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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 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Emissions and new technology programs for conventional spark-ignition aircraft engines

A long-range technology plan in support of general aviation engines was formulated and is being implemented at the Lewis Research Center. The overall program was described, and that part of the program that represents the in-house effort at Lewis was presented in detail. Three areas of government and industry effort involving conventional general-aviation piston engines were part of a coordinated overall plan: (1) FAA/NASA joint program, (2) NASA contract exhaust emissions pollution reduction program, and (3) NASA in-house emissions reduction and new technology program.

Wintucky, W. T.↗
NASA NTRS1977

Characterization of secondary ignition sources in unattended compartments and full-scale baseline test

The characteristics of five fuel loads burned within a metal lavatory were identified. In 15 of the tests the lavatory door remained closed for the 30-minute test period while in 15 additional tests the door was opened after the fire had developed. Upon completion of these tests the most severe source was selected for use in the baseline test. In the baseline test, the lavatory and adjacent panels, all of which were constructed of contemporary materials, were tested for a period of 1 hour. Thermal, environmental, and biological data were obtained for all fuel loads, door conditions, and the baseline test. All tests were conducted in a cabin fire simulator with separate ventilation of the cabin and lavatory representative of an inflight condition. The baseline test established that by using the most severe fuel source: (1) the exposed animal subject survived without complications; (2) no toxic levels of gas within the cabin were detected; (3) a propagating fire did not develop in adjacent structures; (4) the lavatory containing the fire remained structurally intact; (5) decomposition of portions of the lavatory did occur; and (6) cabin visibility would have presented a problem after 5 minutes.

Klink, D. M.↗
NASA NTRS1979

Critical influence of finite rate chemistry and unmixedness on ignition and combustion of supersonic H2-air streams

Good agreement has been obtained between published profiles of composition and pitot pressure and the calculated results from a computer program in which finite rate chemistry was used. Significant differences are noted between results calculated using 7 species and 8 reactions and those calculated using 12 species and 25 reactions. Differences are also found between results in which the effect of unmixedness on reaction in turbulent flow is applied or is not applied.

Evans, J. S.↗
NASA NTRS1980

Effect of propellant deformation on ignition and combustion processes in solid propellant cracks

A comprehensive theoretical model was formulated to study the development of convective burning in a solid propellant crack which continually deforms due to burning and pressure loading. In the theoretical model, the effect of interrelated structural deformation and combustion processes was taken into account by considering (1) transient, one dimensional mass, momentum, and energy conservation equations in the gas phase; (2) a transient, one dimensional heat conduction equation in the solid phase; and (3) quasi-static deformation of the two dimensional, linear viscoelastic propellant crack caused by pressure loading. Partial closures may generate substantial local pressure peaks along the crack, implying a strong coupling between chamber pressurization, crack combustion, and propellant deformation, especially when the cracks are narrow and the chamber pressurization rates high. The maximum pressure in the crack cavity is generally higher than that in the chamber. The initial flame-spreading process is not affected by propellant deformation.

Kumar, M.↗
NASA NTRS1982

Plasma ignition for laser propulsion

For a specific optical system a pulsed carbon dioxide laser having an energy output of up to 15 joules was used to initiate a plasma in air at one atmosphere pressure. The spatial and temporal development of the plasma were measured using a multiframe image converter camera. In addition the time dependent velocity of the laser supported plasma front which moves opposite to the direction of the laser pulse was measured in order to characterize the type of wavefront developed. Reliable and reproducible spark initiation was achieved. The lifetime of the highly dense plasma at the initial focal spot was determined to be less than 100 nanoseconds. The plasma front propagates toward the laser at a variable speed ranging from zero to 1.6 x 1,000,000 m/sec. The plasma front propagates for a total distance of approximately five centimeters for the energy and laser pulse shape employed.

