Shock Turbulent Boundary Layer Interaction Research Articles

Characteristics of the cylinder-induced shock wave and turbulent boundary layer interactions

Characteristics of the cylinder-induced shock wave and turbulent boundary layer interactions

Wall modeled large eddy simulation of supersonic flow physics over compression–expansion ramp

In the present work, wall modeled large-eddy simulation (WMLES) in the Fluent software is used to investigate the flow physics of a three-dimensional shock–turbulent boundary layer interaction, as an important phenomenon in aerospace science, on a compression–expansion ramp with the angle of 25°. Fine flow structures are obtained via Laplacian of density that called shadowgraph, in which shock wave structures are visible distinctly. The results are compared with the experimental data of Zheltovodov et al., 1990 [33], in the same condition regarding geometry, boundary conditions, etc. as those used by them. Results show that not only there are a good agreement with experimental trends concerning wall pressure, friction coefficient distribution and mean velocity profiles, but also in comparison with those presented by Grilli et al., 2013 [24]. LES simulation, used in this study, presents more accurate results with fewer computational costs. Afterwards, we investigated the influence of discontinuity in wall temperature, varying stagnation pressure and Reynolds number on physics of flow in order to control the shock behavior. Our simulations shows that, discontinuity in wall temperature, varying free stream stagnation pressure and Reynolds number (the free stream Mach number remained essentially constant) influences the starting point of shock, shock strength, separation length and the collision angle of separated and reattachment shock waves.

Uncertainty Assessment of Hypersonic Aerothermodynamics Prediction Capability

The present paper provides the background of a focused effort to assess uncertainties in predictions of heat flux and pressure in hypersonic flight (airbreathing or atmospheric entry) using state-of-the-art aerothermodynamics codes. The assessment is performed for four mission relevant problems: (1) shock turbulent boundary layer interaction on a compression corner, (2) shock turbulent boundary layer interaction due a impinging shock, (3) high-mass Mars entry and aerocapture, and (4) high speed return to Earth. A validation based uncertainty assessment approach with reliance on subject matter expertise is used. A code verification exercise with code-to-code comparisons and comparisons against well established correlations is also included in this effort. A thorough review of the literature in search of validation experiments is performed, which identified a scarcity of ground based validation experiments at hypersonic conditions. In particular, a shortage of useable experimental data at flight like enthalpies and Reynolds numbers is found. The uncertainty was quantified using metrics that measured discrepancy between model predictions and experimental data. The discrepancy data is statistically analyzed and investigated for physics based trends in order to define a meaningful quantified uncertainty. The detailed uncertainty assessment of each mission relevant problem is found in the four companion papers.

Experimental investigation of the micro-ramp based shock wave and turbulent boundary layer interaction control

Using a nanoparticle-based planar laser-scattering technique and supersonic particle image velocimetry, we investigated the effects of micro-ramp control on incident shockwave and boundary-layer interaction (SWBLI) in a low-noise supersonic wind-tunnel with Mach number 2.7 and Reynolds number Rθ = 5845. High spatiotemporal resolution wake structures downstream of the micro-ramps were detected, while a complex evolution process containing a streamwise counter-rotating vortex pair and large-scale hairpin-like vortices with Strouhal number Stδ of about 0.5–0.65 was revealed. The large-scale structures could survive while passing through the SWBLI region. Reflected shockwaves are clearly seen to be distorted accompanied by high-frequency fluctuations. Micro-ramp applications have a distinct influence on flow patterns of the SWBLI field that vary depending on spanwise locations. Both the shock foot and separation line exhibit undulations corresponding with modifications of the velocity distribution of the incoming boundary layer. Moreover, by energizing parts of the boundary flow, the micro-ramp is able to dampen the separation.

Development of A Two-Equation Turbulence Model for Hypersonic Shock Wave and Turbulent Boundary Layer Interaction

For hypersonic compressible turbulence, the correlations with respect to the density fluctuation must not be neglected. A Reynolds averaged K-ε model is proposed in the present paper to include these correlations, together with the Reynolds averaged Navier-Stokes equations to describe the mean flowfield. The K-equation is obtained from Reynolds averaged single-point second moment equations which are deduced from the instantaneous compressible Navier-Stokes equations. Under certain hypotheses and scales estimation of the compressible terms, the K-equation is simplified. The correlation terms of the fluctuation field appearing in the resulting K-equation, together with a conventional form of the ε-equation, are thus correlated with the variables in the average field. The new modeling coefficients of closure terms are optimized by computing the hypersonic turbulent flat-plate measured by Coleman and Stollery [J. Fliud Mech., Vol. 56 (1972), p. 741]. The proposed model is then applied to simulate hypersonic turbulent flows over a wedge compression corner angle of 34 degree. The predicting results compare favorably with the experimental results. Also, comparisons are made with other turbulence models. Additionally, an entropy modification function of Harten-Yee’s TVD scheme is introduced to reduce artificial diffusion near boundary layers and provide the required artificial diffusion to capture the shockwaves simultaneously.

