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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

SETI low-frequency feed design study for DSS 24

The Search for Extraterrestrial Intelligence Sky Survey project requires operation from 1 to 10 GHz on the beam waveguide (BWG) antenna DSS 24. The BWG reflectors are undersized in the 1- to 3.02-GHz range, resulting in poor performance. Horn designs and a method for implementing 1- to 3.02-GHz operation on DSS 24 are presented. A combination of a horn and a shaped feed reflector placed above the main reflector is suggested. The horn and feed reflector could be hidden in the RF shadow of the subreflector and struts. Results from computer analysis of this design indicate that adequate performance could be achieved.

Stanton, P. H.↗
NASA NTRS1976

Design study of a gas turbine combustor with heat recirculation

A means of avoiding stoichiometric combustion, reducing emissions, and yet providing stable burning for lean mixtures is based on the use of heat recirculation rather than flow recirculation. This paper is concerned with the calculations of the design parameters of a gas turbine combustor with heat exchanger to produce the desired preheat temperature. The combustor inlet temperature, maximum temperature, equivalence ratio and recirculated heat are determined by thermodynamic analysis. The heat transfer analysis then provides the dimensions of the system to produce the predetermined boundary conditions. It is indicated that practical combustor design may be feasible for reactant mixtures as low as equivalence ratio 0.2.

Ganji, A.↗
NASA NTRS1980

Preliminary design study of a higher harmonic blade feathering control system

The feasibility to incorporate an active higher harmonic control (HHC) system on an OH-6A rotorcraft was demonstrated. The introduction of continuously modulated low amplitude 4P feathering showed potential for reducing rotor transmitted oscillatory loads. The design implementation of this system on a baseline OH-6A required generation of a hydraulic power system, control actuator placement and design integration of an electronic subsystem comprised of an electronic control unit (ECU) and digital microcomputer. Various placements of the HHC actuators in the primary control system are evaluated. Assembly drawings of the actuator concepts and control rigging are presented. The advantages of generating both hydraulic power and 4F control motions in the nonrotating system is confirmed.

Powers, R. W.↗
NASA NTRS1973

Systems design study of the Pioneer Venus spacecraft. Appendices to volume 1, sections 8-11 (part 3 of 3)

Power subsystem cost/weight tradeoffs are discussed for the Venus probe spacecraft. The cost estimations of power subsystem units were based upon DSCS-2, DSP, and Pioneer 10 and 11 hardware design and development and manufacturing experience. Parts count and degree of modification of existing hardware were factored into the estimate of manufacturing and design and development costs. Cost data includes sufficient quantities of units to equip probe bus and orbiter versions. It was based on the orbiter complement of equipment, but the savings in fewer slices for the probe bus balance the cost of the different probe bus battery. The preferred systems for the Thor/Delta and for the Atlas/Centaur are discussed. The weights of the candidate designs were based upon slice or tray weights for functionally equivalent circuitry measured on existing hardware such as Pioneers 10 and 11, Intelsat 3, DSCS-2, or DSP programs. Battery weights were based on measured cell weight data adjusted for case weight or off-the-shelf battery weights. The solar array weight estimate was based upon recent hardware experience on DSCS-2 and DSP arrays.

Source record↗
NASA NTRS1977

Space Settlements: A Design Study

Nineteen professors of engineering, physical science, social science, and architecture, three volunteers, six students, a technical director, and two co-directors worked for ten weeks to construct a convincing picture of how people might permanently sustain life in space on a large scale, and to design a system for the colonization of space. Because the idea of colonizing space has awakened strong public interest, the document presented is written to be understood by the educated public and specialists in other fields. It also includes considerable background material. A table of units and conversion factors is included to aid the reader in interpreting the units of the metric system used in the report.

Richard D Johnson↗
NASA NTRS1972

Design study of shaft face seal with self-acting lift augmentation. 4: Force balance

A method for predicting the operating film thickness of self-acting seals is described. The analysis considers a 16.76-cm mean diameter seal that is typical of large gas turbines for aircraft. Four design points were selected to cover a wide range of operation for advanced engines. This operating range covered sliding speeds of 61 to 153 m/sec, sealed pressures of 45 to 217 N/sq cm abs, and gas temperatures of 311 to 977 K. The force balance analysis revealed that the seal operated without contact over the operating range with gas film thicknesses ranging between 0.00046 to 0.00119 cm, and with gas leakage rates between 0.01 to 0.39 scmm.

