Flow field prediction and analysis study for project RAM B3 Final report
Flow field properties in shock layer surrounding Ram B3 vehicle
FLOW FIELD↗
SEARCH · Engineering Papers
Results for “SHOCK LAYER”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Numerical flow field prediction for Project RAM-C
Shock layer flow field calculations for RAM-C PROJECT
FLOW FIELD↗
Effects of Interaction Between Normal Shock and Boundary Layer
A discussion of the interaction between normal shocks and boundary layers on the basis of experimental evidence obtained in studies of supersonic flows in passages is given. The investigation was made as a result of the inability of the existing normal-shock theory to explain phenomena involving normal shocks that occurred in the presence of boundary layers. Assumptions with regard to the character of the effects of interaction between boundary layer and normal shock are proposed; these assumptions seem to give good agreement with certain experimental results.
Donaldson, Coleman duP.↗
High-resolution experimental spectra and theoretical studies of equilibrium radiation from a blunt body traveling at 37,000 ft/sec.
High resolution equilibrium radiation spectra for shock layer of blunt bodies at reentry velocities and radiative recombination of N and O ions
HIGH TEMPERATURE AIR↗
Hypersonic flow separation in shock wave boundary layer interactions
An assessment is presented for the experimental data on separated flow in shock wave turbulent boundary layer interactions at hypersonic and supersonic speeds. The data base consists mainly of two dimensional and axisymmetric interactions in compression corners or cylinder-flares, and externally generated oblique shock interactions with boundary layers over flat plates or cylindrical surfaces. The conditions leading to flow separation and the subsequent changes in the flow empirical correlations for incipient separation are reviewed. The effects of the Mach number, Reynolds number, surface cooling and the methods of detecting separation are discussed. The pertinent experimental data for the separated flow characteristics in separated turbulent boundary layer shock interaction are also presented and discussed.
Hamed, A.↗
Discussion of flight experiments with an entry research vehicle
The focus of interest is the maneuvering flight of advanced entry vehicles operating at altitudes above 50 km and at velocities of 5 to 8 km/s. Information resulting in more accurate aerodynamic analysis is sought and measurement techniques that appear to be applicable are identified. Measurements discussed include: shock layer or boundary layer profiles of velocity, temperature, species mass fractions, and other gas properties associated with aerodynamic heating; surface energy transfer process; nonequilibrium flow processes and pressure distribution; separated, vortic leeside flow of nonequilibrium fluid; boundary layer transition on highly swept configurations; and shock and surface slip and gas/surface interaction. Further study should focus on evolving measurement techniques, installation requirements, and on identification of the portions of flights where successful results seem probable.
Potter, J. L.↗
Aerothermal Effects of Hypersonic Shock Impingement on a Highly Swept Leading Edge
A numerical study is conducted to investigate aerothermal implications of oblique shock impingement on a highly swept leading edge in hypersonic flow, with flow conditions and geometry relevant to non-propulsive leading edge heating on hypersonic cruise vehicles. In contrast to propulsive inlet leading edge shock impingement, which has been subject to extensive historical study, bow shock impingement on a highly swept wing leading edge has received comparatively little attention in the literature. Distinguishing characteristics of this type of flow include a potentially dominant surface heating contribution from crossflow-induced viscous dissipation, possible wall velocity slip and temperature jump effects, and various modes of shock layer thermal nonequilibrium that can interact with shock impingement flowfield structures. One overall goal of this work is to assess the impact of bow shock impingement and related nonequilibrium phenomena for wing leading edge design, materials selection and thermal management. Another goal is to improve understanding – and thereby reduce associated design margins – for the physical processes and mechanisms that may influence wing leading edge heating in the presence of an impinging shock. A combination of direct simulation Monte Carlo and Reynolds-averaged Navier-Stokes analysis is used to assess surface and flowfield characteristics for a series of hypersonic shock impingement problems, based on historical ground tests and related flight conditions. Favorable comparisons are performed with experimental data, and various thermal nonequilibrium effects are quantified.
