基于声压和声强法对柴油机噪声源的识别

Noise source identification of diesel engine based on sound pressure level and sound intensity methods

为了研究一台4缸柴油机的主要噪声源,采用近场声压法测量了4缸柴油机气缸罩盖、燃油泵和油底壳等14个零部件近场声压级,分析了各零部件噪声对整机噪声的贡献率.应用声强扫描法对柴油机油泵侧、排气侧、风扇侧和摇臂罩盖侧进行了近场声强扫描,采集了主要噪声源近场频谱.结果表明:柴油机在标定工况运行,燃油泵齿轮啮合噪声对整机噪声贡献率为37%,油底壳表面辐射噪声占整机噪声能量的22%;燃油泵齿轮啮合噪声在630 Hz和2 000 Hz处噪声出现峰值,油底壳辐射噪声在各频率段都存在峰值;2种方法识别出的柴油机主要噪声源一致,燃油泵齿轮啮合噪声和油底壳辐射噪声是柴油机主要的噪声源,气缸罩盖辐射噪声、附件箱齿轮啮合噪声和曲轴箱辐射噪声是柴油机的次要噪声源.

By near-field sound pressure level methed, the near-field sound pressure levels of 14 parts were measured for the four-cylinder diesel engine including cylinder cover, fuel pump, oil pan, turbocharger, air filter and so on. The contribution of each part noise to overall noise was analyzed. The sound intensity scanning method was used to measure the sound intensities of fuel pump side, exhaust side, fan side and cylinder head side of the diesel engine, and the near field noise spectrum of main noise sources was collected. The results show that the contribution rate of fuel pump noise to overall noise is 37%, and the oil pan surface radiation noise energy accounts for 22% of whole noise energy at the declared working condition. The noise peaks of fuel pump appear at the frequencies of 630 Hz and 2 （X）0 Hz, and the radiation noise peaks of oil pan appear at every frequency band. The noise of fuel pump and the radiation noise of oil pan are the main noise sources of diesel engine, and the radiation noises of cylinder head, accessory box and crankshaft are secondary noise sources. The results by two indentification ways are consistent.