Search NASA⌕ Search

SEARCH · Search NASA

Results for “EXHAUST GASES - TEMPERATURE”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

Mixing of Supersonic Streams

The Strutjet approach to Rocket Based Combined Cycle (RBCC) propulsion depends upon fuel-rich flows from the rocket nozzles and turbine exhaust products mixing with the ingested air for successful operation in the ramjet and scramjet modes. It is desirable to delay this mixing process in the air-augmented mode of operation present during low speed flight. A model of the Strutjet device has been built and is undergoing test to investigate the mixing of the streams as a function of distance from the Strutjet exit plane during simulate low speed flight conditions. Cold flow testing of a 1/6 scale Strutjet model is underway and nearing completion. Planar Laser Induced Fluorescence (PLIF) diagnostic methods are being employed to observe the mixing of the turbine exhaust gas with the gases from both the primary rockets and the ingested air simulating low speed, air augmented operation of the RBCC. These diagnostics are supplemented by pressure profile measurements across the various jet streams present in the flow duct downstream of the model exit plane. The results of these experiments will be presented.

Hawk, Clark W.↗
NASA NTRS1974

Effluent sampling of Scout D and Delta launch vehicle exhausts

Characterization of engine-exhaust effluents (hydrogen chloride, aluminum oxide, carbon dioxide, and carbon monoxide) has been attempted by conducting field experiments monitoring the exhaust cloud from a Scout-Algol III vehicle launch and a Delta-Thor vehicle launch. The exhaust cloud particulate size number distribution (total number of particles as a function of particle diameter), mass loading, morphology, and elemental composition have been determined within limitations. The gaseous species in the exhaust cloud have been identified. In addition to the ground-based measurements, instrumented aircraft flights through the low-altitude, stabilized-exhaust cloud provided measurements which identified CO and HCI gases and Al2O3 particles. Measurements of the initial exhaust cloud during formation and downwind at several distances have established sampling techniques which will be used for experimental verification of model predictions of effluent dispersion and fallout from exhaust clouds.

Hulten, W. C.↗
NASA NTRS1985

Improved Exhaust Diffuser for Jet-Engine Testing

High-altitude simulator reduced power requirements. Test cell uses its exhaust-capture duct only to remove gases from engine; cooling air evacuated through separate path by auxiliary suction system. This way, capture duct cross-sectional area kept close to exhaust jet area, leading to greatly improved recovery performance.

Parikh, P. G.↗
NASA NTRS1992

Natural Cycles, Gases

The major gaseous components of the exhaust of stratospheric aircraft are expected to be the products of combustion (CO2 and H2O), odd nitrogen (NO, NO2 HNO3), and products indicating combustion inefficiencies (CO and total unburned hydrocarbons). The species distributions are produced by a balance of photochemical and transport processes. A necessary element in evaluating the impact of aircraft exhaust on the lower stratospheric composition is to place the aircraft emissions in perspective within the natural cycles of stratospheric species. Following are a description of mass transport in the lower stratosphere and a discussion of the natural behavior of the major gaseous components of the stratospheric aircraft exhaust.

Douglass, Anne R.↗
NASA NTRS1991

A parametric experimental investigation of a scramjet nozzle at Mach 6 with Freon and argon or air used for exhaust simulation

A parametric experimental investigation of a scramjet nozzle was conducted with a gas mixture used to simulate the scramjet engine exhaust flow at a free-stream Reynolds number of approximately 6.5 x 10(exp 6) per foot. External nozzle surface angles of 16, 20, and 24 deg were tested with a fixed-length ramp and for cowl internal surface angles of 6 and 12 deg. Pressure data on the external nozzle surface were obtained for mixtures of Freon and argon gases with a ratio of specific heats of about 1.23, which matches that of a scramjet exhaust. Forces and moments were determined by integration of the pressure data. Two nozzle configurations were also tested with air used to simulate the exhaust flow. On the external nozzle surface, lift and thrust forces for air exhaust simulation were approximately half of those for Freon-argon exhaust simulation and the pitching moment was approximately a third. These differences were primarily due to the difference in the ratios of specific heats between the two exhaust simulation gases. A 20 deg external surface angle produced the greatest thrust for a 6 deg cowl internal surface angle. A flow fence significantly increased lift and thrust forces over those for the nozzle without a flow fence.

