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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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Transport property difference effect on flow prediction of blunt body stagnation region heat transfer, noting laminar flow and compressible boundary layer equations
Empirical stagnation point-heat transfer relation in gas mixtures at high enthalpy potentials
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Extension to MHD hypersonic stagnation flow theory of Bush, including viscous term and solving boundary value problem from both ends at once
Solutions indicating Boltzmann and Bueger numbers effect on radiant heat transfer and shock standoff distance for inviscid radiating shock layer
Coupling between inviscid and viscid flows in hypersonic stagnation region investigated at high flight velocities with significant radiative heat transfer
Velocity gradient on blunt axisymmetric bodies in stagnation region if pressure distribution is known, using isentropic flow equations
Previously, the stability of a premixed flame in a stagnation flow was discussed for a restricted class of disturbances that are self-similar to the basic undisturbed flow; thus, flame fronts with corrugations only in the cross stream direction were considered. Here, we consider a more general class of three-dimensional flame front perturbations which also permits corrugations in the streamwise direction. It is shown that, because of the stretch experienced by the flame, the hydrodynamic instability is limited only to disturbances of short wavelength. If in addition diffusion effects have a stabilizing influence, as would be the case of mixtures with Lewis number greater than one, a stretched flame could be absolutely stable. Instabilities occur when the Lewis number is below some critical value less than one. Neutral stability boundaries are presented in terms of the Lewis number, the strain rate, and the appropriate wavenumbers. Beyond the stability threshold, the two-dimensional self-similar modes always grow first. However, if disturbances of long wavelength are excluded, it is possible for the three-dimensional modes to be the least stable one. Accordingly, the pattern that will be observed on the flame front, at the onset of instability, will consist of either ridges in the direction of stretch or the more common three-dimensional cellular structure.
The process of ablation is calculated for the stagnation region of a flat disk in a radiation-dominated, massive-blowing environment produced in a ballistic range filled with argon. Flow environments are determined by solving the boundary-layer equations while radiative transfer is calculated through a line-by-line spectral computation. The resulting wall heat-transfer rates are coupled with an existing material's response code to determine surface recession and char thickness. The calculation is performed for six 5-cm-diam models made of carbon-phenolic and carbon-carbon composite launched in the Track-G facility at the Arnold Engineering Development Center. Significant surface recessions are predicted to occur for these models due mostly to radiative heating.
Stagnation pressure and heat transfer measurements of blunt axisymmetric bodies
The results of an earlier paper on the behavior of the boundary layer at an axisymmetric stagnation with hydrogen injection into a hot external airstream are extended to span the entire range from essentially frozen to essentially equilibrium flow. This extension is made possible by the employment of finite difference methods; the accurate treatment of the boundary conditions at 'infinity,' the differencing technique employed and the formulation resulting in block tri-diagonal matrices are slight variants in the present work.
Program computes solutions for flow parameters in arbitrary gas mixtures behind a normal and a reflected normal shock, for in-flight and shock-tube stagnation conditions. Equilibrium flow calculations are made by a free-energy minimization technique coupled with the steady-flow conservation equations and a modified Newton-Raphson iterative scheme.
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Charts of thermodynamic properties of helium showing effects of ionization, particle interactions, temperature, and atmospheric pressure
Solution for shock layer energy equation with mass and convective heat transfer at hypersonic speed
He and Ar arc-heated flows into reservoir and expansion in converging-diverging supersonic nozzles, considering flow equilibrium effect on heat transfer and enthalpy
Necessary improvements to a paper on the flow of a dusty gas by Datta and Mishra (1980) are presented. Particular attention is given to the importance of particle phase compressibility and the hyperbolic nature of the particle momentum conservation equation which prohibits downstream (wall) boundary conditions for the solid phase. Fundamental differences between particulate and ordinary flow boundary layers are discussed, and the correct conservation equations are written.