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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Numerical solution of a three-dimensional shock wave and turbulent boundary-layer interaction

A rapid numerical scheme is used to solve the complete mass-averaged Navier-Stokes equations for supersonic turbulent flow over a three-dimensional compression corner. A simple eddy viscosity model is developed, and the interaction of a swept shock wave and a three-dimensional turbulent boundary layer is studied. Good agreement is obtained between the present results and experimental measurements for the case of a wedge with an angle of 6 deg on a flat-plate sidewall. For the case of a 12-deg wedge angle, the computed results do not show the existence of a peak pressure found experimentally. However, the range of interaction, the plateau pressure, and the peak heat transfer are closely predicted for all cases. The high heat transfer near the axial corner is due to the thinning of the boundary layer and inflow of fresh high-momentum fluid. The heat transfer is relieved through pressure reduction and boundary-layer thickening.

Hung, C. M.↗
NASA NTRS1996

Experimental Investigation of Crossing Shock Wave-Turbulent Boundary Layer-Bleed Interaction

Results of an experimental investigation of a symmetric crossing shock wave/turbulent boundary layer/bleed interaction are presented for a freestream unit Reynolds number of 1.68 x 10(exp 7)/m, a Mach number of 2.81, and deflection angles of 8 degrees. The data obtained in this study are bleed mass flow rate using a trace gas technique, qualitative information in the form of oil flow visualization, flow field Pitot pressures, and static pressure measurements using pressure sensitive paint. The main objective of this test is two-fold. First, this study is conducted to explore boundary layer control through mass flow removal near a large region of separated flow caused by the interaction of a double fin-induced shock wave and an incoming turbulent boundary layer. Also, a comprehensive data set is needed for computational fluid dynamics code validation.

Kim, Hyun↗
NASA NTRS1985

Simulation of Blunt-Fin-Induced Shock-Wave and Turbulent Boundary-Layer Interaction

The Reynolds-averaged Navier-Stokes equations are solved numerically for supersonic flow over a blunt fin mounted on a flat plate. The fin shock causes the boundary layer to separate. which results in a complicated, three-dimensional shock-wave and boundary-layer interaction. The computed results are in good agreement with the mean static pressure measured on the fin and the flat plate. The main features, such as peak pressure on the fin leading edge and a double peak on the plate. are predicted well. The role of the horseshoe vortex is discussed. This vortex leads to the development of high-speed flow and, hence, low-pressure regions on the fin and the plate. Different thicknesses of the incoming boundary layer have been studied. Varying the thicknesses by an order of magnitude shows that the size of the horseshoe vortex and, therefore, the spatial extent of the interaction are dominated by inviscid flow and only weakly dependent on the Reynolds number. Colored graphics are used to show details of the interaction flow field.

Hung, Ching-Mao↗
NASA NTRS1979

A study of the interaction of a normal shock wave with a turbulent boundary layer at transonic speeds

An asymptotic description is derived for the interaction of a weak normal shock wave and a turbulent boundary layer along a plane wall. In the case studied the nondimensional friction velocity is small in comparison with the nondimensional shock strength, and the shock wave extends well into the boundary layer. Analytical results are described for the local pressure distribution and wall shear, and a criterion for incipient separation is proposed. A comparison of predicted pressures with available experimental data includes the effect of longitudinal wall curvature.

Messiter, A. F.↗
NASA NTRS1989

Preliminary study of the interactions caused by crossing shock waves and a turbulent boundary layer

The subject research, the first phase of an extended study of the interaction of crossing shock waves with a turbulent boundary layer, has revealed the complexity of the resulting flow. Detailed surface visualization and mean wall static pressure distributions show little resemblance to the inviscid flow approximation, and the exploratory high frequency measurements show that the flow downstream of the theoretical inviscid shock crossing position has a significant unsteady characteristic. Further developments of the (unsteady) high frequency measurements are required to fully characterize the unsteadiness and the requirements to include this component in flowfield modeling.

Ketchum, A. C.↗
NASA NTRS1974

Analysis of the interaction of a weak normal shock wave with a turbulent boundary layer

The method of matched asymptotic expansions is used to analyze the interaction of a normal shock wave with an unseparated turbulent boundary layer on a flat surface at transonic speeds. The theory leads to a three-layer description of the interaction in the double limit of Reynolds number approaching infinity and Mach number approaching unity. The interaction involves an outer, inviscid rotational layer, a constant shear-stress wall layer, and a blending region between them. The pressure distribution is obtained from a numerical solution of the outer-layer equations by a mixed-flow relaxation procedure. An analytic solution for the skin friction is determined from the inner-layer equations. The significance of the mathematical model is discussed with reference to existing experimental data.

