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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Plasma arc welding torch having means for vortexing plasma gas exiting the welding torch

A plasma arc welding torch is described wherein a plasma gas is directed through the body of the welding torch and out of the body across the tip of the welding electrode disposed at the forward end of the body. The plasma gas is provided with a vortexing motion prior to exiting the body by a vortex motion imparting member which is mounted in an orifice housing member and carried in the forward portion of the torch body. The orifice housing member is provided with an orifice of an predetermined diameter through which the electric arc and the plasma gas exits.

Rybicki, Daniel J.↗
NASA NTRS1982

Reflectance differences between Target and Torch rape cultivars

Spectroradiometric reflectance measurements were made on Target and Torch plants (four and five leaves, respectively) that were growing in 0.09 m2 soil-containing flats. Torch's spectrophotometric single leaf reflectance was consistently lower than Target's at the 650-nm chlorophyll absorption band because Torch's chlorophyll concentration was larger than Target's, which caused more red light absorption. Spectroradiometric measurements indicate that: wet soil strongly absorbs visible light (500 to 700 nm) so that Target's soil-containing flat with 60% plant cover has less reflectance than Torch's soil-containing flat with 75% plant cover; Torch (most foiliage) has higher near-infrared (750 to 1,350 nm) reflectance than Target (least foliage); and the 2,200-nm wavelength is a candidate band to distinguish Target from Torch. The difference in chlorophyll concentrations between Target and Torch, compared with leaf structural differences, is apparently the most important factor that would affect the infrared color film's tonal response to vegetation in the photographic sensitive region (500 to 900 nm).

Gausman, H. W.↗
NASA NTRS1985

Adapter Helps To Aline Plasma Torch

Simple adapter allows plasma welding torch alined accurately on weld seam. Adapter fits over nozzle of torch. Light from pilot arc inside torch passes through central orifice in cone. Light emerges from cone as beam that creates spot of light at point where torch impinges on workpiece. When torch is alined with work, adapter is removed, plasma arc struck, and welding proceeds.

Brosemer, C. A.↗
NASA NTRS1987

Optical Welding Torch

Gas/tungsten-arc welding torch supports electrode at center while enabling viewing of weld area along torch axis. Gas torch accommodates lens and optical fibers, all part of vision system for welding robot. Welding torch includes spoked structure in central bore of optical body. Structure supports welding electrode, carries electric current to it, and takes heat away from it. Spokes formed by drilling six holes 60 degrees apart around center line of torch.

Richardson, R. W.↗
NASA NTRS1986

Welding torch with arc light reflector

A welding torch arc light reflector is disclosed for welding torches having optical viewing systems. A schematic of a welding torch having an internal coaxial viewing system consisting of a lens which focuses the field of view of the weld scene of the workpiece onto the end of the fiberoptic bundle is provided. The transmitted image of the fiberoptic bundle is provided to a camera lens which focuses it onto a TV sensor array for transmission. To improve the parity of the image of the monitoring system, an arc light reflector is shown fitted to the end of the torch housing or gas cup. The arc light reflector has an internal conical section portion which is polished to serve as a mirror which reflects the bright arc light back onto the darker areas of the weld area and thereby provides a more detailed image for the monitoring system. The novelty of the invention lies in the use of an arc light reflector on welding torches having optical viewing systems.

Gordon, Stephen S.↗
NASA NTRS1987

Self-clamping arc light reflector for welding torch

This invention is directed to a coaxial extending metal mirror reflector attached to the electrode housing or gas cup on a welding torch. An electric welding torch with an internal viewing system for robotic welding is provded with an annular arc light reflector to reflect light from the arc back onto the workpiece. The reflector has a vertical split or gap in its surrounding wall to permit the adjacent wall ends forming the split to be sprung open slightly to permit the reflector to be removed or slipped onto the torch housing or gas cup. The upper opening of the reflector is slightly smaller than the torch housing or gas cup and therefore, when placed on the torch housing or gas cup has that springiness to cause it to clamp tightly on the housing or gas cup. The split or gap also serves to permit the feed of weld wire through to the weld area,

Gordon, Stephen S.↗
NASA NTRS1993

Development and use of hydrogen-air torches in an altitude facility

A hydrogen-air ignition torch concept that had been used successfully in two rocket engine test facilities to consume excess hydrogen in their exhausters at atmospheric conditions was experimentally evaluated and developed in an altitude test facility at NASA Lewis Research Center. The idea was to use several of these torches in conjunction with hydrogen detectors and dilution air to prevent excess accumulation of unburned hydrogen or mixtures of hydrogen and air exceeding the sea-level lower flammability limit in the altitude facility exhaust system during hydrogen-fueled propulsion system tests. The torches were evaluated for a range of fuel-to-air ratios from 0.09 to 0.39 and for a range of exit diameters from 19/64 to 49/64 in. From the results of these tests a torch geometry and a fuel-to-air ratio were selected that produced a reasonably sized torch exhaust flame for consumption of unburned hydrogen at altitude pressures from sea level to 4 psia.

