A physically undistorted smoothing method for higher derivatives of engine cylinder pressure curve
The variation of the engine cylinder pressure with crankshaft angle was an important basis for engine combustion process analysis.The higher derivatives of cylinder pressure with respect to crankshaft angle contains profound information about the thermal process.Because of measurement errors,the derivatives beyond second order calculated directly from the measured cylinder pressure was often submerged in the noise.A method for engine cylinder pressure smoothing was proposed with Gaussian function as the basis and the number of extreme points of the higher derivatives as the constraints.The results showed that the proposed method could obtain the fourth order derivatives of cylinder pressure with respect to crankshaft angle without violation to real physical trends.It provided a novel method for the application of higher derivatives in analyzing the thermal process in the engine cylinder.
NETL
NSTL
万方数据
维普
