The low frequency noise at idle speed for a passenger car was researched and it was found that the noise source was the fuel pulsation produced by the repeated opening of gasoline injector .Commercial fluid software was applied to simulate the pressure pulsation in fuel rail at the closing moment of gasoline injector and the fuel pressure variation law was acquired .Based on the original model ,the effects of fuel rail size and cross section on fuel pressure were researched .The results show that in-creased cross section of fuel rail can suppress the fuel pressure pulsation to a certain extent .The fuel rail with a large length/width ratio has better effect at the same cross section .In addition ,the square rail has less noise than the circular rail .Howev-er ,the circular rail with inner damper has better effect and could decrease vehicle noise by 3 .2 dB .%针对某乘用车开发过程中出现的怠速低频噪声进行了研究 ,发现噪声源为汽油机喷油器反复开启产生的燃油压力脉动.应用商业流体软件对喷油器关闭瞬间燃油在油轨内的传播过程进行三维仿真 ,得到油轨内的油压变化规律.并在原机模型的基础上分析了油轨尺寸和横截面积的变化对油压的影响.分析表明 :油轨横截面面积加大对油压脉动有一定的降低作用 ;相同横截面积条件下 ,长宽比越大 ,抑制油压脉动的效果越好.优化方案的噪声测试结果表明 ,方轨比圆轨的噪声小 ,但圆轨带内置缓冲器 ,效果最佳 ,可降低车内噪声3 .2 dB.
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