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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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Combustor produces uniform circumferential and radial combustor exit temperature profiles and high combustion efficiency at high temperature loads. Absence of diluent air entry ports eliminates stress concentration points, low pressure fuel alleviates nozzle fouling, and abundant air at all burning stages reduces smoke.
Ball locking device which releases in response to small forces when subjected to high axial loads
Program predicts expected deformations and stresses in nonlinear simple geometric structures subjected to high-impact loading. Technique is based on node-wise predictor-corrector approach and requires moderate computer storage and run time for most problems. Program extends to include physical and geometrical nonlinearities.
Transducer amplifies vibrations produced by piezoelectric drivers, creating greater amplitudes than were possible with direct drive devices. Drivers isolated from bearing surfaces result in bearings with high axial load capacity and stiffness, thus, wear on ceramic cylinders is reduced.
Gearing system for eliminating backlash and filtering input torque fluctuations from high inertia load
Turn on current transient limiter for controlling peak current flow in high capacity load
Longitudinalfilm gate and lock mechanism for securing film in motion picture cameras under vibration and high acceleration loads
Notched metal crack initiation, determining high cyclic loads effects by prior local plastic behavior at stress concentration
Electronic ergometer calibration equipment and errors at high work loads
A cursory review is presented of some of the recent work that has been done in turbine aerodynamic research at NASA-Lewis Research Center. Topics discussed include the aerodynamic effect of turbine coolant, high work-factor (ratio of stage work to square of blade speed) turbines, and computer methods for turbine design and performance prediction. An extensive bibliography is included. Experimental cooled-turbine aerodynamics programs using two-dimensional cascades, full annular cascades, and cold rotating turbine stage tests are discussed with some typical results presented. Analytically predicted results for cooled blade performance are compared to experimental results. The problems and some of the current programs associated with the use of very high work factors for fan-drive turbines of high-bypass-ratio engines are discussed. Turbines currently being investigated make use of advanced blading concepts designed to maintain high efficiency under conditions of high aerodynamic loading. Computer programs have been developed for turbine design-point performance, off-design performance, supersonic blade profile design, and the calculation of channel velocities for subsonic and transonic flow fields. The use of these programs for the design and analysis of axial and radial turbines is discussed.
Buffet of the space shuttle launch and reentry configuration is an area requiring continued evaluation to produce a safe reliable vehicle of minimum weight. Buffet forces result from flow separation and therefore can not be predicted accurately. Buffet loads are highly sensitive to configuration, angle of attack, and Mach number and can be reliably determined only by wind tunnel tests of elastically scaled models.
The OAO-C spacecraft has three circular heat pipes, each of a different internal design, located in the space between the spacecraft structural tube and the experiment tube, which are designed to isothermalize the structure. Two of the pipes are used to transport high heat loads, and the third is for low heat loads. The test problems deal with the charging of the pipes, modifications, the mobile tilt table, the position indicator, and the heat input mechanisms. The final results showed that the techniques used were adequate for thermal-vacuum testing of heat pipes.
The author has identified the following significant results. Areas with high sediment loads and a wide range of water parameters (such as San Francisco Bay, an area not a target of this study but included in the imagery) show dramatic variations in the photographs. Open oceanic areas off California have relatively homogenous water and hence a much lower range of contrast. The mean shore coastal areas show an intermediate range.
Syntactic foam formulations were prepared from mixtures of Pyrrone prepolymers and hollow carbon microspheres. Very low curing shrinkages were obtained for high volume loadings of microspheres. The resulting syntactic foams were found to be remarkably stable over a wide range in temperature. A technique was developed for the emplacement of these foam formulations in polyimide-fiberglass, titanium alloy and stainless steel honeycomb without sacrificing low curing shrinkage or thermal stability.
A comprehensive analytical model which considers time and space development of the flow field in solid propellant rocket motors with high volumetric loading density is described. The gas dynamics in the motor chamber is governed by a set of hyperbolic partial differential equations, that are coupled with the ignition and flame spreading events, and with the axial variation of mass addition. The flame spreading rate is calculated by successive heating-to-ignition along the propellant surface. Experimental diagnostic studies have been performed with a rectangular window motor (50 cm grain length, 5 cm burning perimeter and 1 cm hydraulic port diameter), using a controllable head-end gaseous igniter. Tests were conducted with AP composite propellant at port-to-throat area ratios of 2.0, 1.5, 1.2, and 1.06, and head-end pressures from 35 to 70 atm. Calculated pressure transients and flame spreading rates are in very good agreement with those measured in the experimental system.
Selection of a baseline power subsystem for the probe bus, orbiter, and large and small probes has been performed as a part of the Pioneer Venus Mission Systems Design Study. In each case the selection process has involved trades and incorporated the results of previous related studies. Factors considered primary in the selection of each subsystem approach were cost, and the ability of each of the proposed subsystems to perform reliably under the rigors of the space environment, temperature extremes, and high g loads. A trade was made to consider the advantages of an unregulated primary bus versus a regulated bus. The decision to use an unregulated bus was based on cost, weight, and the increase in load isolation achievable through the use of individual load regulators.
Announced survey directs attention toward low cycle fatigue and thermal fatigue experienced at elevated temperatures equivalent to those found in hot end of gas turbine engine. Majority of bibliographic references are on life prediction for materials exposed to monotonic and cyclic loading in high temperature environments.
A novel variable-conductance heat-pipe approach has been developed that delivers high-capacity loads, while eliminating the problem of artery gas blockage present in conventional designs. The unit, known as a transverse header, uses ammonia as the working fluid and nitrogen as the control gas. Its overall cylindrical shape is 5.1 cm in diameter by 0.61 m long. Under test with a fluid heat source, the maximum load achieved as a VCHP was 3,600W. As with conventional gas-loaded pipes, good temperature control was also obtained. An application of this device as a VCHP header for a heat-pipe radiator is described.-