SEARCH · Search NASA

Results for “COMBUSTION”

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.

SourceResearch connectionFrom yearThrough year

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

At least 433 records · Page 24

All sources NASA NTRS DOE OSTI

NASA NTRS1991

The NASA Microgravity Combustion Space Experiment Program

This paper summarizes the scientific objectives of the expanded microgravity combustion science program including efforts in laminar and turbulent premixed-gas flames, laminar and turbulent gas-jet diffusion flames, droplet combustion, smoldering, flame spreading, pool fires, and metals combustion. Secondly, the paper will summarize the flight hardware that is currently flying and new hardware being proposed to carry out this extensive program of microgravity combustion experiments.

Sacksteder, Kurt↗

NASA NTRS1992

Hydrogen combustion in a hypersonic airstream

An experimental and computational investigation of hypervelocity, hypersonic combustion of hydrogen with air is described which was intended to confirm the presence of combustion at these conditions and then to gauge the pressure rise associated with the heat release of combustion. Experiments were conducted in a square cross section duct and wall pressure was measured. It was found that combustion did occur and that the maximum pressure increase was approximately 72 percent over the intake pressure.

Casey, R. T.↗

NASA NTRS1992

Combustion devices technology team - An overview and status of STME-related activities

The Consortium for CFD applications in propulsion technology has been formed at NASA/Marshall Space Flight Center. The combustion devices technology team is one of the three teams that constitute the Consortium. While generally aiming to advance combustion devices technology for rocket propulsion, the team's efforts for the last 1 and 1/2 years have been focused on issues relating to the Space Transportation Main Engine (STME) nozzle. The nozzle design uses hydrogen-rich turbine exhaust to cool the wall in a film/dump scheme. This method of cooling presents challenges and associated risks for the nozzle designers and the engine/vehicle integrators. Within the nozzle itself, a key concern is the ability to effectively and efficiently film cool the wall. From the National Launch System vehicle base standpoint, there are concerns with dumping combustible gases at the nozzle exit and their potential adverse effects on the base thermal environment. The Combustion Team has developed and is implementing plans to use validated CFD tools to aid in risk mitigation for both areas.

Tucker, P. K.↗

NASA NTRS1992

A combustion driven shock tunnel to complement the free piston shock tunnel T5 at GALCIT

A combustion driven shock tunnel was designed and built at GALCIT to supply the hypersonic facility T5 with 'hot' hydrogen for mixing and combustion experiments. This system was chosen over other options for better flexibility and for safety reasons. The shock tunnel is described and the overall efficiency of the system is discussed. The biggest challenge in the design was to synchronize the combustion driven shock tunnel with T5. To do so, the main diaphragm of the combustion driven shock tunnel is locally melted by an electrical discharge. This local melting is rapidly followed by the complete collapse of the diaphragm in a very repeatable way. A first set of experiments on supersonic hydrogen transverse jets over a flat plate have just been completed with the system and some of the preliminary results are presented.

Belanger, Jacques↗

NASA NTRS1993

Test Would Quantify Combustion Oxygen From Different Sources

Proposed isotope-enrichment scheme enables determination of contributions of dual sources of oxygen for combustion. Liquid oxygen or other artificial stream enriched with O(18) to about 1 percent by weight. Combustion products analyzed by mass spectrometer to measure relative abundances of H2O(18) and H2O(16). From relative abundances of water products measured, one computes relative contribution of oxygen extracted from stream compared to other source of oxygen in combustion process. Used to determine contributions of natural oxygen in air and liquid oxygen supplied in separate stream mixed with air or sent directly into combustion chamber.

Tapphorn, Ralph M.↗

NASA NTRS1993

Metals combustion in normal gravity and microgravity

The study of the combustion characteristics of metallic materials has been an ongoing area of research at the NASA White Sands Test Facility (WSTF). This research has been in support of both government and industrial operations and deals not only with the combustion of specific metallic materials but also with the relative flammabilities of these materials under similar conditions. Since many of the metallic materials that are characterized at WSTF for aerospace applications are to be used in microgravity environments, it was apparent that the testing of these materials needed to proceed in a microgravity environment. It was believed that burning metallic materials in a microgravity environment would allow the evaluation of the validity of applying normal gravity combustion tests to characterize metallic materials to be used in microgravity environments. It was also anticipated that microgravity testing would provide insight into the general combustion process of metallic materials. The availability of the NASA Lewis Research Center's (LeRC) 2.2-second drop tower provided the necessary facility to accomplish the microgravity portion of the testing while the normal gravity testing was conducted at NASA WSTF. The tests, both at LeRC and WSTF, were conducted in the same instrumented system and utilized the standard metal flammability test of upward propagation burning of cylindrical rod samples.

Steinberg, Theodore A.↗

NASA NTRS1993

Characterizing droplet combustion of pure and multi-component liquid fuels in a microgravity environment

The importance of understanding the effects of fuel composition, length scales, and other parameters on the combustion of liquid fuels has motivated the examination of simple flames which have easily characterized flow fields and hence, the potential of being modeled accurately. One such flame for liquid fuel combustion is the spherically symmetric droplet flame which can be achieved in an environment with sufficiently low gravity (i.e., low buoyancy). To examine fundamental characteristics of spherically symmetric droplet combustion, a drop tower facility has been employed to provide a microgravity environment to study droplet combustion. This paper gives a brief review of results obtained over the past three years under NASA sponsorship (grant NAG3-987).

