Simulations on the cavitating flow and corresponding risk of erosion in diesel injector nozzles with double array holes

摘要

Simulations research has been conducted to make a further study about the influences of nozzle K-factor and needle lifts on the cavitation flow and erosion risk inside the diesel nozzle with double array of holes. The relative risk of surface erosion (Rr(s)) was utilized as an index to evaluate the risk of cavitation erosion on the nozzle hole-surface. The simulation results illustrate that the intensity of cavitation on the hole surface decreases significantly with K-factor declining, and the cavitation draws back to the orifice entrance where it initially originates from. The invert conical hole suffering high risk of erosion damage and the positions with highest risk of erosion appear on the supine surface and the entrance of inlet orifice. Besides the needle lifts also have impacts on the cavitation and risk of surface erosion but little influence on mass flow rate. Cavitation can be found around the closing surface on the sac and the supine surface of nozzle holes under low needle lifts. With the needle lift rising, the bubble clouds are depressed efficiently and shrink together towards the inlet orifice corner of the hole, but the risk of erosion for the nozzles is increasing. And L-hole surface is more likely to be damaged due to cavitation erosion for the vapor phase condensates quickly and centrally. (C) 2018 Elsevier Ltd. All rights reserved.