Numerical aeroacoustic analysis was conducted on an M219 cavity geometry, incorporating signature suppression features and leading-edge fluidic spoilers. The numerical model was validated against existing experimental data. The palliative properties of fluidic spoilers were investigated at Mach numbers of 0.85, 1.20, and 1.80 with blowing coefficients of 0.03 and 0.06. The results are presented for the acoustic spectrum, and further analysis was conducted using the Hilbert–Huang methodology. The fluidic spoilers were able to considerably reduce the overall level of acoustic noise and to reduce and/or suppress the resonant modes typical of cavity flows. The effectiveness of the spoilers was a direct consequence of their effect on the detached shear layer, of which the trajectory and coherence were altered. The Hilbert–Huang spectral analysis provided an enhanced understanding of the complex nature of the aeroacoustic behavior of the cavity. Acoustic modes were identified that, together with the Rossiter–Heller tones, governed the behavior of the spectrum. This demonstrated how the generated tones, appearing inside the cavity, were a result of complex nonlinear interactions between shear-layer acoustic instabilities and centrifugal instabilities originating in the flow recirculating in the internal part of the cavity. This also demonstrated that the fundamental frequencies had frequency and amplitude modulation characteristics that spread the energy in a wide bandwidth. This is not captured by classical Fourier analysis.

An experimental and numerical study was conducted on fan-shaped holes on the pressure surface of a high-pressure turbine blade. Blockages in these film holes can arise through dirt accumulation as well as erosion of the thermal barrier coatings. The objective was to study the effects of partial blockages on film cooling effectiveness. Similar studies have been conducted on flat surfaces. This study includes the effect of curvature, which has been shown to be influential on film cooling performance. A blade with a single row of nominal fan-shaped holes at a lateral inclination of 30 deg was tested and used as the baseline performance. Blockage cases were then tested at various blowing ratios, with partial blockages in the throat as well as partial lidding in the fan exit of the film hole. The experiments were carried out using pressure-sensitive paint (PSP) in the high-velocity 2D linear cascade experimental facility at the Oxford Thermofluids Institute, using engine-representative Mach and Reynolds numbers. The results show that lidding with up to 0.5 blocking ratio (defined as the ratio of lidded length to the length of the film hole exit, in the film hole plane) only has a minor impact on film effectiveness, while lidding with 0.75 blocking ratio as well as throat blockage both result in significant deterioration of film cooling effectiveness. The effect of blockages on the discharge coefficient was also studied, and only blockages in the throat were found to reduce the discharge coefficient.

Numerical aeroacoustic analysis using the Shear Stress Transport–Scale Adaptive Simulation turbulence model was conducted on a weapon bay model based on the M219 geometry with doors incorporating radar cross-section reduction features. The effect of the introduction of a gap between the doors and the cavity edge on the aeroacoustic and structural response of the cavity was analyzed at Mach 0.85. The effect of introducing 3 deg of sideslip was also investigated. Both mean and unsteady flow analyses were conducted. The results showed a strong palliative effect of the door gap with and without sideslips. The overall analysis of the spectral signature on the forces and moments acting on the doors indicated the possibility of fluid–acoustic coupling, as all acoustic spectra showed a predominant tone located at the same frequency of the first structural mode.