Validation of URANS Simulation of Truck Cooling Fan Performance

The performance of an axial heavy duty truck cooling fan was investigated by measurements in a test rig and by CFD simulations. In order to account for the unsteadiness of the flow, URANS simulations were employed. Good agreement was achieved between the simulation and test data, in particular in the axial regime, despite the constant density assumption. To improve the simulation accuracy in the radial and transitional regime it is most likely insufficient to assume constant density. New simulations with ideal gas assumptions for these regimes are believed to give better agreement with the test data. The simulations show that URANS CFD can produce results very close to the ones obtained in the test facilities and thereby can be used for the industrial applications when flow unsteadiness has to be taken into account. The fact that it requires long computational time and is CPU-demanding can no longer be regarded as a major preventing factor for its application in the industry. In addition, it provides valuable information about the details of the flow which can contribute to the optimization of the geometry for improved efficiency and higher performance.