Correlation for Length of Impinging Shock-Induced Large Separation Bubble at Hypersonic Speed

Sriram, R.; Jagadeesh, G.

doi:10.2514/1.j053271

Cited by 14 publications

(7 citation statements)

References 17 publications

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“…Similar correlations were also obtained based on experiments for laminar SBLI (Davis & Sturtevant 2000;Sriram & Jagadeesh 2015;Sriram et al 2016). While the variables in the correlations based on experimental and numerical data are the same or a modified form of the variables in the theoretically obtained scaling laws, notably the pressure term (the term in the right hand side of equation 4.1) is linear in the correlations, while the theory predicts a non-linear pressure term with an exponent of 1.5.…”

Section: Scaling Lawsupporting

confidence: 69%

On the scaling of three-dimensional shock-induced separated flow due to protuberances

2022

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Supersonic flow over 3-dimensional bodies protruding out of the turbulent boundary layer was investigated by means of experiments and numerical computations. A parametric study was performed by varying the shape and dimensions of the protuberance, as well as the freestream Mach number (1.5, 2, 2.5, 2.89, 3.5). The rise in surface pressure at mid-span due to separation (plateau pressure) was dependent only on the incoming flow parameters, and independent of protuberance geometry. The 2-dimensional free interaction theory closely predicts the mid-span plateau pressure. Although protuberances are of varying shapes and dimensions, the inviscid bow shock provided generalized scales. The radius of curvature of the inviscid shock on the wall plane at the nose, which is theoretically related to the local second derivative (along the shock) of pressure jump, was found to be a determining parameter of mid-span separation length (Lsep). Since the spanwise distance of the sonic point on the inviscid shock was found to be strongly correlated to its nose radius of curvature, it follows that the 'strong' portion of the inviscid bow shock fixes the mid-span separation location. These observations concerning mid-span plateau pressure, and the role of strong shock portion in fixing mid-span separation, suggest that the Lsep shall be predicted from a modification of the scaling laws for the length of plateau pressure region in 2-dimensional shock boundary layer interaction, with the inclusion of spanwise relieving effect. A correlation is obtained relating the Lsep with various incoming flow parameters and inviscid shock nose radius.

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Section: Scaling Lawsupporting

confidence: 69%

On the scaling of three-dimensional shock-induced separated flow due to protuberances

2022

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“…Previous SBLI experiments in hypersonic impulse facilities examined the high-temperature aerothermodynamic effects of flow separation in various model configurations. Such configurations include compression ramp/double wedge (Mallinson, Gai & Mudford 1997;Bleilebens & Olivier 2006;Swantek & Austin 2015;Knisely & Austin 2016;Wagner et al 2018) and impinging shock (Sandham et al 2014;Sriram & Jagadeesh 2015;Sriram et al 2016). In the two-dimensional impinging shock configuration, Sandham et al (2014) observed enhanced transition from impinging an oblique shock with a deflection angle of 2 • and 4 • at Mach 6; however, the shock strength was not sufficient to fully separate the boundary layer.…”

Section: Introductionmentioning

confidence: 99%

“…In the two-dimensional impinging shock configuration, Sandham et al (2014) observed enhanced transition from impinging an oblique shock with a deflection angle of 2 • and 4 • at Mach 6; however, the shock strength was not sufficient to fully separate the boundary layer. Researchers at the Indian Institute of Science (Sriram & Jagadeesh 2015;Sriram et al 2016) utilised a model with higher deflection angles of 27 • or 31 • to examine the laminar separation length L sep , the streamwise distance from the start of the separation to the impingement point. An inviscid scaling law between L sep and the reattachment pressure ratio was developed using their data.…”

Section: Introductionmentioning

confidence: 99%

Hypersonic shock impingement on a heated flat plate at Mach 7 flight enthalpy

et al. 2020

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“…However, as the wedge shock strength increases, we expect a transition to a normal reattachment where the reattachment pressure ratios are relatively high. The experimental observation of ‘large’ separation bubbles and a detached shock at reattachment that is strongly curved near the wall was reported by Sriram (2013), Sriram & Jagadeesh (2014, 2015), Srinath (2015) and Sriram et al. (2016).…”

Section: Modellingmentioning

confidence: 64%

Shock-induced leading-edge separation in hypersonic flows

et al. 2022

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We investigate the leading-edge separation, also called negligible boundary-layer thickness separation, induced by an impinging shock on a sharp flat plate. The canonical impinging shock wave/boundary-layer interaction configuration consisting of a wedge and a plate wall, placed in hypersonic free stream, is used for the investigations. We first construct a theoretical model for the leading-edge separated flow field (LESF) which predicts separation bubble geometry and surface pressure distribution as a function of three parameters: free-stream Mach number, wedge angle and the reattached flow turning angle. Markedly different predictions of the separated flow field are obtained for an oblique and a near normal reattachment on the plate surface. Experiments in a shock tunnel at a nominal Mach $6$ flow, with an impinging shock generated by a wedge of angle $26.6^{\circ }$ , are used to validate the model. Schlieren flow visualization using a high-speed camera and surface pressure measurements using fast response piezoelectric sensors are the diagnostics employed. For a range of shock impingement locations, the LESFs are observed to be geometrically similar and in good agreement with the LESF model. When the impingement location gets closer to the leading edge, it is observed from experiments that the flow field is no longer geometrically similar, and the separation angle increases as the impingement gets closer to the leading edge beyond the range of similarity. The work thereby offers an elaborate description of the leading-edge separated flow when shock impingement occurs near the plate leading edge.

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Correlation for Length of Impinging Shock-Induced Large Separation Bubble at Hypersonic Speed

Cited by 14 publications

References 17 publications

On the scaling of three-dimensional shock-induced separated flow due to protuberances

On the scaling of three-dimensional shock-induced separated flow due to protuberances

Hypersonic shock impingement on a heated flat plate at Mach 7 flight enthalpy

Shock-induced leading-edge separation in hypersonic flows

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