Cubbage, James M.↗
NASA NTRS1963

THEORY OF TRANSPORT PROPERTIES OF GASES

Kinetic theory of transport properties of dilute gases, relating it to flames processes, noting assumptions of chapman-enksog theory, discussing real and dusty gases as well as rocket exhausts

FLAME↗
NASA NTRS1975

Simulation of hypersonic scramjet exhaust

A plan and some preliminary analysis for the accurate simulation of pressure distributions on the afterbody/nozzle portions of a hypersonic scramjet vehicle are described. The objectives fulfilled were to establish the standards of similitude for a hydrogen/air scramjet exhaust interacting with a vehicle afterbody, determine an experimental technique for validation of the procedures that will be used in conventional wind tunnel facilities, suggest a program of experiments for proof of the concept, and explore any unresolved problems in the proposed simulation procedures. It is shown that true enthalpy, Reynolds number, and nearly exact chemistry can be provided in the exhaust flow for the flight regime from Mach 4 to 10 by a detonation tube simulation. A detailed discussion of the required similarity parameters leads to the conclusion that substitute gases can be used as the simulated exhaust gas in a wind tunnel to achieve the correct interaction forces and moments.

Oman, R. A.↗
NASA NTRS1985

Calculation of Viscous Compressible Flows in Small Gas Turbines

The NASA Lewis Research Center is conducting a program to develop improved technology for the space shuttle main engine (SSmE). This program requires not only a component test program, but also the development of accurate and reliable analyses to support the program. Thus a computer analysis for the prediction of the flow of hot gases, composed of a variety of exhaust products, through rocket and gas turbine components would support this program and also would be suitable for a wide variety of other applications.

Anderson, O. L.↗
NASA NTRS2004

Manufacturing High-Quality Carbon Nanotubes at Lower Cost

A modified electric-arc welding process has been developed for manufacturing high-quality batches of carbon nanotubes at relatively low cost. Unlike in some other processes for making carbon nanotubes, metal catalysts are not used and, consequently, it is not necessary to perform extensive cleaning and purification. Also, unlike some other processes, this process is carried out at atmospheric pressure under a hood instead of in a closed, pressurized chamber; as a result, the present process can be implemented more easily. Although the present welding-based process includes an electric arc, it differs from a prior electric-arc nanotube-production process. The welding equipment used in this process includes an AC/DC welding power source with an integral helium-gas delivery system and circulating water for cooling an assembly that holds one of the welding electrodes (in this case, the anode). The cathode is a hollow carbon (optionally, graphite) rod having an outside diameter of 2 in. (approximately equal to 5.1 cm) and an inside diameter of 5/8 in. (approximately equal to 1.6 cm). The cathode is partly immersed in a water bath, such that it protrudes about 2 in. (about 5.1 cm) above the surface of the water. The bottom end of the cathode is held underwater by a clamp, to which is connected the grounding cable of the welding power source. The anode is a carbon rod 1/8 in. (approximately equal to 0.3 cm) in diameter. The assembly that holds the anode includes a thumbknob- driven mechanism for controlling the height of the anode. A small hood is placed over the anode to direct a flow of helium downward from the anode to the cathode during the welding process. A bell-shaped exhaust hood collects the helium and other gases from the process. During the process, as the anode is consumed, the height of the anode is adjusted to maintain an anode-to-cathode gap of 1 mm. The arc-welding process is continued until the upper end of the anode has been lowered to a specified height above the surface of the water bath. The process causes carbon nanotubes to form in the lowest 2.5 cm of the anode. It also causes a deposit reminiscent of a sandcastle to form on the cathode. The nanotube-containing material is harvested. The cathode and anode can then be cleaned (or the anode is replaced, if necessary) and the process repeated to produce more nanotubes. Tests have shown that the process results in approximately equal to 50-percent yield of carbon nanotubes (mostly of the single-wall type) of various sizes. Whereas the unit cost of purified single-wall carbon nanotubes produced by other process is about $1,000/g in the year 2000, it has been estimated that for the present process, the corresponding cost would be about $10/g.

Benavides, Jeanette M.↗
NASA NTRS2002

Real-time exhaust gas modular flowmeter and emissions reporting system for mobile apparatus

A real-time emissions reporting system includes an instrument module adapted to be detachably connected to the exhaust pipe of a combustion engine to provide for flow of exhaust gas therethrough. The instrument module includes a differential pressure probe which allows for determination of flow rate of the exhaust gas and a gas sampling tube for continuously feeding a sample of the exhaust gas to a gas analyzer or a mounting location for a non-sampling gas analyzer. In addition to the module, the emissions reporting system also includes an elastomeric boot for detachably connecting the module to the exhaust pipe of the combustion engine, a gas analyzer for receiving and analyzing gases sampled within the module and a computer for calculating pollutant mass flow rates based on concentrations detected by the gas analyzer and the detected flowrate of the exhaust gas. The system may also include a particulate matter detector with a second gas sampling tube feeding same mounted within the instrument module.

