Influence of the inlet distortion on fan stall margin at different rotational speeds

The aim of this paper is to develop a reliable and accurate numerical strategy that can be used to study the effects of inlet distortions on the aerodynamic stability of fan blades in aero-engines. As an initial step towards achieving this goal, three-dimensional unsteady Reynolds-Averaged-Navier-Stokes (URANS) simulations were carried out to predict the influence of total pressure distortion on the loss of stall margin of a fan blade. NASA rotor 67, for which a significant amount of measured steady and unsteady data is available, was used for this study. It was observed that the size of the time step has a significant effect on the solution near stall and hence the stall margin of the blade. In the second part of this work, unsteady simulations were carried out to study the effects of rotational speed on the stall margin and stalled operating point of the blade. The results showed that for the same level and pattern of inlet distortion, the stall margin of the blade decreases as the corrected speed decreases. However, the in-stall total pressure losses decrease as the speed decreases. Finally, in our research it has become apparent that there is a big lack of public domain measured data for the cases with inlet distortion, and therefore, validated CFD results can be very helpful to other researchers in the field.