Experimental and numerical investigation of conjugate heat transfer in a HSDI Diesel engine water cooling jacket

The paper presents a combined experimental and numerical program directed at improving the accuracy of conjugate heat transfer CFD simulations of engine water cooling jackets.As a first step in the process, a comparison between experimental measurements from a test facility at Villanova University and CFD numerical predictions by at the University of Modena is reported. The experimental test section consists of a horizontal aluminium channel heated electrically and supplied with a constant volumetric flow rate. The operating fluid is a binary 50/50 mixture by volume of ethylene-glycol and water, in order to reproduce a situation as close as possible to actual engine cooling system operations. Temperatures are measured along the channel at several axial locations.On the CFD side, an extensive program reproducing the experiments is carried out in order to assess the predictive capabilities of some of the most commonly used eddy viscosity models available in literature. Both non-evaporating and evaporating conditions are evaluated, showing severe limitations to the use of simplified boiling models to correctly capture the complex interaction between turbulent boundary layer and vapor bubble dynamics.At the end of the validation process, v2-f model proves to yield the best trade off between numerical accuracy and computational costs at least when reproducing non evaporating or slightly evaporating thermal conditions, and the model is therefore applied to predict the temperature distribution within the engine head and block of a 3.0 L HSDI Diesel engine for automotive applications