spatially variable outflow approach. The errors caused by the basic assumption of spatial invariance of the emitter outflow are minimized when the new alternative approaches are used.Design of a lateral pipe includes the determination of the required operating inlet pressure head, the pipe length or the inside diameter and total friction head losses along the lateral, assuming that the total flow rate at the inlet, characteristic of the emitter, and the acceptable level of uniformity are known previously.In the first stage of this study, basic principles of lateral hydraulics are clearly analyzed, and then basic equations of the seven hydraulic calculation methods are evaluated based on the governing equations for the steady flow in a smooth pipe. In the second stage, for determining optimum value of the inlet pressure head, hydraulic criteria depend on the initial and boundary conditions along the pipe, are also evaluated.In the third stage, the comparison test for the design example based on determination of inlet pressure head was applied for zero and uphill slope cases and various emitter characteristics, and showed graphically in dimensionless form. In these figures, residual flow rate ratios, variation of total friction head losses and uniformity coefficients depend on the operating inlet pressure head range are also evaluated. Comparison test shows that the Forward-Step-Method (FSM) that takes into account the velocity head change and variation of the Reynolds number, which affects the selection of the proper friction coefficient formula to be applied along the different reaches of the lateral pipes, has the highest accuracy because only the basic equations of the hydraulics of steady pipe flow were used. To apply the method, a computer program in Visual Basic 6.0 language named LATCAD was developed for analyzing and designing of micro-irrigation laterals. A comprehensive comparison test clearly shows that the FSM method using LATCAD yields highly accurate results in comparison with the other analytical and numerical procedures examined here.

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Agiralioglu, N., Eren, R. H. ve Yildirim, G., (2000). İstanbul’da peyzaj sulaması için su kaynakları, teknik bülteni, İstanbul Teknik Üniversitesi, İnşaat Fakültesi, İstanbul.
Agiralioglu, N., ve Yildirim, G., (2002). Determining water requirements for landscape irrigation in Istanbul region. Proc., International Conference on Water Resources Management in Arid Regions, Kuwait Institute for Scientific Research, Kuwait.
Al-Amoud, A.I., (1995). Significance of energy losses due to emitter connections in trickle irrigation lines. J. Agricultural Engineering Researches, 60, 1, 1-5.
Anyoji, H., ve Wu, I.P., (1987). Statistical approach for drip lateral design. Transaction ASAE, 30, 1, 187-192.
Anwar, A. A., (1999a). Factor G for pipelines with equally spaced multiple outlets and outflow. J. Irrigation and Drainage Engineering, ASCE, 125, 1, 34-39.
Anwar, A. A., (1999b). Adjusted factor Ga for pipelines with multiple outlets and outflow. J. Irrigation and Drainage Engineering, ASCE, 125, 6, 355-359.
Anwar, A. A., (2000). Inlet pressure for horizontal tapered laterals. J. Irrigation and Drainage Eng., ASCE, 126, 1, 57-63.
Bagarello, V., Ferro, V., Provenzano, G., ve Pumo, D., (1995). Experimental study on flow resistance law for small diameter plastic pipes. J. Irrigation and Drainage Eng., ASCE, 121, 5, 313-316.
Bagarello, V., Ferro, V., Provenzano, G., ve Pumo, D., (1997). Evaluating pressure losses in drip irrigation lines. J. Irrigation and Drainage Eng., ASCE, 123, 1, 1-7.
Bralts, V. F., Kelly, S.F., Shayya, W. H., ve Segerlind, L. J., (1993). Finite element analysis of microirrigation hydraulics using a virtual emitter system. Transaction ASAE, 36, 3, 717-725.
Chadwick, A., ve Morfett, J., (1993). Hydraulics in civil and environmental engineering, E&FN SPON, London, U.K.
Featherstone, R.E., ve Nalluri, C., (1982). Civil engineering hydraulics, essential theory, worked examples. Granada Publishing, New York, N.Y.
Hathoot, H. M., Al-Amoud, A. I., and Mohammad, F. S., (1993). Analysis and design of trickle-irrigation laterals. Journal of Irrigation and Drainage Engineering, ASCE, 119, 5, 756-767.
Hathoot, H.M., Al-Amoud, A.I., Al-Mesned, A.S., (2000). Design of trickle irrigation laterals considering emitter losses. Irrigation and Drainage, 49, 2, 1-14.
Howell, T. A. ve Hiler, E. A., (1974). Trickle irrigation lateral design. Transaction ASAE, 17, 5, 902-908.
Howell, T. A. ve Barinas, F. A., (1980). Pressure losses across trickle irrigation fittings and emitters. Transaction ASAE, 23, 4, 928-933.
Jain, S. K., Singh, K. K., ve Singh, R. P., (2002). Micro-irrigation lateral design using lateral discharge equation. J. Irrigation and Drainage Eng., ASCE, 128, 2, 125-128.
