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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Off-design analysis of a gas turbine powerplant augmented by steam injection using various fuels

Results are compared using coal derived low and intermediate heating valve fuel gases and a conventional distillate. The results indicate that steam injection provides substantial increases in both power and efficiency within the available compressor surge margin. The results also indicate that these performance gains are relatively insensitive as to the type of fuel. Also, in a cogeneration application, steam injection could provide some degree of flexibility by varying the split between power and process steam.

Stochl, R. J.↗
NASA NTRS1984

Role of fuel chemical properties on combustor radiative heat load

In an attempt to rigorously study the fuel chemical property influence on combustor radiative heat load, UTRC has conducted an experimental program using 25 test fuels. The burner was a 12.7-cm dia cylindrical device fueled by a single pressure-atomizing injector. Fuel physical properties were de-emphasized by selecting injectors which produced highly-atomized, and hence rapidly-vaporizing sprays. The fuels were specified to cover the following wide ranges of chemical properties: hydrogen, 9.1 to 15- (wt) pct; total aromatics, 0 to 100 (vol) pct; and naphthalene, 0 to 30 (vol) pct. They included standard fuels, specialty products and fuel blends. Fuel naphthalene content exhibited the strongest influence on radiation of the chemical properties investigated. Smoke point was a good global indicator of radiation severity.

Rosfjord, T. J.↗
NASA NTRS1987

Fuel thermal stability effects on spray characteristics

The propensity of a heated hydrocarbon fuel toward solids deposition within a fuel injector is investigated experimentally. Fuel is arranged to flow through the injector at constant temperature, pressure, and flow rate and the pressure drop across the nozzle is monitored to provide an indication of the amount of deposition. After deposits have formed, the nozzle is removed from the test rig and its spray performance is compared with its performance before deposition. The spray characteristics measured include mean drop size, drop-size distribution, and radial and circumferential fuel distribution. It is found that small amounts of deposition can produce severe distortion of the fuel spray pattern. More extensive deposition restores spray uniformity, but the nozzle flow rate is seriously curtailed.

Lefebvre, A. H.↗
NASA NTRS1984

Role of fuel chemical properties on combustor radiative heat load

In an attempt to rigorously study the fuel chemical property influence on combustor radiative heat load, United Technologies Research Center (UTRC) has conducted an experimental program using 25 test fuels. The burner was a 12.7-cm dia cylindrical device fueled by a single pressure-atomizing injector. Fuel physical properties were de-emphasized by selecting injectors which produced high-atomized, and hence rapidly-vaporizing sprays. The fuels were specified to cover the following wide ranges of chemical properties; hydrogen, 9.1 to 15- (wt) pct; total aromatics, 0 to 100 (vol) pct; and naphthalene, 0 to 30 (vol) pct. They included standard fuels, specialty products and fuel blends. Fuel naphthalene content exhibited the strongest influence on radiation of the chemical properties investigated. Smoke point was a good global indicator of radiation severity.

Rosfjord, T. J.↗
NASA NTRS1972

An intumescent coating for improved fuel fire protection of heat sensitive articles.

Intumescent coating compositions have been prepared using the ammonium salt of 4-nitroaniline-2-sulfonic acid and a copolymer of polysulfide-epoxy resin as the binder, into which have been dispersed various fillers. The fillers used in the study were low density microballoons for density control and fibers for controlled intumescence on contoured substrates. The filler effect on the thermal-physical efficiency of coatings has been measured. The coating utilizing short length silica fibers has been shown to have superior mechanical, environmental, and thermal properties. The coating applied to the exterior of loaded weapons has increased the time-to-detonation from three minutes for the unprotected weapon to 10-13 minutes.

Sawko, P. M.↗
NASA NTRS1978

Impact of future fuel properties on aircraft engines and fuel systems

The effect of modifications in hydrocarbon jet fuels specifications on engine performance, component durability and maintenance, and aircraft fuel system performance is discussed. Specific topics covered include: specific fuel consumption; ignition at relight limits; exhaust emissions; combustor liner temperatures; carbon deposition; gum formation in fuel nozzles, erosion and corrosion of turbine blades and vanes; deposits in fuel system heat exchangers; and pumpability and flowability of the fuel. Data that evaluate the ability of current technology aircraft to accept fuel specification changes are presented, and selected technological advances that can reduce the severity of the problems are described and discussed.

