Assessing the forcing level of air cooled diesel engine considering parameter spread of boosting system

Abstract

Abstract Spread of parameter values of piston internal combustion engine boosting parts is normally due to extreme deviations (spread, error margin) of original parts and quality of assembly. Spread of relation of boosting pressure to counter pressure at outlet of turbo compressors Pk/Pt of the same type affects not only the engine parameters, but also thermal expansion of cylinder-piston group parts and cylinder head. At stable relation value of Pk/Pt, boosting pressure and maximal air flow, turbo compressor allows us to reduce the thermal factor of combustion chamber and cylinder head due to higher values of air excess ratios. This is very important, first of all for air cooled engine as in case of dramatic surge of its thermal factor we face a risk of cracks occurring in inter valve and inter valve- nozzle connectors of cylinder head fire bottom, cracking of setting bevels at valves of gas distribution mechanism. We analyzed the impact of technological spread of boosting details parameter on the value of achieved forcing limit. Impact analysis of technological spread of turbo compressor parameters on diesel engine performance was done on the basis of test results of ten B-400 engines, fitted with randomly selected pairs of TKP8,5-C7 turbo compressors out of a lot of 20 pieces. For each turbo compressor we determined preliminarily characteristics and efficiency factors nK, of turbine nT and of a unit as a whole n™.