Jackson, Gregory S.↗

NASA NTRS1993

A coupled multi-block solution procedure for spray combustion in complex geometries

Turbulent spray-combusting flow in complex geometries is presently treated by a coupled implicit procedure that employs finite-rate chemistry and real gas properties for combustion, as well as the stochastic separated model for spray and a multiblock treatment for complex geometries. Illustrative numerical tests conducted encompass a steady-state nonreacting backward-facing step flow, a premixed single-phase combustion flow, and spray combustion flow in a gas turbine combustor.

Chen, Kuo-Huey↗

NASA NTRS1992

Initiation of combustion in the thermally choked ram accelerator

The methodology for initiating stable combustion in a ram accelerator operating in the thermally choked mode is presented in this paper. The ram accelerator is a high velocity ramjet-in-tube projectile launcher whose principle of operation is similar to that of an airbreathing ramjet. The subcaliber projectile travels supersonically through a stationary tube filled with a premixed combustible gas mixture. In the thermally choked propulsion mode subsonic combustion takes place behind the base of the projectile and leads to thermal choking, which stabilizes a normal shock system on the projectile, thus producing forward thrust. Projectiles with masses in the 45-90 g range have been accelerated to velocities up to 2650 m/sec in a 38 mm bore, 16 m long accelerator tube. Operation of the ram accelerator is started by injecting the projectile into the accelerator tube at velocities in the 700 - 1300 m/sec range by means of a conventional gas gun. A specially designed obturator, which seals the bore of the gun during this initial acceleration, enters the ram accelerator together with the projectile. The interaction of the obturator with the propellant gas ignites the gas mixture and establishes stable combustion behind the projectile.

Bruckner, A. P.↗

NASA NTRS1993

Numerical simulations of the superdetonative ram accelerator combusting flow field

The effects of projectile canting and fins on the ram accelerator combusting flowfield and the possible cause of the ram accelerator unstart are investigated by performing axisymmetric, two-dimensional, and three-dimensional calculations. Calculations are performed using the INCA code for solving Navier-Stokes equations and a guasi-global combustion model of Westbrook and Dryer (1981, 1984), which includes N2 and nine reacting species (CH4, CO, CO2, H2, H, O2, O, OH, and H2O), which are allowed to undergo a 12-step reaction. It is found that, without canting, interactions between the fins, boundary layers, and combustion fronts are insufficient to unstart the projectile at superdetonative velocities. With canting, the projectile will unstart at flow conditions where it appears to accelerate without canting. Unstart occurs at some critical canting angle. It is also found that three-dimensionality plays an important role in the overall combustion process.

Soetrisno, Moeljo↗

NASA NTRS1953

Photographic Investigation of Combustion in a Two-dimensional Transparent Rocket Engine

Motion pictures at camera speeds up to 3000 frames per second were taken of the combustion of liquid oxygen and gasoline in a 100-pound thrust rocket engine. The effect of seven methods of propellant injection on the uniformity of combustion was investigated. The flame front was generally found to extend to the injector faces and all the injection systems showed considerable nonuniformity of combustion. Pressure vibration records indicated combustion vibrations that corresponded to resonant-chamber frequencies.

Bellman, Donald R↗

NASA NTRS1939

The Influence of Directed Air Flow on Combustion in Spark-Ignition Engine

The air movement within the cylinder of the NACA combustion apparatus was regulated by using shrouded inlet valves and by fairing the inlet passage. Rates of combustion were determined at different inlet-air velocities with the engine speed maintained constant and at different engine speeds with the inlet-air velocity maintained approximately constant. The rate of combustion increased when the engine speed was doubled without changing the inlet-air velocity; the observed increase was about the same as the increase in the rate of combustion obtained by doubling the inlet-air velocity without changing the engine speed. Certain types of directed air movement gave great improvement in the reproducibility of the explosions from cycle to cycle, provided that other variables were controlled. Directing the inlet air past the injection valve during injection increased the rate of burning.

Rothrock, A M↗

NASA NTRS1941

A High-Speed Motion-Picture Study of Normal Combustion, Knock and Preignition in a Spark-Ignition Engines

Combustion in a spark-ignition engine was investigated by means of the NACA high-speed motion-picture cameras. This camera is operated at a speed of 40,000 photographs a second and therefore makes possible the study of changes that take place in the intervals as short as 0.000025 second. When the motion pictures are projected at the normal speed of 16 frames a second, any rate of movement shown is slowed down 2500 times. Photographs are presented of normal combustion, of combustion from preignitions, and of knock both with and without preignition. The photographs of combustion show that knock may be preceded by a period of exothermic reaction in the end zone that persists for a time interval of as much as 0.0006 second. The knock takes place in 0.00005 second or less.

