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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1968

Fluid thrust control system

A pure fluid thrust control system is described for a pump-fed, regeneratively cooled liquid propellant rocket engine. A proportional fluid amplifier and a bistable fluid amplifier control overshoot in the starting of the engine and take it to a predetermined thrust. An ejector type pump is provided in the line between the liquid hydrogen rocket nozzle heat exchanger and the turbine driving the fuel pump to aid in bringing the fluid at this point back into the regular system when it is not bypassed. The thrust control system is intended to function in environments too severe for mechanical controls.

Howell, W. L.↗
NASA NTRS1979

Performance deterioration based on in-service engine data: JT9D jet engine diagnostics program

Results of analyses of engine performance deterioration trends and levels with respect to service usage are presented. Thirty-two JT9D-7A engines were selected for this purpose. The selection of this engine fleet provided the opportunity of obtaining engine performance data starting before the first flight through initial service such that the trend and levels of engine deterioration related to both short and long term deterioration could be more carefully defined. The performance data collected and analyzed included in-flight, on wing (ground), and test stand prerepair and postrepair performance calibrations with expanded instrumentation where feasible. The results of the analyses of these data were used to: (1) close gaps in previously obtained historical data as well as augment the historical data with more carefully obtained data; (2) refine preliminary models of performance deterioration with respect to usage; (3) establish an understanding of the relationships between ground and altitude performance deterioration trends; (4) refine preliminary recommendations concerning means to reduce and control deterioration; and (5) identify areas where additional effort is required to develop an understanding of complex deterioration issues.

Sallee, G. P.↗
NASA NTRS2007

Environmental Testing of the NEXT PM1R Ion Engine

The NEXT propulsion system is an advanced ion propulsion system presently under development that is oriented towards robotic exploration of the solar system using solar electric power. The subsystem includes an ion engine, power processing unit, feed system components, and thruster gimbal. The Prototype Model engine PM1 was subjected to qualification-level environmental testing in 2006 to demonstrate compatibility with environments representative of anticipated mission requirements. Although the testing was largely successful, several issues were identified including the fragmentation of potting cement on the discharge and neutralizer cathode heater terminations during vibration which led to abbreviated thermal testing, and generation of particulate contamination from manufacturing processes and engine materials. The engine was reworked to address most of these findings, renamed PM1R, and the environmental test sequence was repeated. Thruster functional testing was performed before and after the vibration and thermal-vacuum tests. Random vibration testing, conducted with the thruster mated to the breadboard gimbal, was executed at 10.0 Grms for 2 min in each of three axes. Thermal-vacuum testing included three thermal cycles from 120 to 215 C with hot engine re-starts. Thruster performance was nominal throughout the test program, with minor variations in a few engine operating parameters likely caused by facility effects. There were no significant changes in engine performance as characterized by engine operating parameters, ion optics performance measurements, and beam current density measurements, indicating no significant changes to the hardware as a result of the environmental testing. The NEXT PM1R engine and the breadboard gimbal were found to be well-designed against environmental requirements based on the results reported herein. The redesigned cathode heater terminations successfully survived the vibration environments. Based on the results of this test program and confidence in the engineering solutions available for the remaining findings of the first test program, specifically the particulate contamination, the hardware environmental qualification program can proceed with confidence

Snyder, John S.↗
NASA NTRS2017

Survey of Constellation-Era LOX/Methane Development Activities and Future Development Needs

NASA formed the Constellation Program in 2005 to achieve the objectives of maintaining American presence in low-Earth orbit, returning to the moon for purposes of establishing an outpost, and laying the foundation to explore Mars and beyond in the first half of the 21st century. The Exploration Technology Development Program (ETDP) was formulated to address the technology needs to address Constellation architecture decisions. The Propellants and Cryogenic Advanced Development (PCAD) project was tasked with risk mitigation of specific propulsion related technologies to support ETDP. Propulsion systems were identified as critical technologies owing to the high gear-ratio of lunar Mars landers Cryogenic propellants offer performance advantage over storables (NTOMMH) Mass savings translate to greater payload capacity In-situ production of propellant an attractive feature; methane and oxygen identified as possible Martian in-situ propellants New technologies were required to meet more difficult missions High performance LOX/LH2 deep throttle descent engines High performance LOX/LCH4 ascent main and reaction control system (RCS) engines The PCAD project sought to provide those technologies through Reliable ignition pulse RCS Fast start High efficiency engines Stable deep throttling.

