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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Pressure distributions on a 0.02-scale Space Shuttle orbiter nose at Mach 21.5 in helium

Pressure distributions on a 0.02-scale model of the Space Shuttle orbiter forward fuselage were obtained in the 22-inch aerodynamic leg of the Langley Hypersonic Helium Tunnel Facility at a nominal free-stream Mach number of 21.5 and a ratio of specific heats of 1.67 for inclusion in the database of the Shuttle entry air data system (SEADS). The data were measured at model angles of attack of 0 deg to 50 deg in 5 deg increments for zero sideslip angle and at model sideslip angles of -5 deg to 5 deg for angles of attack equal to 5, 20, 35, and 40 deg. These data displayed trends similar to those observed in other wind tunnels at Mach 6 and 10 in air. Specifically noted is a shift in the location of the stagnation point at angles of attack above 15 deg; this effect did not, however, occur in flight. By comparison, the data obtained at Mach 6 in the Langley Hypersonic CF4 Tunnel, corresponding to a lower ratio of specific heats in the postshock region than those in helium and air, showed some reduction of the stagnation point shift at the higher angles of attack. The differences between flight and wind tunnel pressure distributions are believed due primarily to high-temperature gas chemistry effects in flight, which include lower effective specific heat ratios but which were not completely duplicated in the wind tunnels.

Ashby, George C., Jr.↗
NASA NTRS1995

Low-speed wind-tunnel investigation of a porous forebody and nose strakes for yaw control of a multirole fighter aircraft

Low-speed wind-tunnel tests were conducted in the Langley 12-Foot Low-Speed Tunnel on a model of the Boeing Multirole Fighter (BMRF) aircraft. This single-seat, single-engine configuration was intended to be an F-16 replacement that would incorporate many of the design goals and advanced technologies of the F-22. Its mission requirements included supersonic cruise without afterburner, reduced observability, and the ability to attack both air-to-air and air-to-ground targets. So that it would be effective in all phases of air combat, the ability to maneuver at angles of attack up to and beyond maximum lift was also desired. Traditional aerodynamic yaw controls, such as rudders, are typically ineffective at these higher angles of attack because they are usually located in the wake from the wings and fuselage. For this reason, this study focused on investigating forebody-mounted controls that produces yawing moments by modifying the strong vortex flowfield being shed from the forebody at high angles of attack. Two forebody strakes were tested that varied in planform and chordwise location. Various patterns of porosity in the forebody skin were also tested that differed in their radial coverage and chordwise location. The tests were performed at a dynamic pressure of 4 lb/ft(exp 2) over an angle-of-attack range of -4 deg to 72 deg and a sideslip range of -10 deg to 10 deg. Static force data, static pressures on the surface of the forebody, and videotapes of flow-visualization using laser-illuminated smoke were obtained.

Fears, Scott P.↗
NASA NTRS1961

Boundary-Layer Transition on a Group of Blunt Nose Shapes at a Mach Number of 2.20

An investigation has been made to study boundary-layer transition on six axisymmetrical blunt bodies of revolution. Model shapes were selected with respect to the degree of favorable pressure gradient over the model surface. Tests were conducted at a Mach number of 2.20 and over a range of free-stream Reynolds number per foot of about 1.4 x 10(exp 6) to 6.5 x 10(exp 6). The tests were made at an angle of attack of 0 deg. with zero heat transfer. For the hemisphere, the flow remained essentially laminar over the model surface length for the entire pressure range of the tests. For a strong favorable pressure gradient followed by any weak favorable, neutral, or adverse gradient, the tendency was for transition to occur at or immediately behind the shoulder. A single strip of three-dimensional roughness in the region of strong favorable pressure gradient did not fix transition on the models at the roughness location except at the maximum test pressures, whereas a second roughness strip added in a region of neutral or adverse pressure gradient did fix transition. Experimental pressure coefficients agreed closely with modified Newtonian theory except in the shoulder region.

Jackson, Mary W.↗
NASA NTRS1959

Fluid-Dynamic Properties of Some Simple Sharp- and Blunt-Nosed Shapes at Mach Numbers from 16 to 24 in Helium Flow

The fluid-dynamic characteristics of flat plates, 5 deg and 10 deg wedges, and 5 deg and 10 deg cones have been investigated at Mach numbers from 16.3 to 23.9 in helium flow. The flat-plate results are for a leading-edge Reynolds number range of 584 to 19,500 and show that the induced pressure distribution is essentially linear with the hypersonic viscous interaction parameter bar X within the scope of this investigation. It is also shown that the rate at which the induced pressure varies with bar X is a linear function of the leading-edge Reynolds number. The wedge and cone results show that as the flow-deflection angle increases, the induced-pressure effects decrease and the measured pressures approach those predicted by inviscid shock theory.

Henderson, Arthur, Jr.↗
NASA NTRS1959

The Stabilizing Effectiveness of Conical Flares on Bodies with Conical Noses

An analysis is presented of published results of force tests on 80 cone-cylinder-flare configurations at Mach numbers of 2.18, 2.81, and 4.04. The contributions, excluding interference effects, of the cone-cylinder bodies to the over-all normal force derivatives have been removed by means of the second-order shock-expansion method, and the normal force derivatives at zero angle of attack due to the flares alone are shown. The results from a wide variety of configurations are correlated by plotting ratios of the normal force derivatives of the flares to the normal force derivatives of cones having the same included angle. Comparisons are made of the experimental normal force results with the normal force derivatives obtained by assuming conical flow over the flares and with those obtained by use of the second-order shock-expansion method. The comparisons show that use of the second-order shock-expansion method is generally the superior of the two, and in most cases gives values of the normal force derivatives of the flares which agree very well with the experimental results. Centers of pressure of the flares are presented and comparisons are made with results obtained from the theories mentioned. In general, the comparisons show that the assumption of conical flow over the flares is comparable to use of the second-order shock-expansion method in determining the centers of pressure, and in many cases both methods give values which agree closely with the experimental results.

