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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 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Feasibility study of liquid pool burning in reduced gravity

The feasibility of conducting experiments in the Spacelab on ignition and flame spread with liquid fuel pools which are initially at a temperature lower than the fuel's flash point temperature was studied. Theories were developed for the ignition and flame spread processes, and experiments were conducted to understand the factors influencing the ignition process and the spread rate. The results were employed to devise a conceptual Spacelab experiment which is expected to be feasible for a safe conduct and to be suitable for obtaining crucial data on the concerned processes.

Kanury, A. M.↗
NASA NTRS1979

Review of composite propellant burn rate modeling

Steady-state combustion modeling of composite solid propellants is discussed with emphasis on the Beckstead-Derr-Price (BDP) model. The BDP model and some revisions are considered with respect to the analysis of monomodal ammonium perchlorate/inert binder propellants: topics examined include continuity relations, surface area relations, characteristic surface dimension, flame heights, and energy balance. Application of the BDP model to more complicated propellants containing multiple active ingredients is described. These propellants include multimodal, mixed oxidizer, active binder, aluminized, catalyzed, and nitramine propellants. Example cases of modeling (with comparison to experimental data) are presented, and strengths and weaknesses of current modeling approaches are evaluated.

Cohen, N. S.↗
NASA NTRS1979

Use of a duct-burning turbofan for an earth-to-orbit vehicle booster

The Space Shuttle will soon reduce the cost of transportation to orbit. The resulting traffic growth will lead to economic pressure for a new vehicle. Several vehicles have been studied. A supersonically staged system with twin turbojet boosters may be attractive but the development of a large supersonic turbojet engine would be required. Subsonic staging with a reasonable number of turbojet engines does not provide the desired payload capability with existing engines. The addition of a duct burner to an existing large turbofan engine provides sufficient thrust to allow the design of an attractive system with twin boosters staged subsonically.

Martin, J. A.↗
NASA NTRS1979

Investigation of critical burning of fuel droplets

The general problem of spray combustion was investigated. The combustion of bipropellent droplets; combustion of hydrozine fuels; and combustion of sprays were studied. A model was developed to predict mean velocities and temperatures in a combusting gas jet.

Faeth, G. M.↗
NASA NTRS1980

Smoke characteristics of distillate and residual fuel burning in gas turbine combustors

During the development of a rich-lean staged dry low NOx combustor, the conventional trend of increasing smoke with increasing operating equivalence ratio was found when tests were run with distillate fuel (% H = 13.0). However, when tests were run with residual fuel (% H = 11.4), the trend was reversed. In addition, when the same combustor was run with blends of distillate fuel and residual fuel, a drastic improvement of smoke was observed when only 6 percent of residual fuel was mixed with distillate fuel, and for any blending of more than 10 percent of residual fuel the combustor was practically smoke free. A chemical analysis of fuel samples revealed an appreciable amount of trace metals in the residual fuel, giving rise to the suspicion that the smoke reduction may have been due in part to these trace metals. Of these elements found, vanadium is believed to be the most likely to cause smoke reduction because of its relatively high concentration.

Liu, T. M.↗
NASA NTRS1980

Experimental evaluation of combustor concepts for burning broad property fuels

A baseline CF6-50 combustor and three advanced combustor designs were evaluated to determine the effects of combustor design on operational characteristics using broad property fuels. Three fuels were used in each test: Jet A, a broad property 13% hydrogen fuel, and a 12% hydrogen fuel blend. Testing was performed in a sector rig at true cruise and simulated takeoff conditions for the CF6-50 engine cycle. The advanced combustors (all double annular, lean dome designs) generally exhibited lower metal temperatures, exhaust emissions, and carbon buildup than the baseline CF6-50 combustor. The sensitivities of emissions and metal temperatures to fuel hydrogen content were also generally lower for the advanced designs. The most promising advanced design used premixing tubes in the main stage. This design was chosen for additional testing in which fuel/air ratio, reference velocity, and fuel flow split were varied.

Kasper, J. M.↗
NASA NTRS1981

Low NO/x/ combustion systems for burning heavy residual fuels and high-fuel-bound nitrogen fuels

Design concepts are presented for lean-lean and staged rich-lean combustors. The combustors are designed for the dry reduction of thermal NO(x), control of NO(x) from fuels containing high levels of organic nitrogen, and control of smoke from low hydrogen content fuels. The combustor concepts are tested with a wide variety of fuels including a middle distillate, a petroleum based heavy residual, a coal derived synthetic, and ratios of blends of these fuels. The configurations of the lean-lean and rich-lean combustion systems are provided along with a description of the test rig and test procedure.

