Effects of the depth of the needle‐shaped water dispersion device inserted into the jet on the jet breakup of sprinklers

Abstract

AbstractNeedle‐shaped water dispersion devices (NSWDDs) can break the jet and make the sprinkler spray evenly even under low working pressure. However, an inappropriate selection of the depth at which the NSWDD is inserted into the jet will affect the sprinkler pattern radius. To study the effect of the NSWDD insertion depth on the jet breakup, the jet structure, atomization, vorticity, static pressure and velocity distribution are studied using a combination of the lattice Boltzmann method and high‐speed photography. The results show that as the insertion depth increases, the jet structures gradually evolve from liquid films to ligaments, causing the diffusion angle of the jet to increase. Under the same operating pressure, the degree of jet atomization increases with increasing insertion depth. Meanwhile, the velocity pulsation degree on the central axis gradually increases, which will cause the jet to have a shorter air travelling distance. As the insertion depth and the radial position distance from the nozzle outlet increase, the velocity on the radial line first exhibits a symmetrical distribution, then an asymmetric one and finally a symmetric one again. The results can fill the gap in previous research on the effects of the NSWDD on jet breakup.