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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 379 records · Page 21

Preliminary design of a supersonic Short-Takeoff and Vertical-Landing (STOVL) fighter aircraft

A preliminary study of a supersonic short takeoff and vertical landing (STOVL) fighter is presented. Three configurations (a lift plus lift/cruise concept, a hybrid fan vectored thrust concept, and a mixed flow vectored thrust concept) were initially investigated with one configuration selected for further design analysis. The selected configuration, the lift plus lift/cruise concept, was successfully integrated to accommodate the powered lift short takeoff and vertical landing requirements as well as the demanding supersonic cruise and point performance requirements. A supersonic fighter aircraft with a short takeoff and vertical landing capability using the lift plus lift/cruise engine concept seems a viable option for the next generation fighter.

Source record↗

Evolution of the Orszag-Tang vortex system in a compressible medium. II - Supersonic flow

A study is presented on the effect of embedded supersonic flows and the resulting emerging shock waves on phenomena associated with MHD turbulence, including reconnection, the formation of current sheets and vortex structures, and the evolution of spatial and temporal correlations among physical variables. A two-dimensional model problem, the Orszag-Tang (1979) vortex system, is chosen, which involves decay from nonrandom initial conditions. The system is doubly periodic, and the initial conditions consist of single-mode solenoidal velocity and magnetic fields, each containing X points and O points. The initial mass density is flat, and the initial pressure fluctuations are incompressible, balancing the local forces for a magnetofluid of unit mass density. Results on the evolution of the local structure of the flow field, the global properties of the system, and spectral correlations are presented. The important dynamical properties and observational consequences of embedded supersonic regions and emerging shocks in the Orszag-Tang model of an MHD system undergoing reconnection are discussed. Conclusions are drawn regarding the effects of local supersonic regions on MHD turbulence.

Picone, J. Michael↗

Supersonic laminar flow control on commercial transports

This paper provides an overview of the status of supersonic laminar flow control. Existing research into the aerodynamic problems of subsonic and supersonic laminar flow control is first reviewed to provide a prospective for subsequent discussions of recent studies to evaluate the potential performance benefits of the application of laminar flow control to supersonic transports. A flight research program to provide a realistic assessment of the technical feasibility is then described.

Wagner, R. D.↗

Nonlinear evolution of subsonic and supersonic disturbances on a compressible free shear layer

The effects of a nonlinear-nonequilibrium-viscous critical layer on the spatial evolution of subsonic and supersonic instability modes on a compressible free shear layer is considered. It is shown that the instability wave amplitude is governed by an integrodifferential equation with cubic-type nonlinearity. Numerical and asymptotic solutions to this equation show that the amplitude either ends in a singularity at a finite downstream distance or reaches an equilibrium value, depending on the Prandtl number, viscosity law, viscous parameter and a real parameter which is determined by the linear inviscid stability theory. A necessary condition for the existence of the equilibrium solution is derived, and whether or not this condition is met is determined numerically for a wide range of physical parameters including both subsonic and supersonic disturbances. it is found that no equilibrium solution exists for the subsonic modes unless the temperature ratio of the low-to-high-speed streams exceeds a critical value, while equilibrium solutions for the most rapidly growing supersonic mode exist over most of the parameter range examined.

Leib, S. J.↗

Plasma motion in the Venus ionosphere - Transition to supersonic flow

A remarkable feature of the ionosphere of Venus is the presence of nightward supersonic flows at high altitude near the terminator. In this paper it is shown that the relatively high pressure dayside plasma wells up slowly, and at high altitude it is accelerated horizontally through a relatively constricted region near the terminator toward the low-density nightside. In effect, the plasma flows through a 'nozzle' that is first converging, then diverging, permitting the transition to supersonic flow. The model plasma accelerates to supersonic speeds, reaching sonic speed just behind the terminator. The ion transport rates are sufficient to produce and maintain the nightside ionosphere.

