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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 379 records · Page 21

All sources NASA NTRS DOE OSTI

NASA NTRS1948

Investigation of Effectiveness of Air-Heating a Hollow Steel Propeller for Protection Against Icing. 2: 50% Impartitioned Blades

The icing protection afforded an internal air-heated propeller blade by radial partitioning at 50-percent chord to confine the heated air to the forward half of the blade was determined in the NACA Cleveland icing research tunnel. A modified production-model hollow steel propeller, was used for the investigation. Temperatures of the blade surfaces for several heating rates were measured under various tunnel Icing' conditions. Photographic observations of ice formations on blade surfaces and blade heat-exchanger effectiveness were obtained. With 50-percent partitioning of the blades, adequate icing protection at 1050 rpm was obtained with a heating rate of 26,000 Btu per hour per blade at the blade shank using an air temperature of 400 F with a flow rate of 280 pounds per hour per blade, which is one-third less heat than was found necessary for similar Ice protection with unpartitioned blades. The chordwise distribution of the applied heat, as determined by surface temperature measurements, was considered unsatisfactory with much of the heat dissipated well back of the leading edge. Heat-exchanger effectiveness of approximately 56 percent also Indicated poor utilization of available heat. This effectiveness was, however, 9 percent greater than that obtained from unpartitioned blades.

Perkins, Porter J.↗

NASA NTRS1987

Development and test of the Shuttle/Centaur cryogenic tankage thermal protection system

The Thermal Protection System (TPS) for the Shuttle/Centaur had to provide fail-safe thermal protection during prelaunch, launch ascent, and on-orbit operations as well as during potential abort where the Shuttle and Centaur would return to earth. The TPS selected used a helium-purged polyimide foam beneath three radiation shields for the liquid hydrogen (LH2) tank and radiation shields only for the liquid oxygen (LO2) tank (three shields on the tank sidewall and four on the aft bulkhead). An evacuated common intermediate bulkhead separated the two tanks. The LH2 tank had one 1.9-cm thick layer of foam on the forward bulkhead and two layers on the larger area side-wall. Full scale tests of the flight vehicle in a simulated Shuttle cargo bay, that was purged with gaseous nitrogen, gave total prelaunch heating rates of 25.9 kW and 12.9 kW for LH2 and LO2 tanks, respectively. Calorimeter tests on a representative LH2 tank sidewall TPS sample indicated that the measured unit heating rate would rapidly decrease from the prelaunch rate of 300 W/sq m to a desired rate of less than 4 W/sq m once on-orbit.

Knoll, R. H.↗

NASA NTRS1992

Detailed examination of LDEF's frame and the A0178 thermal blankets by the meteoroid and debris special investigations group

A responsibility of the group is to define the hypervelocity particle environment encountered by LDEF during its stay in low Earth orbit. LDEF's 6061-T6 aluminum frame and the 'Teflon silver-inconel paint' thermal blankets represent large surface areas that were widely distributed around the spacecraft. The results are reported of high resolution scans of approx. 0.36 and approx. 0.31 sq m for the intercostals and thermal blankets, respectively. The findings are in qualitative agreement with existing model predictions that suggest high differential bombardment histories for surfaces pointing into specific directions relative to the velocity vector of a non-spinning platform in LEO. The production rate for craters greater than or = 50 microns in diameter in aluminum and penetration holes greater than or = 100 microns in diameter in thin foil materials differ by more than a factor of 10 between forward and rearward facing surfaces. These are substantial differences that must be considered during the design of future long duration space platforms in LEO.

See, Thomas H.↗

NASA NTRS1993

Check valve with poppet damping mechanism

An inline check valve for a flow line is presented where the valve element is guided for inline travel forward and rearward of a valve sealing member and is spring biased to a closed sealing condition. One of the guides for the valve element includes a dashpot bore and plunger member to control the rate of travel of the valve element in either direction as well as provided a guiding function. The dashpot is not anchored to the valve body so that the valve can be functional even if the plunger member becomes jammed in the dashpot.

