INVESTIGATION OF JET ENGINE INTAKE DISTORTIONS CAUSED BY CROSSWIND CONDITIONS
Lennart Harjes, Christoph Bode, Jonas Grubert, Philip Frantzheld, Patrick Koch, Jens Friedrichs
Abstract
The Propulsion Test Facility of the TU Braunschweig is capable of investigating future jet engine intakes and fan aerodynamics to a high level of detail. A goal of this facility is the examination of coupled fan-intake-interactions which is not possible in any existing test bench around the world. Before doing research on these interactions, it is important to undergo proper studies of isolated aspirated intakes and fans under varying operating conditions (design and off-design). Therefore comparable result of the well-known LARA nacelle to existing experimental and numerical data has been generated for a first validation purpose. Therefore, comparable studies have been conducted with the LARA nacelle, to that of experimental and numerical investigations performed in the early 1990s at the ONERA F1 wind tunnel (mention reference), in order to generate results for validation. The first results of the validation experiment show differences in peak Mach number between the ONERA F1 and PTF experimental data for identical boundary conditions based on Mach number and crosswind. To investigate this further, a comprehensive numerical study has been carried out. It was inferred that the discrepancy was mainly caused by the Reynolds number effect within the PTF environment and its sensitivity to the inlet flow angle distribution with regard to angle of attack for crosswind. Within the validation test campaign, the experimental investigations showed a separation and reattachment hysteresis, which was identified when crosswind as well as nacelle mass flow had been increased or decreased to set up the different operating points. This phenomenon has still no established theoretical basis for understanding the aerodynamic behaviour. Overall, the applicability of conventional RANS models is shown. Additionally, the sensitivity to the aforementioned boundary conditions and the numerical reproducibility of the hysteresis phenomenon are discussed and compared to new experimental data in detail.