Study On The Combustion Process Of Marine Diesel Engine Based On The Indicator Diagram

The diesel engines are widely used in various fields of national economy, because of the large range of power, high thermal efficiency and reliability. Especially in the large shipping vessels the diesel engines act major roles. The combustion process of the engines is directly related to characteristic of the power and economy, so improvements and diagnoses of the diesel combustion process is the problem concerned by diesel researchers. With the application of computers and data processing systems in the research of internal combustion engines, the numerical calculation and experimental research powerfully promote the research of the internal combustion engine.In this paper, the mathematical and physical models by using indicator diagram to calculate combustion heat release rate are built. The interface of calculation program of the combustion heat release rate is designed with VB6.0 software. A simple and practical function of data analysis is developed. In the process of calculation, the necessity of smoothing treatment is discussed, By the comparison of the results with and without considering indicator diagram smoothing treatment, It shows that the result curve of heat release rate is of serious oscillation, which means the indicator diagram is not carried out smoothing treatment to calculate heat release rate, and it is not favored to analyze the combustion process. In the process of calculating heat transfer, four kinds of classical empirical formula calculating heat transfer coefficient are introduced, different heat transfer models are made use of to calculate the combustion heat release rate, and the results show that the heat transfer had little effect on the combustion heat release rate. In the process of TDC correction, two TDC correction methods are introduced, the program blocks according with the theory of TDC correction are edited, and with the program, the TDC of four-stroke diesel engine is corrected. The results show that with increase of rotational speed, the leakage and heat loss and the heat loss angle decreased. At last, the combustion heat release rate is calculated based on indicator diagram of the two-stroke diesel engine, and the calculation results of the main combustion parameters are analyzed.