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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 451 records · Page 25

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NASA NTRS1981

Optimal air-breathing launch vehicle design

A generalized two-point boundary problem methodology, similar to techniques used in deterministic optimal control studies, is applied to the design and flight analysis of a two-stage air-breathing launch vehicle. Simultaneous consideration is given to configuration and trajectory by treating geometry, dynamic discontinuities, and time-dependent flight variables all as controls to be optimized with respect to a single mathematical performance measure. While minimizing fuel consumption, inequality constraints are applied to dynamic pressure and specific force. The optimal system fuel consumption and staging Mach number are found to vary little with changes in the inequality constraints due to substantial geometry and trajectory adjustments. Staging, from an air-breathing first stage to a rocket-powered second stage, consistently occurs near Mach 3.5. The dynamic pressure bound has its most pronounced effects on vehicle geometry, particularly the air-breathing propulsion inlet area, and on the first-stage altitude profile. The specific force has its greatest influence on the second-stage thrust history.

Hattis, P. D.↗

NASA NTRS1991

Catalysis and biocatalysis program

The annual report presents the fiscal year (FY) 1990 research activities and accomplishments for the Catalysis and Biocatalysis Program of the Advanced Industrial Concepts Division (AICD), Office of Industrial Technologies of the Department of Energy (DOE). The mission of the AICD is to create a balanced program of high risk, long term, directed interdisciplinary research and development that will improve energy efficiency and enhance fuel flexibility in the industrial sector. The Catalysis and Biocatalysis Program's technical activities were organized into five work elements: the Molecular Modeling and Catalysis by Design element; the Applied Microbiology and Genetics element; the Bioprocess Engineering element; the Separations and Novel Chemical Processes element; and the Process Design and Analysis element.

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NASA NTRS1992

Limiting critical speed response on the SSME Alternate High Pressure Fuel Turbopump (ATD HPFTP) with bearing deadband

Yammamoto (1954) described the influence of bearing deadband on the critical speed response of a rotor-bearing system. Practical application of these concepts to limit critical speed response of turbopump rotors is described. Nonlinear rotordynamic analyses are used to define the effect of bearing deadband and rotor unbalance on the Space Shuttle Main Engine Alternate High Pressure Fuel Turbopump. Analysis results are used with hot fire test data to verify the presence of a lightly damped critical speed within the operating speed range. With the proper control of rotor unbalance and bearing deadband, the response of this critical speed is reduced to acceptable levels without major design modifications or additional sources of damping.

Goggin, David G.↗

NASA NTRS1996

Heuristic Modeling for TRMM Lifetime Predictions

Analysis time for computing the expected mission lifetimes of proposed frequently maneuvering, tightly altitude constrained, Earth orbiting spacecraft have been significantly reduced by means of a heuristic modeling method implemented in a commercial-off-the-shelf spreadsheet product (QuattroPro) running on a personal computer (PC). The method uses a look-up table to estimate the maneuver frequency per month as a function of the spacecraft ballistic coefficient and the solar flux index, then computes the associated fuel use by a simple engine model. Maneuver frequency data points are produced by means of a single 1-month run of traditional mission analysis software for each of the 12 to 25 data points required for the table. As the data point computations are required only a mission design start-up and on the occasion of significant mission redesigns, the dependence on time consuming traditional modeling methods is dramatically reduced. Results to date have agreed with traditional methods to within 1 to 1.5 percent. The spreadsheet approach is applicable to a wide variety of Earth orbiting spacecraft with tight altitude constraints. It will be particularly useful to such missions as the Tropical Rainfall Measurement Mission scheduled for launch in 1997, whose mission lifetime calculations are heavily dependent on frequently revised solar flux predictions.