Morris, Brian G.↗

NASA NTRS2013

Investigation of VEGGIE Root Mat

VEGGIE is a plant growth facility that utilizes the phenomenon of capillary action as its primary watering system. A cloth made of Meta Aramid fiber, known as Nomex is used to wick water up from a reservoir to the bottom of the plants roots. This root mat system is intended to be low maintenance with no moving parts and requires minimal crew interface time. Unfortunately, the water wicking rates are inconsistent throughout the plant life cycle, thus causing plants to die. Over-wicking of water occurs toward the beginning of the cycle, while under-wicking occurs toward the middle. This inconsistency of wicking has become a major issue, drastically inhibiting plant growth. The primary objective is to determine the root cause of the inconsistent wicking through experimental testing. Suspect causes for the capillary water column to break include: a vacuum effect due to a negative pressure gradient in the water reservoir, contamination of material due to minerals in water and back wash from plant fertilizer, induced air bubbles while using syringe refill method, and material limitations of Nomex's ability to absorb and retain water. Experimental testing will be conducted to systematically determine the cause of under and over-wicking. Pressure gages will be used to determine pressure drop during the course of the plant life cycle and during the water refill process. A debubbler device will be connected to a root mat in order to equalize pressure inside the reservoir. Moisture and evaporation tests will simultaneously be implemented to observe moisture content and wicking rates over the course of a plant cycle. Water retention tests will be performed using strips of Nomex to determine materials wicking rates, porosity, and absorptivity. Through these experimental tests, we will have a better understanding of material properties of Nomex, as well as determine the root cause of water column breakage. With consistent test results, a forward plan can be achieved to resolve the issue and give valuable insight for the next generation of VEGGIE.

Subbiah, Arun M.↗

NASA NTRS1997

The Use of a Lidar Forward-Looking Turbulence Sensor for Mixed-Compression Inlet Unstart Avoidance and Gross Weight Reduction on a High Speed Civil Transport

Inlet unstart causes a disturbance akin to severe turbulence for a supersonic commercial airplane. Consequently, the current goal for the frequency of unstarts is a few times per fleet lifetime. For a mixed-compression inlet, there is a tradeoff between propulsion system efficiency and unstart margin. As the unstart margin decreases, propulsion system efficiency increases, but so does the unstart rate. This paper intends to first, quantify that tradeoff for the High Speed Civil Transport (HSCT) and second, to examine the benefits of using a sensor to detect turbulence ahead of the airplane. When the presence of turbulence is known with sufficient lead time to allow the propulsion system to adjust the unstart margin, then inlet un,starts can be minimized while overall efficiency is maximized. The NASA Airborne Coherent Lidar for Advanced In-Flight Measurements program is developing a lidar system to serve as a prototype of the forward-looking sensor. This paper reports on the progress of this development program and its application to the prevention of inlet unstart in a mixed-compression supersonic inlet. Quantified benefits include significantly reduced takeoff gross weight (TOGW), which could increase payload, reduce direct operating costs, or increase range for the HSCT.

Soreide, David↗

NASA NTRS1994

Telemetry distribution and processing for the second German Spacelab Mission D-2

For the second German Spacelab Mission D-2 all activities related to operating, monitoring and controlling the experiments on board the Spacelab were conducted from the German Space Operations Control Center (GSOC) operated by the Deutsche Forschungsanstalt fur Luft- und Raumfahrt (DLR) in Oberpfaffenhofen, Germany. The operational requirements imposed new concepts on the transfer of data between Germany and the NASA centers and the processing of data at the GSOC itself. Highlights were the upgrade of the Spacelab Data Processing Facility (SLDPF) to real time data processing, the introduction of packet telemetry and the development of the high-rate data handling front end, data processing and display systems at GSOC. For the first time, a robot on board the Spacelab was to be controlled from the ground in a closed loop environment. A dedicated forward channel was implemented to transfer the robot manipulation commands originating from the robotics experiment ground station to the Spacelab via the Orbiter's text and graphics system interface. The capability to perform telescience from an external user center was implemented. All interfaces proved successful during the course of the D-2 mission and are described in detail in this paper.

