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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 73 records · Page 4
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NASA NTRS1974

Apollo 16 mission report. Supplement 2: Service Propulsion system final flight evaluation

The Apollo 16 Mission was the sixteenth in a series of flights using Apollo flight hardware and included the fifth lunar landing of the Apollo Program. The Apollo 16 Mission utilized CSM 113 which was equipped with SPS Engine S/N 66 (Injector S/N 137). The engine configuration and expected performance characteristics are presented. Since previous flight results of the SPS have consistently shown the existence of a negative mixture ratio shift, SPS Engine S/N 66 was reorificed to increase the mixture ratio for this mission. The propellant unbalance for the two major engine firings is compared with the predicted unbalance. Although the unbalance at the end of the TEI burn is significantly different than the predicted unbalance, the propellant mixture ratio was well within limits. The SPS performed six burns during the mission, with a total burn duration of 575.3 seconds. The ignition time, burn duration and velocity gain for each of the six SPS burns are reported.

Smith, R. J.↗
NASA NTRS1961

Size Distribution and Velocity of Ethanol Drops in a Rocket Combustor Burning Ethanol and Liquid Oxygen

Single jets of ethanol were studied photomicrographically inside a rocket chamber as they broke up into sprays of drops which underwent simultaneous acceleration and vaporization with chemical reaction occurring in the surrounding combustion gas stream. In each rocket test-firing, liquid oxygen was used as the oxidant. Both drop velocity and drop size distribution data were obtained from photomicrographs of the ethanol drops taken with an ultra-high speed tracking camera developed at NASA, Lewis Research Center.

Ingebo, Robert D.↗
NASA NTRS1989

Computing Optimal Multiarc Trajectories

Optimal Multi-Arc Trajectories (OMAT) computer program designed to calculate solution to optimal-trajectory problem in cases of low thrust-to-weight ratios. Developed for two-body exoatmospheric problem with three degrees of freedom in inverse-square force field. Offers two different options: impulsive changes in velocity and finite burns with low thrust-to-weight ratios. Two distinct solutions available from program: optimal multi-impulse (OMI) solution and optimal multiburn (OMB) solution. Two solutions obtained separately, or results of OMI solution used to guess unknown parameters of OMB solution. Written for DEC VAX-series computer. Written completely in FORTRAN 77.

Jezewski, Donald J.↗
NASA NTRS1989

Pre-main-sequence stars in the young cluster IC 2391

Seven or eight new, late-type members of the poor open cluster IC 2391 are identified, and membership is confirmed for two other stars. The new members fall approximately along a 3 x 10 to the 7th yr isochrone, which is the age estimated for the cluster on the basis of it super main-seqence turnoff. Echelle spectra were obtained for the most probable cluster members. Most show H-alpha in emission and a strong Li 6707 A absorption line, and a few are rapid rotators. The Li abundances for cluster stars cooler than the sun are considerably less than the primordial Li abundance, providing the first direct evidence for substantial premain-sequence Li burning. The rotational velocities show a range from about 15 to 150 km/s, with a distribution of rotational velocities not significantly different from that observed for low-mass stars in the Pleiades.

Stauffer, John↗
NASA NTRS1992

Laboratory test methods for combustion stability properties of solid propellants

An overview is presented of experimental methods for determining the combustion-stability properties of solid propellants. The methods are generally based on either the temporal response to an initial disturbance or on external methods for generating the required oscillations. The size distribution of condensed-phase combustion products are characterized by means of the experimental approaches. The 'T-burner' approach is shown to assist in the derivation of pressure-coupled driving contributions and particle damping in solid-propellant rocket motors. Other techniques examined include the rotating-valve apparatus, the impedance tube, the modulated throat-acoustic damping burner, and the magnetic flowmeter. The paper shows that experimental methods do not exist for measuring the interactions between acoustic velocity oscillations and burning propellant.

Strand, L. D.↗
NASA NTRS2004

Research Performed within the Non-Destructive Evaluation Team at NASA Glenn Research Center

Non-destructive testing is essential in many fields of manufacturing and research in order to perform reliable examination of potentially damaged materials and parts without destroying the inherent structure of the materials. Thus, the Non-Destructive Evaluation (NDE) Team at NASA Glenn Research Center partakes in various projects to improve materials testing equipment as well as analyze materials, material defects, and material deficiencies. Due to the array of projects within the NDE Team at this time, five research aims were supplemental to some current projects. A literature survey of "DE and testing methodologies as related to rocks was performed. Also, Mars Expedition Rover technology was assessed to understand the requirements for instrumentation in harsh space environments (e.g. temperature). Potential instrumentation and technologies were also considered and documented. The literature survey provided background and potential sources for a proposal to acquire funding for ultrasonic instrumentation on board a future Mars expedition. The laboratory uses a Santec Systems AcousticScope AS200 acoustography system. Labview code was written within the current program in order to improve the current performance of the acoustography system. A sample of Reinforced Carbon/Carbon (RCC) material from the leading edge of the space shuttle underwent various non-destructive tests (guided wave scanning, thermography, computed tomography, real time x-ray, etc.) in order to characterize its structure and examine possible defects. Guided wave scan data of a ceramic matrix composite (CMC) panel was reanalyzed utilizing image correlations and signal processing variables. Additional guided wave scans and thermography were also performed on the CMC panel. These reevaluated data and images will be used in future presentations and publications. An additional axis for the guided wave scanner was designed, constructed, and implemented. This additional axis allowed incremental spacing of the previously fixed transducers for ultrasonic velocity measurements.

