Unsteady Heat Transfer Enhancement Around an Engine Cylinder in Order to Detect Knock

This paper deals with the transient thermal signal around an engine cylinder in order to propose a new and nonintrusive method of knock detection. Numerical simulations of unsteady heat transfer through the cylinder and inside the coolant flow are carried out to account for heat flux variations due to normal and knocking combustion. The effect of rib roughened surfaces on thermal signal amplification is investigated. The geometric parameters are fixed at Pi/h=10 and w/h=1 with a Reynolds number based on hydraulic diameter of 12,000. The results reveal that square ribs give better performance in term of thermal signal amplification within the fluid. An amplification of the temperature variation up to 20 times higher is found. Finally, flow analysis shows that amplification depends on the position where the thermal signal is collected.