Numerical study of shock-turbulent boundary layer interactions with incipient and complete separation

This paper aims at describing the main features of a separated boundary layer in shock reflection at a Mach number of 2.3. The data used for this analysis were taken from large eddy simulations of the interactions for three-shock intensities, resulting in flow cases from incipient to fully separated. Computational results were validated versus experimental data. The main space-time properties of the reflected shock motion are described together with their link with the other flow regions. The analysis of the correlations between the shock motion and the unsteady pressure field provides information about the origins of shock unsteadiness.

Direct Numerical Simulation of Supersonic Turbulent Boundary Layer over a Compression Ramp

A direct numerical simulation of shock wave and turbulent boundary layer interaction for a 24 deg compression ramp configuration at Mach 2.9 and Re θ 2300 is performed. A modified weighted, essentially nonoscillatory scheme is used. The direct numerical simulation results are compared with the experiments of Bookey et al. at the same flow conditions. The upstream boundary layer, the mean wall-pressure distribution, the size of the separation bubble, and the velocity profile downstream of the interaction are predicted within the experimental uncertainty. The change of the mean and fluctuating properties throughout the interaction region is studied. The low frequency motion of the shock is inferred from the wall-pressure signal and freestream mass-flux measurement.

1609 正方形ダクト内における衝撃波と乱流境界層の干渉に関する実験的研究(S35-2 圧縮性流れの基礎と応用(2),S35 圧縮性流れの基礎と応用)

1609 正方形ダクト内における衝撃波と乱流境界層の干渉に関する実験的研究(S35-2 圧縮性流れの基礎と応用(2),S35 圧縮性流れの基礎と応用)

Study on shock wave and turbulent boundary layer interactions in a square duct at Mach 2 and 4

In this paper, the outline of the Mach 4 supersonic wind tunnel for the investigation of the supersonic internal flows in ducts was firstly described. Secondly, the location, structure and characteristics of the Mach 2 and Mach 4 pseudo-shock waves in a square duct were investigated by color schlieren photographs and duct wall pressure fluctuation measurements. Finally, the wall shear stress distributions on the side, top and bottom walls of the square duct with the Mach 4 pseudo-shock wave were investigated qualitatively by the shear stress-sensitive liquid crystal visualization method. The side wall boundary layer separation region under the first shock is narrow near the top wall, while the side wall boundary layer separation region under the first shock is very wide near the bottom wall.

Study on Supersonic Internal Flows with Shock Waves Investigation by Numerical Analysis on the Internal Structure of Mach 2 Pseudo-Shock Wave in a Two-Dimensional Channel.

This paper describes an investigation by numerical simulation and experiment on the structure and characteristics of the multiple shock waves and turbulent boundary layer interaction, that is, pseudo-shock wave in a Mach 2 two-dimensional channel. The numerical simulation was carried out with Harten-Yee's second-order accuracy TVD scheme and Baldwin-Lomax's algebraic compressible model for turbulent flows. Good agreement between the numerical analysis and the experiment for the shape of the shock train of the pseudo-shock wave and the wall pressure distribution along the channel was obtained. Based on this agreement, the flow quantities, which are very difficult to obtained by experiment, were analyzed by numerical simulation. These analyses are very valuable for understanding of the detailed structure and characteristics of the pseudo-shock wave. The study conditions are M∞≅2.0 (free stream Mach number), Re∞=2.5×107m-1 (unit Reynolds number), δ∞/h=0.25 (flow confinement), respectively.

Computation of internal high-speed separated flow with modified B-L and J-K models

The existence of shock–turbulent boundary layer interactions lead to very complicated flow phenomena and pose a challenge for numerical simulation. In this paper, two turbulence models, the Baldwin–Lomax (B–L) model and the Johnson–King (J–K) model, which were originally developed for simple external flow simulation, are modified to model complex high-speed internal separated flows. The full Navier–Stokes solver used in this paper is based on a cell-centered finite volume method and multistepping time marching scheme. Both implicit residual smoothing and local time stepping techniques are incorporated to accelerate the convergence rate. To ensure the numerical stability with the present explicit scheme, a point-implicit treatment to the source term in the ordinary differential equation (ODE) of the J–K model has been developed and has proved to be very effective in modeling such a complex flow. An arc-bump channel flow case has been studied. Comparisons of computed results with experimental data show that the present solver, with the modified turbulence models, predicts the shock and the flow separation very well. The J–K model is found to predict the size of the separation bubble with a higher accuracy. © 1998 John Wiley & Sons, Ltd.

Fluorescent paint for measurement of heat transfer in shock - turbulent boundary layer interaction

The principles of the fluorescent paint technique for surface heat transfer measurement are presented. This technique allows determination of the heat transfer from a surface with good accuracy and high spatial resolution. To examine the capabilities of this technique, the temperature-sensitive paint is used to visualize and measure heat transfer in several typical shock-turbulent boundary layer interactions. Quantitative comparison of the measured heat transfer with existing data obtained using conventional methods is discussed.

Aerodynamic heating in the region of shock and turbulent boundary layer interaction induced by a cylinder

Detailed distributions of heat flux in the region of shock wave and turbulent boundary layer interaction induced by a cylinder were measured in the shock tunnel. Oil flow patterns and Schlieren photographs were taken. Empirical relations were given for determining separation shock angle, peaks of heat flux and their locations on both cylinder leading edge and flat plate surface, and other characteristic parameters of the interaction region.