Jordan, P. S.↗

NASA NTRS2000

Mixing, Noise and Thrust Benefits Using Corrugated Designs

These projects are directed toward the analysis of several concepts for nozzle and inlet performance improvement and noise reduction from jet exhausts. Currently. The FM&AL also initiates new joint research between the HU/FM&AL, the Hyper-X Program Team at the LaRC, and the Central Institute of Aviation Motors (CIAM), Moscow, Russia in the field of optimization of fuel injection and mixing in air-breathing propulsion systems. The main results of theoretical, numerical simulation and experimental tests obtained in the previous research are in the papers and patents. The goals of the 14U/FM&AL programs are twofold: 1) to improve the working efficiency of the HU/FM&AL team in generating new innovative ideas and in conducting research in the field of fluid dynamics and acoustics, basically for improvement of supersonic and subsonic aircraft engines, and 2) to attract promising minority students to this research and training and, in cooperation with other HU departments, to teach them basic knowledge in Aerodynamics, Gas Dynamics, and Theoretical and Experimental Methods in Aeroacoustics and Computational Fluid Dynamics (CFD). The research at the HU/FM&AL supports reduction schemes associated with the emission of en 'ne pollutants for commercial aircraft and concepts for reduction of 91 observables for military aircraft. These research endeavors relate to the goals of the NASA Strategic Enterprise in Aeronautics concerning the development of environmentally acceptable aircraft. It is in this precise area, where the US aircraft industry, academia, and Government are in great need of trained professionals and which is a high priority goal of the Minority University Research and Education (MLTREP) Program, that the HU/FM&AL can make its most important contribution.

Morgan, Morris H., III↗

NASA NTRS1975

Phase 2 program on ground test of refanned JT8D turbofan engines and nacelles for the 727 airplane. Volume 4: Airplane evaluation and analysis

The retrofit of JT8D-109 (refan) engines are evaluated on a 727-200 airplane in terms of airworthiness, performance, and noise. Design of certifiable hardware, manufacture, and ground testing of the essential nacelle components is included along with analysis of the certifiable airplane design to ensure airworthiness compliance and to predict the in-flight performance and noise characteristics of the modified airplane. The analyses confirm that the 727 refan airplane is certifiable. The refan airplane range would be 15% less that of the baseline airplane and block fuel would be increased by 1.5% to 3%. However, with this particular 727-200 model, with a brake release gross weight of 172,500 lb (78,245 kg), it is possible to operate the airplane (with minor structural modifications) at higher gross weights and increase the range up to 15% over the 727-200 (baseline) airplane. The refan airplane FAR Part 36 noise levels would be 6 to 8 EPNdB (effective perceived noise in decibels) below the baseline. Noise footprint studies showed that approach noise contour areas are small compared to takeoff areas. The 727 refan realizes a 68% to 83% reduction in annoyance-weighted area when compared to the 727-200 over a range of gross weights and operational procedures.

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NASA NTRS1983

Review of alternative fuels data bases

Based on an analysis of the interaction of fuel physical and chemical properties with combustion characteristics and indicators, a ranking of the importance of various fuel properties with respect to the combustion process was established. This ranking was used to define a suite of specific experiments whose objective is the development of an alternative fuels design data base. Combustion characteristics and indicators examined include droplet and spray formation, droplet vaporization and burning, ignition and flame stabilization, flame temperature, laminar flame speed, combustion completion, soot emissions, NOx and SOx emissions, and the fuels' thermal and oxidative stability and fouling and corrosion characteristics. Key fuel property data is found to include composition, thermochemical data, chemical kinetic rate information, and certain physical properties.

Harsha, P. T.↗

NASA NTRS1987

Density uncertainty effect on cost of space station reboost

If the space station is designed for operation in a nominal atmosphere for ten years and the atmosphere is two-sigma higher than nominal during the entire ten year period, the impact would be an additional cost of $70.1 million, based on a resupply cost of $3200/lb. A cost analysis of the space station fuel consumption with reboost is presented.

