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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Experimental evaluation of two premixing-prevaporizing fuel injection concepts for a gas turbine catalytic combustor

A premixing-prevaporizing fuel system to be used with a catalytic combustor was evaluated for possible application in an automotive gas turbine. Spatial fuel distribution and degree of vaporization were measured using jet A fuel. Two types of air blast injectors were tested, a splash groove injector and a multiple jet cross stream injector. Air swirlers with vane angles of 15 deg and 30 deg were used to improve the spatial fuel distribution in a 12 cm diameter tubular rig. Distribution and vaporization measurements were made 35.5 cm downstream of the injector. The spatial fuel distribution was nearly uniform with the multiple jet contrastream injector and the splash-groove injector with a 30 deg air swirler. The vaporization was nearly 100 percent at an inlet air temperature of 600 K, and at 800 K inlet air temperature fuel oxidation reactions were observed. The total pressure loss was less than 0.5 percent of the total pressure for the multiple jet cross stream injector and the splash groove injector (without air swirler) and less than 1 percent for the splash groove with a 30 deg air swirler.

Tacina, R.↗
NASA NTRS1980

Status of the Ford program to evaluate ceramics for stator applications in automotive gas turbine engines

The paper reviews the progress of the major technical tasks of the DOE/NASA/Ford program Evaluation of Ceramics for Stator Applications in Automotive Gas Turbine Engines: reliability prediction, stator fabrication, material characterization, and stator evaluation. A fast fracture reliability model was prepared for a one-piece ceramic stator. Periodic inspection results are presented.

Trela, W.↗
NASA NTRS2003

Tracking and Control of Gas Turbine Engine Component Damage/Life

This paper describes damage mechanisms and the methods of controlling damages to extend the on-wing life of critical gas turbine engine components. Particularly, two types of damage mechanisms are discussed: creep/rupture and thermo-mechanical fatigue. To control these damages and extend the life of engine hot-section components, we have investigated two methodologies to be implemented as additional control logic for the on-board electronic control unit. This new logic, the life-extending control (LEC), interacts with the engine control and monitoring unit and modifies the fuel flow to reduce component damages in a flight mission. The LEC methodologies were demonstrated in a real-time, hardware-in-the-loop simulation. The results show that LEC is not only a new paradigm for engine control design, but also a promising technology for extending the service life of engine components, hence reducing the life cycle cost of the engine.

Jaw, Link C.↗
NASA NTRSDate not supplied

Advanced Environmental Barrier Coating Testing and Development for Gas Turbine Engines

Environmental barrier coatings (EBCs) are an enabling technology for the use of SiC-based ceramic matrix composites (CMCs) in next generation gas turbine engines. SiC-based CMCs are lightweight and have higher temperature stability than traditional nickel based superalloys. However, SiC is susceptible to rapid oxidation and recession due to high temperature reactions with water vapor and other combustion species. Thus, EBCs were developed to protect these components and extend operating lifetime. In the extreme engine environment, EBCs must be able to withstand a variety of damage mechanisms and the synergies of degradation between them. This presentation will provide an overview of NASA Glenn Research Center, current aeronautics research, and an introduction to EBC failure modes and environmental durability test methods.

Jamesa L Stokes↗
NASA NTRS1945

Cooling of Gas Turbines: Effectiveness of Rim Cooling of Blades - 2

An analysis of rim cooling, which cools the blade by condition alone, was conducted. Gas temperatures ranged from 1300 degrees to 1900 degrees F and rim temperatures from 0 degrees to 1000 degrees F below gas temperatures. Results show that gas temperature increases up to 200 degrees F are permissible provided that the blades are cooled by 400 degrees to 500 degrees F below the gas temperature. Relatively small amounts of blade cooling, at constant gas temperature, give large increases in blade life. Dependence of rim cooling on heat-transfer coefficient, blade dimensions, and thermal conductivity is determined by a single parameter.

ATI COLLECTION↗
NASA NTRS1978

Gas turbine engine emission reduction technology program

Progress in the development of combustor technology to meet the standards for the allowable pollutant emission levels of aircraft gas turbine engines is reported. The high-bypass-ratio turbofan engines which power the large commercial aircraft were emphasized along with efforts to reduce emission for near term applications. Recommendations for continuing research to reduce emissions to meet far term needs are given.

