Numerical Investigation of High-lift Airfoil Fitted with Slat Cove Filler

摘要

Slat noise is well known as one of the dominant noise components of airframe noise. The slat cove has been demonstrated to be one of the primary sound source responsible for narrowband and broadband noise from high-lift devices. In order to reduce slat noise, several studies on slat cove fillers have been carried out in the past. In the present study Large Eddy Simulation with Dynamic Smagorinsky model has been used to assess the aerodynamic and aeroacoustic performance of a 30P30N high-lift airfoil with and without slat cove filler. The tests were carried out at an angle of attack of α = 5.5° at an inlet velocity of U_∞ = 58 m/s, corresponding to a chord-based Reynolds number of Re_c = 1.71 × 10~6. The steady and unsteady pressure measurements validate well with the experimental data available in the literature. Contours of detailed flow field components such as mean velocity, turbulent kinetic energy and spanwise vorticity for both the baseline and slat cove filler configuration has been presented in a systematic manner. Contours of spanwise vorticity validate well with previous particle image velocimetry experimental measurements. Unsteady surface pressure spectra at various locations on the slat and main-element show that the application of slat cove filler eliminates the narrowband noise source and reduces the broadband noise for the tested cases. The pressure-velocity correlation results show us that the shear layer impingement on the slat lower surface contributes to the increase in low-mid frequency energy spectra. The use of slat cove filler eliminates the shear layer thus reducing the spectral levels at low-mid frequencies.