Shu Gequn

Research on Couple Mechanism of Heat Release and Acoustic Characteristics during Combustion of Butane in Close Chamber

By the combination of combustion and acoustic theories,a combustion model and an acoustic model were linked together to describe the oscillation in actual close combustion chamber.According to the mathema-tic model,a two-dimensional procedure was compiled to calculate the isometric combustion of butane which was pre-mixed with atmosphere.After the wave equations being taken into account,the results of solution are diffe-rent from those without wave equations.Contour graphs of pressure were drawn and compared.The couple mechanism of heat release and acoustic characteristics were analyzed based on the experimental and calculated pressure data of an SI engine.It is shown that the heat release and pressure wave influence each other in close chamber,thus while studying the process of combustion in IC engine,the acoustic characteristics should be taken into account.

Numerical simulation of low temperature oxygen-enriched combustion of diesel engine with the CFD & n-heptane sample model's coupling

Multi-dimensional transient numerical simulation was done for low-temperature oxygen-enriched combustion process of 4100QBZL-2 diesel engine by using CFD software AVL-Fire and a simplified model of n-heptane oxidation coupling. To establish combustion chamber model and generate mesh with the ESE, in the computation process, FIRE will transfer and calculate the chemical kinetics model in each cell. Adjusting component volume fraction in intake air with: 21% O2(atmosphere), 24% O2 (oxygen-enriched combustion) and 24% O2/10% CO2 (low temperature oxygen-enriched combustion), then the calculation could use them. The results show: O2 concentration 24% compared with 21% , the combustion rate is faster and the maximum pressure rise more than 0.2MPa relatively. Combustion with 24% O2/10% CO2 intake air make the ignition time delay to TDC, the maximum pressure decreased to 10.7MPa, the maximum temperature was 1548.4K, which is reduced 60.2K and achieved low temperature oxygen-rich combustion comparing with air combustion. With reduction of combustion temperature, NO emission is also lower than the case of combustion air.

Progress and Recent Trends in the Torsional Vibration of Internal Combustion Engine

With modern machinery industry developing, the application of internal combustion engine is getting wider and research direction is towards high-power, high speed and strong loads. So the issue of torsional vibration of the engine is becoming more prominent. All kinds of work conditions of the engine may have great impacts on the shafting, leading to all sorts of torsional vibration and resonance, and many accidents which lead to much detriment have occurred at home and abroad due to torsional vibration. As the problem of torsional vibration of the engine is becoming more and more prominent, broad research is made both at home and abroad. This article mainly refers to the literatures on torsional vibration issue published in recent years, summarizes on the modeling of torsional vibration, corresponding analysis methods, appropriate measures and torsional vibration control, and points out the problems to be solved in the study and some new research directions.