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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 1,027 records · Page 57
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

A rotating hot-wire technique for spatial sampling of disturbed and manipulated duct flows

A duct flow spatial sampling technique, in which an X-wire probe is rotated about the center of a cylindrical test section at a radius equal to one-half that of the test section in order to furnish nearly instantaneous multipoint measurements of the streamwise and azimuthal components, is presently evaluated in view of the control of flow disturbances downstream of various open inlet contractions. The effectiveness of a particular contraction in controlling ingested flow disturbances was ascertained by artificially introducing disturbances upstream of the contractions; control effectiveness if found to be strongly dependent on inlet contraction, with consequences for the reduction of passing-blade frequency noise during gas turbine engine ground testing.

Wark, C. E.↗
NASA NTRS1991

Reduced-Wiring Tactile Sensor

Proposed tactile sensor on robot finger puts out multiplexed analog signals transmitted to control computer on fewer wires than needed to transmit equivalent digital signals. Analog output represents data on contact area of object being gripped, on position of object, and on direction and rate of slippage if any. Consists of chains of normally open switches and resistors on surface of finger. Each resistance double preceding resistance in each chain. Constant-current sources supply power to chains.

Ohm, Timothy R.↗
NASA NTRS1991

Selection of wires and circuit protective devices for STS Orbiter vehicle payload electrical circuits

Electrical designers of Orbiter payloads face the challenge of determining proper circuit protection/wire size parameters to satisfy Orbiter engineering and safety requirements. This document is the result of a program undertaken to review test data from all available aerospace sources and perform additional testing to eliminate extrapolation errors. The resulting compilation of data was used to develop guidelines for the selection of wire sizes and circuit protection ratings. The purpose is to provide guidance to the engineering to ensure a design which meets Orbiter standards and which should be applicable to any aerospace design.

Gaston, Darilyn M.↗
NASA NTRS1991

Low cost, formable, high T(sub c) superconducting wire

A ceramic superconductivity part such as a wire is produced through the partial oxidation of a specially formulated copper alloy in the core. The alloys contain low level quantities of rare earth and alkaline earth dopant elements. Upon oxidation at high temperature, superconducting oxide phases are formed as a thin film.

Smialek, James L.↗
NASA NTRS1992

Mechanical Backup For Fly-By-Wire Control System

Mechanical device eliminates need for redundant fly-by-wire subsystems. Main components are two linkages. One connected to control column in conventional, reversible control system. Other slides inside first linkage and connected to pilot's control wheel. In addition to aircraft applications, design used in control systems in which computer control desirable but safety backup systems required; for example, in boat rudders, engine controls in boats and automobiles, and controls in construction equipment.

Stewart, Eric C.↗
NASA NTRS1992

Frequency Responses Of Hot-Wire Anemometers

Report describes theoretical study of frequency response of constant-temperature hot-wire anemometer, with view toward increasing frequency response while maintaining stable operation in supersonic flow. Effects of various circuit parameters discussed.

Watmuff, Jonathan H.↗
NASA NTRS1991

Fluctuation diagrams for hot-wire anemometry in subsonic compressible flows

The concept of using 'fluctuation diagrams' for describing basic fluctuations in compressible flows was reported by Kovasznay in the 1950's. The application of this technique, for the most part, was restricted to supersonic flows. Recently, Zinovev and Lebiga published reports where they considered the fluctuation diagrams in subsonic compressible flows. For the above studies, the velocity and density sensitivities of the heated wires were equal. However, there are considerable data, much taken in the 1950's, which indicate that under some conditions the velocity and density sensitivities are not equal in subsonic compressible flows. Therefore, possible fluctuation diagrams are described for the cases where the velocity and density sensitivities are equal and the more general cases where they are unequal.

Stainback, P. C.↗
NASA NTRS1992

Wiring for aerospace applications

In this paper, the authors summarize the current state of knowledge of arc propagation in aerospace power wiring and efforts by the National Aeronautics and Space Administration (NASA) towards the understanding of the arc tracking phenomena in space environments. Recommendations will be made for additional testing. A database of the performance of commonly used insulating materials will be developed to support the design of advanced high power missions, such as Space Station Freedom and Lunar/Mars Exploration.

Christian, J. L., Jr.↗
NASA NTRS1990

Cyclic hot firing results of tungsten-wire-reinforced, copper-lined thrust chambers

An advanced thrust liner material for potential long life reusable rocket engines is described. This liner material was produced with the intent of improving the reusable life of high pressure thrust chambers by strengthening the chamber in the hoop direction, thus avoiding the longitudinal cracking due to low cycle fatigue that is observed in conventional homogeneous copper chambers, but yet not reducing the high thermal conductivity that is essential when operating with high heat fluxes. The liner material produced was a tungsten wire reinforced copper composite. Incorporating this composite into two hydrogen-oxygen test rocket chambers was done so that its performance as a reusable liner material could be evaluated. Testing results showed that both chambers failed prematurely, but the crack sites were perpendicular to the normal direction of cracking indicating a degree of success in containing the tremendous thermal strain associated with high temperature rocket engines. The failures, in all cases, were associated with drilled instrumentation ports and no other damages or deformations were found elsewhere in the composite liners.

