EXPERIMENTAL INVESTIGATION OF THE INSTANTANEOUS HEAT TRANSFER IN THE CYLINDER OF A HIGH SPEED DIESEL ENGINE

Measurements of instantaneous surface temperature variations have been made at five positions of the combustion chamber side of the cylinder head of a modern four-valve, high speed Diesel engine with external supercharging. By means of analysing the measured data and calculating the engine cycle local and local-average instantaneous heat transfer coefficients have been derived. It became evident that the steady-state component of the total heat flux into the solid wall normal to the surface can only be determined inexactly by measurements, because of none-one-dimensional temperature distribution in the wall, whereas the fluctuating component can be calculated exactly enough from the measured surface temperature variation. Finally the measured local and local-mean instantaneous heat transfer coefficients are compared with the results of Woschni's formula for the local-average heat transfer coefficient. The agreement is very good as far as the variation with time and the integral of the high pressure phase of the cycle are concerned.