Ludwig, L. P.↗
NASA NTRS1990

Proximity operations concept design study, task 6

The feasibility of using optical technology to perform the mission of the proximity operations communications subsystem on Space Station Freedom was determined. Proximity operations mission requirements are determined and the relationship to the overall operational environment of the space station is defined. From this information, the design requirements of the communication subsystem are derived. Based on these requirements, a preliminary design is developed and the feasibility of implementation determined. To support the Orbital Maneuvering Vehicle and National Space Transportation System, the optical system development is straightforward. The requirements on extra-vehicular activity are such as to allow large fields of uncertainty, thus exacerbating the acquisition problem; however, an approach is given that could mitigate this problem. In general, it is found that such a system could indeed perform the proximity operations mission requirement, with some development required to support extra-vehicular activity.

Williams, A. N.↗
NASA NTRS1980

Design study of flat belt CVT for electric vehicles

A continuously variable transmission (CVT) was studied, using a novel flat belt pulley arrangement which couples the high speed output shaft of an energy storage flywheel to the drive train of an electric vehicle. A specific CVT arrangement was recommended and its components were selected and sized, based on the design requirements of a 1700 KG vehicle. A design layout was prepared and engineering calculations made of component efficiencies and operating life. The transmission efficiency was calculated to be significantly over 90% with the expected vehicle operation. A design consistent with automotive practice for low future production costs was considered, together with maintainability. The technology advancements required to develop the flat belt CVT were identified and an estimate was made of how the size of the flat belt CVT scales to larger and smaller design output torques. The suitability of the flat belt CVT for alternate application to an electric vehicle powered by an electric motor without flywheel and to a hybrid electric vehicle powered by an electric motor with an internal combustion engine was studied.

Kumm, E. L.↗
NASA NTRS1979

Initial conceptual design study of self-critical nuclear pumped laser systems

An analytical study of self-critical nuclear pumped laser system concepts was performed. Primary emphasis was placed on reactor concepts employing gaseous uranium hexafluoride (UF6) as the fissionable material. Relationships were developed between the key reactor design parameters including reactor power level, critical mass, neutron flux level, reactor size, operating pressure, and UF6 optical properties. The results were used to select a reference conceptual laser system configuration. In the reference configuration, the 3.2 m cubed lasing volume is surrounded by a graphite internal moderator and a region of heavy water. Results of neutronics calculations yield a critical mass of 4.9 U(235) in the form (235)UF6. The configuration appears capable of operating in a continuous steady-state mode. The average gas temperature in the core is 600 K and the UF6 partial pressure within the lasing volume is 0.34 atm.

Rodgers, R. J.↗
NASA NTRS1980

Preliminary design study of advanced composite blade and hub and nonmechanical control system for the tilt-rotor aircraft. Volume 2: Project planning data

Project planning data for a rotor and control system procurement and testing program for modifications to the XV-15 tilt-rotor research demonstrator aircraft is presented. The design, fabrication, and installation of advanced composite blades compatible with the existing hub, an advanced composite hub, and a nonmechanical control system are required.

Source record↗
NASA NTRS1980

Single-mode laser studies: Design and performance of a fixed-wave length source and coupling of lasers to thin-film optical waveguides

A module developed for the generation of a stable single wavelength to be used for a fiber optic multiplexing scheme is described. The laser is driven with RZ pulses, and the temperature is stabilized thermoelectrically. The unit is capable of maintaining a fixed wavelength within about 6 A as the pulse duty cycle is changed between 0 and 100 percent. This is considered the most severe case, and much tighter tolerances are obtainable for constant input power coding schemes. Using a constricted double heterostructure laser, a wavelength shift of 0.083 A mA is obtained due to laser self-heating by a dc driving current. The thermoelectric unit is capable of maintaining a constant laser heat-sink temperature within 0.02 C. In addition, miniature lenses and couplers are described which allow efficient coupling of single wavelength modes of junction lasers to thin film optical waveguides. The design of the miniature cylinder lenses and the prism coupling techniques allow 2 mW of single wavelength mode junction laser light to b coupled into thin film waveguides using compact assemblies. Selective grating couplers are also studied.

