A Measurement of Instability Wave in the Hypersonic Boundary Layer on a Sharp Cone

Fujii, Keisuke; Hirabayashi, Noriaki; Ogawa, Hiroshi; Koyama, Tadao; Tsuda, S.; Nakagawa, Muneyoshi; Itabashi, Yukihiro; Nakamura, Akihiro

doi:10.2514/6.2011-3871

Cited by 9 publications

(4 citation statements)

References 5 publications

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“…For experiments in hypersonic wind tunnels, the frequency is typically in the high kHz region (Maslov et al 2005;Casper et al 2009;Fujii et al 2011;Wagner et al 2013). There are a few high-speed sensors, that allow the direct measurement of the second (Mack) modes.…”

Section: Introductionmentioning

confidence: 99%

Experiments on the effect of laminar–turbulent transition on the SWBLI in H2K at Mach 6

2015

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than two and an increase in the heat flux by a factor of more than four. Therefore, big areas of laminar flow are desirable to increase the performance of a propelled vehicle and to reduce the weight of the necessary thermal protection systems of a propelled or re-entry vehicle. On the other hand, turbulent boundary layers have a lower tendency to separate and are preferred in regions of large pressure gradients. Hence, the correct prediction of the transition is essential for the design of future hypersonic vehicles and their thermal protection systems.Shock wave-boundary layer interactions (SWBLI) are inevitable for most of the practical applications. They can cause locally increased pressure and thermal loads, cause separations and have a great influence onto the transition process. Most of the existing publications in this field deal with interactions of shock waves with turbulent boundary layers (Dupont et al. 2006; Schülein 2006;Humble et al. 2009; Helmer 2011;Grilli et al. 2012), some handle the case of interactions of shock waves with laminar boundary layers (Boin et al. 2006;Lüdeke and Sandham 2009;Brown and Boyce 2009) but investigations of the interaction between shock waves and transitional boundary layers are rare (Dolling 2001;Arnal and Delery 2004;Benay et al. 2006;Vanstone et al. 2013). In order to study these phenomena in detail within the framework of the ESA-TRP "laminar to turbulent transition in hypersonic flows," experiments in three different facilities using several measuring techniques have been carried out (Sandham et al. 2014). This paper describes the results of the experiments performed in the hypersonic wind tunnel H2K at DLR in Cologne.The transition process of undisturbed hypersonic boundary layers is most likely driven by instabilities called second (Mack) modes (Mack 1975). These are acoustic waves trapped between the wall and the sonic line. Therefore, Abstract This paper presents the results of the experiments performed in the hypersonic wind tunnel H2K in the framework of the ESA technology research project "laminar to turbulent transition in hypersonic flows". The investigations include the free boundary-layer transition on a flat plate as well as the influence of a shock wave-boundary layer interaction on the transition. The shock is created by a wedge with a small angle of attack resulting in a moderate shock intensity. The experiments were performed at Mach 6.0, at three different unit Reynolds numbers and with a translational displacement of the shock generator. Besides the optical methods-Schlieren photography and infrared thermography-several intrusive sensors were used. High-speed measurements were carried out using PCB and atomic layer thermo pile sensors. Kulite sensors were used for low-and mid-speed pressure measurements. The data analysis includes the comparison of the absolute values, the frequency spectra and wavelets and their distributions in time and space.

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Section: Introductionmentioning

confidence: 99%

Experiments on the effect of laminar–turbulent transition on the SWBLI in H2K at Mach 6

2015

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“…Fujii et al (2011) used surface-mounted pressure transducers to measure the second-mode instability and its growth rate along a generator of the cone; additionally, the nonlinear phase coupling of the disturbances was analysed by the bicoherence method. Casper (2009) and Berridge (2010) made hypersonic boundary-layer instability measurements with piezo-electric pressure transducers in a low-disturbance hypersonic facility.…”

Section: Measurement Of Second-mode Instabilitymentioning

confidence: 99%

Observations of hypervelocity boundary-layer instability

2015

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A novel optical method is used to measure the high-frequency (up to 3 MHz) density fluctuations that precede transition to turbulence within a laminar boundary layer in a hypervelocity flow. This optical method, focused laser differential interferometry, enables measurements of short-wavelength, high-frequency disturbances that are impossible with conventional instrumentation such as pressure transducers or hot wires. In this work, the T5 reflected-shock tunnel is used to generate flows in air, nitrogen and carbon dioxide with speeds between 3.5 and 5 km s ), density fluctuations are observed to grow in amplitude and transition from a single narrow band of frequencies consistent with the Mack or second mode of boundary-layer instability to bursts of large-amplitude and spectrally broad disturbances that appear to be precursors of turbulent spots. Disturbances that are sufficiently small in initial amplitude have a wavepacket-like signature and are observed to grow in amplitude between the upstream and downstream measurement locations. A cross-correlation analysis indicates propagation of wavepackets at speeds close to the edge velocity. The free stream flow created by the shock tunnel and the resulting boundary layer on the cone are computed, accounting for chemical and vibrational non-equilibrium processes. Using this base flow, local linear and parabolized stability (PSE) analyses are carried out and compared with the experimental results. Reasonable agreement is found between measured and predicted most unstable frequencies, with the greatest differences being approximately 15 %. The scaling of the observed frequency with the inverse of boundary-layer thickness and directly with the flow velocity are consistent with the characteristics of Mack's second mode, as well as results of previous researchers on hypersonic boundary layers.

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“…One such ground-test facility to generate "high-enthalpy" flows is the reflected-shock tunnel. In the past, researchers have used shock tunnels and reflected-shock tunnels to study BLT [7][8][9][10][11][12][13]. More recently, in the HEG reflected-shock tunnel, Laurence et al [14][15][16] report a schlieren-based technique for the investigation of disturbances in hypervelocity boundary layers.…”

Section: Introductionmentioning

confidence: 99%

Effects of Shock-Tube Cleanliness on Slender-Body Hypersonic Instability and Transition Studies at High-Enthalpy

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53rd AIAA Aerospace Sciences Meeting

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A Measurement of Instability Wave in the Hypersonic Boundary Layer on a Sharp Cone

Cited by 9 publications

References 5 publications

Experiments on the effect of laminar–turbulent transition on the SWBLI in H2K at Mach 6

Experiments on the effect of laminar–turbulent transition on the SWBLI in H2K at Mach 6

Observations of hypervelocity boundary-layer instability

Effects of Shock-Tube Cleanliness on Slender-Body Hypersonic Instability and Transition Studies at High-Enthalpy

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