direct simulation Monte Carlo↗
Characterization of Titan Entry Radiative Heating in the Low Density Electric Arc Shock Tube
Prediction of aftbody radiative heating for Dragonfly’s entry at Titan requires accurate models to inform the design of its thermal protection systems. Previously reported investigations of shock layer aftbody radiation in the Electric Arc Shock Tube (EAST) at NASA Ames Research Center focused on the lower altitude/higher density part of the trajectory. This paper presents the first optical emission spectroscopy measurements of an ongoing test series in the new aluminum Low Density Shock Tube (LDST), recently installed at EAST, focusing on the radiative heating characterization through the higher altitude portion of Dragonfly’s entry path. Experimental data collected at a fill pressure of 0.1 Torr and shock velocities between 5.2 and 6.2 km/s show favorable agreement to similar conditions previously tested in the 4" High-Velocity Shock Tube, as well as improvements in the signal to noise ratio and available test time. Simulations employing DPLR and NEQAIR underpredict the experimental radiance, with increasing discrepancy from the NIR towards the UV wavelength range, thus motivating further efforts in improving the current non-Boltzmann model for the CN molecule.
A Fagnani↗
Numerical study of shock-wave/boundary layer interactions in premixed hydrogen-air hypersonic flows
A computational study of shock wave/boundary layer interactions involving premixed combustible gases, and the resulting combustion processes is presented. The analysis is carried out using a new fully implicit, total variation diminishing (TVD) code developed for solving the fully coupled Reynolds-averaged Navier-Stokes equations and species continuity equations in an efficient manner. To accelerate the convergence of the basic iterative procedure, this code is combined with vector extrapolation methods. The chemical nonequilibrium processes are simulated by means of a finite-rate chemistry model for hydrogen-air combustion. Several validation test cases are presented and the results compared with experimental data or with other computational results. The code is then applied to study shock wave/boundary layer interactions in a ram accelerator configuration. Results indicate a new combustion mechanism in which a shock wave induces combustion in the boundary layer, which then propagates outwards and downstream. At higher Mach numbers, spontaneous ignition in part of the boundary layer is observed, which eventually extends along the entire boundary layer at still higher values of the Mach number.
Yungster, Shaye↗
Numerical study of shock-wave/boundary layer interactions in premixed hydrogen-air hypersonic flows
A computational study of shock wave/boundary layer interactions involving premixed combustible gases, and the resulting combustion processes is presented. The analysis is carried out using a new fully implicit, total variation diminishing (TVD) code developed for solving the fully coupled Reynolds-averaged Navier-Stokes equations and species continuity equations in an efficient manner. To accelerate the convergence of the basic iterative procedure, this code is combined with vector extrapolation methods. The chemical nonequilibrium processes are simulated by means of a finite-rate chemistry model for hydrogen-air combustion. Several validation test cases are presented and the results compared with experimental data or with other computational results. The code is then applied to study shock wave/boundary layer interactions in a ram accelerator configuration. Results indicate a new combustion mechanism in which a shock wave induces combustion in the boundary layer, which then propagates outwards and downstream. At higher Mach numbers, spontaneous ignition in part of the boundary layer is observed, which eventually extends along the entire boundary layer at still higher values of the Mach number.
Yungster, Shaye↗
Heat transfer, velocity-temperature correlation, and turbulent shear stress from Navier-Stokes computations of shock wave/turbulent boundary layer interaction flows
The properties of 2-D shock wave/turbulent boundary layer interaction flows were calculated by using a compressible turbulent Navier-Stokes numerical computational code. Interaction flows caused by oblique shock wave impingement on the turbulent boundary layer flow were considered. The oblique shock waves were induced with shock generators at angles of attack less than 10 degs in supersonic flows. The surface temperatures were kept at near-adiabatic (ratio of wall static temperature to free stream total temperature) and cold wall (ratio of wall static temperature to free stream total temperature) conditions. The computational results were studied for the surface heat transfer, velocity temperature correlation, and turbulent shear stress in the interaction flow fields. Comparisons of the computational results with existing measurements indicated that (1) the surface heat transfer rates and surface pressures could be correlated with Holden's relationship, (2) the mean flow streamwise velocity components and static temperatures could be correlated with Crocco's relationship if flow separation did not occur, and (3) the Baldwin-Lomax turbulence model should be modified for turbulent shear stress computations in the interaction flows.
