A method for determining the high-frequency in-cylinder pressure of an internal combustion engine using a pressure sensor dynamically calibrated with a shock tube

A key parameter for determining the different dynamic parameters of an internal combustion engine (ICE) is the high-frequency pressure in the combustion chamber. The uncertainty of these parameters is dominated by the dynamic accuracy of pressure sensors (PSs). However, PSs used in dynamic applications are typically calibrated quasi-statically with conventional static standards, which limits their accuracy. To address this limitation, this paper proposes and evaluates a method for determining the high-frequency in-cylinder pressure of an ICE using a PS dynamically calibrated with a shock tube (ST). The method reconstructs the in-cylinder pressure by applying an inverse discrete Fourier transform to the ratio of the frequency spectrum of the PS voltage output response and the complex frequency response function of the PS obtained with a dynamic calibration using a ST. The method was tested on a diesel ICE over a wide range of operating conditions using a piezoelectric PS calibrated in a diaphragmless ST. The Monte Carlo uncertainty analysis shows that the proposed method improves the accuracy of high-frequency in-cylinder pressure determination. Consequently, it significantly improves the accuracy of other dynamic ICE parameters, such as the rate of pressure rise, the average in-cylinder gas temperature and the rate of heat release.