压力示功图的频谱分析及其处理

The Spectrum Property and Processing of pressure Indicator Graph

测压通道是影响柴油机示功图测量精度的主要因素之一 ,示功图的压力波动直接影响到放热规律的计算和燃烧性能的评价。通常采用的光顺方法只是根据数学上的平滑与逼近原理 ,而不是按照系统的物理特性建立的 ,很难证明其光顺结果是否符合实际。本文根据对SD2 10 0柴油机实测示功图的频谱特性的研究 ,提出了一种根据测压通道的传递函数 ,通过傅立叶逆变换消除示功图压力波动的方法。与一般的光顺方法相比 ,它不但有效地消除了测压通道造成的压力波动 ,而且更多的保留了示功图上的有用信息 。

Pressure measuring passage is one of the main factors influencing measuring accuracy of indicator graph. The pressure oscillation of indicator graph can influence the calculation of release rate and the evaluation of combustion performance. Smooth method is generally used to process the indicator, but it cant remove the oscillation of SD2100 diesel engine indicator graph. The author analyzes the pressure spectra of indicator graph and gives a method that is based on reverse Fourior transfer to process indicator graph. This method can eliminate pressure oscillation that derives from pressure measuring passage. Obviously it is a good method for processing indicator graph.