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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 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Neutronics analysis of an open-cycle high-impulse gas core reactor concept

A procedure was developed to calculate the critical fuel mass, including the effects of propellant pressure, for coaxial-flow gas-core reactors operating at 196,600 newtons thrust and 4400 seconds specific impulse. Data were generated for a range of cavity diameter, reflector-moderator thickness, and quantity of structural material. Also presented are such core characteristics as upper limits on cavity pressure, spectral hardening in very-high-temperature hydrogen, and reactivity coefficients.

Whitmarsh, C. L., Jr.↗
NASA NTRS1972

Fluid flow analysis of a hot-core hypersonic wind-tunnel nozzle concept

A hypersonic-wind-tunnel nozzle concept which incorporates a hot-core flow surrounded by an annular flow of cold air offers a promising technique for maximizing the model size while minimizing the power required to heat the test core. This capability becomes especially important when providing the true-temperature duplication needed for hypersonic propulsion testing. Several two-dimensional wind-tunnel nozzle configurations that are designed according to this concept are analyzed by using recently developed analytical techniques for prediction of the boundary-layer growth and the mixing between the hot and cold coaxial supersonic airflows. The analyses indicate that introduction of the cold annular flow near the throat results in an unacceptable test core for the nozzle size and stagnation conditions considered because of both mixing and condensation effects. Use of a half-nozzle with a ramp on the flat portion does not appear promising because of the thick boundary layer associated with the extra length. However, the analyses indicate that if the cold annular flow is introduced at the exit of a full two-dimensional nozzle, an acceptable test core will be produced. Predictions of the mixing between the hot and cold supersonic streams for this configuration show that mixing effects from the cold flow do not appreciably penetrate into the hot core for the large downstream distances of interest.

Anders, J. B.↗
NASA NTRS1972

Feasibility Study of a Pressure-fed Engine for a Water Recoverable Space Shuttle Booster

Detailed mass properties are presented for a gimbaled, fixed thrust, regeneratively cooled engine having a coaxial pintle injector. The baseline design parameters for this engine are tabulated. Mass properties are also summarized for several other engine configurations i.e., a hinge nozzle using a Techroll seal, a gimbaled duct cooled engine and a regeneratively cooled engine using liquid injection thrust vector control (LITVC). Detailed engine analysis and design trade studies leading to the selection of a regeneratively cooled gimbaled engine and pertaining to the selection of the baseline design configuration are also given.

Gerstl, E.↗
NASA NTRS1972

Liquid inflow to a baffled cylindrical tank during weightlessness

An experimental investigation was conducted in which the behavior of liquid inflow to a cylindrical tank containing inlet baffles was observed during weightlessness. A single tank radius (2 cm), inlet radius (0.2 cm), and liquid (ethanol)were used. The inlet end of the tank was hemispherical with a 30 deg convergent inlet. All the baffle configurations tested were cylindrically symmetric and mounted coaxially with the tank within the hemispherical end. Both stable and unstable inflow behavior were observed using each baffle. It was found that, depending on which of the baffles was used, the critical inflow velocity at which a transition to unstable inflow began was from 2.5 to 12 times greater than the corresponding velocity in an unbaffled tank.

Staskus, J. V.↗
NASA NTRS1972

Oxygen-hydrogen injector performance and compatibility with ablative chambers

An experimental investigation was conducted to develop a high-thrust, high-performance, concentric tube injector element for use with near liquid hydrogen and liquid oxygen propellants. A parallel tube coaxial injector yielded 98 percent theoretical characteristic exhaust velocity efficiency. Installation of swirlers in the oxidizer tube improved performance but caused high ablative erosion near the injector. Film cooling significantly reduced ablative erosion near the injector but did not completely alleviate gouging adjacent to each outer injection element.

Wanhainen, J. P.↗
NASA NTRS1972

Rotor systems research aircraft of predesign study. Volume 1: Summary and conclusions

The results are summarized of a study to develop a versatile research aircraft for flight testing a wide variety of advanced helicopter and compound rotor systems. The aircraft is required to accept these rotors with minimal changes in the basic vehicle. Rotors envisioned for testing include conventional rotors plus variable geometry, variable twist, variable diameter, coaxial, jet flap, circulation control, and slowed rotors. Various disc loadings would be accommodated. The aircraft must be configured to measure performance more accurately than past test vehicles. In addition, the aircraft would have a wing to off load the rotor while measuring performance during lightly loaded conditions. It would have variable drag and propulsive force so that the rotor can be tested while producing different values of horizontal force.

Linden, A. W.↗
NASA NTRS1971

Effect of buoyancy on fuel containment in an open-cycle gas-core nuclear rocket engine.

Analysis aimed at determining the scaling laws for the buoyancy effect on fuel containment in an open-cycle gas-core nuclear rocket engine, so conducted that experimental conditions can be related to engine conditions. The fuel volume fraction in a short coaxial flow cavity is calculated with a programmed numerical solution of the steady Navier-Stokes equations for isothermal, variable density fluid mixing. A dimensionless parameter B, called the Buoyancy number, was found to correlate the fuel volume fraction for large accelerations and various density ratios. This parameter has the value B = 0 for zero acceleration, and B = 350 for typical engine conditions.

Putre, H. A.↗
NASA NTRS1971

An analysis of the flow field near the fuel injection location in a gas core reactor.

