Engineering topics

Delguidice, P.

Publications and source records attributed to Delguidice, P..

6 records

NASA NTRS1978

Shock capturing finite-difference and characteristic reference plane techniques for the prediction of three-dimensional nozzle-exhaust flowfields

This report summarizes work accomplished under Contract No. NAS1-12726 towards the development of computational procedures and associated numerical. The flow fields considered were those associated with airbreathing hypersonic aircraft which require a high degree of engine/airframe integration in order to achieve optimized performance. The exhaust flow, due to physical area limitations, was generally underexpanded at the nozzle exit; the vehicle afterbody undersurface was used to provide additional expansion to obtain maximum propulsive efficiency. This resulted in a three dimensional nozzle flow, initialized at the combustor exit, whose boundaries are internally defined by the undersurface, cowling and walls separating individual modules, and externally, by the undersurface and slipstream separating the exhaust flow and external stream.

Dash, S.↗

NASA NTRS1974

Methodology for Three Dimensional Nozzle Design

Criteria for the selection and methods of analysis for designing a hypersonic scramjet nozzle are discussed. The criteria are based on external and internal flow requirements, related to drag, lift, and pitching moments of the vehicle and thrust of the engine. The steps involved in establishing the criteria are analyzed. Mathematical models of the design procedure are provided.

Ferri, A.↗

NASA NTRS1974

A source flow characteristic technique for the analysis of scramjet exhaust flow field

The factors which influence the design and selection of a nozzle for a hypersonic scramjet are described. A two dimensional second-order characteristic procedure capable of analyzing the aerodynamic performance of typical nozzle configurations is presented. Equations of motion governing the two dimensional, axisymmetric, or axially expanding inviscid flow of a gas mixture, with frozen chemistry, are provided. Diagrams of the flow conditions for various configurations are included.

Delguidice, P.↗

NASA NTRS1973

A numerical procedure for the parametric optimization of three dimensional scramjet nozzles

A numerical procedure permitting the rapid determination of the internal performance of a class of scramjet nozzle configurations is presented. The approach developed is based on the construction of quasi two dimensional simple wave networks, where lateral expansion effects are incorporated by one dimensional approximations. A numerical procedure following this approach has has been developed and results obtained are highly comparable to those obtained employing a characteristic procedure. The numerical program developed permits the parametric variation of cowl length, turning angles on the cowl and vehicle undersurface and lateral expansion and is subject to fixed constraints such as the vehicle length and nozzle exit height. The program requires uniform initial conditions at the burner exit station and yields the location of all predominant wave zones, accounting for lateral expansion effects. In addition, the program yields the detailed pressure distribution on the cowl and vehicle undersurface and calculates the nozzle thrust, lift and pitching moment.

Dash, S.↗

NASA NTRS1972

Analysis of supersonic combustion flow fields with embedded subsonic regions

The viscous characteristic analysis for supersonic chemically reacting flows was extended to include provisions for analyzing embedded subsonic regions. The numerical method developed to analyze this mixed subsonic-supersonic flow fields is described. The boundary conditions are discussed related to the supersonic-subsonic and subsonic-supersonic transition, as well as a heuristic description of several other numerical schemes for analyzing this problem. An analysis of shock waves generated either by pressure mismatch between the injected fluid and surrounding flow or by chemical heat release is also described.

Dash, S.↗

NASA NTRS1972

Analysis and design of three dimensional supersonic nozzles. Volume 1: Nozzle-exhaust flow field analysis by a reference plane characteristics technique

A second order numerical method employing reference plane characteristics has been developed for the calculation of geometrically complex three dimensional nozzle-exhaust flow fields, heretofore uncalculable by existing methods. The nozzles may have irregular cross sections with swept throats and may be stacked in modules using the vehicle undersurface for additional expansion. The nozzles may have highly nonuniform entrance conditions, the medium considered being an equilibrium hydrogen-air mixture. The program calculates and carries along the underexpansion shock and contact as discrete discontinuity surfaces, for a nonuniform vehicle external flow.

Dash, S.↗