Petrash, D. A.↗
NASA NTRS1978

Calculation of CO concentration for liquid fueled gas turbine combustor

The extensive computation time required for the numerical integration of the differential equations obtained in studies of the concentrations of pollutants emitted by gas turbine combustors, can be reduced significantly by assuming the heat releasing hydrocarbon reactions to be in local equilibrium. In determining the CO and NO concentrations produced in spray combustion, it is, therefore, tempting to use the same local equilibrium assumption in order to simplify the kinetic calculations. An investigation of the validity of the local equilibrium assumption is conducted by using a simple analytical model, and then by actually carrying out the kinetic and local equilibrium calculations for typical case.

Patil, P. B.↗
NASA NTRS1982

Multiroller traction drive speed reducer: Evaluation for automotive gas turbine engine

Tests were conducted on a nominal 14:1 fixed-ratio Nasvytis multiroller traction drive retrofitted as the speed reducer in an automotive gas turbine engine. Power turbine speeds of 45,000 rpm and a drive output power of 102 kW (137 hp) were reached. The drive operated under both variable roller loading (proportional to torque) and fixed roller loading (automatic loading mechanism locked). The drive operated smoothly and efficiently as the engine speed reducer. Engine specific fuel consumption with the traction speed reducer was comparable to that with the original helical gearset.

Rohn, D. A.↗
NASA NTRS1988

Two-Equation Low-Reynolds-Number Turbulence Modeling of Transitional Boundary Layer Flows Characteristic of Gas Turbine Blades

The use of low Reynolds number (LRN) forms of the k-epsilon turbulence model in predicting transitional boundary layer flow characteristic of gas turbine blades is developed. The research presented consists of: (1) an evaluation of two existing models; (2) the development of a modification to current LRN models; and (3) the extensive testing of the proposed model against experimental data. The prediction characteristics and capabilities of the Jones-Launder (1972) and Lam-Bremhorst (1981) LRN k-epsilon models are evaluated with respect to the prediction of transition on flat plates. Next, the mechanism by which the models simulate transition is considered and the need for additional constraints is discussed. Finally, the transition predictions of a new model are compared with a wide range of different experiments, including transitional flows with free-stream turbulence under conditions of flat plate constant velocity, flat plate constant acceleration, flat plate but strongly variable acceleration, and flow around turbine blade test cascades. In general, calculational procedure yields good agreement with most of the experiments.

Schmidt, Rodney C.↗
NASA NTRS2002

Progress in SiC/SiC Ceramic Composite Development for Gas Turbine Hot-Section Components under NASA EPM and UEET Programs

The successful application of ceramic matrix composites as hot-section components in advanced gas turbine engines will require the development of constituent materials and processes that can provide the material systems with the key thermostructural properties required for long-term component service. Much initial progress in identifying these materials and processes was made under the former NASA Enabling Propulsion Materials Program using stoichiometric Sylramic (trademark) silicon-carbide (SiC) fibers, 2D (two dimensional)-woven fiber architectures, chemically vapor-infiltrated (CVI) BN fiber coatings (interphases), and SiC-based matrices containing CVI SiC interphase over-coatings, slurry-infiltrated SiC particulate, and melt-infiltrated (MI) silicon. The objective of this paper is to discuss the property benefits of this SiC/SiC composite system for high-temperature engine components and to elaborate on further progress in SiC/SiC development made under the new NASA Ultra Efficient Engine Technology Program. This progress stems from the recent development of advanced constituent materials and manufacturing processes, including specific treatments at NASA that improve the creep, rupture, and environmental resistance of the Sylramic fiber as well as the thermal conductivity and creep resistance of the CVI SiC over-coatings. Also discussed are recent observations concerning the detrimental effects of inadvertent carbon in the fiber-BN interfacial region and the beneficial effects of certain 2D-architectures for thin-walled SiC/SiC panels.

DiCarlo, J. A.↗
NASA NTRS2009

History of Thermal Barrier Coatings for Gas Turbine Engines: Emphasizing NASA's Role from 1942 to 1990

NASA has played a central role in the development of thermal barrier coatings (TBCs) for gas turbine applications. This report discusses the history of TBCs emphasizing the role NASA has played beginning with (1) frit coatings in the 1940s and 1950s; (2) thermally sprayed coatings for rocket application in the 1960s and early 1970s; (3) the beginnings of the modern era of turbine section coatings in the mid 1970s; and (4) failure mechanism and life prediction studies in the 1980s and 1990s. More recent efforts are also briefly discussed.