Burns, Erin A.↗
NASA NTRS1974

Development of a miniature solid propellant rocket motor for use in plume simulation studies

A miniature solid propellant rocket motor has been developed to be used in a program to determine those parameters which must be duplicated in a cold gas flow to produce aerodynamic effects on an experimental model similar to those produced by hot, particle-laden exhaust plumes. Phenomena encountered during the testing of the miniature solid propellant motors included erosive propellant burning caused by high flow velocities parallel to the propellant surface, regressive propellant burning as a result of exposed propellant edges, the deposition of aluminum oxide on the nozzle surfaces sufficient to cause aerodynamic nozzle throat geometry changes, and thermal erosion of the nozzle throat at high chamber pressures. A series of tests was conducted to establish the stability of the rocket chamber pressure and the repeatibility of test conditions. Data are presented which define the tests selected to represent the final test matrix. Qualitative observations are also presented concerning the phenomena experienced based on the results of a large number or rocket tests not directly applicable to the final test matrix.

Baran, W. J.↗
NASA NTRS1992

A numerical study of Li-SF6 wick combustion - Forced and mixed convective burning

A numerical study is conducted to study Li-SF6 wick diffusion flames under mixed convective burning conditions at a pressure of 0.01 MPa. Both planar and cylindrical wicks are considered. The model is based on a conserved scalar approach. The objective of this study is to assess the effects of particular parameters on the burning rate and heat transfer. The flat-plate solution yields a fuel mass burning rate per unit surface area following the x exp -1/2 dependence of the classical similarity solution, where x is the streamwise distance. Cylindrical wick geometries yield enhanced burning rates over planar wicks. For the case of mixed convective burning, the burning rate results approach either the forced or natural convective burning limits as ambient streamwise velocity is changed. Critical Richardson numbers specifying these burning limits are determined for a given condition. Reducing gravity results in a lower burning rate because the influence of natural convection is diminished. Under reduced gravity of 1/1000 of the sea-level value, mixed convective burning nearly resembles forced convection.

Damaso, R. C.↗
NASA NTRS1991

Recovery from an anomalous thruster input during a simulated docking maneuver

An experiment was performed in the Space Station Proximity Operations Simulator at the NASA Ames Research Center. Five test subjects were instructed to perform twenty simulated remote docking maneuvers of an orbital maneuvering vehicle (OMV) to the space station in which they were located. The OMV started from an initial range of 304.8 m (1000 ft) on the space station's negative velocity vector. Anomalous out-of-plane thruster firings of various magnitudes (simulating a faulty thruster) occurred at one of five ranges from the target. Initial velocity, range of anomalous burn, and magnitude of anomalous burn were the factors varied. In addition to whether the trial was successful, time and fuel to return to a nominal trajectory, total mission duration, total fuel consumption, and time histories of commanded burns were recorded. Analysis of the results added support to the hypothesis that slow approach velocities are not inherently safer than their more rapid counterparts. Naive subjects were capable of docking successfully at velocities faster than those prescribed by the 0.1 percent rule even when a simulated faulty thruster disturbed the nominal trajectory. Little to no justification for slow approach velocities remains from a human factors standpoint.

Brody, Adam R.↗
NASA NTRS1994

Convection, nucleosynthesis, and core collapse

We use a piecewise parabolic method hydrodynamics code (PROMETHEUS) to study convective burning in two dimensions in an oxygen shell prior to core collapse. Significant mixing beyond convective boundaries determined by mixing-length theory brings fuel (C-12) into the convective regon, causing hot spots of nuclear burning. Plumes dominate the velocity structure. Finite perturbations arise in a region in which O-16 will be explosively burned to Ni-56 when the star explodes; the resulting instabilities and mixing are likely to distribute Ni-56 throughout the supernova envelope. Inhomogeneities in Y(sub e) may be large enough to affect core collapse and will affect explosive nucleosynthesis. The nature of convective burning is dramatically different from that assumed in one-dimensional simulations; quantitative estimates of nucleosynthetic yields, core masses, and the approach to core collapse will be affected.

