Investigation of Jet Engine Intake Distortions Caused by Crosswind Conditions

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.

Areas of Investigation into Air Intake Systems for the Impact on Compressor Performance Stability in Aircraft Turbine Engines

“…The research of Harjesn et al [11] of the air intakes of this type of engine has shown that there is a significant disturbance of the air flow supplied into the engine in the presence of crosswinds. The high dependence and sensitivity of these air intake assemblies to the speed and incidence angle of crosswinds was also demonstrated.…”

Development of Aspirated Ultra-Short Intakes for Aerodynamic Off-Design Analysis

“…Ma FF [-] 0.64 0.55 As previous investigations (observed by Pinkerton (1938) and Harjes et al (2020)) have shown, that a smaller Reynolds number shifts the onset of separation in the intake to lower crosswind velocities, full annulus steady state compressible RANS simulations were performed. Based on the results of Harjes et al (2020) for intake flow, SST turbulence modelling in combination with γ − Re Θ transition modelling was used, modelled by Ansys CFX 18.2 instead of TAU. As convergence criteria, the momentum and mass residuals should be of the order of 10-5.…”

Flow Separation Control of Nacelle Inlets in Crosswinds by Dielectric Barrier Discharge Plasma Actuation

“…Minaker and Defoe [9,10] proposed a fan gas path and airframe force model design process, applied it to the problem of predicting flow separation over an engine nacelle lip caused by crosswinds, and used a body force model to assess the accuracy of the design process-based approach. Harjes et al [11] explored jet engine inlet distortions caused by crosswind conditions, and through comparative experiments, numerical studies showed that the isentropic peak Mach number depends on the Reynolds number as well as the size of the separation bubble that occurs.…”