Cavitation and Wear Characteristic of Seal Surface in Pintle Nozzle

Abstract

Nozzle is one of key parts in diesel engine.The cavitation and wear characteristics of seal surface in the pintle nozzle have important influences on atomization,combustion and dynamical performance of diesel engine.The diesel flow in the pintle nozzle of diesel engine is investigated through visualization apparatus and numerical simulation method.The results show that there are a lot of bubbles in nozzle before the needle opened;the cavitation located on the upstream of seal surface is severer than that located on the downstream.The wear characteristics of the pintle nozzle are studied in S195 diesel engine.The surface appearances of original and operated nozzle seal surface are observed by scanning electric microscope(SEM).The results show that the original defects of pits which located on the upstream have obvious wear after the diesel operated for 20 h,on the contrary on the downstream.That is,the location of severe wear is the same place with the severe cavitation area.The reason for the wear is that the original defects of pits tend to collect the wandering cavitation bubbles.The wear on the solid wall is the result of collapse of cavitation bubbles.The research results provide the theoretical bases for slowing down the growth of the wear of seal surface of needle in pintle nozzle.