Kazaroff, John M.↗
NASA NTRS1991

A fine-wire thermocouple probe for measurement of stagnation temperatures in real gas hypersonic flows of nitrogen

A fine-wire thermocouple probe was used to determine freestream stagnation temperatures in hypersonic flows. Data were gathered in a N2 blowdown wind tunnel with runtimes of 1-5 s. Tests were made at supply pressures between 30 and 1400 atm and supply temperatures between 700 and 1900 K, with Mach numbers of 14 to 16. An iterative procedure requiring thermocouple data, pilot pressure measurements, and supply conditions was used to determine test cell stagnation temperatures. Probe conduction and radiation losses, as well as real gas behavior of N2, were accounted for during analysis. Temperature measurement error was found to be 5 to 10 percent. A correlation was drawn between thermocouple diameter Reynolds number and temperature recovery ratio. Transient probe behavior was studied and was found to be adequate in temperature gradients up to 1000 K/s.

Hollis, Brian R.↗
NASA NTRS1993

Welding Wires To Thin Thermocouple Films

Parallel-gap resistance welding yields joints surviving temperatures of about 1,000 degrees C. Much faster than thermocompression bonding. Also exceeds conductive-paste bonding and sputtering thin films through porous flame-sprayed insulation on prewelded lead wires. Introduces no foreign material into thermocouple circuit and does not require careful control of thickness of flame-sprayed material.

Holanda, Raymond↗
NASA NTRS1993

Risk management in fly-by-wire systems

A general description of various types of fly-by-wire systems is provided. The risks inherent in digital flight control systems, like those used in the Space Shuttle, are identified. The results of a literature survey examining risk management methods in use throughout the aerospace industry are presented. The applicability of these methods to the Space Shuttle program is discussed.

Knoll, Karyn T.↗
NASA NTRS1943

Some investigations of the general instability of stiffened metal cylinders III : continuation of tests of wire-braced specimens and preliminary tests of sheet-covered specimens

This is the third of a series of reports covering an investigation of the general instability problem by the California Institute of Technology. The first five reports of this series cover investigations of the general instability problem under the loading conditions of pure bending and were prepared under the sponsorship of the Civil Aeronautics Administration. The succeeding reports of this series cover the work done on other loading conditions under the sponsorship of the National Advisory Committee for Aeronautics. This report is concerned primarily with the continuation of the tests of wire-braced specimens, and preliminary tests of sheet-covered specimens that had been made in the experimental investigation on the problem of the general instability of stiffened metal cylinders at the C.I.T.

ALUMINUM ALLOYS, SHEETS, ALCOA 17ST↗
NASA NTRS1951

Preliminary Investigation of the Supersonic Flow Field Downstream of Wire-mesh Nozzles in a Constant-area Duct / Lawrence I. Gould

An investigation was conducted in a 3.4- by 3.4-inch duct to determine the characteristics of the supersonic flow downstream of four wire-mesh screen nozzles with nominal design Mach numbers in the range between 1.97 and 2.58. Two types of disturbances were observed in the flow field: a fine network of interacting expansion and compression waves which were formed immediately downstream of the screens and appeared to dissipate within 25 to 40 wave intersections; and relatively strong oblique shock waves that originated at the junctions of the screens and the walls and were reflected throughout the length of the duct. Regions of fairly uniform flow were found to exist. The total-pressure loss across the screens varied from 22 percent at Mach number 1.58 to 43 percent at Mach number 2.06.

WIND TUNNELS↗
NASA NTRS1942

The resistance coefficient of commercial round wire grids

The resistance coefficients of commercial types of round wire grids were examined for the purpose of obtaining the necessary data on supercharger test stands for throttling the inducted air to a pressure corresponding to a desired air density. The measurements of the coefficients ranged up to Reynolds numbers of 1000. In the arrangement of two grids in tandem, which was necessary in order to obtain high resistance coefficients with the solidity, that is, mesh density of grid, was found to be accompanied by a further relationship with the mutual spacing of the individual grids.

Eckert, B↗
NASA NTRS1985

Requirements for Conformal Coating and Staking of Printed Wiring Boards and Electronic Assemblies

In order to maintain the high standards of the NASA conformal coating and staking program, this publication: prescribes NASA's requirements for assuring reliable conformal coating and staking for printed wiring boards and electronic assemblies; describes and incorporates basic considerations necessary to assure reliable conformal coating and staking; establishes the supplier's responsibility to train and certify personnel; provides for supplier documentation of the fabrication and inspection procedures to be used for NASA work, including supplier innovations and changes in technology; and provides visual workmanship standards to aid those responsible for determining quality conformance to the established requirements.

Source record↗
NASA NTRS1994

Robust 300 C wire insulation system

The objective of this program is to identify, develop, and demonstrate an optimum wire insulation system that is capable of continuous operation at 300 C. The system is to possess a combination of superior electrical (AC or DC), mechanical, and physical properties over the KAPTON (trademark) derived insulations described in MIL-W-81381 and those hybrid constructions identified in Air Force contract F33615-89-C-5606, commonly known as TKT constructions.

Nairus, John G.↗