基于实时性优化的内燃机燃烧分析系统研究

采用缸压传感器、数据采集卡、光电编码器和Lab VIEW软件,搭建在线缸压采集和实时燃烧分析系统平台,研究HCCI和RCCI燃烧模式的循环波动特性。针对单循环缸压测量过程中的通道效应干扰,基于频谱分析,采用FFT、线性插值法和IFFT等方法相结合的滤波方式,实现共振峰的在线自适应识别与实时滤波,较好地减少了单循环缸压的干扰误差,使单循环的实时燃烧分析成为可能。随后,基于实时滤波后的缸压曲线,计算得到内燃机的最大压力升高率、燃烧放热率、爆发压力等重要燃烧参数。利用程序算法中同步性良好的生产者/消费者运算模式提高数据的共享能力,实现了数据实时运算与数据快速储存的并行处理,提高了燃烧计算的实时性;针对发动机不同工作阶段采用了不同精度层次的计算方法,减少了进排气、压缩和膨胀阶段的计算耗时,在计算量较大的燃烧放热率计算部分,通过适当简化计算公式和公式节点运算模块来提高燃烧系统的实时性。最后,分析了燃烧分析系统的实时性,并进行了燃烧分析系统的实验验证。

Development of Real-time Combustion Analysis System for IC Engine Based on Real-time Optimization

The homogeneous charge compression ignition(HCCI)and reactivity controlled compression ignition(RCCI)engines are very sensitive to the in-cylinder compression temperature,the spatial distribution of fuel and air,and the component of fuels.Variation of these facts will result in the cyclic variation in IC engine.Based on the needs of cyclic variation research in HCCI engine and RCCI engine,an online cylinder pressure acquisition and real-time combustion analysis system adopting in-cylinder pressure sensor,data acquisition card,photoelectric encoder and LabVIEW software was built.In order to improve the real-time performance of combustion analysis system,only single cycle cylinder pressure was collected and calculated.There were much pressure fluctuation in single cycle cylinder pressure resulting from channel effect and other effect,and a real-time filtering of in-cylinder pressure was adopted to reduce the interference error of single cycle in-cylinder pressure data.The filtering methods based on spectrum analysis,like fast Fourier transformation(FFT),linear interpolation and inverse fast Fourier transform(IFFT),can realize the online adaptive identification and auto pressure smooth for the single cycle in-cylinder pressure,which made the real-time combustion analysis system for HCCI and RCCI mode possible.Then,based on the smoothed cylinder pressure,some important combustion parameters such as the maximum pressure increase rate,combustion heat release rate and in-cylinder peak pressure were calculated.In order to further improve the real-time performance of the combustion analysis system,the producer/consumer operation mode which can achieve the synchronized process of real-time data calculation and fast data storage was used.The improved data sharing ability can improve the real-time ability of the combustion calculation.Different accuracy levels of calculation methods were adopted for different working stages in engine,which can reduce the calculation time for intake,exhaust,compression and expansion stages.In combustion stage,which had the largest calculating workload,the appropriate simplified calculation formulas and formula node operation modules were adopted to improve the real-time performance.Finally,the real-time performance of the combustion analysis system was analyzed and an experimental verification of the combustion analysis system was carried out.