Experimental Study of Crossflow Instability over a Delta Flat Plate at Mach 6

Niu, Haibo; Yi, Shihe; Liu, Xiaolin; Lu, Xiaoge; He, Lin

doi:10.2514/1.j058576

Cited by 19 publications

(4 citation statements)

References 29 publications

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“…Much attention has been paid to transition over three-dimensional (3-D) configurations due to its strong relevance to realistic hypersonic vehicles. Related 3-D geometries that have previously been investigated include bodies of rotation at non-zero angles of attack (Ward, Henderson & Schneider 2015;Craig & Saric 2016), elliptic cones (Kimmel et al 2013), the lifting body (Chen et al 2021b) and the delta wing model (Niu et al 2019). These 3-D bodies are subject to an azimuthal or spanwise pressure gradient that transfers fluid from a high-pressure to a low-pressure region.…”

Section: Introductionmentioning

confidence: 99%

“…Experimentally, stationary vortices can be observed as time-averaged streak structures using surface temperature measurements or oil-flow visualisation, while travelling ones are much more difficult to visualise. Niu et al (2019) investigated the cross-flow instability over a delta flat plate at Mach 6. The model's flat surface was convenient for planar laser diagnostics to capture the flow structure of travelling cross-flow vortices at the frequency of 14 kHz.…”

Section: Introductionmentioning

confidence: 99%

“…2021 b ) and the delta wing model (Niu et al. 2019). These 3-D bodies are subject to an azimuthal or spanwise pressure gradient that transfers fluid from a high-pressure to a low-pressure region.…”

Section: Introductionmentioning

confidence: 99%

“…Niu et al. (2019) investigated the cross-flow instability over a delta flat plate at Mach 6. The model's flat surface was convenient for planar laser diagnostics to capture the flow structure of travelling cross-flow vortices at the frequency of 14 kHz.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Boundary layer transition of hypersonic flow over a delta wing

Qiu,

Shi,

Zhu

et al. 2024

J. Fluid Mech.

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Cross-flow transition over a delta wing is systematically studied in a Mach 6.5 hypersonic wind tunnel, employing the Rayleigh scattering flow visualisation, high-speed schlieren and fast-response pressure sensors. Direct numerical simulations and analysis based on linear stability theory under the same flow conditions are applied to analyse the transition mechanism. Three unstable modes are identified: the travelling cross-flow instabilities, the second mode and the low-frequency waves. It is shown that the travelling cross-flow vortices first appear in the cross-flow region near the leading edge of the model. These vortices can modulate the mean profile of the flow, which benefits the growth of second mode. A phase-locked interaction mechanism transfers energy from the cross-flow instabilities to the high-frequency second mode, leading to amplification at the expense of the cross-flow instability. As the second mode grows to a critical amplitude, it triggers a $z$ -type secondary instability within a similar frequency range, which introduces secondary finger-like structures connecting to the cross-flow vortex. It is further found that the generation of these finger-like structures is related to the expansion and compression of the second mode. These finger vortices further evolve along the streamwise direction into low-frequency waves and corresponding hairpin-like structures that finally trigger turbulence. An interaction mechanism likely exists between the secondary instability and the low-frequency waves, since their phase speeds are approaching each other. These observations of the interaction mechanism are consistent with those of previous studies on hypersonic boundary layers (Zhang et al., Phys. Fluids, vol. 32 (7), 2020, 071702; Li et al., Phys. Fluids, vol. 32 (5), 2020, 051701).

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