周红秀1，张奥1，刘悦闻2，吴宇靖1
1.大连理工大学能源与动力学院，辽宁 大连 116024； 2.一汽奔腾轿车有限公司，吉林 长春 130012
摘要：为了研究柴油机喷孔表面粗糙度对小直径喷孔内空化流动的影响，采用Fluent流体仿真软件，对不同喷油压力、不同孔壁粗糙度下直径为0.1 mm喷孔的内部空化流动特性进行仿真分析。结果表明：光滑壁面条件下，喷油压力及压差越大，空化水平越强，喷孔流量因数下降越严重；粗糙壁面条件下，流场内气体体积分数随粗糙度增大而降低，粗糙度增大使壁面流体的湍动能增加，但同时使壁面流体的速度降低，导致喷孔流量因数随粗糙度的增大先增后减，喷油压力越高，流量因数出现最高点粗糙度也越大；壁面粗糙度增大会增大对近壁面流场的干扰，抑制近壁面流体空化，在全空化压力、低壁面粗糙度的条件下抑制作用更为明显。
关键词：柴油机；微喷孔；空化；壁面粗糙度；流动特性
Abstract：In order to study the effect of diesel engine nozzle surface roughness on cavitation flow in small diameter nozzle, Fluent are used to analyze the internal cavitation flow characteristics of nozzle with diameter of 0.1 mm under different injection pressures and different hole wall roughness. The results show that smooth wall under the condition of the higher injection pressure, the higher the pressure difference, the stronger the cavitation level, and the lower orifice discharge coefficient. For the rough wall condition, gas volume fraction of the flow will be deceased with the increase of roughness. The increasing of the roughness increases wall turbulent kinetic energy, and reduces wall speed at the same time, which makes the orifice discharge coefficient firstly increase and then decease with the increase of the roughness. The higher the injection pressure, the larger the roughness of the highest point of flow coefficient. Therefore, the increasing of wall roughness height will enhance the interference to the flow field near the wall and have a certain inhibition effect on the fluid cavitation near the wall, which is more obvious under the condition of full cavitation pressure and low wall roughness.
Keywords:diesel engine；micro nozzle；cavitation；wall surface roughness；flow characteristic
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