Research On Lateral Local Head Loss In Micro-irrigation System

This paper selected several common emitters and the laterals from market. Testing designed to determine the local head loss and its impact factors, through theoretical analysis and derivation, proposed lateral head loss calculating formula, and made lateral head loss numerical simulation, compared the head loss coefficient calculated from experiment and theoretical research, then determined the feasibility of this simulation method, the preliminary study made the following progress:(1) Local head loss was proportional to lateral flow. Local head loss increased as the lateral flow increased. Local head loss was proportional to emitter plug sectional area. Local head loss increased as the emitter plug sectional area increased. Lateral diameter is the main affecting factor to local head loss. Local head loss was inversely proportional to lateral diameter. Local head loss decreased as the lateral diameter increased.(2) The percentage of local head loss in total head loss was affected by emitter type,lateral diameter, it was proportional to emitter plug sectional area, and inversely proportional to lateral diameter. The percentage of local head loss in total head loss differ 0.6 for different treatments.This paper proposed the formula for calculating the percentage of local head loss in total head loss, and recommended to use formula (3-6) to precisely calculate the local head loss in the actual irrigation design.(3) Different types of emitters and laterals'local head loss coefficient varied dramatically. This paper proposed 10 different emitters'local head loss coefficients through the experimental data in Chapter II. If the above emitters were selected in irrigation design, using this paper's formula to calculate the local head loss coefficient was recommended(4) This paper proposed a calculating formula for emitter local head loss coefficient, which was increased as the emitter plug sectional area, and decreased as the lateral diameter. This formula had a relatively high reliability and was verified that can be used in irrigation design.(5) Through the simulation of local head loss coefficient, as to turbulence pipe section where the emitter flow was small, it was recommended to use this paper's method to determine the local head loss coefficient, as to the section where emitter flow was big, it was recommended to determine the local head loss coefficient through experiments. (6) Emitters which had different plug size had different velocity reduce area. It was recommend to factory that, when producing the emitters, the plug size should be uniformed, which to facilitate the sediment deposition analysis.