Stationary-traveling cross-flow mode interactions with periodic distributed roughness

53rd AIAA Aerospace Sciences Meeting

Hofferth

et al. 2015

A 2:1 elliptic cone model was tested in a variable-Mach-number conventional hypersonic wind tunnel. Freestream Reynolds number, Mach number, model streamwise location, and model wall temperature were all varied to ascertain the effect of each on measured disturbances. A low-frequency disturbance was observed at Mach 5.8. It experienced some growth in excess of the increasing freestream pressure and noise for a narrow Reynolds number range. Disturbance properties were similar to what was measured in another conventional hypersonic wind tunnel. For Mach 6.5 and 7, there was no evidence of traveling crossflow waves. However, higher-frequency disturbances were observed. These disturbances were nearly two-dimensional and had phase speeds near the expected edge velocity. It is possible that these disturbances were second mode waves. None of the measured disturbances corresponded to any feature of the freestream Pitot spectra.

Section: Introductionmentioning

confidence: 99%

Freestream Effects on Boundary Layer Disturbances for HIFiRE-5

53rd AIAA Aerospace Sciences Meeting

Hofferth

et al. 2015

“…4 Considerable study has been made of crossflow instabilities for incompressible flows. [3][4][5][6][7][8][9] It has been established that stationary modes undergo a period of linear growth, saturate nonlinearly, and then develop secondary instabilities that rapidly lead to transition. 3,7 The majority of historic crossflow research has focused on stationary modes, since this is expected to be the dominant crossflow instability in the lownoise flight environment.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Infrared and Pressure Measurements of Crossflow Instability Modes for HIFiRE-5

54th AIAA Aerospace Sciences Meeting

2016

“…Considerable study has been made of crossflow instabilities for incompressible flows [5][6][7][8][9][10][11]. It has been established that stationary modes undergo a period of linear growth, saturate nonlinearly, and then develop secondary instabilities that rapidly lead to transition [5,9].…”

mentioning

confidence: 99%

Traveling Crossflow Instability for the HIFiRE-5 Elliptic Cone

Journal of Spacecraft and Rockets

Stanfield

2015

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