Experimental and computational study of laminar cavity flows at hypersonic speeds

Jackson, A.; Hillier, R.; Soltani, Saeed

doi:10.1017/s0022112000002433

Cited by 37 publications

(14 citation statements)

References 27 publications

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“…In this case an additional parameter is introduced in the problem, namely the angle φ between the lid motion and the axial direction of the duct. Besides providing the link between the PCF and LDC flows, the combined wall-bounded-Couette/LDC flow serves as a model of three-dimensional flow in open cavities at high speeds, where experimental and numerical work has related hypersonic flow in an open cavity to incompressible LDC flow (Jackson, Hillier & Soltani 2001). Despite its relative complexity, such a model offers substantial simplifications in instability investigations of open cavities (Rowley, Colonius & Basu 2002) and represents the first effort employing non-parallel global instability analysis techniques to a cavity flow comprising a three-component velocity vector.…”

Section: Introductionmentioning

confidence: 99%

Viscous linear stability analysis of rectangular duct and cavity flows

2004

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The viscous linear stability of four classes of incompressible flows inside rectangular containers is studied numerically. In the first class the instability of flow through a rectangular duct, driven by a constant pressure gradient along the axis of the duct (essentially a two-dimensional counterpart to plane Poiseuille flow – PPF), is addressed. The other classes of flow examined are generated by tangential motion of one wall, in one case in the axial direction of the duct, in another perpendicular to this direction, corresponding respectively to the two-dimensional counterpart to plane Couette flow (PCF) and the classic lid-driven cavity (LDC) flow, and in the fourth case a combination of both the previous tangential wall motions. The partial-derivative eigenvalue problem which in each case governs the temporal development of global three-dimensional small-amplitude disturbances is solved numerically. The results of Tatsumi & Yoshimura (1990) for pressure-gradient-driven flow in a rectangular duct have been confirmed; the relationship between the eigenvalue spectrum of PPF and that of the rectangular duct has been investigated. Despite extensive numerical experimentation no unstable modes have been found in the wall-bounded Couette flow, this configuration found here to be more stable than its one-dimensional limit. In the square LDC flow results obtained are in line with the predictions of Ding & Kawahara (1998b), Theofilis (2000) and Albensoeder et al. (2001b) as far as one travelling unstable mode is concerned. However, in line with the predictions of the latter two works and contrary to all previously published results it is found that this mode is the third in significance from an instability analysis point of view. In a parameter range unexplored by Ding & Kawahara (1998b) and all prior investigations two additional eigenmodes exist, which are both more unstable than the mode that these authors discovered. The first of the new modes is stationary (and would consequently be impossible to detect using power-series analysis of experimental data), whilst the second is travelling, and has a critical Reynolds number and frequency well inside the experimentally observed bracket. The effect of variable aspect ratio $A\in[0.5,4]$ of the cavity on the most unstable eigenmodes is also considered, and it is found that an increase in aspect ratio results in general destabilization of the flow. Finally, a combination of wall-bounded Couette and LDC flow, generated in a square duct by lid motion at an angle $\phi\in(0,{\pi}/{2})$ with the homogeneous duct direction, is shown to be linearly unstable above a Reynolds number $\Rey\,{=}\,800$ (based on the lid velocity and the duct length/height) at all $\phi$ parameter values examined. The excellent agreement with experiment in LDC flow and the alleviation of the erroneous prediction of stability of wall-bounded Couette flow is thus attributed to the presence of in-plane basic flow velocity components.

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Section: Introductionmentioning

confidence: 99%

Viscous linear stability analysis of rectangular duct and cavity flows

2004

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“…An important feature to note from both the Stanton number (figure 7) and skin friction (figure 8) distributions is that they all go to zero at the bottom corner of the step. This is a characteristic feature of a two-dimensional laminar flow at a concave corner, as pointed out by Jackson et al (2001).…”

Section: Grid Independence Studymentioning

confidence: 75%

“…In figure 6, details of the grid are illustrated for Grid-5. Jackson, Hillier & Soltani (2001) and others (Papadopoulos et al 1999;Bertin & Cummings 2006) consider the surface heat flux as one of the critical variables for determining grid independence since this is said to provide a sensitive test for CFD calculations. In the present investigation also, the surface heat flux is chosen for determining grid independence in addition to considering the skin friction coefficient.…”

Section: Grid Independence Studymentioning

confidence: 99%

High-enthalpy flow over a rearward-facing step – a computational study

2012

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Hypersonic, high-enthalpy flow over a rearward-facing step has been numerically investigated using computational fluid dynamics (CFD). Two conditions relevant to suborbital and superorbital flow with total specific enthalpies of 26 and 50 MJ kg −1 , are considered. The Mach number and unit Reynolds number per metre were 7.6, 11.0 and 1.82 × 10 6 , 6.23 × 10 5 respectively. The Reynolds number based on the step height was correspondingly 3.64 × 10 3 and 12.5 × 10 2 . The computations were carried out assuming the flow to be laminar throughout and the real gas effects such as thermal and chemical non-equilibrium are studied using Park's two-temperature model with finite-rate chemistry and Gupta's finite-rate chemistry models. In the close vicinity of the step, detailed quantification of flow features is emphasised. In particular, the presence of the Goldstein singularity at the lip and separation on the face of the step have been elucidated. Within the separated region and downstream of reattachment, the influence of real gas effects has been identified and shown to be negligible. The numerical results are compared with the available experimental data of surface heat flux downstream of the step and reasonable agreement is shown up to 30 step heights downstream.

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“…A good example of this approach is the ogive-cylinder-flare model of Wideman et al 45 shown in figure 2. It is also recognised 29 , however, that an axisymmetric configuration cannot guarantee (time-averaged) two-dimensionality, in particular the formation of cellular (streamwise) structures or Goertler-type vortices especially once flow separation is involved 9,22,29,30,35,40 . Figure 3 shows a rearward-facing step separated flow, generated at the base of a sting-supported circular section cone and conducted in the Imperial College Gun Tunnel.…”

Section: Introductionmentioning

confidence: 99%

Gun Tunnel Studies of Shock-Wave/Boundary-Layer Interactions; Laminar, Transitional and Turbulent

Hillier¹

2015

20th AIAA International Space Planes and Hypersonic Systems and Technologies Conference

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This paper reviews projects carried out in the Imperial College Gun Tunnel and presents experimental results for shock-wave/boundary-layer interactions, generally severe enough to cause flow separation. Our objective is to target test cases that can be regarded as building blocks for complete vehicles and to produce benchmark data that may be suitable for code validation and to improve knowledge of the flow physics. The first results review our studies on two-dimensional axisymmetric shock wave interactions with a turbulent boundary layer. This is followed by a managed three-dimensional distortion of these flows to produce a range of separations that could be regarded as ranging from weakly threedimensional to strongly three-dimensional. Finally a study is made of the interaction between turbulent spots convecting past an, initially laminar, axisymmetric separated flow.

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Experimental and computational study of laminar cavity flows at hypersonic speeds

Cited by 37 publications

References 27 publications

Viscous linear stability analysis of rectangular duct and cavity flows

Viscous linear stability analysis of rectangular duct and cavity flows

High-enthalpy flow over a rearward-facing step – a computational study

Gun Tunnel Studies of Shock-Wave/Boundary-Layer Interactions; Laminar, Transitional and Turbulent

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