Askew, R. F.↗
NASA NTRS1983

An analytical investigation of NO sub x control techniques for methanol fueled spark ignition engines

A thermokinetic SI engine simulation was used to study the effects of simple nitrogen oxide control techniques on performance and emissions of a methanol fueled engine. As part of this simulation, a ring crevice storage model was formulated to predict UBF emissions. The study included spark retard, two methods of compression ratio increase and EGR. The study concludes that use of EGR in high turbulence, high compression engines will both maximize power and thermal efficiency while minimizing harmful exhaust pollutants.

Browning, L. H.↗
NASA NTRS1985

Heaterless ignition of inert gas ion thruster hollow cathodes

Heaterless inert gas ion thruster hollow cathodes were investigated with the aim of reducing ion thruster complexity and increasing ion thruster reliability. Cathodes heated by glow discharges are evaluated for power requirements, flowrate requirements, and life limiting mechanisms. An accelerated cyclic life test is presented.

Schatz, M. F.↗
NASA NTRS1986

Spontaneous ignition delay characteristics of hydrocarbon fuel-air mixtures

The influence of pressure on the autoignition characteristics of homogeneous mixtures of hydrocarbon fuels in air is examined. Autoignition delay times are measured for propane, ethylene, methane, and acetylene in a continuous flow apparatus featuring a multi-point fuel injector. Results are presented for mixture temperatures from 670K to 1020K, pressures from 1 to 10 atmospheres, equivalence ratios from 0.2 to 0.7, and velocities from 5 to 30 m/s. Delay time is related to pressure, temperature, and fuel concentration by global reaction theory. The results show variations in global activation energy from 25 to 38 kcal/kg-mol, pressure exponents from 0.66 to 1.21, and fuel concentration exponents from 0.19 to 0.75 for the fuels studied. These results are generally in good agreement with previous studies carried out under similar conditions.

Lefebvre, A. H.↗
NASA NTRS1985

Heaterless ignition of inert gas ion thruster hollow cathodes

Heaterless inert gas ion thruster hollow cathodes were investigated with the aim of reducing ion thruster complexity and increasing ion thruster reliability. Cathodes heated by glow discharges are evaluated for power requirements, flowrate requirements, and life limiting mechanisms. An accelerated cyclic life test is presented.

Schatz, M. F.↗
NASA NTRS1988

Investigation of energy transfer in the ignition mechanism of a NASA standard initiator

The principal objective of the proposed research was to construct a detailed computer model of the NASA Standard Initiator (NSI). The NSI plays a critical role in initiating various pyrotechnic events in the National Space Transportation System and is also used in Shuttle payload applications. Several initiators failed when being tested at very low temperatures (4 to 20 K). During subsequent investigation an unacceptable high failure rate was found even at higher temperatures (100 to 150 K) but the precise cause of failure was not determined. The modelling work was undertaken to investigate reasons for failure and to predict the performance of alternate firing schemes. The work has shown that the most likely cause of failure at low temperature is poor thermal contact between the electrically heated bridgewire and the pyrotechnic charge. This problem may be masked if there is good thermal contact between the bridgewire and the alumina charge cup. The high thermal conductivity of alumina at cryogenic temperatures was overlooked in previous analyses, which assumed that the charge cup acted as a thermal insulator.

Varghese, Philip L.↗
NASA NTRS1989

Rocket-triggered lightning strikes and forest fire ignition

Background information on the rocket-triggered lightning project at Kennedy Space Center (KSC), a summary of the forecasting problem there, the facilities and equipment available for undertaking field experiments at KSC, previous research activity performed, a description of the atmospheric science field laboratory near Mosquito Lagoon on the KSC complex, methods of data acquisition, and present results are discussed. New sources of data for the 1989 field experiment include measuring the electric field in the lower few thousand feet of the atmosphere by suspending field measuring devices below a tethered balloon. Problems encountered during the 1989 field experiment are discussed. Future prospects for both triggered lightning and lightning-kindled forest fire research at KSC are listed.

Fenner, James H.↗