Inlet Distortion Sensitivity of Fans with Different Pressure Ratios

Abstract

The interaction of two different fans with a generic inflow distortion typical for boundary layer ingestion is investigated with regard to aerodynamic effects and operating behavior. The arising results are used to quantify the influence of the total pressure ratio of a rotor on the sensitivity of the specific rotor to in-flow distortions. The employed test cases include the fan of the commercial IAE V2500 engine, an engine of a typical single aisle airplane, and the DLR Fan135 as an example of a low pressure fan for fu-ture ultra high bypass ratio engines. Both fans feature a very similar meridional Mach number but different total pressure ratios. The character of the applied cir-cumferentially inhomogeneous inflow distortion de-manded for the application of a newly developed stream tube based post-processing. This post-processing reveals that the operating point for both fans exceeded the stability limit during the interaction with the inflow distortion. For all investigated quanti-ties, including transient blade forces, operating point excursions and distortion damping during rotor pas-sage, the low pressure fan Fan135 showed a higher sensitivity to the inflow distortion.