Scale effects on the performance of sawtooth spoilers in transonic rectangular cavity flow

Saddington, Alistair J.; Knowles, K.; Thangamani, Varun

doi:10.1007/s00348-015-2088-2

Cited by 15 publications

(6 citation statements)

References 20 publications

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“…The various cavity flow control methods aim at disrupting one or more components of the feedback cycle that is responsible for the oscillations (Saddington et al, 2016a; Thangamani et al, 2014; Zhang et al, 1998). While detrimental otherwise, the self-sustained oscillations have the potential to power micropowered devices if harvested efficiently.…”

Section: Introductionmentioning

confidence: 99%

Energy harvesting from cavity flow oscillations

Thangamani

Kok

2021

Journal of Intelligent Material Systems and Structures

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This study investigates the energy harvesting prospects of self-sustained flow oscillations emanating from grazing flow over a rectangular cavity by employing experimental and computational methods. Two cavity geometries with length-to-depth ratios of 2 and 3, exposed to an incoming flow of 30 m/s, were selected for the purpose. The power spectral density of the baseline cavity flows showed the presence of high-amplitude peaks whose frequencies agreed to those estimated from Rossiter’s feedback model. For energy harvesting, a piezoelectric beam was placed perpendicular to the aft wall and its natural frequency tuned to match closely with the dominant frequencies of the cavity flow oscillations. From the experiments, an average and maximum instantaneous power of 21.11 and 284.18 µW was recorded for the cavity with L/ D = 2 whereas for the cavity with L/ D = 3 the corresponding values were 32.16 and 403.46 µW respectively. Time-frequency analysis showed the forcing of the beam at the cavity oscillation frequency and the substantial increase in the amplitude of beam vibrations when this frequency was close to the natural frequency of the beam.

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Section: Introductionmentioning

confidence: 99%

Energy harvesting from cavity flow oscillations

Thangamani

Kok

2021

Journal of Intelligent Material Systems and Structures

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“…To reduce the flight resistance and radar signature, it has become common for modern fighters to utilise an internal weapons bay [1][2][3] . However, internal weapon bays also cause many complicated aerodynamic problems, such as boundary layer separation, aerodynamic noise, and shock waves, occur when high-speed airflow passes through the bay [4][5][6] . When the missile is released from the bay of fighter aircraft, it may bounce back to the bay under certain flight conditions 7 .…”

Section: Introductionmentioning

confidence: 99%

Effect of a Jet Control Device on the Process of Missile and Internal Weapons Bay Separation

Shan-an

Cheng

et al. 2021

Def. Sc. J.

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To ensure that the missile is safely separated from the internal weapons bay, the jet is used to control the process of missile separation, which is mounted on the front edge of the bay. The length-to-depth ratio of the bay was L/D=8, the diameter of the missile was d1 =0.178 m, the diameter of the jet was d2 =0.05 m . The FLUENT software was combined with our group-developed code under the platform of a user-defined function (UDF) to solve the flow field and the six-degrees-of-freedom (6DOF) of missile. The detached eddy simulation method and dynamic mesh technology were used in the numerical calculations. The boundary condition of missile, bay, and aircraft was no-slip wall condition. The boundary condition of the jet was the pressure-inlet. The pressure far-field boundary was selected as other boundaries. The constraint of the ejection device on the missile was considered. It was found that the jet control device thickens the shear layer, so the shear layer with more gradual velocity gradients, which is beneficial to the separation of missile. The distance between the internal weapons bay and the missile in the positive z-direction with the jet is 1.74 times that without the jet at t=0.5 s. In the case of the jet control device, the pitching angle of the missile ranged from 0.93° to -3.94° , the angular motion range of the missile with the jet is smaller than that without. The jet can make the characteristics of the flow field friendly, and enable the missile to separate from the bay quickly, stably, and safely.

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“…[10][11][12] Noise control of the landing gear and bay noise is an important research area in the aeroacoustic studies, and to date, a few approaches have been proposed to attenuate the landing gear or the bay noise (e.g. solid/ perforated fairings 13,14 and air curtain [15][16][17] for the landing gear noise control, leading-edge spoiler [18][19][20][21] and fluid injection 22,23 for the cavity noise control). However, these techniques have not yet been tested to suppress the coupling noise of the landing gear and the bay.…”

Section: Introductionmentioning

confidence: 99%

“…Shaw et al 24 performed one of the first attempts to use the chevron spoiler on a 4.9%-scaled F-111 generic weapon bay model, and the flow speed was managed to be within 0.7-2.0 Mach number. To date, it has been studied both experimentally and numerically by different researchers at high subsonic, transonic and supersonic speeds, [19][20][21] and good noise reduction was achieved. For low subsonic flow (Ma\0:3), the usefulness of the chevron spoiler has not yet been confirmed.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the aircraft bay/landing gear coupling noise at low subsonic speeds and its suppression using leading-edge chevron spoiler

Zhao

Liang

Yue

et al. 2019

Advances in Mechanical Engineering

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When the aircraft opens the bay door to let the landing gear either drop or retract, the incoming flow will result in a significant amount of coupling noise from the bay and the landing gear. Here, an experimental study was reported to characterise the acoustic performance and flow field at low subsonic speeds. Also, we examined a passive control method leading-edge chevron spoiler to suppress the noise. The experiment was performed in a low-speed aeroacoustic wind, the bay was simplified as a rectangular cavity and the spoiler was mounted to the leading edge. Both acoustic and aerodynamic measurements were performed through two microphone arrays, pressure transducers and particle image velocimetry. It was found that installation of the landing gear model can attenuate cavity oscillation noise to some extent by disturbing the shear layer of the cavity leading edge. Moreover, acoustic measurement confirmed the noise control when the spoiler was used. In addition, a parametric study on the effects of chevron topology was performed, and an optimised value was found for each parameter. From the aerodynamic measurement, the noise reduction was explained from the perspective of fluid dynamics. It was observed that installation of the chevron can raise the leading-edge shear layer and break up the large-scale vortices, thereby controlling the Rossiter mode noise and the landing gear model noise at certain frequencies.

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Scale effects on the performance of sawtooth spoilers in transonic rectangular cavity flow

Cited by 15 publications

References 20 publications

Energy harvesting from cavity flow oscillations

Energy harvesting from cavity flow oscillations

Effect of a Jet Control Device on the Process of Missile and Internal Weapons Bay Separation

Characterization of the aircraft bay/landing gear coupling noise at low subsonic speeds and its suppression using leading-edge chevron spoiler

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