Abstract
This work provides an effective numerical approach to predict thermofluidics in a tu rbocharger. In the standard CFD approach, a huge number of meshes are required to represent a complicated blade shape in the turbine or the compressor. In order to reduce the calculation cost, the present work proposes a momentum source model, in which the effect of the blade-rotation is taken into account through the source terms representing the momentum-generation by the blade-rotation without considering the actual shape of the blade. In the original model,1) the obtained solution of the flow field did not agree sufficiently with that by the Multiple Reference Frame (MRF) method, where the blade shape is highly-resolved. In order to solve the accuracy problem an irreversible loss, which has not taken into account in the original model, is considered in the present work by modeling the viscous dissipation near the blade surfaces. In addition, a geometrical fidelity of the rotating axis, which has been approximated with the cylinder, is improved by the use of a body-fitted function. The proposed method is validated by comparing the solutions obtained by the present method and that obtained by the MRF method. The relative errors are evaluated for the rotational velocity, the expansion ratio, temperature difference between the inlet and outlet, and the amount of energy loss. Both the modified points introduced in the present work are confirmed to contribute to accuracy improvement.
