Browsing by Author "Saddington, Alistair J."
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Item Open Access Aero-whisker for the measurement of aircraft flight speed and angle of attack in compressible flow conditions(AIAA, 2023-06-08) Debiasi, Marco; Atkinson, Kevin; Saddington, Alistair J.; Finnis, MarkA whisker-like device has been designed and tested that simultaneously measures the speed and the direction of a flow in which it protrudes. The device consists of a thin cylindrical probe longer than the thickness of the local boundary layer whose aerodynamic drag produces a moment at its base which is measured by a solid-state torque transducer. With proper calibration, the orthogonal components of the moment can be used to measure the speed and the direction of the flow. Measurements have been performed in a wind tunnel to validate the design at flow velocities ranging from Mach 0.15 to Mach 0.87 and for flow angles relative to the probe ranging from -88° to +88°. The results obtained indicate that the aero-whisker is capable to accurately measure the Mach number and direction of the flow with potential for further optimization for aircraft applications.Item Open Access Exploring angle-of-attack effects in the aero-acoustic response of a weapons bay at transonic and supersonic Mach number(AIAA, 2022-06-13) Bacci, David; Saddington, Alistair J.Numerical aero-acoustic analysis was conducted on a weapon bay model with doors, incorporating radar cross section reduction features. The effect of angle of attack on the aero-acoustic response of the cavity was analysed at a transonic Mach number of 0.85, and at a supersonic Mach number of 1.20. It was found that incidence had influence on both mean-flow features and acoustic response. Further, linear and angular accelerations induced by the flow on doors revealed potential adverse fluid-structure coupling when results were compared with modal analysis. Again, angle of attack did influence the aeroacoustic effects on the cavity door structure.Item Open Access Hilbert–Huang spectral analysis of cavity flows incorporating fluidic spoilers(AIAA, 2022-10-07) Bacci, David; Saddington, Alistair J.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.