ANALYSIS OF THE HEAT EMISSION OF A D100-LIKE DIESEL ENGINE USING THE KNOWN α FORMULAS

Abstract

While the development of alternative pistons for D100-like engines, the authors of this paper have encountered the problem. It consists in modeling of the thermal boundary conditions, which are directly related to a specific working process. The simulation of the working process of a 2-stroke diesel engine with counter-moving pistons is discussed in this study aimed to analyze the effect of various formulas of the heat-transfer coefficient (α-formulas) used for calculating the thermal balance of the engine. The nine α-formulas by the well-known authors for nominal and partial regimes were analyzed. The simulation based on the known α-formulas with original coefficients gives the variation of the average heat transfer rate to the walls at the nominal mode equal to 1.4 to 13%. Thus, the result differs by almost 10 times. Moreover, all values of the average heat transfer are understated. It is shown that any of the considered formulas can be used for the mentioned engine type with minor modifications, i.e. changing one of the input coefficients. The coefficient can be obtained from the experimental data special treatment. The authors calculated the appropriate coefficients one for each α-formula assuming 20% heat loss to the cylinder wall. A comparison with the available experimental data showed that for the considered engine type, it is preferable to use the modified α-formula by R.Z. Kavtaradze.