Bazan, Grant↗
NASA NTRS1991

The effect of multi-periapse burns on planetary escape and capture

The use of multiple periapse burns to transfer between a planetocentric parking orbit and a hyperbolic trajectory with a high thrust propulsion system having constant, finite thrust is investigated. Such multiple burns offer propellant savings as a consequence of reduced velocity losses which accrue over the finite burn time of thrusting maneuvers. Velocity losses for an earth escape phase are calculated for an optimum steering program over a range of parameters that are typical of a Mars mission. These numerically integrated results are compared to velocity losses evaluated with a leading analytic approximation to establish boundaries within which the accuracy of the analytic approximation is adequate for preliminary mission planning purposes. Finally, results of the investigation are used to define typical benefits of the multi-periapse burn concept for Mars exploration missions.

Horsewood, Jerry L.↗
NASA NTRS1974

Mars surface-to-orbit vehicles for sample return missions

Review of the results of a Mars surface-to-orbit launch vehicle study using an upgraded atmospheric density profile and an ascent trajectory optimization program. Orbit insertion was achieved with velocity losses less than those found in an earlier study. Values of thrust-to-mass ratio which minimize velocity losses for dual-burn vehicles were found to be significantly greater than the values of thrust-to-launch-mass ratio for the minimum-velocity-loss continuous-burn vehicle. The use of a two-stage solid-propellant vehicle employing a spin-stabilized second stage offers an attractive design option for a Mars surface-to-orbit launch vehicle.

Weaver, W. L.↗
NASA NTRS1988

The eivaN: A forward-looking interactive orbital trajectory plotting tool for use with proximity operations (PROX OPS) and other maneuvers: Description and user's manual

The results of vehicle burns on-orbit are very difficult to anticipate because of nonlinearities in the equations of motion governing orbiting bodies. This confusion was noticed firsthand in prior experimentation. Out of plane motion is relatively simple as it is uncoupled from the other two degrees of freedom. However, in plane thrusts are more complex because the motions resulting from these inputs are coupled. An interactive planning device, eivaN, was developed to plot resulting trajectories, to provide a better comprehension of orbital mechanics effects, and to help the user to develop heuristics for on-orbit mission planning. The eivaN runs with Microsoft Excel on a Macintosh computer. It provides a forward looking display: burn parameters in the three orthogonal axes in addition to time inputted, and the resultant trajectory is then plotted. Position and velocity components for any burn at any user specified time are readily available. A new area of research related to the human factors of real time, on-orbit mission planning was identified and is currently being investigated.

Brody, Adam R.↗
NASA NTRS1986

Opposed jet burner studies of silane-methane, silane-hydrogen and hydrogen diffusion flames with air

An atmospheric pressure tubular opposed jet burner technique was used to characterize certain diffusion-flame transitions and associated burning rates for N2-diluted mixtures of highly-reactive fuels. Presented are: (1) details of the technique, with emphasis on features permitting the study of flames involving pyrophoric gases and particle-forming combustion reactions: (2) discoveries on the properties of these flames which correspond to physically and chemically distinct stages of silane and hydrogen combustion; and (3) unburnt gas velocity data obtained from flames based on SiH4-CH4-N2, SiH4-H2-N2, and H2-N2 fuel mixtures, and plotted as functions of combustible-fuel mole fraction and fuel/oxygen molar input flow ratios. In addition, these burning velocity results are analyzed and interpreted.

Pellett, G. L.↗
NASA NTRS1972

Asymptotic expansion of an impulse for an optimal finite burn

Closed form expressions are derived for the position and velocity of a spacecraft during a finite burn using the method involving the theory of asymptotic expansion of the optimal impulsive solution. The small parameter is given by the reciprocal of the mass flow rate. The expansion is given in terms of the impulsive solution and holds up through third-order for the velocity and fourth-order for the position.

Pines, S.↗
NASA NTRS1986

Opposed jet burner studies of silane-methane, silane-hydrogen, and hydrogen diffusion flames with air

An atmospheric pressure tubular opposed jet burner technique was used to characterize certain diffusion-flame transitions and associated burning rates for N2-diluted mixtures of highly-reactive fuels. The paper presents: (1) details of the technique, with emphasis on features permitting the study of flames involving pyrophoric gases and particle-forming combustion reactions; (2) discoveries on the properties of these flames which correspond to physically and chemically distinct stages of silane and hydrogen combustion; and (3) unburnt gas velocity data obtained from flames based on SiH4-CH4-N2, SiH4-H2-N2, and H2-N2 fuel mixtures, and plotted as functions of combustible-fuel mole fraction and fuel/oxygen molar input flow ratios. In addition, these burning velocity results are analyzed and interpreted.

Pellett, G. L.↗