Rabenau, E.↗

NASA NTRS2010

Investigation of Control System and Display Variations on Spacecraft Handling Qualities for Docking with Stationary and Rotating Targets

This paper documents the investigation into the manual docking of a preliminary version of the Crew Exploration Vehicle with stationary and rotating targets in Low Earth Orbit. The investigation was conducted at NASA Langley Research Center in the summer of 2008 in a repurposed fixed-base transport aircraft cockpit and involved nine evaluation astronauts and research pilots. The investigation quantified the benefits of a feed-forward reaction control system thruster mixing scheme to reduce translation-into-rotation coupling, despite unmodeled variations in individual thruster force levels and off-axis center of mass locations up to 12 inches. A reduced rate dead-band in the phase-plane attitude controller also showed some promise. Candidate predictive symbology overlaid on a docking ring centerline camera image did not improve handling qualities, but an innovative attitude status indicator symbol was beneficial. The investigation also showed high workload and handling quality problems when manual dockings were performed with a rotating target. These concerns indicate achieving satisfactory handling quality ratings with a vehicle configuration similar to the nominal Crew Exploration Vehicle may require additional automation.

Jackson, E. Bruce↗

NASA NTRS2015

Initial Thrust Measurements of Marshall's Ion-ioN Thruster

Electronegative ion thrusters are a variation of tradition gridded ion thruster technology differentiated by the production and acceleration of both positive and negative ions. Benefits of electronegative ion thrusters include the elimination of lifetime-limiting cathodes from the thruster architecture and the ability to generate appreciable thrust from both charge species. Following the continued development of electronegative ion thruster technology as exhibited by the PEGASES (Plasma Propulsion with Electronegative GASES) thruster, direct thrust measurements are required to push interest in electronegative ion thruster technology forward. For this work, direct thrust measurements of the MINT (Marshall's Ion-ioN Thruster) will be taken on a hanging pendulum thrust stand for propellant mixtures of Sulfur Hexafluoride and Argon at volumetric flow rates of 5-25 sccm at radio frequency power levels of 100-600 watts at a radio frequency of 13.56 MHz. Acceleration grid operation is operated using a square waveform bias of +/-300 volts at a frequency of 25 kHz.

Schloeder, Natalie R.↗

NASA NTRS1978

Effects of mass addition on blunt-body boundary-layer transition and heat transfer

The model bodies tested at Mach number 7.32 were hemispheres, blunt cones, and spherical segments. The mass addition consisted of air ejected through porous forward surfaces of the models. The experimental data consisted of heat transfer measurements from which boundary layer transitions were deduced. The data verified various applicable boundary layer codes in the laminar and transitional flow regimes. Empirical heating rate data correlations were developed for the laminar and turbulent flow regimes.

Kaattari, G. E.↗

NASA NTRS1995

Alterations in glomerular and tubular dynamics at 1 and 14 days simulated microgravity and after acute return to orthostasis

Head-down tilt (HDT) is utilized to simulate microgravity and produces a cephalad fluid shift, which results in alterations in fluid and electrolyte balance. These changes in volume homeostasis are due, in part, to alterations in multiple volume control mechanisms in which renal function is a major participant. We have previously demonstrated that glomerular filtration rate increases early in HDT and eventually returns to values not different from non-tilt measurements. This early increase in glomerular filtration rate was also demonstrated during days 2 and 8 of the SLS-1 mission. However, urine flow and electrolyte excretion does not parallel the alternations in glomerular filtration rate and the site of this change in nephron fluid reabsorption pattern has not been previously examined. Through determination of the location of alterations in tubular fluid reabsorption within the nephron, a more detailed hypothesis can be forwarded as to which specific neuro-humoral agents participating in control or renal function in microgravity conditions. the importance of this type of examination is that measurements in circulating neuro-humoral agents and urinary excretion patterns alone are not accurate predictors of how renal functional response may alter to head-down tilt or other models of simulated weightlessness. To examine this issue, renal micropuncture techniques were utilized in Munich-Wistar rats submitted 24 hour and 14 day head-down tilt, measuring all the determinants of glomerular ultrafiltration and obtaining data regarding segmental tubular fluid reabsorption. Following these measurements, the rats were returned to an orthostatic position and after 60 minutes, the measurements were repeated.