Rothrock, A M↗

NASA NTRS1993

Combustion for future supersonic transport propulsion

Even with it's marginal performance, Concorde has demonstrated that supersonic civil aircraft are a practical proposition. A second generation machine will need sufficiently good performance for a robust operating system that can provide reliable, frequent service with competitive economics. Additionally, the propulsion system must be acceptable environmentally. That is it must create acceptable noise levels around airports and have acceptable emissions throughout its mission including cruise. Whatever devices may be used to improve the acceptability at subsonic flight conditions, the high operating temperatures at cruise can create difficult targets for the operation of the combustion system both mechanically and in the combustion process itself. While the driving force is ever better fuel consumption and weight to achieve economic viability, a future supersonic transport engine will have cycle temperatures limited only by the mechanical integrity of the major components. The environment of the major components in modern gas turbine engines is dominated by the air delivered by the compressor system. Consequently the maximum compression temperature is governed by materials available for the turbine and compressor discs. The continued improvement of the disc material leads to combustion inlet temperatures beyond today's experience and sets difficult targets for combustion system emissions. This is worsened by the requirement being at cruise and therefore maintained for the major part of the mission. Problems such as creep and oxidation of metallic parts are also considered.

B. W. Lowrie↗

NASA NTRS1993

An emergency response mobile robot for operations in combustible atmospheres

A mobile, self-powered, self-contained, and remote-controlled robot is presented. The robot is capable of safely operating in a combustible atmosphere and providing information about the atmosphere to the operator. The robot includes non-sparking and non-arcing electro-mechanical and electronic components designed to prevent the robot from igniting the combustible atmosphere. The robot also includes positively pressurized enclosures that house the electromechanical and electronic components of the robot and prevent intrusion of the combustible atmosphere into the enclosures. The enclosures are interconnected such that a pressurized gas injected into any one of the enclosures is routed to all the other enclosures through the interconnections. It is preferred that one or more sealed internal channels through structures intervening between the enclosures be employed. Pressure transducers for detecting if the pressure within the enclosures falls below a predetermined level are included. The robot also has a sensing device for determining the types of combustible substances in the surrounding atmosphere, as well as the concentrations of each type of substance relative to a pre-determined lower explosive limit (LEL). In addition, the sensing device can determine the percent level of oxygen present in the surrounding atmosphere.

Stone, Henry W.↗

NASA NTRS1994

Modeling aerosol emissions from the combustion of composite materials

The use of advanced composite materials (ACM) in the B-2 bomber, composite armored vehicle, and F-22 advanced tactical fighter has rekindled interest concerning the health risk of burned or burning ACM. The objective of this work was to determine smoke production from burning ACM and its toxicity. A commercial version of the UPITT II combustion toxicity method developed at the University of Pittsburgh, and subsequently refined through a US Army-funded basic research project, was used to established controlled combustion conditions which were selected to evaluate real-world exposure scenarios. Production and yield of toxic species varied with the combustion conditions. Previous work with this method showed that the combustion conditions directly influenced the toxicity of the decomposition products from a variety of materials.

Roop, J. A.↗

NASA NTRS1995

Microgravity Combustion Science: 1995 Program Update

Microgravity greatly benefits the study of fundamental combustion processes. In this environment, buoyancy-induced flow is nearly eliminated, weak or normally obscured forces and flows can be isolated, gravitational settling or sedimentation is nearly eliminated, and temporal and spatial scales can be expanded. This document reviews the state of knowledge in microgravity combustion science with the emphasis on NASA-sponsored developments in the current period of 1992 to early 1995. The subjects cover basic research in gaseous premixed and diffusion-flame systems, flame structure and sooting, liquid droplets and pools, and solid-surface ignition and flame spread. They also cover applied research in combustion synthesis of ceramic-metal composites, advanced diagnostic instrumentation, and on-orbit fire safety. The review promotes continuing research by describing the opportunities for Principal Investigator participation through the NASA Research Announcement program and the available NASA Lewis Research Center ground-based facilities and spaceflight accommodations. This review is compiled by the members and associates of the NASA Lewis Microgravity Combustion Branch, and it serves as an update of two previous overview reports.

Ross, Howard D.↗

NASA NTRS1995

Numerical study of contaminant effects on combustion of hydrogen, ethane, and methane in air

A numerical study was performed to assess the effects of vitiated air on the chemical kinetics of hydrogen, ethane, and methane combustion with air. A series of calculations in static reacting systems was performed, where the initial temperature was specified and reactions occurred at constant pressure. Three different types of test flow contaminants were considered: NO, H2O, and a combination of H2O and CO2. These contaminants are present in the test flows of facilities used for hypersonic propulsion testing. The results were computed using a detailed reaction mechanism and are presented in terms of ignition and reaction times. Calculations were made for a wide range of contaminant concentrations, temperatures and pressures. The results indicate a pronounced kinetic effect over a range of temperatures, especially with NO contamination and, to a lesser degree, with H2O contamination. In all cases studied, CO2 remained kinetically inert, but had a thermodynamically effect on results by acting as a third body. The largest effect is observed with combustion using hydrogen fuel, less effect is seen with combustion of ethane, and little effect of contaminants is shown with methane combustion.

Lai, H. T.↗