Propulsion system components↗
NASA NTRS1973

Motor starting a Brayton cycle power conversion system using a static inverter

The power conversion module of a 2- to 15-kWe Brayton engine was motor started using a three-phase, 400-hertz static inverter as the power source. Motor-static tests were conducted for initial gas loop pressures of 10, 14, and 17 N/sq cm (15, 20, and 25 psia) over a range of initial turbine inlet temperatures from 366 to 550 K (200 to 530 F). The data are presented to show the effects of temperature and pressure on the motor-start characteristics of the rotating unit. Electrical characteristics during motoring are also discussed.

Curreri, J. S.↗
NASA NTRS1984

Optimization applications in aircraft engine design and test

Starting with the NASA-sponsored STAEBL program, optimization methods based primarily upon the versatile program COPES/CONMIN were introduced over the past few years to a broad spectrum of engineering problems in structural optimization, engine design, engine test, and more recently, manufacturing processes. By automating design and testing processes, many repetitive and costly trade-off studies have been replaced by optimization procedures. Rather than taking engineers and designers out of the loop, optimization has, in fact, put them more in control by providing sophisticated search techniques. The ultimate decision whether to accept or reject an optimal feasible design still rests with the analyst. Feedback obtained from this decision process has been invaluable since it can be incorporated into the optimization procedure to make it more intelligent. On several occasions, optimization procedures have produced novel designs, such as the nonsymmetric placement of rotor case stiffener rings, not anticipated by engineering designers. In another case, a particularly difficult resonance contraint could not be satisfied using hand iterations for a compressor blade, when the STAEBL program was applied to the problem, a feasible solution was obtained in just two iterations.

Pratt, T. K.↗
NASA NTRS1965

Nasa research on the aerodynamics of jet vtol engine installations

This paper summarizes some of the more pertinent results of NASA investigations related to the aerodynamics of jet VTOL engine installations. It shows that there is a base loss in hovering due to suction forces creased on the underside of the fuselage by the entrainment of ambient air in the slipstream, and that the magnitude of this effect is related to the turbulence in the jet stream and its consequent rate of mixing with ambient air. It also shows that there are large lift losses and pitching moments due to jet-free-stream interference and that these characteristics can be significantly altered by proximity to the ground. And, finally, it shows that simple bellmouth inlets give good pressure recovery and low distortion for vertically mounted lift engines if the inlet lip radius is sufficiently large, but that such inlets are not suitable for windmill starting of the engines.

VTOL AIRCRAFT↗
NASA NTRS2009

Graphical User Interface for Simulink Integrated Performance Analysis Model

The J-2X Engine (built by Pratt & Whitney Rocketdyne,) in the Upper Stage of the Ares I Crew Launch Vehicle, will only start within a certain range of temperature and pressure for Liquid Hydrogen and Liquid Oxygen propellants. The purpose of the Simulink Integrated Performance Analysis Model is to verify that in all reasonable conditions the temperature and pressure of the propellants are within the required J-2X engine start boxes. In order to run the simulation, test variables must be entered at all reasonable values of parameters such as heat leak and mass flow rate. To make this testing process as efficient as possible in order to save the maximum amount of time and money, and to show that the J-2X engine will start when it is required to do so, a graphical user interface (GUI) was created to allow the input of values to be used as parameters in the Simulink Model, without opening or altering the contents of the model. The GUI must allow for test data to come from Microsoft Excel files, allow those values to be edited before testing, place those values into the Simulink Model, and get the output from the Simulink Model. The GUI was built using MATLAB, and will run the Simulink simulation when the Simulate option is activated. After running the simulation, the GUI will construct a new Microsoft Excel file, as well as a MATLAB matrix file, using the output values for each test of the simulation so that they may graphed and compared to other values.