Rudey, R. A.↗
NASA NTRS1996

On-Line Measurement of Heat of Combustion of Gaseous Hydrocarbon Fuel Mixtures

A method for the on-line measurement of the heat of combustion of gaseous hydrocarbon fuel mixtures has been developed and tested. The method involves combustion of a test gas with a measured quantity of air to achieve a preset concentration of oxygen in the combustion products. This method involves using a controller which maintains the fuel (gas) volumetric flow rate at a level consistent with the desired oxygen concentration in the combustion products. The heat of combustion is determined form a known correlation with the fuel flow rate. An on-line computer accesses the fuel flow data and displays the heat of combustion measurement at desired time intervals. This technique appears to be especially applicable for measuring heats of combustion of hydrocarbon mixtures of unknown composition such as natural gas.

Sprinkle, Danny R.↗
NASA NTRS1996

Metallized Gelled Propellants: Oxygen/RP-1/Aluminum Rocket Heat Transfer and Combustion Measurements

A series of rocket engine heat transfer experiments using metallized gelled liquid propellants was conducted. These experiments used a small 20- to 40-lb/f thrust engine composed of a modular injector, igniter, chamber and nozzle. The fuels used were traditional liquid RP-1 and gelled RP-1 with 0-, 5-, and 55-percentage by weight loadings of aluminum particles. Gaseous oxygen was used as the oxidizer. Three different injectors were used during the testing: one for the baseline O(2)/RP-1 tests and two for the gelled and metallized gelled fuel firings. Heat transfer measurements were made with a rocket engine calorimeter chamber and nozzle with a total of 31 cooling channels. Each chamber used a water flow to carry heat away from the chamber and the attached thermocouples and flow meters allowed heat flux estimates at each of the 31 stations. The rocket engine Cstar efficiency for the RP-1 fuel was in the 65-69 percent range, while the gelled 0 percent by weight RP-1 and the 5-percent by weight RP-1 exhibited a Cstar efficiency range of 60 to 62% and 65 to 67%, respectively. The 55-percent by weight RP-1 fuel delivered a 42-47% Cstar efficiency. Comparisons of the heat flux and temperature profiles of the RP-1 and the metallized gelled RP-1/A1 fuels show that the peak nozzle heat fluxes with the metallized gelled O2/RP-1/A1 propellants are substantially higher than the baseline O2/RP-1: up to double the flux for the 55 percent by weight RP-1/A1 over the RP-1 fuel. Analyses showed that the heat transfer to the wall was significantly different for the RP-1/A1 at 55-percent by weight versus the RP-1 fuel. Also, a gellant and an aluminum combustion delay was inferred in the 0 percent and 5-percent by weight RP-1/A1 cases from the decrease in heat flux in the first part of the chamber. A large decrease in heat flux in the last half of the chamber was caused by fuel deposition in the chamber and nozzle. The engine combustion occurred well downstream of the injector face based on the heat flux estimates from the temperature measurements.

Palaszewski, Bryan↗
NASA NTRS1986

Stirling engine external heat system design with heat pipe heater

This final report presents the conceptual design of a liquid fueled external heating system (EHS) and the preliminary design of a heat pipe heater for the STM-4120 Stirling cycle engine, to meet the Air Force mobile electric power (MEP) requirement for units in the range of 20 to 60 kW. The EHS design had the following constraints: (1) Packaging requirements limited the overall system dimensions to about 330 mm x 250 mm x 100 mm; (2) Heat flux to the sodium heat pipe evaporator was limited to an average of 100 kW/m and a maximum of 550 kW/m based on previous experience; and (3) The heat pipe operating temperature was specified to be 800 C based on heat input requirements of the STM4-120. An analysis code was developed to optimize the EHS performance parameters and an analytical development of the sodium heat pipe heater was performed; both are presented and discussed. In addition, construction techniques were evaluated and scale model heat pipe testing performed.