Whitten, R. C.↗

Results from computational analysis of a mixed compression supersonic inlet

A numerical study was performed to simulate the critical flow through a supersonic inlet. This flowfield has many phenomena such as shock waves, strong viscous effects, turbulent boundary layer development, boundary layer separations and mass flow suction through the walls (bleed). The computational tools used in this study were two full Navier-Stokes (FNS) codes. The supersonic inlet that was analyzed in this study is the Variable Diameter Centerbody (VDC), inlet. This inlet is a candidate concept for the next generation supersonic transport. Application of the code to the inlet geometry involved effort in generating an efficient grid geometry and specifying boundary conditions, particularly in the bleed region and at the outflow boundary. Results for a critical inlet operation compare favorably to Method of Characteristics predictions and experimental data.

Saunders, J. D.↗

Results from computational analysis of a mixed compression supersonic inlet

A numerical study was performed to simulate the critical flow through a supersonic inlet. This flow field has many phenomena such as shock waves, strong viscous effects, turbulent boundary layer development, boundary layer separations, and mass flow suction through the walls, (bleed). The computational tools used were two full Navier-Stokes (FNS) codes. The supersonic inlet that was analyzed is the Variable Diameter Centerbody, (VDC), inlet. This inlet is a candidate concept for the next generation supersonic involved effort in generating an efficient grid geometry and specifying boundary conditions, particularly in the bleed region and at the outflow boundary. Results for a critical inlet operation compare favorably to Method of Characteristics predictions and experimental data.

Saunders, J. D.↗

A critical evaluation of a three-dimensional Navier-Stokes CFD as a tool to design supersonic turbine stages

Three-dimensional flow phenomena in a supersonic turbine blade row were studied numerically to evaluate CFD as a tool to design supersonic turbine stages. The details of the three-dimensional flow structure inside the supersonic turbine blade row and the overall aerodynamic performance at design and off-design conditions are analyzed and the results are compared between the experimental data and the numerical results.

Hah, C.↗

Supersonic investigation of two dimensional hypersonic exhaust nozzles

An experimental investigation was conducted in the NASA Lewis 10 x 10 ft supersonic Wind Tunnel to determine the performance characteristics of 2D hypersonic exhaust nozzles/afterbodies at low supersonic conditions. Generally, this type of application requires a single expansion ramp nozzle (SERN) that is highly integrated with the airframe of the hypersonic vehicle. At design conditions (hypersonic speeds), the nozzle generally exhibits acceptable performance. At off-design conditions (transonic to mid-supersonic speeds), nozzle performance of a fixed geometry configuration is generally poor. Various 2-D nozzle configurations were tested at off-design conditions from Mach 2.0 to 3.5. Performance data is presented at nozzle pressure ratios from 1 to 35. Jet exhaust was simulated with high-pressure air. To study performance of different geometries, nozzle configurations were varied by interchanging the following model parts: internal upstream contour, expansion ramp, sidewalls, and cowl.

Carboni, Jeanne D.↗

The Edge supersonic transport

As intercontinental business and tourism volumes continue their rapid expansion, the need to reduce travel times becomes increasingly acute. The Edge Supersonic Transport Aircraft is designed to meet this demand by the year 2015. With a maximum range of 5750 nm, a payload of 294 passengers and a cruising speed of M = 2.4, The Edge will cut current international flight durations in half, while maintaining competitive first class, business class, and economy class comfort levels. Moreover, this transport will render a minimal impact upon the environment, and will meet all Federal Aviation Administration Part 36, Stage III noise requirements. The cornerstone of The Edge's superior flight performance is its aerodynamically efficient, dual-configuration design incorporating variable-geometry wingtips. This arrangement combines the benefits of a high aspect ratio wing at takeoff and low cruising speeds with the high performance of an arrow-wing in supersonic cruise. And while the structural weight concerns relating to swinging wingtips are substantial, The Edge looks to ever-advancing material technologies to further increase its viability. Heeding well the lessons of the past, The Edge design holds economic feasibility as its primary focus. Therefore, in addition to its inherently superior aerodynamic performance, The Edge uses a lightweight, largely windowless configuration, relying on a synthetic vision system for outside viewing by both pilot and passengers. Additionally, a fly-by-light flight control system is incorporated to address aircraft supersonic cruise instability. The Edge will be produced at an estimated volume of 400 aircraft and will be offered to airlines in 2015 at $167 million per transport (1992 dollars).