Unterberg, Walter↗

NASA NTRS1992

Project APEX: Advanced Phobos Exploration. Manned mission to the Martian moon Phobos

The manned exploration of Mars is a massive undertaking which requires careful consideration. A mission to the moon of Mars called Phobos as a prelude to manned landings on the Martian surface offers some advantages. One is that the energy requirements, in terms of delta 5, is only slightly higher than going to the Moon's surface. Another is that Phobos is a potential source of water and carbon which could be extracted and processed for life support and cryogenic propellants for use in future missions; thus, Phobos might serve as a base for extended Mars exploration or for exploration of the outer planets. The design of a vehicle for such a mission is the subject of our Aerospace System Design course this year. The materials and equipment needed for the processing plant would be delivered to Phobos in a prior unmanned mission. This study focuses on what it would take to send a crew to Phobos, set up the processing plant for extraction and storage of water and hydrocarbons, conduct scientific experiments, and return safely to Earth. The size, configuration, and subsystems of the vehicle are described in some detail. The spacecraft carries a crew of five and is launched from low Earth orbit in the year 2010. The outbound trajectory to Mars uses a gravitational assisted swing by of Venus and takes eight months to complete. The stay at Phobos is 60 days at which time the crew will be engaged in setting up the processing facility. The crew will then return to Earth orbit after a total mission duration of 656 days. Both stellar and solar observations will be conducted on both legs of the mission. The design of the spacecraft addresses human factors and life science; mission analysis and control; propulsion; power generation and distribution; thermal control; structural analysis; and planetary, solar, and stellar science. A 0.5 g artificial gravity is generated during transit by spinning about the lateral body axis. Nuclear thermal rockets using hydrogen as fuel are selected to reduce total launch mass and to shorten the duration of the mission. The nuclear systems also provide the primary electrical power via dual mode operation. The overall spacecraft length is 110 meters and the total mass departing from low Earth orbit is 900 metric tons.

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NASA NTRS1976

Investigation of Critical Burning of Fuel Droplets

An earlier analysis for the combustion response of a liquid monopropellant strand (hydrazine) was extended to consider individual droplets and sprays. While small drops gave low or negative response, large droplets provided response near unity at low frequencies, with the response declining at frequencies greater than the characteristic liquid phase frequency. Temperature gradients in the liquid phase resulted in response peaks greater than unity. A second response peak was found for large drops which corresponded to gas phase transient effects. Spray response was generally reduced from the response of the largest injected droplet, however, even a small percentage of large droplets can yield appreciable response. An apparatus was designed and fabricated to allow observation of bipropellant fuel spray combustion at elevated pressures. A locally homogeneous model was developed to describe this combustion process which allows for high pressure phenomena associated with the thermodynamic critical point.

Chanin, S. P.↗

NASA NTRS2008

Modeling of Slosh Dynamics in Cryogenic Propellant Tanks in Microgravity Environments

The slosh dynamics in cryogenic fuel tanks under microgravity is a pressing problem that severely affects the reliability of launching spacecraft. After reaching low Earth orbit, the propellant in a multistage rocket experiences large and cyclic changes in temperature as a result of solar heating. Tank wall heating can induce thermal stratification and propellant boiloff, particularly during slosh-inducing vehicle maneuvers. Precise understanding of the dynamic and thermodynamic effects of propellant slosh caused by these maneuvers is critical to mission performance and success. Computational fluid dynamics (CFD) analysis is used extensively within the space vehicle industry in an attempt to characterize the behavior of liquids in microgravity, yet experimental data to quantify these predictions is very limited and reduces confidence in the analytical predictions. A novel approach designed to produce high-fidelity data for correlation to CFD model predictions is being developed with the assistance of Florida Institute of Technology (FIT) and Sierra Lobo, Inc. With few exceptions, previous work in slosh dynamics was theoretical or treated the mass of fuel as a variable of inertia only; such models did not consider the viscosity, surface tension, or other important fluid effects. The challenges in this research are in the development of instrumentation able to measure the required parameters, the computational ability to quantify the fluid behaviors, and the means to assess both the measurements and predictions. The design of this experiment bridges the understanding of slosh dynamics in microgravity by a comprehensive approach that combines CFD tools, dynamic simulation tools, semianalytical models of the predominant fluid effects, and an experimental framework that includes measurement and characterization of liquid slosh in one-degree-of-freedom (DOF) and two-DOF experiments, and ultimately experiments in a NASA low-gravity aircraft.

