Effects of cylinder head temperature and coolant velocity on the erosion behavior of water jacket in a diesel engine

Effects of surface temperatures and coolant velocities on the erosion behavior of the engine water jacket was investigated in a test bench, which was designed to provide similar conditions to the water jacket in an engine. Rectangular specimens were fabricated using the water jacket material (aluminum alloy A356T5), then installed in the test bench and heated using fire torches. To evaluate the effects of two parameters, high speed camera, scanning electron microscope (SEM), mass scale, energy dispersive spectroscopy (EDS) were used. If any pits appeared as a result of erosion, the pit size growth rates were calculated. In addition, the single bubble collapse pressure was calculated using an erosion model to quantify the interaction between the bubble and the solid surface. It was found that higher mass reduction and surface changes appear under the condition of the higher surface temperature and the faster coolant velocity. Surface temperature affected the bubble and pit formation, while, the coolant velocity influenced the overall trend of mass reduction. As a result of calculation, the single bubble collapse pressure was order of 109 Pa. Detailed effects of two parameters on erosion behavior are discussed.