Juana, L., Sinobas, L. R., Losada, A., (2002a). Determining minor head losses in drip irrigation laterals.I: methodolgy. J. Irrigation and Drainage Eng., ASCE, 128, 6, 376-384.
Juana, L., Sinobas, L. R., Losada, A., (2002b). Determining minor head losses in drip irrigation laterals.II: experimental study and validation. J. Irrigation and Drainage Engineering ASCE, 128, 6, 385-396.
Kang, Y., ve Nishiyama, S., (1996a). Analysis and design of microirrigation laterals. J. Irrigation and Drainage Eng., ASCE, 122, 2, 75-81.
Kang, Y., ve Nishiyama, S., (1996b). Design of microirrigation submain units. J. Irrigation and Drainage Engineering, ASCE, 122, 2, 83-89.
Keller, J., ve Karmeli, D., (1974). Trickle irrigation design parameters. Transaction ASAE, 17, 4, 678-683.
Keller, J., ve Bliesner, R. D., (1990). Sprinkle and trickle irrigation, Van Nostrand Reinhold, New York.
Provenzano, G., Pumo, D., (2004). Experimental analysis of local pressure losses for microirrigation laterals. Journal of Irrigation and Drainage Eng., ASCE, 130, 4, 318-324.
Provenzano G., Pumo, D., ve Di Dio, P., (2005). Simplified procedure to evaluate head losses in drip irrigation laterals. Journal of. Irrigation and Drainage Eng., ASCE, 131, 6, 525-532.
Saad, J. C. C., ve Marino, M. A., (2002). Optimum design of micro-irrigation systems in sloping lands. Journal of Irrigation and Drainage Eng., ASCE, 128, 2, 116-124.
Scaloppi, E. J., ve Allen, R.G., (1993). Hydraulics of irrigation laterals: Comparative analysis. Journal of Irrigation and Drainage Eng., ASCE, 119, 1, 91-115.
Sinobas, L. R., Juana, L., Losada, A., (1999). Effects of temperature changes on emitter discharge. Journal of. Irrigation and Drainage Eng., ASCE, 125, 2, 64-73.
Streeter, V. I., ve Wylie, B. E., (1983). Fluid Mechanics, McGraw-Hill Co., New York, N.Y.
Valiantzas, J. D., (1998). Analytical approach for direct drip lateral hydraulic calculation. Journal of Irrigation and Drainage Eng., ASCE, 124, 6, 300-305.
Valiantzas, J. D., (2002). Continuous outflow variation along irrigation laterals: Effect of the number of outlets. Journal of Irrigation and Drainage Eng., ASCE, 128, 1, 34-42.
Vallesquino, P., ve Luque-Escamilla, P. L., (2001). New algorithm for hydraulic calculation in irrigation laterals. Journal of Irrigation and Drainage Eng., ASCE, 127, 4, 254-260.
Vallesquino, P., ve Luque-Escamilla, P. L., (2002). Equivalent friction factor method for hydraulic calculation in irrigation laterals. Journal of Irrigation and Drainage Eng., ASCE, 128, 5, 278-286.
von Bernuth, R. D., (1990). Simple and accurate friction loss equation for plastic pipe. Journal of Irrigation and Drainage Eng., ASCE, 116, 2, 294-298.
von Bernuth, R. D., ve Wilson, T., (1989). Friction factors for small diameter plastic pipes. Journal of Hydraulic Eng., ASCE, 115, 2, 183-192.
Warrick, A.W., ve Yitayew, M., (1987). An analytical solution for flow in a manifold. Advances in Water Resources, 10, 58-63.
Warrick, A. W., ve Yitayew, M., (1988). Trickle lateral hydraulics.I: Analytical solution. Journal of Irrigation and Drainage Eng., ASCE, 114, 2, 281- 288.
Watters, G. Z., ve Keller, J., (1978). Trickle irrigation tubing hydraulics. Summer Meeting of ASAE, Utah State University, Logan, Utah.
Wu, I. P., ve Gitlin, H. M., (1973). Hydraulics and uniformity for drip irrigation. Journal of Irrigation and Drainage Div., ASCE, 99, IR2, Proc. Paper 9786, June, pp. 157-168.
Wu, I.P., ve Gitlin, H. M., (1974). Drip irrigation design based on uniformity. Transaction. ASAE, 17, 429-432.
Wu, I. P., ve Gitlin, H. M., (1975). Energy gradient line for drip irrigation laterals. Journal of Irrigation and Drainage Eng., ASCE, 101, 4, 323-326.
Wu, I. P., (1992). Energy gradient line approach for direct hydraulic calculation in drip irrigation design. Irrigation Science, 13, 21-29.