Godett, Ted M.↗
NASA NTRS1978

Utilization of waste heat in trucks for increased fuel economy

Improvements in fuel economy for a broad spectrum of truck engines and waste heat utilization concepts are evaluated and compared. The engines considered are the diesel, spark ignition, gas turbine, and Stirling. The waste heat utilization concepts include preheating, regeneration, turbocharging, turbocompounding, and Rankine engine compounding. Predictions were based on fuel-air cycle analyses, computer simulation, and engine test data. The results reveal that diesel driving cycle performance can be increased by 20% through increased turbocharging, turbocompounding, and Rankine engine compounding. The Rankine engine compounding provides about three times as much improvement as turbocompounding but also costs about three times as much. Performance for either is approximately doubled if applied to an adiabatic diesel.

Leising, C. J.↗
NASA NTRS1978

Impact of future fuel properties on aircraft engines and fuel systems

From current projections of the availability of high-quality petroleum crude oils, it is becoming increasingly apparent that the specifications for hydrocarbon jet fuels may have to be modified. The problems that are most likely to be encountered as a result of these modifications relate to engine performance, component durability and maintenance, and aircraft fuel-system performance. The effect on engine performance will be associated with changes in specific fuel consumption, ignition at relight limits, at exhaust emissions. Durability and maintenance will be affected by increases in combustor liner temperatures, carbon deposition, gum formation in fuel nozzles, and erosion and corrosion of turbine blades and vanes. Aircraft fuel-system performance will be affected by increased deposits in fuel-system heat exchangers and changes in the pumpability and flowability of the fuel. The severity of the potential problems is described in terms of the fuel characteristics most likely to change in the future. Recent data that evaluate the ability of current-technology aircraft to accept fuel specification changes are presented, and selected technological advances that can reduce the severity of the problems are described and discussed.

Rudey, R. A.↗
NASA NTRS1973

Design considerations for the airframe-integrated scramjet

Research programs at the NASA Langley Research Center on the development of airframe-integrated scramjet concepts (supersonic combustion ramjet) are reviewed briefly. The design and performance of a specific scramjet configuration are examined analytically by use of recently developed and substantiated techniques on boundary-layer development, heat transfer, fuel-air mixing, heat-release rates, and engine-cycle analysis. These studies indicate that the fixed-geometry scramjet module will provide practical levels of thrust performance with low cooling requirements. Areas which need particular emphasis in further development work are the combustor design for low speeds and the integrated nozzle design.

Henry, J. R.↗
NASA NTRS2010

Nitrous Oxide/Paraffin Hybrid Rocket Engines

Nitrous oxide/paraffin (N2OP) hybrid rocket engines have been invented as alternatives to other rocket engines especially those that burn granular, rubbery solid fuels consisting largely of hydroxyl- terminated polybutadiene (HTPB). Originally intended for use in launching spacecraft, these engines would also be suitable for terrestrial use in rocket-assisted takeoff of small airplanes. The main novel features of these engines are (1) the use of reinforced paraffin as the fuel and (2) the use of nitrous oxide as the oxidizer. Hybrid (solid-fuel/fluid-oxidizer) rocket engines offer advantages of safety and simplicity over fluid-bipropellant (fluid-fuel/fluid-oxidizer) rocket en - gines, but the thrusts of HTPB-based hybrid rocket engines are limited by the low regression rates of the fuel grains. Paraffin used as a solid fuel has a regression rate about 4 times that of HTPB, but pure paraffin fuel grains soften when heated; hence, paraffin fuel grains can, potentially, slump during firing. In a hybrid engine of the present type, the paraffin is molded into a 3-volume-percent graphite sponge or similar carbon matrix, which supports the paraffin against slumping during firing. In addition, because the carbon matrix material burns along with the paraffin, engine performance is not appreciably degraded by use of the matrix.

Zubrin, Robert↗