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NASA NTRS1992

Development of a CFD code for internal flows in liquid fueled engines

To support the design efforts of engines in which liquid propellants are used, one is often required to analyze incompressible, two-dimensional or axisymmetric flows within ducts and cavities with rotating walls and complicated geometries. The steady-state solution is of interest in most cases. This code is intended to provide a tool for efficient computational fluid dynamics (CFD) analysis of such flow problems, taking advantage of the artificial compressibility concept and the Beam-Warming numerical scheme modified for second order accurate, implicit boundary conditions. These concepts ensure a stable, robust, and accurate algorithm due to the reduced speed of sound and the accuracy of the boundary conditions. The code is dedicated only to two-dimensional or axisymmetric flows with or without swirl. Three-dimensional computation is excluded to increase efficiency and speed. This paper briefly presents the theory of the code, as well as several benchmark applications with comparison to well known analytical solutions. In all these test cases, the code produced accurate results.

Dakhoul, Youssef↗

NASA NTRS1984

Development of an advanced pitch active control system for a wide body jet aircraft

An advanced PACS control law was developed for a commercial wide-body transport (Lockheed L-1011) by using modern control theory. Validity of the control law was demonstrated by piloted flight simulation tests on the NASA Langley visual motion simulator. The PACS design objective was to develop a PACS that would provide good flying qualities to negative 10 percent static stability margins that were equivalent to those of the baseline aircraft at a 15 percent static stability margin which is normal for the L-1011. Also, the PACS was to compensate for high-Mach/high-g instabilities that degrade flying qualities during upset recoveries and maneuvers. The piloted flight simulation tests showed that the PACS met the design objectives. The simulation demonstrated good flying qualities to negative 20 percent static stability margins for hold, cruise and high-speed flight conditions. Analysis and wind tunnel tests performed on other Lockheed programs indicate that the PACS could be used on an advanced transport configuration to provide a 4 percent fuel savings which results from reduced trim drag by flying at negative static stability margins.

Guinn, Wiley A.↗

NASA NTRS1987

Ground tests confirm the promise of hypersonic propulsion

The feasibility of developing a hypersonic hydrogen-fueled airbreathing vehicle capable of Mach 8 is examined. A modular dual-mode scramjet concept integrated with the airframe has been proposed. The research involved in the formation of this design is discussed. Particular attention is given to studies concerned with airframe integration; the evaluation of hypersonic inlets; and the analysis of viscous phenomena. The injector and combustor configurations of the modular engine, which is designed to operate as a ramjet and scramjet, are analyzed. The engine thrust performance of subscale engine modules was tested, and positive results were obtained. Simulation testing of a full-size model is being planned.

Anderson, Griffin Y.↗

NASA NTRS1993

Computation of incompressible viscous flows through turbopump components

Flow through pump components, such as an inducer and an impeller, is efficiently simulated by solving the incompressible Navier-Stokes equations. The solution method is based on the pseudocompressibility approach and uses an implicit-upwind differencing scheme together with the Gauss-Seidel line relaxation method. the equations are solved in steadily rotating reference frames and the centrifugal force and the Coriolis force are added to the equation of motion. Current computations use a one-equation Baldwin-Barth turbulence model which is derived from a simplified form of the standard k-epsilon model equations. The resulting computer code is applied to the flow analysis inside a generic rocket engine pump inducer, a fuel pump impeller, and SSME high pressure fuel turbopump impeller. Numerical results of inducer flow are compared with experimental measurements. In the fuel pump impeller, the effect of downstream boundary conditions is investigated. Flow analyses at 80 percent, 100 percent, and 120 percent of design conditions are presented.