Tucker, Bryan J.↗

NASA NTRS2005

Monitoring Eruptive Activity at Mount St. Helens with TIR Image Data

Thermal infrared (TIR) data from the MASTER airborne imaging spectrometer were acquired over Mount St. Helens in Sept and Oct, 2004, before and after the onset of recent eruptive activity. Pre-eruption data showed no measurable increase in surface temperatures before the first phreatic eruption on Oct 1. MASTER data acquired during the initial eruptive episode on Oct 14 showed maximum temperatures of similar to approximately 330 C and TIR data acquired concurrently from a Forward Looking Infrared (FLIR) camera showed maximum temperatures similar to approximately 675 C, in narrow (approximately 1-m) fractures of molten rock on a new resurgent dome. MASTER and FLIR thermal flux calculations indicated a radiative cooling rate of approximately 714 J/m(exp 2)/s over the new dome, corresponding to a radiant power of approximately 24 MW. MASTER data indicated the new dome was dacitic in composition, and digital elevation data derived from LIDAR acquired concurrently with MASTER showed that the dome growth correlated with the areas of elevated temperatures. Low SO2 concentrations in the plume combined with sub-optimal viewing conditions prohibited quantitative measurement of plume SO2. The results demonstrate that airborne TIR data can provide information on the temperature of both the surface and plume and the composition of new lava during eruptive episodes. Given sufficient resources, the airborne instrumentation could be deployed rapidly to a newly-awakening volcano and provide a means for remote volcano monitoring.

thermal emissions↗

NASA NTRS2005

System Regulates the Water Contents of Fuel-Cell Streams

An assembly of devices provides for both humidification of the reactant gas streams of a fuel cell and removal of the product water (the water generated by operation of the fuel cell). The assembly includes externally-sensing forward-pressure regulators that supply reactant gases (fuel and oxygen) at variable pressures to ejector reactant pumps. The ejector supply pressures depend on the consumption flows. The ejectors develop differential pressures approximately proportional to the consumption flow rates at constant system pressure and with constant flow restriction between the mixer-outlet and suction ports of the ejectors. For removal of product water from the circulating oxygen stream, the assembly includes a water/gas separator that contains hydrophobic and hydrophilic membranes. The water separator imposes an approximately constant flow restriction, regardless of the quality of the two-phase flow that enters it from the fuel cell. The gas leaving the water separator is nearly 100 percent humid. This gas is returned to the inlet of the fuel cell along with a quantity of dry incoming oxygen, via the oxygen ejector, thereby providing some humidification.

Vasquez, Arturo↗

NASA NTRS2012

Reusable Solid Rocket Motor - V(RSRMV)Nozzle Forward Nose Ring Thermo-Structural Modeling

During the developmental static fire program for NASAs Reusable Solid Rocket Motor-V (RSRMV), an anomalous erosion condition appeared on the nozzle Carbon Cloth Phenolic nose ring that had not been observed in the space shuttle RSRM program. There were regions of augmented erosion located on the bottom of the forward nose ring (FNR) that measured nine tenths of an inch deeper than the surrounding material. Estimates of heating conditions for the RSRMV nozzle based on limited char and erosion data indicate that the total heat loading into the FNR, for the new five segment motor, is about 40-50% higher than the baseline shuttle RSRM nozzle FNR. Fault tree analysis of the augmented erosion condition has lead to a focus on a thermomechanical response of the material that is outside the existing experience base of shuttle CCP materials for this application. This paper provides a sensitivity study of the CCP material thermo-structural response subject to the design constraints and heating conditions unique to the RSRMV Forward Nose Ring application. Modeling techniques are based on 1-D thermal and porous media calculations where in-depth interlaminar loading conditions are calculated and compared to known capabilities at elevated temperatures. Parameters such as heat rate, in-depth pressures and temperature, degree of char, associated with initiation of the mechanical removal process are quantified and compared to a baseline thermo-chemical material removal mode. Conclusions regarding postulated material loss mechanisms are offered.