Melnik, R. E.↗
NASA NTRS1976

Experiments planned specifically for developing turbulence models in computations of flow fields around aerodynamic shapes

Building block experiments and companion numerical simulations intended to verify and guide turbulence modeling are described. A series of experiments and computations being used to enhance modeling development for the shock wave turbulent boundary layer interaction problem is emphasized. Results are given for transonic flow over a circular arc airfoil undergoing shock wave induced, boundary layer separation for supersonic flow along a tube wall undergoing normal shock wave induced, boundary layer separation. Experimental data which use the complete Navier-Stokes equations are discussed.

Marvin, J. G.↗
NASA NTRS1983

An experimental investigation of the impingement of a planar shock wave on an axisymmetric body at Mach 3

An experimental study of the flow caused by a planar shock wave impinging obliquely on a cylinder is presented. The complex three dimensional shock wave and boundary layer interaction occurring in practical problems, such as the shock wave impingement from the shuttle nose on an external fuel tank, and store carriage interference on a supersonic tactical aircraft were investigated. A data base for numerical computations of complex flows was also investigated. The experimental techniques included pressure measurements and oil flow patterns on the surface of the cylinder, and shadowgraphs and total and static pressure surveys on the leeward and windward planes of symmetry. The complete data is presented in tabular form. The results reveal a highly complex flow field with two separation zones, regions of high crossflow, and multiple reflected shocks and expansion fans.

Brosh, A.↗
NASA NTRS1991

Pressure and temperature fluctuations in an axisymmetric flowfield due to shock-boundary layer interactions at high Reynolds numbers at Mach 6

Pressure and temperature fluctuations have been meausred in the vicinity of shock wave-boundary layer interactions due to conical compression ramps on an axisymmetric body. The basic model is a cylindrical body with a 10-deg conical nose. Four conical ramps of vertex angles, 20, 25, 30, and 35 deg serve as shock wave generators. Surface temperature and pressure surveys have been made in the vicinity of the conical ramp vertex, the separation point, and the reattachment point. The temperature response within the flowfield appears to be steady-state for all compression ramp angles and all Reynolds numbers. The pressure response shows some oscillations in the vicinity of the separation point. The characteristic frequency of these fluctuations appears to be in the range from 200 to 1200 Hz with most of the power near 400 Hz. These data indicate the flowfield to be steady-state for all locations with the exception of localized pressure fluctuations in the vicinity of the separation point.

Flanagan, M. J., Jr.↗
NASA NTRS1984

Simulation of blunt-fin-induced shock wave and turbulent boundary-layer interaction

A supersonic flow over a blunt fin mounted on a flat plate is numerically simulated. The fin shock causes the boundary layer to separate and results in a complicated, three-dimensional shockwave and boundary-layer interaction. The computed result is in good agreement with the measured pressure on the fin and the flat plate. The main features, such as peak pressure on the fin leading edge and a double peak pressure on the plate, are closely predicted. The role of the horseshoe vortex is discussed. The vortex leads to the development of high-speed flow, and, hence, low-pressure regions on the fin and the plate. Different thicknesses of the incoming boundary layer have been studied. Varying the thicknesses by an order of magnitude shows that the size of the horseshoe vortex and therefore the spatial extent of the interaction are inviscid-dominated, and are weakly dependent on the Reynolds number. Colored graphics are used to show details of the interaction flow field.

Hung, C.-M.↗
NASA NTRS1972

Shock wave oscillation driven by turbulent boundary layer fluctuations

Pressure fluctuations due to the interaction of a shock wave with a turbulent boundary layer were investigated. A simple model is proposed in which the shock wave is convected from its mean position by velocity fluctuations in the turbulent boundary layer. Displacement of the shock is assumed limited by a linear restoring mechanism. Predictions of peak root mean square pressure fluctuation and spectral density are in excellent agreement with available experimental data.

Plotkin, K. J.↗
NASA NTRS1975

On the calculation of supersonic, separating, and reattaching flows

A method is developed for solving the laminar and turbulent compressible boundary-layer equations for separating and reattaching flows. Results of this method are compared with experimental data for two laminar and three turbulent boundary-layer, shock-wave interactions. Several Navier-Stokes solutions were obtained for each of the laminar boundary-layer, shock-wave interactions considered. Comparison of these solutions indicates a first-order sensitivity in C sub f to the computational mesh selected in both the viscous and inviscid portions of the flow.

Murphy, J. D.↗