Kiris, Cetin↗

NASA NTRS2001

One-Dimensional Spontaneous Raman Measurements Made in a Gas Turbine Combustor

The NASA Glenn Research Center and the aerospace industry are designing and testing low-emission combustor concepts to build the next generation of cleaner, more fuel efficient aircraft powerplants. These combustors will operate at much higher inlet temperatures and at pressures that are up to 3 to 5 times greater than combustors in the current fleet. From a test and analysis viewpoint, there is an increasing need for measurements from these combustors that are nonintrusive, simultaneous, multipoint, and more quantitative. Glenn researchers have developed several unique test facilities (refs. 1 and 2) that allow, for the first time, optical interrogation of combustor flow fields, including subcomponent performance, at pressures ranging from 1 to 60 bar (1 to 60 atm). Experiments conducted at Glenn are the first application of a visible laser-pumped, one-dimensional, spontaneous Raman-scattering technique to analyze the flow in a high-pressure, advanced-concept fuel injector at pressures thus far reaching 12 bar (12 atm). This technique offers a complementary method to the existing two- and three-dimensional imaging methods used, such as planar laser-induced fluorescence. Raman measurements benefit from the fact that the signal from each species is a linear function of its density, and the relative densities of all major species can be acquired simultaneously with good precision. The Raman method has the added potential to calibrate multidimensional measurements by providing an independent measurement of species number-densities at known points within the planar laser-induced fluorescence images. The visible Raman method is similar to an ultraviolet-Raman technique first tried in the same test facility (ref. 3). However, the visible method did not suffer from the ultraviolet technique's fuel-born polycyclic aromatic hydrocarbon fluorescence interferences.

DeGroot, Wilhelmus A.↗

NASA NTRS2006

Trade Studies of Space Launch Architectures using Modular Probabilistic Risk Analysis

A top-down risk assessment in the early phases of space exploration architecture development can provide understanding and intuition of the potential risks associated with new designs and technologies. In this approach, risk analysts draw from their past experience and the heritage of similar existing systems as a source for reliability data. This top-down approach captures the complex interactions of the risk driving parts of the integrated system without requiring detailed knowledge of the parts themselves, which is often unavailable in the early design stages. Traditional probabilistic risk analysis (PRA) technologies, however, suffer several drawbacks that limit their timely application to complex technology development programs. The most restrictive of these is a dependence on static planning scenarios, expressed through fault and event trees. Fault trees incorporating comprehensive mission scenarios are routinely constructed for complex space systems, and several commercial software products are available for evaluating fault statistics. These static representations cannot capture the dynamic behavior of system failures without substantial modification of the initial tree. Consequently, the development of dynamic models using fault tree analysis has been an active area of research in recent years. This paper discusses the implementation and demonstration of dynamic, modular scenario modeling for integration of subsystem fault evaluation modules using the Space Architecture Failure Evaluation (SAFE) tool. SAFE is a C++ code that was originally developed to support NASA s Space Launch Initiative. It provides a flexible framework for system architecture definition and trade studies. SAFE supports extensible modeling of dynamic, time-dependent risk drivers of the system and functions at the level of fidelity for which design and failure data exists. The approach is scalable, allowing inclusion of additional information as detailed data becomes available. The tool performs a Monte Carlo analysis to provide statistical estimates. Example results of an architecture system reliability study are summarized for an exploration system concept using heritage data from liquid-fueled expendable Saturn V/Apollo launch vehicles.

Mathias, Donovan L.↗

NASA NTRS2018

CFD Predictions of N+3 Cycle Emissions for a Three-Cup Gas-Turbine Combustor

The National Combustion Code (OpenNCC) was used to perform non-reacting and two-phase reacting flow computations for a unique pre-filming type LDI-3 fuel injector for a three-cup, nineteen-element flametube configuration. All computations were performed with a consistent approach of mesh-generation, spray modeling, reduced finite-rate kinetics and turbulence-chemistry interaction, as developed for CFD analysis of single-element and multi-element LDI-3 designs with OpenNCC. Emissions and flowfield characteristics were predicted for a generic NASA N+3 engine cycle, with particular focus on the 7% and 30% ICAO power operating conditions. For both the conditions studied, the CFD analysis provided very good predictions for EINOx when compared with experimental data measured at NASA Glenn Research Center.

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