Wang, C. R.↗
Measurements of the response of a panel excited by shock boundary-layer interaction
Plate excitation by supersonic turbulent and shock boundary layers, measuring wall pressure fluctuation and panel displacement
Linden, T. L. J.↗
A documentation of two- and three-dimensional shock-separated turbulent boundary layers
A shock-related separation of a turbulent boundary layer has been studied and documented. The flow was that of an axisymmetric turbulent boundary layer over a 5.02-cm-diam cylinder that was aligned with the wind tunnel axis. The boundary layer was compressed by a 30 deg half-angle conical flare, with the cone axis inclined at an angle alpha to the cylinder axis. Nominal test conditions were P sub tau equals 1.7 atm and M sub infinity equals 2.85. Measurements were confined to the upper-symmetry, phi equals 0 deg, plane. Data are presented for the cases of alpha equal to 0. 5. and 10 deg and include mean surface pressures, streamwise and normal mean velocities, kinematic turbulent stresses and kinetic energies, as well as reverse-flow intermittencies. All data are given in tabular form; pressures, streamwise velocities, turbulent shear stresses, and kinetic energies are also presented graphically.
Brown, J. D.↗
Correlation of heat transfer for the zero pressure gradient hypersonic laminar boundary layer for several gases
A theoretical study of heat transfer for zero pressure gradient hypersonic laminar boundary layers for various gases with particular application to the flows produced in an expansion tube facility was conducted. A correlation based on results obtained from solutions to the governing equations for five gases was formulated. Particular attention was directed toward the laminar boundary layer shock tube splitter plates in carbon dioxide flows generated by high speed shock waves. Computer analysis of the splitter plate boundary layer flow provided information that is useful in interpreting experimental data obtained in shock tube gas radiation studies.
Cook, W. J.↗
Double layers and electrostatic shocks
It is shown that it is useful to define double layers and shocks so that the ion phase spaces of double layers are the mirror image (about zero ion velocity) of the ion phase spaces for laminar electrostatic shocks. The distinguishing feature is the direction of the free ion velocity. It is also shown that double layers can exist without the presence of trapped ions. The Bohm condition for double layers, that the ion drift velocity on the high potential side must be greater than the ion sound velocity, is shown to be related to a requirement of a lower limit on the Mach number of laminar electrostatic shocks
Hershkowitz, N.↗
Radiation Modeling for the Reentry of the Hayabusa Sample Return Capsule
Predicted shock-layer emission signatures during the reentry of the Japanese Hayabusa capsule are presented and compared with flight measurements conducted during an airborne observation mission in NASA's DC-8 Airborne Laboratory. For selected altitudes at 11 points along the flight trajectory of the capsule, lines of sight were extracted from flow field solutions computed using the in-house high-fidelity CFD code, DPLR. These lines of sight were used as inputs for the line-by-line radiation code NEQAIR, and emission spectra of the air plasma were computed in the wavelength range from 300 nm to 1600 nm, a range which covers all of the different experiments onboard the DC-8. In addition, the computed flow field solutions were post-processed with the material thermal response code FIAT, and the resulting surface temperatures of the heat shield were used to generate thermal emission spectra based on Planck radiation. Both spectra were summed and integrated over the flow field. The resulting emission at each trajectory point was propagated to the DC-8 position and transformed into incident irradiance to be finally compared with experimental data.
shock-layer radiation↗
Numerical study of boundary layer interaction with shocks: Method and code validation
A major problem in modeling of turbulent supersonic flows is the correct assessment of viscous-inviscid interaction problems. Of particular interest is the interaction of boundary layers with shocks. Present turbulence models give in most cases unsatisfactory results in the region of rapid distortion and in the separation region (if one is present) in particular with regard to mean flow profiles and turbulence quantities. The objective of the present work is the direct numerical simulation of shock boundary layer interaction. This report summarizes the first phase during which a numerical method suitable for this problem has been developed and a computer code has been written and tested.
Adams, Nikolaus A.↗
Flow separation in shock wave boundary layer interactions at hypersonic speeds
An assessment is presented for the experimental data on separated flow in shock wave turbulent boundary layer interactions at hypersonic and supersonic speeds. The data base consists mainly of two dimensional and axisymmetric interactions in compression corners or cylinder-flares, and externally generated oblique shock interactions with boundary layers over flat plates or cylindrical surfaces. The conditions leading to flow separation and the subsequent changes in the flow empirical correlations for incipient separation are reviewed. The effects of the Mach number, Reynolds number, surface cooling and the methods of detecting separation are discussed. The pertinent experimental data for the separated flow characteristics in separated turbulent boundary layer shock interaction are also presented and discussed.
Hamed, A.↗