Wavelet Analysis of Complex Geometry Transonic Cavity Flows

David Bacci, Alistair Saddington, Derek Bray
2016 8th AIAA Flow Control Conference   unpublished
The aero-acoustic analysis of a weapon bay of an Unmanned Combat Air Vehicle (UCAV) was predicted using Computational Fluid Dynamics (CFD) methods. Along the reference geometry, consisting in the installation of the Boeing M219 modified type cavity in the Boeing UCAV1303 airframe, two additional configurations, developed modifying the leading and trailing edge geometries of the bay, were tested. Pressure signals inside the cavity were post-processed using Joint Time Frequency Analysis (JTFA)
more » ... hniques, consisting in a combination of frequency domain and time-frequency domain techniques based respectively on the Fourier and wavelet transform. Results showed an intermittency nature of the modes present in the spectra as well as a continuous change, during the temporal evolution of the signal, of the dominant mode. Also were recorded, using second order wavelet spectral moments, non-linear phenomena between the main modes like phase coupling. ஶ = air density in undisturbed flow [kg/m 3 ] ஶ = air pressure in undisturbed flow [Pa] ஶ = air temperature in undisturbed flow [K] ஶ = kinematic viscosity in undisturbed flow [m 2 /s] ஶ = dynamic viscosity in undisturbed flow [kg/ms] ஶ = sound speed in undisturbed flow [m/s] = ratio of specific heats (1.4 for air) ஶ = turbulent kinetic energy at far-field [m 2 /s 2 ] ஶ = turbulent specific dissipation rate at far-field [1/s] = angle of attack [deg] = angle of sideslip [deg] = root mean square = n th Rossiter-Heller mode ெ = m th sub-harmonic of n th Rossiter-Heller mode ெ = m th harmonic of n th Rossiter-Heller mode ெ ±ெ = sub-mode created by the non-linear interaction in sum/difference of p th mode and q th mode I.
doi:10.2514/6.2016-3177 fatcat:7gmburjzxvczletfqhjl56ctz4