Clayton, J. Louie↗

NASA NTRS1977

Heuristic approach to the development of ratings and tactics applicable to the one-on-one aerial combat (dogfight) encounter

Computer simulations of the one-on-one aerial combat encounter are generated under the control of specified guidance laws. Given an initial state, the vehicle and atmospheric characteristics, and the guidance laws, the aerial combat encounter is simulated by forward integration of the two vehicles' motions. The development of a combat guidance law which converts positional advantage into an improved firing opportunity is reported. A combination of lag, line of sight, and lead pursuit steering paths are followed in the guidance law. The law is based on steering error, target angle-off and the relative velocities. It readily is automated either as an onboard aid to manned aircraft pilots or as a combat guidance law for unmanned vehicles.

Hague, D. S.↗

NASA NTRS1983

An advanced control system for a next generation transport aircraft

The use of modern control theory to develop a high-authority stability and control system for the next generation transport aircraft is described with examples taken from work performed on an advanced pitch active control system (PACS). The PACS was configured to have short-period and phugoid modes frequency and damping characteristics within the shaded S-plane areas, column force gradients with set bounds and with constant slope, and a blended normal-acceleration/pitch rate time history response to a step command. Details of the control law, feedback loop, and modal control syntheses are explored, as are compensation for the feedback gain, the deletion of the velocity signal, and the feed-forward compensation. Scheduling of the primary and secondary gains are discussed, together with control law mechanization, flying qualities analyses, and application on the L-1011 aircraft.

Rising, J. J.↗

NASA NTRS1985

Shuttle Communications and Tracking Systems Modeling and TDRSS Link Simulations Studies

An analytical simulation package (LinCsim) which allows the analytical verification of data transmission performance through TDRSS satellites was modified. The work involved the modeling of the user transponder, TDRS, TDRS ground terminal, and link dynamics for forward and return links based on the TDRSS performance specifications (4) and the critical design reviews. The scope of this effort has recently been expanded to include the effects of radio frequency interference (RFI) on the bit error rate (BER) performance of the S-band return links. The RFI environment and the modified TDRSS satellite and ground station hardware are being modeled in accordance with their description in the applicable documents.

Chie, C. M.↗

NASA NTRS1993

Effects of flow-path variations on internal reversing flow in a tailpipe offtake configuration for ASTOVL aircraft

A one-third-scale model of a generic tailpipe offtake system for an advanced short takeoff, vertical landing (ASTOVL) aircraft was tested at the NASA Lewis Research Center Powered Lift Facility. The basic model consisted of a tailpipe with a center body to form an annulus simulating turbine outflow with no swirl; twin offtake ducts with elbows at the ends to turn the flow to a downward direction; flow control nozzles at the ends of the elbows; and a blind flange at the end of the tailpipe to simulate a closed cruise nozzle. The offtake duct-to-tailpipe diameter ratio was 0.74. Modifications of a generic nature were then made to this basic configuration to measure the effects of flow-path changes on the flow and pressure-loss characteristics. The modifications included adding rounded entrances at the forward edges of the offtake openings, blocking the tailpipe just aft the openings instead of at the cruise nozzle, changing the location of the openings along the tailpipe, removing the center body, and varying the Mach number (flow rate) over a wide range in the tailpipe ahead of the openings by changing the size of the flow control nozzles. The tests were made with unheated air at tailpipe-to-ambient pressure ratios from 1.4 to 5. Results are presented and compared with performance graphs, total-pressure contour plots, paint streak flow visualization photographs, and a flow-angle probe traverse at the offtake entrance.

Mcardle, Jack G.↗