Breton, Leo Alphonse Gerard↗
NASA NTRS1993

ASRM Multi-Port Igniter Flow Field Analysis

The Advanced Solid Rocket Motor (ASRM) program was initiated by NASA in response to the need for a new generation rocket motor capable of providing increased thrust levels over the existing Redesigned Solid Rocket Motor (RSRM) and thus augment the lifting capacity of the space shuttle orbiter. To achieve these higher thrust levels and improve motor reliability, advanced motor design concepts were employed. In the head end of the motor, for instance, the propellent cast has been changed from the conventional annular configuration to a 'multi-slot' configuration in order to increase the burn surface area and guarantee rapid motor ignition. In addition, the igniter itself has been redesigned and currently features 12 exhaust ports in order to channel hot igniter combustion gases into the circumferential propellent slots. Due to the close proximity of the igniter ports to the propellent surfaces, new concerns over possible propellent deformation and erosive burning have arisen. The following documents the effort undertaken using computational fluid dynamics to perform a flow field analysis in the top end of the ASRM motor to determine flow field properties necessary to permit a subsequent propellent fin deformation analysis due to pressure loading and an assessment of the extent of erosive burning.

Kania, Lee↗
NASA NTRS1998

Laminae in the Tropical Middle Stratosphere: Origin and Age Estimation

Isentropic transport of stratospheric air from mid-latitudes into the tropics has been a subject of considerable interest recently. This exchange process is important for the understanding of the distribution of trace gases and ozone, and for the prediction of the exhaust dispersion of a proposed fleet of high speed civil transport aircraft (HSCT), which would operate in the 15 to 20 km altitude range.

middle↗
NASA NTRS2008

SiO2/TiO2 Composite for Removing Hg from Combustion Exhaust

Pellets made of a high-surface-area composite of silica and titania have shown promise as means of removing elemental mercury from flue gases. With further technical development and commercialization, this material could become economically attractive as a more effective, less-expensive alternative to activated carbons for removing mercury from exhaust streams of coal-burning power plants, which are the sources of more than 90 percent of all anthropogenic airborne mercury.

Mazyck, David↗
NASA NTRS1990

Controlled decomposition and oxidation: A treatment method for gaseous process effluents

The safe disposal of effluent gases produced by the electronics industry deserves special attention. Due to the hazardous nature of many of the materials used, it is essential to control and treat the reactants and reactant by-products as they are exhausted from the process tool and prior to their release into the manufacturing facility's exhaust system and the atmosphere. Controlled decomposition and oxidation (CDO) is one method of treating effluent gases from thin film deposition processes. CDO equipment applications, field experience, and results of the use of CDO equipment and technological advances gained from the field experiences are discussed.

Mckinley, Roger J. B., Sr.↗
NASA NTRS1981

Performance tests of a gas blending system based on mass-flow controllers

The system provides many of the gas mixtures required for calibrating analytical instruments used in engine exhaust gas analysis and is capable of blending from one to four additive gases with either of two carrier gases in concentrations from 20 ppm to 50%. Two mixtures can be flowing simultaneously. Performance tests were made to determine the stability accuracy of the system while it was in limited use for a period of 2 years. The accuracy of the blender was measured by comparing binary mixtures from the blender with National Bureau of Standards standard reference materials. Analytical instruments were used to make these comparisons. The expected accuracy of 2% was obtained in some of the tests, by the majority showed a systematic biAs of -5%. Although these tests revealed subtle instabilities in the flow controllers that contributed to the random scatter of data, the accuracy of wet test meters and bubble flowmeters used for calibration is marginal for this purpose. A simple procedure is recommended that should enable the full potential of the system to be realized.

Evans, A., Jr.↗
NASA NTRS1991

The effects of the exhaust plume on the lightning triggering conditions for launch vehicles

Apollo 12 and Atlas Centaur 67 are two launch vehicles that have experienced triggered lightning strikes. Serious consequences resulted from the events; in the case of Atlas Centaur 67, the vehicle and the payload were lost. These events indicate that it is necessary to develop launch rules which would prevent such occurrences. In order to develop valid lightning related rules, it is necessary to understand the effects of the plume. Some have assumed that the plume can be treated as a perfect conductor, and have computed electric field enhancement factors on that basis. The authors have looked at the plume, and believe that these models are not correct, because they ignore the fluid motion of the conducting plates. The authors developed a model which includes this flow character. In this model, the external field is excluded from the plume as it would be for any good conductor, but, in addition, the charge must distribute so that the charge density is zero at some location in the exhaust. When this condition is included in the calculation of triggering enhancement factors, they can be two to three times larger than calculated by other methods which include a conductive plume but don't include the correct boundary conditions. Here, the authors review the relevant features of rocket exhausts for the triggered lightning problem, present an approach for including flowing conductive gases, and present preliminary calculations to demonstrate the effect that the plume has on enhancement factors.

Eriksen, Frederick J.↗