1. DESIGN OF AUTO-COMPENSATING NOZZLE FOR GATED IRRIGATION PIPES. Dr. Mohamed El-sayed El-HAGAREY irrigation and drainage unit, Desert Research Center. Dr. Ahmed Mohammed Al-kot Soil conservation, Desert Research Center. Prof. Abdel-Ghany Mohamed El-Gindy Agricultural Engineering Dep., Faculty of agriculture, Ain-Shams Univ. Email: elhagarey@gmail.comelhagarey@gmail.com

2. INTRODUCTION

5. Bryant et al. (1981) invented pneumatically operated gated irrigation system. A gated irrigation pipe is operated by a pneumatic control system which automatically opens and closes the gates. Each gate is slid able along the pipe surface and is coupled to a pair of parallel air conduits extending longitudinally along the pipe. The conduits are connected midway between their ends to a common movable pneumatic cylinder which receives therein a piston fixed to the exterior of the pipe. The conduits communicate with opposite ends of the cylinder, and serve as both an air line to the cylinder and an operating linkage which opens and closes the gates and which will not cause damage to the gates in response to differentials of expansion and contraction. A plurality of pipes thus equipped are serially connected to form an irrigation pipeline and the air conduits are interconnected at the pipe joints by flexible hose couplings which may be preset any time during each watering interval. The conduits are pressurized at the end of each interval to change the gates in accordance with a sequential irrigation plan without the necessity of the operator being present to manually open and close the gates. Spendlow et al. (1982) said an improved fluid control gate for selective insertion through a wall such as a flexible irrigation tube to a pressurized fluid medium such as water under gravity feed. The fluid control gate having a hollow extender mounted through and to the wall for

6. El Awady et al. (2005) reported the principal aim of this work is to study the hydraulic and the engineering factors affecting the design of Self-compensating Gated Outlet (SCGO) for gated pipes in order to design and test a developed prototype. Average discharge from 10.75 to 21.7 L/min were obtained pressure range of 0.02 to 0.09 bar. Mathematical model and dimensional analysis approach were developed to predict the Self Compensating Gate Outlet discharge and optimize the design parameters considering the material used and size for the design (SCGO).

7. Experimental site Hydraulic laboratory experimental site: Hydraulic experiments were conducted at the experimental Laboratory experiments were conducted at Experimental Hydraulic laboratory of Agricultural Engineering Department, Faculty of Agriculture, Ain Shams University, Field experimental site: The applied irrigation system was self-compensating gated irrigation pipes located at the Farm of Al-Hag.Hessien, Ezbt Ezzat, Al-dabeaa, Ismailia City. MATERIALS AND METHODS

8. Side view for poppet nozzle 2cm 3.5cm4.5cm 2cm 1cm

9. Q = C (A *V) Δr x = Δr ο – 0.105 δ Tan θ = Δr / δ A = (π /4) [ d n 2 - d d 2 ] ∆r ο d dndn θ δ Flow Relationship between spring deflection and flow area is changeable.

10. 2.5 cm Flow 21 cm 8 cm 12 cm Side view for auto-compensating nozzle body (poppet nozzle).

12. Helical compression spring design: Where : DwDw =Spring wire diameter (mm) F=Force at disc and spring (N) C=Spring index NaNa =Active coils δ=Spring deflection (mm) G=Factor of Shearing (80*10 3 N/mm 2 )

13. Geometry dimensions for helical compression spring.

14. Measurements and calculations: Hydraulic measurements: Outlet discharge: Pump discharge: Outlets pressure Control head pressure: Helical compression spring deflection: Field experiments for poppet nozzle irrigation pipes:

15. Isometric view for auto-compensating nozzle body (poppet nozzle). 4.5cm 8cm 2cm 2.5cm 4cm

16. Nozzle body Guide Compression spring Disc/stem assemble (poppet) Basic inside components of Auto-compensating nozzle.

17. Body and poppet material of poppet nozzle Transparent acrylic plastic Delrin plastic

22. Poppet nozzle irrigation pipes during irrigation operation.

23. Flow performance curve for disc diameters (25, 27 and 29mm) under operating pressure head.

24. (a) (b) Gates flow rate under various operating pressure head and Poppet nozzle flow rate under various operating pressure head.

25. Spring deflection for three disc diameter under operating pressure RESULTS AND DISCUSSION

26. 1 Flow rate versus pressure, spring deflection and flow area.

27. Operating pressure head along PN pipes.

28. Flow performance for poppet nozzle under three initial pressure

29. CONCLUSIONS Based on the testing and experiments results, can be summarized as a follow: There is no flow rate change with constant value (0.81l/s) with pressure head increased from 10-34 k Pa (100-340) when 25 mm diameter disc is used Flow performance for discs with diameters 27mm was constant in spite of pressure increasing as a next 6.8, 30and 33kPa (68, 300and 330cm) with lower mean flow (0.48 l/s) and poppet nozzle with diameter 29mm shut down under operating pressure 12kPa (120cm). The mean discharge of poppet nozzle with initial pressure along pipes for pressure head (50, 100 and 150cm) was 0.5, 0.56 and 0.64l/s, mean coefficient discharge was 0.77, 0.75 and 0.72 respectively, Uniformity efficiency is 99, 91.7 and 90.2% for initial pressure (50, 100 and 150cm) respectively, and manufacture coefficient of variation is 0.094, 0.12 and 0.065 respectively and Poppet nozzle compensating the pressure head along irrigation pipes and flow performance was regulator along pipes