Agosta, Roxana↗

An extended supersonic combustion model for the dynamic analysis of hypersonic vehicles

The development of an advanced dynamic model for aeroelastic hypersonic vehicles powered by air breathing engines requires an adequate engine model. This report provides a discussion of some of the more important features of supersonic combustion and their relevance to the analysis and design of supersonic ramjet engines. Of particular interest are those aspects of combustion that impact the control of the process. Furthermore, the report summarizes efforts to enhance the aeropropulsive/aeroelastic dynamic model developed at the Aerospace Research Center of Arizona State University by focusing on combustion and improved modeling of this flow. The expanded supersonic combustor model described here has the capability to model the effects of friction, area change, and mass addition, in addition to the heat addition process. A comparison is made of the results from four cases: (1) heat addition only; (2) heat addition plus friction; (3) heat addition, friction, and area reduction, and (4) heat addition, friction, area reduction, and mass addition. The relative impact of these effects on the Mach number, static temperature, and static pressure distributions within the combustor are then shown. Finally, the effects of frozen versus equilibrium flow conditions within the exhaust plume is discussed.

Bossard, J. A.↗

Hypersonic engine component experiments in high heat flux, supersonic flow environment

A major concern in advancing the state-of-the-art technologies for hypersonic vehicles is the development of an aeropropulsion system capable of withstanding the sustained high thermal loads expected during hypersonic flight. Even though progress has been made in the computational understanding of fluid dynamics and the physics/chemistry of high speed flight, there is also a need for experimental facilities capable of providing a high heat flux environment for testing component concepts and verifying/calibrating these analyses. A hydrogen/oxygen rocket engine heat source was developed at the NASA Lewis Research Center as one element in a series of facilities at national laboratories designed to fulfill this need. This 'Hot Gas Facility' is capable of providing heat fluxes up to 450 w/sq cm on flat surfaces and up to 5,000 w/sq cm at the leading edge stagnation point of a strut in a supersonic flow stream. Gas temperatures up to 3050 K can also be attained. Two recent experimental programs conducted in this facility are discussed. The objective of the first experiment is to evaluate the erosion and oxidation characteristics of a coating on a cowl leading edge (or strut leading edge) in a supersonic, high heat flux environment. Macrophotographic data from a coated leading edge model show progressive degradation over several thermal cycles at aerothermal conditions representative of high Mach number flight. The objective of the second experiment is to assess the capability of cooling a porous surface exposed to a high temperature, high velocity flow environment and to provide a heat transfer data base for a design procedure. Experimental results from transpiration cooled surfaces in a supersonic flow environment are presented.

Gladden, Herbert J.↗

The effects of temperature on supersonic jet noise emission

This paper examines the generation of sound produced by high temperature supersonic jets. In particular, the question of the importance of supersonic instability waves to noise emission is considered relative to the role of Kelvin-Helmholtz (K-H) instability waves. Here, these waves are taken to be synonymous with the Mach emission process. Jet total temperatures from 313 to 1534 K are investigated using an axisymmetric water cooled supersonic nozzle designed for Mach 2. The aerodynamic and acoustic results of this study indicate that the dominant noise contributors are the K-H waves over the entire temperature range. Good agreement between measured and numerically predicted plume properties are obtained and an elliptic nozzle is used to demonstrate reduction of the K-H waves.