An analytical study is presented which shows the effects of large energy release and the concurrent high acceleration of inner stream fluid on the coaxial flow field in a gas core reactor. The governing equations include the assumptions of only radial radiative transport of energy represented as an energy diffusion term in the Euler equations. The method of integral relations is used to obtain the numerical solution. Results show that the rapidly accelerating, heat generating inner stream actually shrinks in radius as it expands axially.

Weinstein, H.↗
NASA NTRS1973

Digital data command bus

Command bus constructed from coaxial cable has short segments of its outer jacket and shield removed and replaced with small ferrite cores carrying multiturn windings connected to decoder. Device reduces number of wire pairs required to communicate command data to systems and subsystems.

Milligan, G. C.↗
NASA NTRS1973

A vacuum chamber feedthrough

Simple and inexpensive microwave feedthrough has been designed which transfers 130 ns, 5kV pulse into vacuum chamber. Feedthrough may be used over wide range and is adaptable to most coaxial cables, since either multistrand or single strand center conductor cable can be used.

Brown, V. D.↗
NASA NTRS1973

Circularly-polarized multiband telemetry tracking antenna

Utilize coaxial horn feed to illuminate reflector; feed has inner horn for X-band, and outer horn for S-band. Tracking error signals for servo correction are derived from measurements of relative phase and relative amplitude between two modes.

Woo, K. E.↗
NASA NTRS1974

Means for mapping radiated fields and for measuring differential movement of antenna elements

Null seeking system uses two transponders located at selected points on dish to detect phase-front of received signal. One signal line has continuously variable phase shifter driven by reversible stepmotor. Each of two transponders on dish is a dipole with mixer crystal between elements. Crystal is driven, in turn, by 181.6MHz signal carried by miniature coaxial cable.

Lundy, C. C.↗
NASA NTRS1972

A wideband 12 GHz down converter

The design, fabrication, and evaluation of a single ended 12 GHz down-converter suitable for use in a low cost satellite ground terminal is described. The mixer uses waveguide, coaxial and MIC (microwave integrated circuit) transmission line components. Theoretical and experimental analyses of several microstrip circuit elements are presented including the traveling wave-directional filter, quarter wave-length proximity directional coupler, low pass filter and the quarterwave band stop filter. The optimum performance achieved for the mixer using a packaged diode was 9.4 db conversion loss and a bandwidth of 275 MHz.

Newman, B. A.↗
NASA NTRS1973

Control of turbofan lift engines for VTOL aircraft

The use of turbofan engines as lift units for VTOL aircraft poses new engine control problems. At low flight speeds, the lift units must provide the fast thrust response needed for aircraft attitude and height control. The results are presented of an analytical study of the dynamics and control of turbofan lift engines, and methods are proposed for meeting the response requirements imposed by the VTOL aircraft application. Two types of lift fan engines are discussed: the integral and remote. The integral engine is a conventional two-spool, high bypass ratio turbofan designed for low noise and short length. The remote engine employs a gas generator and a lift fan which are separated by a duct, and which need not be coaxial. For the integral engine, a control system design is presented which satisfies the VTOL response requirements. For the remote engine, two unconventional methods of control involving flow transfer between lift units are discussed. Both methods are shown to have thrust response near the required levels.

Sellers, J. F.↗
NASA NTRS1972

A millimeter wave mixer

The mixer consists of a small metallic wafer, in which are embedded the semiconductor diodes, the waveguide mount is used to couple the diode wafer to the signal circuit, an RF tuning element, and a 3 mm coaxial connector for the IF output terminal. The cross-sectional dimension is that of the waveguide flange (19 mm x 19 mm, 0.75" x 0.75"), the overall length is nominally 25 mm (1.0 inch). This component is to be used as a single-ended RF mixer with four replacement mixer diodes, operating in the three millimeter wavelength band.

Dickens, L. E.↗
NASA NTRS1973

Injector design guidelines for gas/liquid propellant systems

Injector design guidelines are provided for gas/liquid propellant systems. Information was obtained from a 30-month applied research program encompassing an analytical, design, and experimental effort to relate injector design parameters to simultaneous attainment of high performance and component (injector/thrust chamber) compatibility for gas/liquid space storable propellants. The gas/liquid propellant combination studied was FLOX (82.6% F2)/ ambient temperature gaseous methane. Design criteria that provide for simultaneous attainment of high performance and chamber compatibility are presented for both injector types. Parametric data are presented that are applicable for the design of circular coaxial and like-doublet injectors that operate with design parameters similar to those employed. However, caution should be exercised when applying these data to propellant combinations whose elements operate in ranges considerably different from those employed in this study.

Falk, A. Y.↗
NASA NTRS1973

Analysis and testing of two-dimensional slot nozzle ejectors with variable area mixing sections

Finite difference computer techniques have been used to calculate the detailed performance of air to air two-dimensional ejectors with symmetric variable area mixing sections and coaxial coverging primary nozzles. The analysis of the primary nozzle assumed correct expansion of the flow and is suitable for subsonic and slightly supersonic velocity levels. The variation of the mixing section channel walls is assumed to be gradual so that the static pressure can be assumed uniform on planes perpendicular to the axis. A test program was run to provide two-dimensional ejector test data for verification of the computer analysis. A primary converging nozzle with a discharge geometry of 0.125 inch x 8.0 inch was supplied with 600 SCFM of air at about 35 psia and 180 F. This nozzle was combined with two mixing section geometries with throat sizes of 1.25 inch x 8.0 inch and 1.875 inch x 8.0 inch and was tested at a total of 11 operating points.

Gilbert, G. B.↗