关键词: 动力机械工程, 喷孔积碳, 喷雾特性, 内部流动, 流体体积方法

Abstract: The cold spray characteristics experiment of diesel injector is carried out in a constant volume bomb. The spray penetration distances and cone angles of carbon-deposited injector and new injector in the condition of different injections are analyzed. The results show that the spray penetration distance and cone angle of carbon-deposited injector decrease compared to those of new injector. The value gap is great at the initial stage of injection and is reduced at the late stage of injection. If the injection pressure is increased, spray penetration distance and cone angle would be decreased. The optical micrograph reveals that nozzle external deposit distributes along the orifice, and the original structure is changed. VOF (volume of fluid) is used to numerically calculate the internal flow, and the effects of internal and external deposits and increase in nozzle length on internal flow are analyzed. The results show that the internal and external deposits and increase in nozzle length could result in weakening the cavitation effect, reducing the mass flow rate, velocity and turbulent kinetic energy, and deteriorating the atomization quality. Compared with internal deposit and increase in nozzle length, the external deposit has more impact on internal flow. Key

Key words: powermachineryengineering, nozzledeposit, spraycharacteristic, internalflow, volumeoffluidmethod