Kirk, Donn B.↗
NASA NTRS2001

Cyrano "Nose" The Smell of Success

Cyrano Sciences, Inc. has commercialized a simple, accurate, non- invasive tool that enables "machines to smell". The Cyranose 320 is used for quality control purposes in the food and chemical industries. Using a sensor array and onboard pattern recognition algorithms, the lightweight, portable device works by exposing an array of polymer composite sensors to the chemical components in a vapor. When the sensors come in contact with the vapor, the polymer expands like a sponge, changing the resistance of the composites. The change in resistance is measured, and from that measurement, the presence of a pre-trained substance is determined with a quick and accurate diagnosis. This real-time, portable device enables food companies to spot test raw materials for batch-to-batch consistency, spoilage, or contamination. The Cyranose 320 is also used by chemical and petrochemical companies for quick assessment of the chemical status associated with various industrial processes. Profiling a chemical environment in a hazardous materials situation allows emergency crews to accurately select fire retardants, containment strategies, and protective gear. Future applications for the Cyranose 320 are fast growing and other uses of this technology are on the horizon.

Source record↗
NASA NTRS2004

Wind Tunnel Test Results for Gas Flows Inside Axisymmetric Cavities on Cylindric Bodies with Nose Cones

Experimental test results of air flow inside and at the cylindrical cavity located on axisymmetric body are presented. These tests were conducted in the wind tunnel A-7 of Institute of Mechanics at Moscow State University. Pressure distribution along the cavities and optical measurements were obtained. Dependence of these characteristics of length of a cavity in the range: L/D = 0.5 - 14 and free stream Mach in the range: M(sub infinity) = 0.6 - 3.0 was determined. Flow structure inside the cavity, cause of flow regime change, separation zones geometry and others were studied. In particular, the flow modes of with open and closed separation zones are determined.

Shvets, A. L.↗
NASA NTRS1962

Unitary Plan Wind Tunnel Tests of Cook Technological Center Parachutes in the Wake of a Conical-Nosed Cylindrical Body Having a Base Diameter of 2.375-Inches (Part 5 of 6)

The film depicts two tests of a flat roof, conical inlet canopy parachute. The first test is a series of wind tunnel trials with a flat circular ribbon roof of 22 percent porosity. The second test is a single series of wind tunnel trials with a flat circular ribbon roof of 25 percent porosity. Variables for both trials include Mach number, dynamic pressure, longitudinal separation distances (x/d), and drag coefficient C(sub d).

Source record↗
NASA NTRS1962

Unitary Wind Tunnel Tests of 30-Degree Conical Ribbon Parachute and a Rotofoil Parachute Towed in the Wake of a Conical Nosed Cylindrical Body

Multiple wind tunnel test trials were conducted on a 30 degree conical ribbon parachute with porosities of 30, 27, and 24 percent. Variables were Mach number, dynamic pressure, towline length, and coefficient of drag. A Rotofoil parachute having a porosity of approximately 24 percent was tested, but failed after about 30 seconds of operation at a Mach number of 1.8 All of the parachutes had a nominal diameter and shroud line length of 10 inches. Drag coefficients were based on the area of a circle having a diameter two-thirds of the nominal parachute diameter.

WIND TUNNEL TESTS↗
NASA NTRS2012

Computational Investigation of Supersonic Boundary Layer Transition Over Canonical Fuselage Nose Configurations

Boundary layer transition over axisymmetric bodies at non-zero angle of attack in supersonic flow is numerically investigated as part of joint research between the National Aeronautics and Space Administration (NASA) and Japan Aerospace Exploration Agency (JAXA). Transition over four axisymmetric bodies (namely, Sears-Haack body, semi-Sears-Haack body, 5-degree straight cone and flared cone) with different axial pressure gradients has been studied at Mach 2 in order to understand the effect of axial pressure gradient on instability amplification along the leeward symmetry plane and in the region of nonzero crossflow away from it. Comparisons are made with measured transition data in Mach 2 facilities as well as with predicted and measured transition characteristics for a 5-degree straight cone in a Mach 3.5 low disturbance tunnel. Limitations of using linear stability correlations for predicting transition over axisymmetric bodies at angle of attack are pointed out.

Choudhari, Meelan M.↗
NASA NTRS2017

Low Pressure Flame Blowoff from the Forward Stagnation Region of a Blunt-Nosed Cast PMMA Cylinder in Axial Mixed Convective Flow

Low-pressure blowoff experiments were conducted with a stagnation flame stabilized on the forward tip of cast PMMA rods in a vertical wind tunnel. Pressure, forced flow velocity, gravity, and ambient oxygen concentration were varied. Stagnation flame blowoff is determined from a time-stamped video recording of the test. The blowoff pressure is determined from test section pressure transducer data that is synchronized with the time stamp. The forced flow velocity is also determined from the choked flow orifice pressure. Most of the tests were performed in normal gravity, but a handful of microgravity tests were also conducted to determine the influence of buoyant flow velocity on the blowoff limits. The blowoff limits are found to have a linear dependence between the partial pressure of oxygen and the total pressure, regardless of forced flow velocity and gravity level. The flow velocity (forced and/or buoyant) affects the blowoff pressure through the critical Damkohler number residence time, which dictates the partial pressure of oxygen at blowoff. This is because the critical stretch rate increases linearly with increasing pressure at low pressure (sub-atmospheric pressures) since a second-order overall reaction rate with two-body reactions dominates in this pressure range.

flammability↗