Influence of the Inclination Angle of the Side Wall of Drip Emitters on Local Head Loss in Drip Irrigation Tubes

ABSTRACT To study the influence of the end face inclination angle of an emitter on local head loss in a drip irrigation pipe, the end face of an in‐line emitter was designed with various inclination angles; four levels—15°, 30°, 45°, and 90°—were set; and irrigation experiments and numerical simulations were carried out. Research indicates that the velocity and pressure gradient of the shrinking section and the expanding section of the drip irrigation pipe decrease with decreasing end face inclination angle of the emitter. Through the principles of dimensional harmony and multiple linear regression analysis, a model for calculating the local head loss of a drip irrigation pipe considering the inclination angle of the drip head is constructed. The local head loss is inversely proportional to 0.706 square of the cotangent value of the dip angle. Through the analysis of an example, when the distance between emitters is 0.6 m, the local head loss of a 60‐m‐long drip irrigation pipe with face inclination angles of 15°, 30°, and 45° is reduced to 26%, 45%, and 65%, respectively, compared with the 90° loss of the same specification. The research results can provide some reference for drip irrigation design and pipe network optimization.