Wu, I. P., ve Yue, R., (1993). Drip lateral design using energy gradient line approach. Transaction ASAE, 36, 2, 389-394.
Wu, I. P., (1997). An assessment of hydraulic design of microirrigation systems. Agricultural Water Management, 32, 275-284.
Yıldırım, G., (2001). Damla sulamasında lateral boruların bilgisayar destekli projelendirilmesi. Yüksek lisans tezi, Istanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, Istanbul.
Yıldırım, G., ve Ağıralioğlu, N., (2001). Computer aided design of lateral pipes in drip irrigation. Proc., International Symposium on Water Resources and Environmental Impact Assessment, Technical University of Istanbul, Istanbul.
Yıldırım, G., ve Ağıralioğlu, N., (2002a). Variation of total friction head losses and uniformity coefficients based on inlet pressure head in trickle laterals. Proc., International Conference on Water Resources Management in Arid Regions, Kuwait Institute for Scientific Research, Kuwait.
Yıldırım, G., ve Ağıralioğlu, N., (2002b). Variation of design parameters in micro-irrigation laterals. Proc., International Conference on Advances of Civil Engineering, Technical University of Istanbul, Istanbul.
Yıldırım, G., ve Ağıralioğlu, N., (2003a). Discussion of “New algorithm for hydraulic calculation in irrigation laterals” Journal of Irrigation and Drainage Eng., ASCE, 129, 2, 142-143.
Yıldırım, G., ve Ağıralioğlu, N., (2003b). Discussion of “Continuous outflow variation along irrigation laterals: effect of the number of outlets” Journal of Irrigation and Drainage Eng., ASCE, 129, 5, 382-386.
Yıldırım, G., ve Ağıralioğlu, N., (2004a). Linear solution for hydraulic analysis of tapered microirrigation laterals. Journal of Irrigation and Drainage Eng., ASCE, 130, 1, 78-87.
Yıldırım, G., ve Ağıralioğlu, N., (2004b). Comparative analysis of hydraulic calculation methods in design of microirrigation laterals. Journal of Irrigation and Drainage Eng., ASCE, 130, 3, 201-217.
Yıldırım, G., ve Ağıralioğlu, N., (2004c). Discussion of “Determining minor losses in drip irrigation laterals.I: methodology” Journal of Irrigation and Drainage Eng., ASCE, 130, 3, 248-252.
Yıldırım, G., ve Ağıralioğlu, N., (2004d). Discussion of “Equivalent friction factor method for hydraulic calculation in irrigation laterals” Journal of Irrigation and Drainage Eng., ASCE, 130, 4, 335-339.
Yıldırım, G., ve Ağıralioğlu, N., (2004e). Discussion of “Determining minor losses in drip irrigation laterals.II: experimental study and validation” Journal of Irrigation and Drainage Eng., ASCE, 130, 4, 344-346.
Yıldırım, G., ve Ağıralioğlu, N., (2004f). Variation of design parameters in micro-irrigation laterals. ARI Interdisciplinary Journal of Physical and Engineering Sciences, 54, 1, 42-53.
Yıldırım, G., ve Ağıralioğlu, N., (2005a). Discussion of “Inlet pressure, energy cost, and economic design of tapered irrigation submains” Journal of Irrigation and Drainage Eng., ASCE, 131, 2, 220-224.
Yıldırım, G., ve Ağıralioğlu, N., (2005b). Discussion of “Explicit hydraulic design of microirrigation submain units with tapered manifold and laterals” Journal of Irrigation and Drainage Eng., ASCE, 131, 3, 299-300.
Yıldırım, G., ve Ağıralioğlu, N., (2005c). Closure to “Linear solution for hydraulic analysis of tapered microirrigation laterals” Journal of Irrigation and Drainage Eng., ASCE, 131, 5, 490-491.
Yıldırım, G., ve Ağıralioğlu, N., (2006). Closure to “Comparative analysis of hydraulic calculation methods in design of microirrigation laterals” Journal of Irrigation and Drainage Eng., ASCE, 132, 1, 85-88.
Yıldırım, G., (2006). Discussion of “Experimental analysis of local pressure losses for microirrigation laterals.” Journal of Irrigation and Drainage Eng., 132, 2, 189-192.
Yitayew, M., (1989). Head loss in manifolds or trickle lateral: Simplified approach. Journal of Irrigation and Drainage Eng., ASCE, 115, 4, 739-743.
Yitayew, M., ve Warrick, A. W., (1988). Trickle lateral hydraulics.II: Design and examples. Journal of Irrigation and Drainage Eng., ASCE, 114, 2, 289-300.
Yitayew, M., ve Warrick, A. W., (1987). Velocity head considerations for trickle laterals. Journal of Irrigation and Drainage Eng., ASCE, 113, 4, 611-615.