Lottig, Roy A.↗
NASA NTRS1993

Development and use of hydrogen-air torches in an altitude facility

A hydrogen-air ignition torch concept that had been used successfully in two rocket engine test facilities to consume excess hydrogen in their exhausters at atmospheric conditions was experimentally evaluated and developed in an altitude test facility at NASA Lewis Research Center. The idea was to use several of these torches in conjunction with hydrogen detectors and dilution air to prevent excess accumulation of unburned hydrogen or mixtures of hydrogen and air exceeding the sea-level lower flammability limit in the altitude facility exhaust system during hydrogen-fueled propulsion system tests. The torches were evaluated for a range of fuel-to-air ratios from 0.09 to 0.39 and for a range of exit diameters from 19/64 to 49/64 in. From the results of these tests a torch geometry and a fuel-to-air ratio were selected that produced a reasonably sized torch exhaust flame for consumption of unburned hydrogen at altitude pressures from sea level to 4 psia.

Lottig, Roy A.↗
NASA NTRS2009

Plasma torch for ignition, flameholding and enhancement of combustion in high speed flows

Preheating of fuel and injection into a plasma torch plume fro adjacent the plasma torch plume provides for only ignition with reduced delay but improved fuel-air mixing and fuel atomization as well as combustion reaction enhancement. Heat exchange also reduced erosion of the anode of the plasma torch. Fuel mixing atomization, fuel mixture distribution enhancement and combustion reaction enhancement are improved by unsteady plasma torch energization, integral formation of the heat exchanger, fuel injection nozzle and plasma torch anode in a more compact, low-profile arrangement which is not intrusive on a highspeed air flow with which the invention is particularly effective and further enhanced by use of nitrogen as a feedstock material and inclusion of high pressure gases in the fuel to cause effervescence during injection.

O'Brien, Walter F.↗
NASA NTRS1978

Computerized system for translating a torch head

The system provides a constant travel speed along a contoured workpiece. It has a driven skate characterized by an elongated bed, with a pair of independently pivoted trucks connected to the bed for support. The trucks are mounted on a contoured track of arbitrary configuration in a mutually spaced relation. An axially extensible torch head manipulator arm is mounted on the bed of the carriage and projects perpendicular from the midportion. The torch head is mounted at its distal end. A real-time computerized control drive subsystem is used to advance the skate along the track of a variable rate for maintaining a constant speed for the torch head tip, and to position the torch axis relative to a preset angle to the workpiece.

Wall, W. A., Jr.↗
NASA NTRS1986

Plasma torch igniter for scramjets

A small, uncooled plasma torch was developed and used in combination with an injector designed to study ignition and flameholding in hydrogen-fueled supersonic flows. The plasma torch was operated on mixtures of hydrogen and argon with total flows of 10 to 70 scfh. The fuel injector design consisted of five small upstream pilot fuel injectors, a rearward facing step for recirculation, and three main fuel injectors downstream of the step. The plasma torch was located in the recirculation region, and all injection was perpendicular to the Mach 2 stream. Both semi-freejet and ducted tests were conducted. The experimental results indicate that a low power plasma torch operating on a 1:1 volumetric mixture of hygrogen and argon and located in the recirculation zone fueled by the upstream pilot fuel injectors is a good igniter for flow conditions simulating a flight Mach number of 3.7. The total temperature required to autoignite the hydrogen fuel for this injector geometry was 2640 R. The injector configuration was shown to be a good flameholder over a wide range of total temperature. Spectroscopic measurements were used to verify the presence of air total temperatures below 1610 R.

Wagner, Timothy C.↗
NASA NTRS1989

Operating characteristics of a hydrogen-argon plasma torch for supersonic combustion applications

The residence time of the combustible mixture in the combustion chamber of a scramjet engine is much less than the time normally required for complete combustion. Hydrogen and hydrocarbon fuels require an ignition source under conditions typically found in a scramjet combustor. Analytical studies indicate that the presence of hydrogen atoms should greatly reduce the ignition delay in this environment. Because hydrogen plasmas are prolific sources of hydrogen atoms, a low-power, uncooled hydrogen plasma torch has been built and tested to evaluate its potential as a possible flame holder for supersonic combustion. The torch was found to be unstable when operated on pure hydrogen; however, stable operation could be obtained by using argon as a body gas and mixing in the desired amount of hydrogen. The stability limits of the torch are delineated and its electrical and thermal behavior documented. An average torch thermal efficiency of around 88 percent is demonstrated.

