Showing papers on "Scramjet published in 1981"

Numerical analysis of the scramjet inlet flow field using two-dimensional Navier-Stokes equations

Abstract: A computer code was developed to solve the full two dimensional Navier-Stokes equations in a supersonic combustion ramjet (scramjet) inlet. In order to be able to consider a general inlet geometry with embedded bodies, a numerical coordinate transformation is used which generates a set of boundary-fitted curvilinear coordinates. The explicit finite difference algorithm of MacCormack is used to solve the governing equations. An algebraic, two-layer eddy-viscosity model is used for the turbulent flow. The code can analyze both inviscid and viscous flows with no strut, one strut, or multiple struts in the flow field. The application of the two dimensional analysis in the preliminary parametric design studies of a scramjet inlet is discussed. Detailed results are presented for one model problem and for several actual scramjet-inlet configurations.

A parametric study of staged fuel injector configurations for scramjet applications

Abstract: A parametric study of staged (multiple) perpendicular fuel injector configurations has been conducted using a computer code which solves the two-dimensional elliptic Navier-Stokes equations. The program computes the turbulent mixing and reaction of hydrogen fuel and air and allows the study of separated regions of the flow immediately preceding and following the injectors. The validity of the code is demonstrated in a cold flow helium injection study with a single injector. Results are presented that describe the flow field near opposing staged injectors over a range of parameters. Parameters that are varied include injector size, fuel split, and distance between injectors. Comparisons of the configurations are made to assess their mixing and potential flame-holding qualities.

Operating characteristics of the Langley Mach 7 Scramjet Test Facility

Abstract: Operating characteristics of the Langley Mach 7 Scramjet Test Facility are described. The facility is designed for testing airframe integrated scramjet (supersonic combustion ramjet) engine models. Features include duplication of the flight Mach number total enthalpy, flight altitude simulation, and simulation of engine airframe integration effects such a bow shock wave precompression and boundary layer ingestion by the engine. Data obtained from facility calibration and from tests of a hydrogen burning, airframe integrated scramjet are discussed. An adverse interaction between the facility flow and the scramjet engine flow during combustion of the fuel is described.

Multiple-scale turbulence modeling of boundary layer flows for scramjet applications

Abstract: As part of an investigation into the application of turbulence models to the computation of flows in advanced scramjet combustors, the multiple-scale turbulence model was applied to a variety of flowfield predictions The model appears to have a potential for improved predictions in a variety of areas relevant to combustor problems This potential exists because of the partition of the turbulence energy spectrum that is the major feature of the model and which allows the turbulence energy dissipation rate to be out of phase with turbulent energy production The computations were made using a consistent method of generating experimentally unavailable initial conditions An appreciable overall improvement in the generality of the predictions is observed, as compared to those of the basic two-equation turbulence model A Mach number-related correction is found to be necessary to satisfactorily predict the spreading rate of the supersonic jet and mixing layer

Critical considerations in the design of supersonic combustion ramjet /scramjet/ engines

Abstract: The design and estimation of the performance of a supersonic combustion ramjet (scramjet) engine is critically dependent on the geometry and efficiency of each of the engine components. Therefore, it is mandatory to be cognizant of all the available experimental data and theoretical modeling that has been established if a credible design is to be obtained. The purpose of this paper is to reiterate norms for component geometries, lengths, internal losses, and combustion kinetics that have been established and/or substantiated in the technical literature and to illustrate the sensitivity of engine performance to deviations from those norms. A specific exemplary engine design is presented and used to illustrate these effects. The results show that the maximum predicted net engine thrust can be overestimated by as much as 45% if more idealistic assumptions, similar to those used in the design of conventional subsonic combustion ramjet engines, are used.

A survey of heating and turbulent boundary layer characteristics of several hypersonic research aircraft configurations

Abstract: Four of the configurations investigated during a proposed NASA-Langley hypersonic research aircraft program were selected for phase-change-paint heat-transfer testing and forebody boundary layer pitot surveys. In anticipation of future hypersonic aircraft, both published and unpublished data and results are reviewed and presented with the purpose of providing a synoptic heat-transfer data base from the research effort. Engineering heat-transfer predictions are compared with experimental data on both a global and a local basis. The global predictions are shown to be sufficient for purposes of configuration development, and even the local predictions can be adequate when interpreted in light of the proper flow field. In that regard, cross flow in the forebody boundary layers was examined for significant heating and aerodynamic effect on the scramjet engines. A design philosophy which evolved from the research airplane effort is used to design a forebody shape that produces thin, uniform, forebody boundary layers on a hypersonic airbreathing missile. Finally, heating/boundary layer phenomena which are not predictable with state-of-the-art knowledge and techniques are shown and discussed.