Seiner, John M.↗

Supersonic jet noise reduction by coaxial rectangular nozzles

A physical understanding of noise reduction mechanisms in supersonic, single, and coaxial rectangular jets is quantified and obtained, with emphasis on shock noise reduction. For all conditions, corresponding acoustic measurements for an equivalent round jet are also obtained so that the noise characteristics of the two types of jets can be compared directly to quantify the noise reductions. Comparisons are thus provided for a single rectangular nozzle vs a single equivalent round nozzle, and a coaxial rectangular nozzle vs an equivalent round nozzle. It is shown that different operating conditions and nozzle arrangements for the same thrust, total exit area, and mass flow rate can produce different noise levels. With at least one stream operated supersonically, the coaxial rectangular nozzle operated in the inverted-velocity profile is always quieter than in the normal velocity profile mode for the same thrust, exit area, and mass flow rate. In general, the coaxial rectangular nozzle is shown to be quieter than an equivalent circular nozzle only for those conditions for which both nozzles are operated supersonically.

Ahuja, K. K.↗

Pdf prediction of supersonic hydrogen flames

A hybrid method for the prediction of supersonic turbulent flows with combustion is developed consisting of a second order closure for the velocity field and a multi-scalar pdf method for the local thermodynamic state. It is shown that for non-premixed flames and chemical equilibrium mixture fraction, the logarithm of the (dimensionless) density, internal energy per unit mass and the divergence of the velocity have several advantages over other sets of scalars. The closure model is applied to a supersonic non-premixed flame burning hydrogen with air supplied by a supersonic coflow and the results are compared with a limited set of experimental data.

Eifler, P.↗

Supersonic laminar flow control

A development status evaluation is presented for the theoretical understanding and design conceptualization of boundary layer control (BLC) systems applicable to supersonic transports, such as the currently envisioned NASA High Speed Civil Transport. By reducing fuel burned, supersonic BLC techniques could expand ranges to Pacific-crossing scales, while lowering sonic boom effects and upper-atmosphere pollution and even reducing skin friction temperature. The critical consideration for supersonic BLC is the presence of wave effects.

Bushnell, D. M.↗

Application of natural laminar flow to a supersonic transport concept

Results are presented of a preliminary investigation into an application of supersonic natural laminar flow (NLF) technology for a high speed civil transport (HSCT) configuration. This study focuses on natural laminar flow without regard to suction devices which are required for laminar flow control (LFC) or hybrid laminar flow control (HLFC). An HSCT design is presented with a 70 deg inboard leading-edge sweep and a 20 deg leading-edge outboard crank to obtain NLF over the outboard crank section. This configuration takes advantage of improved subsonic performance and NLF on the low-sweep portion of the wing while minimizing the wave drag and induced drag penalties associated with low-sweep supersonic cruise aircraft. In order to assess the benefits of increasing natural laminar flow wetted area, the outboard low-sweep wing area is parametrically increased. Using a range of supersonic natural laminar flow transition Reynolds numbers, these aircraft are then optimized and sized for minimum take-off gross weight (TOGW) subject to mission constraints. Results from this study indicate reductions in TOGW for the NLF concepts, due mainly to reductions in wing area and total wing weight. Furthermore, significant reductions in block fuel are calculated throughout the range of transition Reynolds numbers considered. Observations are made on the benefits of unsweeping the wingtips with all turbulent flow.

Fuhrmann, Henri D.↗

Notes on the theoretical characteristics of two-dimensional supersonic airfoils

The shock expansion method of the NACA TN No. 1143 was used to determine the principal aerodynamic characteristics of two-dimensional supersonic airfoils. A discussion is given of the effect of thickness ratio, free-stream Mach number, angle of attack, camber, thickness distribution, and aileron deflection. The calculations indicated that the minimum drag of supersonic airfoils is obtained when the maximum thickness is behind the 0.50 chord. The center of pressure obtained for a symmetrical supersonic airfoil was found to be ahead of the 0.50 chord.

Ivey, H Reese↗