The Research And Application Of Combustion Analyzer

The thesis programmed data acquisition and processing software with computerlanguages of VB6.0and VC6.0, by optimizing algorithms to improve the operatingefficiency of software. The precision of the top dead center’s location is veryimportant to the subsequent data analysis. The thesis used the method of polytropicindex to correct the location of top dead center which ensured the deviation waswithin0.1°CA. Besides some common functions such as the drawing of indicatordiagram, calculation of the rate of heat release and pressure rise, the software alsorealised some other functions such as the analysis of transient speed, the probabilitydensity distribution and the correlation coefficient calculation of indicated meaneffective pressure(IMEP), maximum explosion pressure as well as the crank angleoccuring maximum explosion pressure.The experiment was carried out on a CG125gasline engine. By using a A/D card,a cylinder pressure sensor, a charge amplifer and other hardwares, combined with dataacquisition and processing software to study the cyclic variations of IMEP, maximumexplosion pressure and the crank angle occuring maximum explosion pressure whenthe gasline engine was in the idle condition. As the sampling numbers increased, thecyclic variation of the indicators reduced. By calculation and found that the rationalsampling numbers should be no less than1750when the differences among sampleswere slight. The thesis selected1750samples to study and found only55.6%belonged to normal combustion. The results show that the cyclic variations of IMEP,maximum explosion pressure and the crank angle occuring maximum explosionpressure reduced in the condition of normal combustion.The thesis also studied load changes at the speed of5000r/min by uniformlyselecting eight conditions from30%to100%load. The results show that IMEP andmaximum explosion pressure increase with increase of load. There is a goodrelationship between maximum explosion pressure and the crank angle occuringmaximum explosion pressure at100%load which the correlation coefficient is-0.799.On the other hand, when the load is light the correlation coefficient is not obvious.The relationship between IMEP and maximum explosion pressure is obvious and at 50%load the correlation coefficient reaches the maximum of0.866and thecorrelation coefficient reaches the minimum of0.638at90%load.