Reacting Viscous-shock-layer Solutions with Multicomponent Diffusion and Mass Injection


Book Description

This study presents numerical solutions of the viscous-shock-layer equations where the chemistry is treated as being either frozen, equilibrium, or nonequilibrium. Also the effects of the diffusion model, surface catalysis, and mass injection on surface transport and flow parameters are considered. The flow is treated as a mixture of five inert and thermally perfect species. The viscous-shock-layer equations are solved by using an implicit-difference scheme. All calculations are for hyperboloids with included angles of 20° and 45°. The flight conditions are those for various altitudes and velocities in the Earth's atmosphere. Data are presented to show the effects of the chemical models; diffusion models; surface catalysis; and mass injection of air on heat transfer; skin friction; shock standoff distance; wall pressure distribution; and tangential victory, temperature, and species profiles. The results show that an equilibrium analysis can substantially overpredict the heat-transfer rates for flow conditions experienced by earth-orbital entry vehicles. Moreover, at such conditions surface catalysis significantly influences heat-transfer and flow-field properties. If a binary rather than a multicomponent diffusion model is assumed, negligible errors in most flow properties result. Quantitative results are presented that show the effect of mass injection on flow properties within and downstream of the injection region.







Nonreacting and Chemically Reacting Viscous Flows Over a Hyperboloid at Hypersonic Condition


Book Description

Contents: A survey of higher-order boundary-layer theory; Finite difference solution of the first-order boundary-layer equations; Laminar boundary-layer calculations on bodies of revolution in hypersonic flow; Solution of the viscous shock-layer equations for a binary mixture; Viscous shock-layer problem for the stagnation point of a blunt body; Chemically reacting boundary layer effects for the agard engineering applications body and flow conditions; Computation of higher-order boundary-layer effects with a first-order treatment and comparison with experimental data; Higher-order boundary-layer effects for the agard engineering applications body and flow conditions; The hypersonic viscous shock-layer problem; Numerical methods for nonreacting and chemically reacting laminar flows - tests and comparisons.




A Thin-shock-layer Solution for Nonequilibrium, Inviscid Hypersonic Flows in Earth, Martian, and Venusian Atmospheres


Book Description

An approximate inverse solution is presented for the nonequilibrium flow in the inviscid shock layer about a vehicle in hypersonic flight. The method is based upon a thin-shock-layer approximation and has the advantage of being applicable to both subsonic and supersonic regions of the shock layer. The relative simplicity of the method makes it ideally suited for programming on a digital computer with a significant reduction in storage capacity and computing time required by other more exact methods. Comparison of nonequilibrium solutions for an air mixture obtained by the present method is made with solutions obtained by two other methods. Additional cases are presented for entry of spherical nose cones into representative Venusian and Martian atmospheres. A digital computer program written in FORTRAN language is presented that permits an arbitrary gas mixture to be employed in the solution. The effects of vibration, dissociation, recombination, electronic excitation, and ionization are included in the program.




Viscous Shock-layer Analysis on Hypersonic Flow Over Reentry Capsule with Nonequilibrium Chemistry


Book Description

The aerothermodynamic environment around a "EXPRESS" reentry capsule at hypersonic speed is studied in the flight regime of the severe wall heating rate with emphasis on the effects of the wall catalycity and temperature by using the axisymmetric viscous shock-layer equations with the seven-air-species non equilibrium chemistry. The wall heating rate and the electron number density in the shock-layer over the capsule are predicted at various altitudes on its night trajectory. In order to evaluate the wall catalycity, the finite catalytic wall model is introduced. The sensitivity of the wall heating rate to the uncertainties in the chemical reaction model and the wall condition model is investigated parametrically. The extent of the influences of the wall conditions on the shock-layer flow properties strongly depends on the extent of flow non equilibrium.