White, D. J.↗
NASA NTRS1982

Supersonic burning in separated flow regions

The trough vortex phenomena is used for combustion of hydrogen in a supersonic air stream. This was done in small sizes suitable for igniters in supersonic combustion ramjets so long as the boundary layer displacement thickness is less than 25% of the trough step height. A simple electric spark, properly positioned, ignites the hydrogen in the trough corner. The resulting flame is self sustaining and reignitable. Hydrogen can be injected at the base wall or immediately upstream of the trough. The hydrogen is introduced at low velocity to permit it to be drawn into the corner vortex system and thus experience a long residence time in the combustion region. The igniters can be placed on a skewed back step for angles at least up to 30 deg. without affecting the igniter performance significantly. Certain metals (platinum, copper) act catalytically to improve ignition.

Zumwalt, G. W.↗
NASA NTRS1983

OPTIM: Computer program to generate a vertical profile which minimizes aircraft fuel burn or direct operating cost. User's guide

A profile of altitude, airspeed, and flight path angle as a function of range between a given set of origin and destination points for particular models of transport aircraft provided by NASA is generated. Inputs to the program include the vertical wind profile, the aircraft takeoff weight, the costs of time and fuel, certain constraint parameters and control flags. The profile can be near optimum in the sense of minimizing: (1) fuel, (2) time, or (3) a combination of fuel and time (direct operating cost (DOC)). The user can also, as an option, specify the length of time the flight is to span. The theory behind the technical details of this program is also presented.

Source record↗
NASA NTRS1982

Analyses of processing variables in propellant burn rate and modulus. I - Mixing times

The effect of the final mixing time on quality of smokeless AP/HTPB propellant with bimodal AP was examined. Identical ingredients were mixed for various intervals, cast in a circular tube, then fired in a static test. Mechanical properties were measured and initial moduli were calculated from the initial slope of the S-N curves. A theoretical model was developed using the data to quantitatively configure a quality control procedure. A minimum time for mixing fine and coarse AP particles was identified and was approximated to within a factor of two or three using a viscous dispersion time and the surface areas of the particles. The model could be improved by considering settling time and particle size distribution effects.

Ramohalli, K.↗
NASA NTRS1985

Corrosive Effects of Burning Fuels

Literature synthesized to develop corrosion predictions for unconventional fuels. Report presents studies of probable corrosive effects of such unconventional fuels as liquefied coal. Report prepared by analyzing probable composition of fuels when they come into wide use, identifying important compounds, and searching literature for information about corrosion problems associated with compounds in environments like those in industrial and commercial boilers and furnaces.

Bellan, J.↗
NASA NTRS1985

Scramjet sidewall burning: Preliminary shock tunnel results

Experiments performed with a two dimensional model scramjet with particular emphasis on the effect of fuel injection from a wall are reported. Air low with a nominal Mach number of 3.5 and varied enthalpies was produced. It was found that neither hydrogen injection angle nor combustor divergence angle had any appreciable effect on thrust values while increased combustor length appeared to increase thrust levels. Specific impulse was observed to peak when hydrogen was injected at an equivalence ratio of about 2. Lowering the Mach number of the injected hydrogen at low equivalence ratios, less than 4, appeared to benefit specific impulse while hydrogen Mach number had little effect at higher equivalence ratios. When a 1:1 mixture by volume of nitrogen and oxygen is used instead of air as a test gas, it is found that hydrogen combustion is enhanced but only at high enthalpies.

Morgan, R. G.↗
NASA NTRS1988

Biomass-burning emissions and associated haze layers over Amazonia

The characteristics of haze layers, which were visually observed over the central Amazon Basin during many of the Amazon Boundary Layer Experiment 2A flights in July/August 1985, were investigated by remote and in situ measurements, using the broad range of instrumentation and sampling equipment on board the Electra aircraft. It was found that these layers strongly influenced the chemical and optical characteristics of the atmosphere over the eastern Amazon Basin. Relative to the regional background, the concentrations of CO, CO2, O3, and NO were significantly elevated in the plumes and haze layers, with the NO/CO ratio in fresh plumes much higher than in the aged haze layers. The haze aerosol was composed predominantly of organic material, NH4, K(+), NO3(-), SO4(2-), and organic anions (formate, acetate, and oxalate).

Andreae, M. O.↗
NASA NTRS1989

Effects of a Venus swingby periapsis burn during an earth-Mars trajectory

Interplanetary missions were analyzed that utilize the gravity-assist orbital transfer technique to increase mission capabilities. This swingby maneuver provides a nonpropulsive change in the spacecraft's heliocentric energy which can reduce the amount of propellant needed to complete an interplanetary mission. For certain planetary orientations, incorporating a propulsive manuever at the periapsis of the swingby trajectory decreases the mission's propellant requirement. This decrease results in a reduced initial vehicle mass in low-earth orbit. This study analyzed the feasibility of using a three-dimensional powered swingby to reduce the initial vehicle size for an excursion class mission during the 2010-2025 time frame.

Striepe, Scott A.↗