Determining Minor Head Losses in Drip Irrigation Laterals. II: Experimental Study and Validation

Values of friction coefficient K and equivalent length $\mathrm{le}$ were determined for various emitter models using analytical and experimental procedures developed in the companion paper by Juana et al. in 2002. Flow contraction coefficient $C_c$ for water jets discharging through orifices with angle α=45° is suggested when the emitters have hydrodynamic geometry at the insertion. Otherwise, α=90° or, as an extreme value, α=180° is preferred. Both criteria K and $\mathrm{le}$ showed a reasonable agreement for minor losses evaluation produced at emitter insertions along drip laterals. Accuracy on their determination was analyzed. Larger dispersion of K and $\mathrm{le}$ values was observed when lateral head losses were small. Inlet head, Reynolds number, and emitter spacing did not show a clear effect on K and $\mathrm{le}$ values, whereas the effect of obstruction ratio r of the pipe cross-sectional area at the emitter location was of practical significance. Parameters of the emitter discharge equation determined with lateral tests were comparable to those obtained on an emitter testing bench using the International Standard procedure.