Aerodynamic Noise in Supersonic Wind Tunnels

Laufer, John

doi:10.2514/8.9150

Cited by 194 publications

(63 citation statements)

References 3 publications

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“…Schneider [19] presents an extensive review of the effect of tunnel noise on transition. Using transition locations measured in noisy tunnels to infer transition locations in the low-noise flight environment introduces significant uncertainty in expected flight transition locations [23]. Transition data from noisy tunnels can still be helpful for studying the various instabilities themselves, provided the noise does not alter their evolution.…”

Section: Experimental Overviewmentioning

confidence: 99%

Traveling Crossflow Instability for the HIFiRE-5 Elliptic Cone

Borg

Kimmel

Stanfield

2015

Journal of Spacecraft and Rockets

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A 38.1%-scale model of the Hypersonic International Flight Research Experimentation Program's Flight Five 2:1 elliptic cone flight vehicle was used to investigate the traveling crossflow instability in a Mach 6 quiet wind tunnel. Traveling crossflow waves were detected with pressure sensors mounted flush with the model surface. The crossflow instability phase speed and wave angle were calculated from the cross spectra of the three pressure sensors. Both quantities showed good agreement with linear stability theory. Duplicate runs at the same initial conditions showed excellent repeatability in traveling crossflow wave properties. Traveling crossflow waves in quiet flow showed very low levels of nonlinear interactions. No traveling crossflow waves were observed for any Reynolds number for elevated freestream noise levels, but transition occurred for a much lower Reynolds number than in quiet flow. Due to the lack of nonlinear growth in quiet flow and the absence of traveling crossflow waves in noisy flow, it appeared that the traveling crossflow instability was not the primary transition mechanism on the model for quiet or noisy flow in this wind tunnel. Nomenclature c r = phase speed, m∕s E = expected value operator f = frequency, kHz I = imaginary part of complex number p 0 = fluctuating component of pressure, Pa R = real part of complex number Re = freestream unit Reynolds number, 1∕m S = cross spectrum s = Fourier transform of signal s T = temperature or record length, K or s x = Streamwise coordinate, mm y = spanwise coordinate, mm γ 2 = coherence η = circumferential coordinate ξ = axial coordinate σ = standard deviation τ = time delay, μs ϕ = phase of cross spectrum, deg Ψ = wave angle, angle between phase velocity and axial direction, deg Subscripts aw = evaluated at adiabatic wall conditions stat = static conditions w = evaluated at wall conditions Superscripts = complex conjugate 0 = rotated coordinate system

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Section: Experimental Overviewmentioning

confidence: 99%

Traveling Crossflow Instability for the HIFiRE-5 Elliptic Cone

Borg

Kimmel

Stanfield

2015

Journal of Spacecraft and Rockets

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“…Because the second-mode waves exist for a long distance, a clear and complete visualization of the transition process has not been reported before. Figure 4 shows the PCB time series filtered with passband (300, 400) and (11,50) kHz. Figure 3 shows frequency spectra of the pressure time series for Re unit 9.7 × 10 6 per meter.…”

Section: A Rayleigh-scattering Visualizationsmentioning

confidence: 99%

“…in which, for air, S 110 K, μ r 1.716 × 10 −5 N · s∕m 2 , and T r 273 K. Disturbances in hypersonic wind tunnels are dominated by sound waves, which are radiated by the turbulent boundary layers of the nozzle walls [49][50][51]. A measurement of the normalized pitot pressure has been accepted as a standard method to characterize the freestream disturbance level in the test section [52].…”

Section: A Test Facilitymentioning

confidence: 99%

Transition in Hypersonic Boundary Layers: Role of Dilatational Waves

et al. 2016

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Transition and turbulence production in a hypersonic boundary layer is investigated in the Mach 6 wind tunnel at Peking University, using Rayleigh-scattering visualization, fast-response pressure measurements, and particle image velocimetry. Detailed analysis of the experimental observations is provided. It is found that, although the second mode is primarily an acoustic wave, it causes the formation of high-frequency vortical waves. Moreover, the second mode interacts strongly with low-frequency waves, which leads to immediate transition to turbulence.freestream velocity, m∕s u = velocity vector, m∕s u = x component of the velocity, m∕s v = y component of the velocity, m∕s w = z component of the velocity, m∕s x = streamwise coordinate along the cone's surface, mm y = coordinate normal to the cone's surface, mm z = transverse coordinate normal to the x-y plane, mm= viscous normal stress, Pa ρ = density, kg∕m 3 τ f = flow time scale, s τ p = particle relaxation time, s Φ = viscous dissipation function per unit volume, kg∕m · s 3 ω = vorticity, 1∕s

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“…We performed those simulations based on the experimental observation 14 that in the transitional zone of the axisymmetric nozzle in SLDT the noise sources are propagating at this speed. But experimental observations [22][23][24] and direct numerical simulations 24 show that noise sources in two-dimensional nozzle wall boundary layers and in flat-plate turbulent boundary layers propagate close to 0.4 ~ 0.5 times the freestream velocity at supersonic Mach numbers. Additionally, measurements of source velocity ~0.2 to 0.5 times the freestream velocity were done in the 2D nozzle of SLDT at Mach 3.5.…”

Section: Interaction Of Nonuniform Three-dimensional Radiated Acoustimentioning

confidence: 99%

Receptivity and Forced Response to Acoustic Disturbances in High-Speed Boundary Layers

et al. 2018

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Supersonic boundary-layer receptivity to freestream acoustic disturbances is investigated by solving the Navier-Stokes equations for Mach 3.5 flow over a sharp flat plate and a 7-deg halfangle cone. The freestream disturbances are generated from a wavy wall placed at the nozzle wall. The freestream acoustic disturbances radiated by the wavy wall are obtained by solving the linearized Euler equations. The results for the flat plate show that instability modes are generated at all the incident angles ranging from zero to highly oblique. However, the receptivity coefficient decreases by about 20 times when the incident angle increases from zero to a highly oblique angle of 68 degrees. The results for the cone show that no instability modes are generated when the acoustic disturbances impinge the cone obliquely. The results show that the perturbations generated inside the boundary layer by the acoustic disturbances are the response of the boundary layer to the external forcing. The amplitude of the forced disturbances inside the boundary layer are about 2.5 times larger than the incoming field for zero azimuthal wavenumber and they are about 1.5 times for large azimuthal wavenumbers.

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Aerodynamic Noise in Supersonic Wind Tunnels

Cited by 194 publications

References 3 publications

Traveling Crossflow Instability for the HIFiRE-5 Elliptic Cone

Traveling Crossflow Instability for the HIFiRE-5 Elliptic Cone

Transition in Hypersonic Boundary Layers: Role of Dilatational Waves

Receptivity and Forced Response to Acoustic Disturbances in High-Speed Boundary Layers

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