Ladany, I.↗
NASA NTRS1986

Liquid belt radiator design study

The Liquid Belt Radiator (LBR) is an advanced concept developed to meet the needs of anticipated future space missions. A previous study documented the advantages of this concept as a lightweight, easily deployable alternative to present day space heat rejection systems. The technical efforts associated with this study concentrate on refining the concept of the LBR as well as examining the issues of belt dynamics and potential application of the LBR to intermediate and high temperature heat rejection applications. A low temperature point design developed in previous work is updated assuming the use of diffusion pump oil, Santovac-6, as the heat transfer media. Additional analytical and design effort is directed toward determining the impact of interface heat exchanger, fluid bath sealing, and belt drive mechanism designs on system performance and mass. The updated design supports the earlier result by indicating a significant reduction in system specific system mass as compared to heat pipe or pumped fluid radiator concepts currently under consideration (1.3 kg/sq m versus 5 kg/sq m).

Teagan, W. P.↗
NASA NTRS1979

Computer aided design study of hypermixing nozzles

The development of a nozzle which combines the hypermixing and lobe mechanisms to achieve further increases in jet entrainment and ejector performance is investigated. A computer program which incorporates a two equation turbulence model and is used to predict and compare the evolution of jets from various nozzle designs is discussed. Increasing the length of the nozzle lobes and an alternating lobe nozzle are a methods examined for increasing the entrainment rate.

Mefferd, L. A.↗
NASA NTRS1980

Engineering support for magnetohydrodynamic power plant analysis and design studies

The major factors which influence the economic engineering selection of stack inlet temperatures in combined cycle MHD powerplants are identified and the range of suitable stack inlet temperatures under typical operating conditions is indicated. Engineering data and cost estimates are provided for four separately fired high temperature air heater (HTAH) system designs for HTAH system thermal capacity levels of 100, 250, 500 and 1000 MWt. An engineering survey of coal drying and pulverizing equipment for MHD powerplant application is presented as well as capital and operating cost estimates for varying degrees of coal pulverization.

Carlson, A. W.↗
NASA NTRS1979

Lean, premixed, prevaporized combustor conceptual design study

The seven month study program has the objective to identify and evaluate promising lean, premixed, prevaporized combustor concepts utilizing variable geometry and/or other flow control techniques. The general approach taken to accomplish this objective is outlined and consists of combustor design, design analysis and design ranking. The schedule being taken to achieve this program is shown. Although the ultimate goal of this program is the significant reduction of cruise oxides of nitrogen, both the EPA emission standards and combustor performance levels outlined are retained as goals as well.

Fiorentino, A. J.↗
NASA NTRS1972

Space shuttle auxiliary propulsion system design study. Phase C report: Oxygen-hydrogen RCS/OMS integration study

A comparison of the concepts of auxiliary propulsion systems proposed for the space shuttle vehicle is discussed. An evaluation of the potential of integration between the reaction control system and the orbit maneuvering system was conducted. Numerous methods of implementing the various levels of integration were evaluated. Preferred methods were selected and design points were developed for two fully integrated systems, one partially integrated system, and one separate system.

Bruns, A. E.↗
NASA NTRS1977

Design study of a feedback control system for the Multicyclic Flap System rotor (MFS)

The feasibility of automatically providing higher harmonic control to a deflectable control flap at the tip of a helicopter rotor blade through feedback of selected independent parameter was investigated. Control parameters were selected for input to the feedback system. A preliminary circuit was designed to condition the selected parameters, weigh limiting factors, and provide a proper output signal to the multi-cyclic control actuators. Results indicate that feedback control for the higher harmonic is feasible; however, design for a flight system requires an extension of the present analysis which was done for one flight condition - 120 kts, 11,500 lbs gross weight and level flight.

Weisbrich, R.↗
NASA NTRS1980

A design study of a signal detection system

A system is described which can aid in the search for radio signals from extraterrestrial sources, or in other applications characterized by low signal-to-noise ratios and very high data rates. The system follows a multichannel (16 million bin) spectrum analyzer, and has critical processing, system control, and memory fuctions. The design includes a moderately rich set of algorithms to be used in parallel to detect signals of unknown form. A multi-threshold approach is used to obtain high and low signal sensitivities. Relatively compact and transportable memory systems are specified.

Healy, T. J.↗