Features of the fastest pressure growth point during compression stroke

Abstract

The article contains description of method, which enables to synchronize indicator diagram of diesel engine using the parameters of fastest pressure growth point during compression stroke. It means calculation of this point position relatively to top dead center (TDC). At first, experimentally obtained data has to be smoothed by the Butterworth low pass filter. Afterwards, assumed that the process is stationary, compression stroke is expressed by equation of polytropic compression. Then the first and the second pressure derivatives are determined by crank angle. The condition, when the second pressure derivative by crank angle equals zero, enables us to find the position of the fastest pressure growth point relatively to TDC. The angle, which was found in such a way, is used later as first approximation for finding the TDC position with adequate accuracy. It’s also shown how to calculate the volume of compression chamber (compression ratio) using parameters of this point. Results of the calculation are compared with experimentally obtained data.