Computation of Tone Noise from Supersonic Jet Impinging on Flat Plates

Loh, Ching Y.; Blech, Richard A.

doi:10.2514/6.2005-418

Cited by 9 publications

(4 citation statements)

References 17 publications

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“…The axially symmetric or three-dimensional (3-D) Euler equations have for instance been solved by Sakakibara & Iwamoto (2002) in order to study the oscillatory phenomenon of an underexpanded jet impinging on a flat plate perpendicularly. Similarly, Kim & Park (2005) and Loh (2005) carried out simulations using the axisymmetric Navier-Stokes equations. The latter authors investigated the staging behaviour of the oscillation frequency with the nozzle-to-plate distance and jet pressure ratio.…”

Section: Introductionmentioning

confidence: 99%

Feedback loop and upwind-propagating waves in ideally expanded supersonic impinging round jets

2017

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The aeroacoustic feedback loop establishing in a supersonic round jet impinging on a flat plate normally has been investigated by combining compressible large-eddy simulations and modelling of that loop. At the exit of a straight pipe nozzle of radius $r_{0}$, the jet is ideally expanded, and has a Mach number of 1.5 and a Reynolds number of $6\times 10^{4}$. Four distances between the nozzle exit and the flat plate, equal to $6r_{0}$, $8r_{0}$, $10r_{0}$ and $12r_{0}$, have been considered. In this way, the variations of the convection velocity of the shear-layer turbulent structures according to the nozzle-to-plate distance are shown. In the spectra obtained inside and outside of the flow near the nozzle, several tones emerge at Strouhal numbers in agreement with measurements in the literature. At these frequencies, by applying Fourier decomposition to the pressure fields, hydrodynamic-acoustic standing waves containing a whole number of cells between the nozzle and the plate and axisymmetric or helical jet oscillations are found. The tone frequencies and the mode numbers inferred from the standing-wave patterns are in line with the classical feedback-loop model, in which the loop is closed by acoustic waves outside the jet. The axisymmetric or helical nature of the jet oscillations at the tone frequencies is also consistent with a wave analysis using a jet vortex-sheet model, providing the allowable frequency ranges for the upstream-propagating acoustic wave modes of the jet. In particular, the tones are located on the part of the dispersion relations of the modes where these waves have phase and group velocities close to the ambient speed of sound. Based on the observation of the pressure fields and on frequency–wavenumber spectra on the jet axis and in the shear layers, such waves are identified inside the present jets, for the first time to the best of our knowledge, for a supersonic jet flow. This study thus suggests that the feedback loop in ideally expanded impinging jets is completed by these waves.

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Section: Introductionmentioning

confidence: 99%

Feedback loop and upwind-propagating waves in ideally expanded supersonic impinging round jets

2017

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“…Numerical as well as both experimental and numerical simulations of unsteady impinging jets have also been carried out. Among them, some investigations involved in studying the self-induced oscillation [14], instabilities [15,16], modes of oscillation [17], near-field noise [18], TVD simulations [3], [19] to study the oscillations and generation of acoustic waves, Large Eddy Simulation [20], flow behavior coaxial impinging jets [21], etc. Recently, Yaga et al [22] conducted 3D investigations on the flow characteristics of rectangular under-expanded impinging jets both experimentally and numerically.…”

Section: Introductionmentioning

confidence: 99%

Effect of non-equilibrium homogeneous condensation on the self-induced flow oscillation of supersonic impinging jets

Alam

Matsuo

Setoguchi

2010

International Journal of Thermal Sciences

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“…Kandula and Vu [5] have considered deflection of a single cold jet by a J-deflector and examined the effect of closure of the deflector on the generated noise levels. Krothapalli et al [6], Thurow et al [7], Loh [8], and Varnier and Raguenet [9], are some of the few that have examined the situation of noise from a jet impinging on a plate. From these investigations, it can be summarized that the sound level increases due to the presence of the plate and would be even stronger with edged obstacles due to impingement of subsonic jets.…”

Section: Introductionmentioning

confidence: 99%

Suppression of Jet Noise by Staged Water Injection during Launch Vehicle Lift-Off

Ignatius

Sankaran

Kumar

et al. 2008

International Journal of Aeroacoustics

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Jet noise during the lift-off of a launch vehicle is complicated by the simultaneous flow of multiple jets, and their deflection by jet deflectors. Further, the presence of the launch pedestal, the service structure, and the moving vehicle itself, act as reflecting surfaces, which contribute to the noise environment. The present work involves the suppression of noise as measured at different parts of the launch vehicle in a small-scale replica of a full launch pad, for different locations of the vehicle along its vertical lift-off trajectory. The primary source of noise is the two jets emerging from the base of the launch vehicle at a Mach number of 3.38. Noise is suppressed by water injection at different locations in the launch pad such as the upstream and downstream edges of the jet deflector cover-plate, bottom and top of the launch pedestal, and at two different locations on the service structure. The effect of staged injection of water, i.e., without and with injection at different heights relative to the position of the jets, as the vehicle is at different locations in its trajectory, is examined. It is found that sustained suppression of noise is obtained only with injection of water in successive stages closer to the nozzle exit, as the jet position is moved up. The effect of angle of injection of water is investigated to verify previously reported results that an injection angle of 60°, i.e., along the flow, is superior to injection at 90°to the jet. The effect of injection pressure shows an optimum that supports the effective atomization of the injected water jets into droplets due to shear by the gas jet flow. Investigation with hot jets shows increased noise levels by at least ~2 dB relative to cold jets of nearly the same nozzle-exit Mach number. However, an increased reduction of noise by water injection is apparent with hot jets. The reduction is nearly independent of the jet temperature in the 600-900 K range. The present results collectively confirm the qualitative applicability of different previous studies on single free jets to the complicated launch vehicle noise scenario.

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Computation of Tone Noise from Supersonic Jet Impinging on Flat Plates

Cited by 9 publications

References 17 publications

Feedback loop and upwind-propagating waves in ideally expanded supersonic impinging round jets

Feedback loop and upwind-propagating waves in ideally expanded supersonic impinging round jets

Effect of non-equilibrium homogeneous condensation on the self-induced flow oscillation of supersonic impinging jets

Suppression of Jet Noise by Staged Water Injection during Launch Vehicle Lift-Off

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