Engineering topics

Bruce, Robert A.

Publications and source records attributed to Bruce, Robert A..

5 records

NASA NTRS1997

Combustibility Tests of 1,1,1,2-tetrafluoroethane in a Simulated Compressor Cylinder

The advantages of high-molecular-weight gas (heavy gas) as a wind-tunnel medium have been recognized for some time. The current heavy gas of choice chlorofluorocarbon-12(CFC-12) (refrigerant R12) for the Transonic Dynamics Tunnel(TDT) must be replaced because manufacture of this gas ceased in 1995. An attractive replacement is 1,1,1,2-tetrafluoroethane (refrigerant R134a). Acceptable properties of this gas include molecular weight and speed of sound. Its vapor pressure allows simplified reclamation from mixtures with air. However, it is recognized that R134a is combustible under certain conditions of temperature, pressure, and concentration. A comprehensive study was conducted to identify those conditions and the influence of various parameters on the combustibility of the gas-air mixture.

Babcock, Dale A.↗

NASA NTRS1990

Measuring Monodisperse Small Particles En Masse

New optical method enables determination of sizes of approximately-micron-sized particles. Arrays of particles act as diffraction gratings. Simple and inexpensive apparatus replaces high-magnification microscopes in measurements of diameters of small polystyrene latex spheres. Device being used to determine monodispersity and diameters of polystyrene latex microspheres used as seeding material for laser-velocimetry flow measurements in NASA's wind tunnels. Characterization of particle sizes important in wide range of fields, including manufacture of plastics and ceramics, biochemistry, and medicine.

Bruce, Robert A.↗

NASA NTRS1989

A vapor generator for transonic flow visualization

A vapor generator was developed for use in the NASA Langley Transonic Dynamics Tunnel (TDT). Propylene glycol was used as the vapor material. The vapor generator system was evaluated in a laboratory setting and then used in the TDT as part of a laser light sheet flow visualization system. The vapor generator provided satisfactory seeding of the air flow with visible condensate particles, smoke, for tests ranging from low subsonic through transonic speeds for tunnel total pressures from atmospheric pressure down to less than 0.1 atmospheric pressure.

Bruce, Robert A.↗

NASA NTRS1989

A solution to water vapor in the National Transonic Facility

As cryogenic wind tunnels are utilized, problems associated with the low temperature environment are being discovered and solved. Recently, water vapor contamination was discovered in the National Transonic Facility, and the source was shown to be the internal insulation which is a closed-cell polyisocyanurate foam. After an extensive study of the absorptivity characteristics of the NTF thermal insulation, the most practical solution to the problem was shown to be the maintaining of a dry environment in the circuit at all times. Utilizing a high aspect ratio transport model, it was shown that the moisture contamination effects on the supercritical wing pressure distributions were within the accuracy of setting test conditions and as such were considered negligible for this model.

Gloss, Blair B.↗

NASA NTRS1987

Operational performance of vapor-screen systems for in-flight visualization of leading-edge vortices on the F-106B aircraft

A flight research program was undertaken at the NASA Langley Research Center to apply the vapor-screen technique, widely used in wind tunnels, to an aircraft. The purpose was to obtain qualitative and quantitative information about near-field vortex flows above the wings of fighter aircraft and ascertain the effects of Reynolds and Mach numbers over the angle-of-attack range. The hardware for the systems required for flight application of the vapor-screen technique was successfully developed and integrated. Details of each system, its operational performance on the F-106B aircraft, and pertinent aircraft and environmental data collected are presented.

Lamar, John E.↗