Experimental and simulation study on oscillating flow and heat transfer characteristics of the cooling gallery in steel pistons

Abstract

To characterize the oscillating flow and heat transfer characteristics of the cooling gallery inside a steel piston, a visual experimental platform was designed and constructed. Based on experimental results, simulation models of the cooling gallery under calibration conditions were established, and the oscillating flow and heat transfer characteristics of different oil injection strategies were studied. The results show that adjusting the nozzle diameter has a more significant impact on the fluid charge ratio (FCR) of the cooling gallery compared to the injection pressure. During the reciprocating motion of the steel piston inside the cylinder, the gallery has the largest heat transfer coefficient (HTC) on the Top wall at the top dead center (TDC) and the largest value on the Bottom wall at the bottom dead center (BDC). The average HTC of the Top wall is always the largest, followed by the Bottom wall, the In wall, and the Out wall being the smallest. Compared to the original design, the average HTC of the Top, Bottom, Out, and In walls can be increased by a maximum of 4.39 %, 3.96 %, 8.01 %, and 11.80 %, respectively.