基于试验缸压曲线的船用柴油机燃烧噪声分析

基于某船用柴油机单缸试验机的试验缸压曲线,采用频谱分析的方法,建立缸压曲线和燃烧噪声之间的关系。根据柴油机的燃烧过程,将缸压曲线分解为倒拖缸压、燃烧振荡压力和"剩余"燃烧压力曲线。分析发现:在全负荷工况,10～300 Hz低频声压值主要由倒拖缸压决定; 1. 8～20 kHz高频声压值主要由燃烧振荡压力决定; 0. 3～1. 8 k Hz中高频声压值主要由"剩余"燃烧压力决定。分析表明:喷油正时提前,中低频的声压值增大,高频声压值略有增大;柴油机转速上升,全频段的声压值均增大;负荷越大,10～600 Hz的声压值越大,对2～20 kHz的高频燃烧噪声影响较小。

Marine Diesel Engine Combustion Noise Analysis Based on Experimental In-Cylinder Pressure Curve

Based on the experimental in-cylinder pressure curves got from a marine diesel engine''s single cylinder test bench, the relationship of in-cylinder pressure curve and combustion noise was analyzed using frequency spectrum analysis method. According to the phenomenon during diesel engine working process, the in-cylinder pressure was decomposed to the motored pressure, the resonance excitation pre-ssure and the remained combustion pressure. The analysis results show that at full load condition, the motored pressure mainly affects the sound pressure level (SPL) of 10~300 Hz; the resonance excitation pressure mainly affects the SPL of 1.8~20 kHz; and the remained combustion pressure mainly affects the SPL of 0.3~1.8 kHz. Analysis showed that, the SPL of low and medium frequency would increase while the injection timing was advanced and the SPL of high frequency would also increase a little; the SPL of whole frequency range would increase while the diesel engine speed increased; the SPL of 10~600 Hz would increase while the engine load increased and the SPL of 2~20 kHz would increase little.