Miller, Robert A.↗
NASA NTRS1976

Toward more environmentally resistant gas turbines: Progress in NASA-Lewis programs

A wide range of programs are being conducted for improving the environmental resistance to oxidation and hot corrosion of gas turbine and power system materials. They range from fundamental efforts to delineate attack mechanisms, allow attack modeling and permit life prediction, to more applied efforts to develop potentially more resistant alloys and coatings. Oxidation life prediction efforts have resulted in a computer program which provides an initial method for predicting long time metal loss using short time oxidation data by means of a paralinear attack model. Efforts in alloy development have centered on oxide-dispersion strengthened alloys based on the Ni-Cr-Al system. Compositions have been identified which are compromises between oxidation and thermal fatigue resistance. Fundamental studies of hot corrosion mechanisms include thermodynamic studies of sodium sulfate formation during turbine combustion. Information concerning species formed during the vaporization of Na2SO4 has been developed using high temperature mass spectrometry.

Lowell, C. E.↗
NASA NTRS1978

Catalytic combustion for the automotive gas turbine engine

Fuel-air premixing-prevaporizing systems and commercial catalysts were studied as part of a demonstration of a low emissions combustor for an automotive gas turbine engine. A fuel preparation system which would supply a fuel-air mixture which was uniform to within + or - 10 percent of the mean fuel-air ratio, with 90 percent fuel vaporization and with no autoignition is described. The catalytic reactor was required to produce emissions which were low enough to meet the most stringent proposed U.S. automotive standards. The overall pressure drop for both systems was to be less than 3 percent, with 1 percent allowed in the fuel-air preparation system and the remainder in the catalytic reactor.

Anderson, D. N.↗
NASA NTRS1983

Analysis of a MIL-L-27502 lubricant from a gas-turbine engine test by size-exclusion chromatography

Size exclusion chromatography was used to determine the chemical degradation of MIL-L-27502 oil samples from a gas turbine engine test run at a bulk oil temperature of 216 C. Results revealed a progressive loss of primary ester and additive depletion and the formation of higher molecular weight products with time. The high molecular weight products absorbed strongly in the ultraviolet indicating the presence of chromophoric groups.

Jones, W. R., Jr.↗
NASA NTRS1983

New trends in combustion research for gas turbine engines

Research on combustion is being conducted to provide improved analytical models of the complex flow and chemical reaction processes which occur in the combustor of gas turbine engines, in order to enable engine manufacturers to reduce the development time of these concepts. The elements of the combustion fundamentals program is briefly discussed with examples of research projects described more fully. Combustion research will continue to emphasize the development of analytical models and the support of these models with fundamental flow experiments to assess the models accuracy and shortcomings.

Mularz, E. J.↗
NASA NTRS1983

New trends in combustion research for gas turbine engines

Research on combustion is being conducted to provide improved analytical models of the complex flow and chemical reaction processes which occur in the combustor of gas turbine engines, in order to enable engine manufacturers to reduce the development time of these concepts. The elements of the combustion fundamentals program is briefly discussed with examples of research projects described more fully. Combustion research will continue to emphasize the development of analytical models and the support of these models with fundamental flow experiments to assess the models accuracy and shortcomings. Previously announced in STAR as N83-20947

Mularz, E. J.↗
NASA NTRS1994

High temperature strain gage technology for gas turbine engines

This report summarizes the results of a six month study that addressed specific issues to transfer the Pd-13Cr static strain sensor to a gas turbine engine environment. The application issues that were addressed include: (1) evaluation of a miniature, variable potentiometer for use as the ballast resistor, in conjunction with a conventional strain gage signal conditioning unit; (2) evaluation of a metal sheathed, platinum conductor leadwire assembly for use with the three-wire sensor; and (3) subjecting the sensor to dynamic strain cyclic testing to determine fatigue characteristics. Results indicate a useful static strain gage system at all temperature levels up to 1350 F. The fatigue characteristics also appear to be very promising, indicating a potential use in dynamic strain measurement applications. The procedure, set-up, and data for all tests are presented in this report. This report also discusses the specific strain gage installation technique for the Pd-13Cr gage because of its potential impact on the quality of the output data.

Fichtel, Edward J.↗