Performance Calculation of a Vehicle Radiator Group Based on CFD Simulation with Modified Standard Functions

To shorten the development cycle and ensure the stability of the products, based on RNG k-e turbulence model and porous model, 3 dimension (3D) flow field Computational Fluid Dynamics (CFD) simulation is adopted to calculate the radiator group performance for a engineering vehicle being developed. Air-side flow field simulations of the radiator unit model are carried out firstly to obtain the radiators' air-side characteristics; then, the air flow and heat transfer in the whole air channel containing the radiator group are simulated simultaneously to get the inlet and outlet water temperatures of radiator group, at last, the real vehicle test is carried out to verify the simulation results. To be emphasized, in calculating the near-wall boundary layer of the radiators' unit model flow field, modified standard wall functions (MSWF) whose calculation grids is same to standard wall function (SWF) and computation accuracy of the near-wall first node velocity is higher than SWF is proposed; and compared to the test values, the radiators' inlet and outlet water temperatures obtained from the flow field simulation process using MSWF has relative error 6.4%, which can meet the accuracy requirement in engineering computation.