Technical Paper
Effect of Knock on Time-Resolved Engine Heat Transfer
1989-02-01
890158
The instantaneous local heat flux was determined under knocking conditions in a square piston engine simulator to investigate the relationship for the phase and magnitude between the heat flux and the knock intensity. Two platinum thin film resistance thermometers recorded variations of the the cylinder wall surface temperature at different locations. The wall heat fluxes were then calculated from the measured temperature variations. Schlieren pictures of the combustion process showed the motion of the burned gas during knocking. Pressure oscillations of about 5 kHz occurred after autoignition. Oscillations of the heat flux were at the same frequency and in phase with the pressure oscillations. The maximum heat flux increased almost linearly with the maximum amplitude of the pressure oscillations for pressure oscillations greater than 0.5 MPa. The rate of increase is not uniform spatially.
