Research On The Control And Test System Of Constant Volume Combustion Chamber

With the energy shortage and environmental deterioration, the exploitation of alternative fuel has become a hot research topic. The gas fuel has been acknowledged as the most valuable use of alternative fuels, so study on the laminar combustion characteristics of gas fuel is necessary and of profound significance, which can provide theoretical guidance for the application of gas engine.In this paper an ignition and timing control system is designed for the CVCC(Constant Volume Combustion Chamber), of which ignition energy can be controlled by adjusting the charging time of the ignition coil. A test system is designed for the CVCC including combustion pressure acquisition device, the ion current detection module and flame image acquisition system. And acquisition software, which can be use to achieve signal acquisition and preservation, is written using LabVIEW platform.The flame image recognition algorithm based on Canny operator is improved so that it can set the threshold value automatically, which reducing human disturbance and processing flame images rapidly and accurately. And then combustion analysis system software for gas fuel is developed using mixed programming with matlab and LabVIEW.Based on the CVCC control and test system commissioning, the experimental research on laminar combustion characteristics of low calorific value gas were studied at various equivalence ratios, carbon fractions and initial pressures. The results show that, for the ignition system, electrode structure affects the stability of the spark. Electrode gap changes the ignition quality by affecting the breakdown voltage, which can change the spark ignition energy. For the ion current, electrode geometry and the installation position has little effect of the ion current signal, while only a slight change in the amplitude of ion current signal, and almost no change to the time of each peak; the times reaching the second peak and the third peak can be used to calculate the burned fuel mass fraction, while the accuracy affected by the parameters Xb1 and Xb2. For the laminar combustion characteristics, the maximum rate of pressure rise and flame propagation rate was found at the equivalence ratios is 1.0, whether the mixture is lean or rich combustion, the flame spread rate will decrease, while the burning velocity of rich combustion is greater than lean combustion; The mass burning rate, the flame speed and the laminar burning velocity decrease with the increase of initial pressure.