Barbi, E.↗
NASA NTRS1989

Improved plasma torch for ignition and flame holding in supersonic combustion

A plasma torch system designed for ignition and flame-holding in supersonic combustion studies has been modified, in order to decrease electrode wear and increase stability, through the incorporation of a flow swirler in the gas inlet that adds vortex-stabilization to the arc. The torch body was redesigned in order to achieve superior alignment of the electrodes; the electrode gap was made continuously adjustable, thereby allowing fine tuning during torch operation. Table operation of the improved torch has been demonstrated in pure nitrogen, eliminating the requirement of argon gas for arc stabilization.

O'Brien, W. F.↗
NASA NTRS1989

Plasma torch igniter for scramjets

A small, uncooled plasma torch was developed and used in combination with an injector designed to study ignition and flameholding in hydrogen-fueled supersonic flows. The plasma torch was operated on mixtures of hydrogen and argon with total flows of 10 to 70 scfh. The fuel injector design consisted of five small upstream pilot fuel injectors, a rearward facing step for recirculation, and three main fuel injectors downstream of the step. The plasma torch was located in the recirculation region, and all injection was perpendicular to the Mach 2 stream. Both semi-freejet and ducted tests were conducted. The experimental results indicate that a low power plasma torch operating on a 1:1 volumetric mixture of hydrogen and argon and located in the recirculation zone fueled by the upstream pilot fuel injectors is a good igniter for flow conditions simulating a flight Mach number of 3.7. The total temperature required to autoignite the hydrogen fuel for this injector geometry was 2640 R. The injector configuration was shown to be a good flameholder over a wide range of total temperature. Spectroscopic measurements were used to verify the presence of air total temperatures below 1610 R.

Wagner, Timothy C.↗
NASA NTRS1995

Ternary gas plasma welding torch

A plasma arc welding torch is discussed. A first plasma gas is directed through the body of the welding torch and out of the body across the tip of a welding electrode disposed at the forward end of the body. A second plasma gas is disposed for flow through a longitudinal bore in the electrode. The second plasma gas enters one end of the electrode and exits the electrode at the tip thereof for co-acting with the electric welding arc to produce the desired weld. A shield gas is directed through the torch body and circulates around the head of the torch adjacent to the electrode tip.

Rybicki, Daniel J.↗
NASA NTRS1996

Advanced Welding Torch

In order to more easily join the huge sections of the Space Shuttle external tank, Marshall Space Flight Center initiated development of the existing concept of Variable Polarity Plasma Arc (VPPA) welding. VPPA welding employs a variable current waveform that allows the system to operate for preset time increments in either of two polarity modes for effective joining of light alloys. Marshall awarded the torch contract to B & B Precision Machine, which produced a torch for the Shuttle, then automated the system, and eventually delivered a small torch used by companies such as Whirlpool for sheet metal welding of appliance parts and other applications. The dependability of the torch offers cost and time advantages.

Source record↗
NASA NTRS1987

Electrode support for gas arc welding torch having coaxial vision

An improved electrode mounting structure for a gas tungsten arc welding torch having a coaxial imaging system. The electrode mounting structure includes a support having a central hub and a plurality of spokes which extend from the hub generally radially with respect to the axis of the torch into supporting engagement with the interior walls of the torch. The spaces between the spokes are optical passages for transmission of light to form the image. A tubular collet holder is threadedly engaged at its upper end to the hub and extends downwardly toward the open end of the torch. The collet holder has an inwardly tapering constriction near its lower end. An electrode-retaining, tubular collet is mounted within the collet holder and has a longitudinally split and tapered end seating against the tapered constriction. A spring seats against the upper end of the collet and forces the split end against the tapered constriction to wedge the split end radially inwardly to grip the electrode within the collet.

Richardson, Richard W.↗
NASA NTRS2017

Characterization of a 50kW Inductively Coupled Plasma Torch for Testing of Ablative Thermal Protection Materials

With the development of new manned spaceflight capabilities including NASA's Orion capsule and the Space-X Dragon capsule, there is a renewed importance of understanding the dynamics of ablative thermal protection systems. To this end, a new inductively coupled plasma torch facility is being developed at UT-Austin. The torch operates on argon and/or air at plasma powers up to 50 kW. In the present configuration the flow issues from a low-speed subsonic nozzle and the hot plume is characterized using slug calorimetry and emission spectroscopy. Preliminary measurements using emission spectroscopy have indicated that the torch is capable of producing an air plasma with a temperature between 6,000 K and 8,000 K depending on the power and flow settings and an argon plasma with a temperature of approximately 12,000 K. The operation envelope was measured, and heat flux measured for every point within the envelope using both a slug calorimeter and a Gardon gauge heat flux sensor. The torch was found to induce a stagnation point heat flux of between 90 and 225 W/sq cm.

Greene, Benton R.↗