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Salas, M. D.

Publications and source records attributed to Salas, M. D..

61 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

The Split Coefficient Matrix method for hyperbolic systems of gasdynamic equations

The Split Coefficient Matrix (SCM) finite difference method for solving hyperbolic systems of equations is presented. This new method is based on the mathematical theory of characteristics. The development of the method from characteristic theory is presented. Boundary point calculation procedures consistent with the SCM method used at interior points are explained. The split coefficient matrices that define the method for steady supersonic and unsteady inviscid flows are given for several examples. The SCM method is used to compute several flow fields to demonstrate its accuracy and versatility. The similarities and differences between the SCM method and the lambda-scheme are discussed.

Chakravarthy, S. R.↗
NASA NTRS1979

A careful numerical study of flowfields about external conical corners. I - Symmetric configurations

A numerical study of the flowfield about symmetrical external axial corners formed by the juncture of swept compressive wedges is presented. The geometrical configuration under investigation allows a unified treatment of external corners typical of delta wings and of rectangular inlets. Comparisons are made with other numerical results. For the delta wing configuration, the occurrence of an anomalous shock behavior predicted by Gonor is discussed. A parametric study shows the singular behavior of the pressure at the corner as a function of the external corner angle, and a second parametric study shows the effect of finite corner radius on the location of the crossflow stagnation point. Previous theoretical predictions of certain flow features typical of corner flows agree well with present numerical results.

Salas, M. D.↗
NASA NTRS1979

Flow patterns near a conical sonic line

A study is made in the physical plane of the flow properties near a conical cross flow sonic line. The shapes of the Mach lines at regular and singular sonic points are presented. Through a study of the jump conditions at a singular sonic point, the possibility of a double sonic line is discussed. The properties of bubbles of supersonic cross flow are examined. Numerical results are presented to support some of the theoretical observations.

Salas, M. D.↗
NASA NTRS1978

Structure of the conical flowfield about external axial corners

A theoretical and experimental investigation of the flowfield about symmetrical and asymmetrical external axial corners formed by the juncture of swept compressive wedges is presented. A study is made of the nature of inviscid cross flow stagnation points and their dependence on certain flow parameters is derived. The importance of imposing the physically relevant boundary condition for numerical simulations is discussed. For the asymmetrical wedge configuration, the proper boundary condition along the axial corner is shown to be a conical analog of Prandtl-Meyer flow. Further insight into the flow structure is revealed by the experimental results.

Salas, M. D.↗
NASA NTRS1975

The anatomy of floating shock fitting

The floating shock fitting technique is examined. Second-order difference formulas are developed for the computation of discontinuities. A procedure is developed to compute mesh points that are crossed by discontinuities. The technique is applied to the calculation of internal two-dimensional flows with arbitrary number of shock waves and contact surfaces. A new procedure, based on the coalescence of characteristics, is developed to detect the formation of shock waves. Results are presented to validate and demonstrate the versatility of the technique.

Salas, M. D.↗
NASA NTRS1974

The numerical calculation of inviscid plume flow fields

A numerical method is presented for the computation of inviscid, axisymmetric, underexpanded plumes. The numerical techniques developed by Moretti (1969, 1971, 1972) are used in conjunction with Abbett's (1970) theory for locating the Mach disk. Abbett's theory and three other prediction methods are compared to experimental results. Results are presented for jets exhausting into static ambients and supersonic free stream. Detailed results from a flow field with multiple Mach disks are also presented. Finally, some problems associated with the computation of very small Mach disks are discussed.

Salas, M. D.↗