CFD STUDY OF THE LEAKAGE FLOW IN LOW-SPEED AXIAL-FAN WITH ROTATING SHROUD

The paper reports a study of the effect of the rotational speed on the leakage flow development in a low-speed shrouded axial fan. As the rotor deforms due to centrifugal force and aerodynamic loading, a static structural analysis has been operated at five rotational speeds ranging from 500 to 3000 rev/min, with the pressure distributions on the rotor surfaces derived from RANS-based CFD simulations alternating with FEM ones. Once convergence has been reached, both the structural and aerodynamic results have been validated through available experimental data. Then, the deformed geometries related to two rotational speeds, 2400 rev/min and 3000 rev/min respectively, have been used to perform URANS CFD simulations and then to analyze the effects of the different gap geometries on the leakage flow behavior. The results have allowed interpreting the behavior of the leakage flow evolving in the gap between the rotating shroud and the stationary casing.