Numerical Solutions of the Navier-Stokes Equations for the Supersonic Laminar Flow Over a Two-dimensional Compression Corner


Book Description

Numerical solutions have been obtained for the supersonic, laminar flow over a two-dimensional compression corner. These solutions were obtained as steady-state solutions to the unsteady Navier-Stokes equations using the finite-difference method of Brailovskaya, which has the second-order accuracy in the spatial coordinates. Good agreement was obtained between the computed results and the wall pressure distributions measured experimentally by Lewis, Kubota, and Lees for Mach numbers of 4 and 6.06, and respective Reynolds numbers, based on free-stream conditions and the distance from the leading edge to the corner, of 6.8 x 104 and 1.5 x 105. In those calculations, as well as in others, sufficient resolution was obtained to show the streamline pattern in the separation bubble. Upstream boundary conditions to the compression-corner flow were provided by numerically solving the unsteady Navier-Stokes equations for the flat-plate flow field, beginning at the leading edge. The compression-corner flow field was enclosed by a computational boundary with the unknown boundary conditions supplied by extrapolation from internally computed points. Numerical tests were performed to deduce that the magnitude of the errors introduced by the extrapolation was small. Calculations were made to show the effect of ramp angle and wall suction on the interaction flow field. The pressure distributions obtained in the present calculations, including a case of incipient separation, were plotted together by using the free-interaction scaling of Stewartson and Williams. A good correlation of the numerical results was found, but only fair agreement was found between this correlation and the universal pressure distribution found numerically by Stewartson and Williams.




Scientific and Technical Aerospace Reports


Book Description

Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.







Computational Study of Supersonic Flow Over Backward-Facing Steps at High Reynolds Number


Book Description

The problem of laminar separated flow over a backward-facing step is solved numerically for the limiting case of infinite Reynolds number. The flow model adopted is that deduced by Batchelor for incompressible flow: an inviscid rotational eddy confined within the recirculation portion of the separated shear layer. It is argued that the reattachment process is essentially inviscid in the limit R approaches infinity, and the flow field in the reattachment zone is computed on this basis. The computed results support Chapman's model of the reattachment process as the correct limit case, to second-order accuracy, as the flow angle entering the reattachment zone approaches zero. For the recirculation zone, the boundary-layer equations are simplified by assuming a constant pressure eddy. The Dorodnitsyn transformation is applied and numerical solutions obtained using an implicit finite-difference scheme. The solutions are carried out from station-to-station in the direction of flow over a complete cycle of recirculation. Iteration yields the unique value of the vorticity in the inviscid layer upstream of separation, including the effects of corner expansion and recirculation on the development of the separated shear layer. (Author).







Aeronautical Engineering


Book Description

A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA).







A Second Order Accurate Numerical Method for Supersonic Boundary Layer Flow Past a Compression Corner


Book Description

The compressible and incompressible boundary layer equations are solved for laminar flow past a configuration with an interior (concave) compression region. The approach first employs conformal coordinates to map the body geometry to a flat wall, and then the boundary layer scale laws to identify the principal terms of the compressible counterpart of the Navier-Stokes equations. A Levy-Lees type transformation is identified in these coordinates to simplify the governing equations. These are then solved with a second-order accurate numerical scheme in both the longitudinal and normal directions. Solutions are obtained for adiabatic and 'warm' wall conditions for configurations with and without separation. Emphasis is placed here on achieving accurate reliable results while maintaining minimal computer time expenditure. (Author).