Durham, R. Caitlyn↗
NASA NTRS2014

Combustion Stability Characteristics of the Project Morpheus Liquid Oxygen / Liquid Methane Main Engine

The project Morpheus liquid oxygen (LOX) / liquid methane (LCH4) main engine is a Johnson Space Center (JSC) designed ~5,000 lbf-thrust, 4:1 throttling, pressure-fed cryogenic engine using an impinging element injector design. The engine met or exceeded all performance requirements without experiencing any in- ight failures, but the engine exhibited acoustic-coupled combustion instabilities during sea-level ground-based testing. First tangential (1T), rst radial (1R), 1T1R, and higher order modes were triggered by conditions during the Morpheus vehicle derived low chamber pressure startup sequence. The instability was never observed to initiate during mainstage, even at low power levels. Ground-interaction acoustics aggravated the instability in vehicle tests. Analysis of more than 200 hot re tests on the Morpheus vehicle and Stennis Space Center (SSC) test stand showed a relationship between ignition stability and injector/chamber pressure. The instability had the distinct characteristic of initiating at high relative injection pressure drop at low chamber pressure during the start sequence. Data analysis suggests that the two-phase density during engine start results in a high injection velocity, possibly triggering the instabilities predicted by the Hewitt stability curves. Engine ignition instability was successfully mitigated via a higher-chamber pressure start sequence (e.g., ~50% power level vs ~30%) and operational propellant start temperature limits that maintained \cold LOX" and \warm methane" at the engine inlet. The main engine successfully demonstrated 4:1 throttling without chugging during mainstage, but chug instabilities were observed during some engine shutdown sequences at low injector pressure drop, especially during vehicle landing.

Melcher, John C.↗
NASA NTRS2002

An Investigation of Applications for Thermodynamic Work Potential Methods: Working Tables and Charts for Estimation of Thermodynamic Work Potential in Equilibrium Mixtures of Jet-A and Air

The objective of this report is to provide a tool to facilitate the application of thermodynamic work potential methods to aircraft and engine analysis. This starts with a discussion of the theoretical background underlying these methods, which is then used to derive various equations useful for thermodynamic analysis of aircraft engines. The work potential analysis method is implemented in the form of a set of working charts and tables that can be used to graphically evaluate work potential stored in high-enthalpy gas. The range of validity for these tables is 300 to 36,000 R, pressures between between 0.01 atm and 100 atm, and fuel-air ratios from zero to stoichiometric. The derivations and charts assume mixtures of Jet-A and air as the working fluid. The thermodynamic properties presented in these charts were calculated based upon standard thermodynamic curve fits.

Mavris, Dimitri↗
NASA NTRS2003

Operational Issues in the Development of a Cost-Effective Reusable LOX/LH2 Engine

The NASA Space Launch Initiative (SLI) was initiated in early 2001 to conduct technology development and to reduce the business and technical risk associated with developing the next-generation reusable launch system. In the field of main propulsion, two LOXLH2 rocket engine systems, the Pratt & Whitney / Aerojet Joint Venture (JV) COBRA and the Rocketdyne RS-83, were funded to develop a safe, economical, and reusable propulsion system. Given that a large-thrust reusable rocket engine program had not been started in the U.S. since 1971, with the Space Shuttle Main Engine (SSME), this provided an opportunity to build on the experience developed on the SSME system, while exploiting advances in technology that had occurred in the intervening 30 years. One facet of engine development that was identified as being especially vital in order to produce an optimal system was in the areas of operability and maintainability. In order to achieve the high levels of performance required by the Space Shuttle, the SSME system is highly complex with very tight tolerances and detailed requirements. Over the lifetime of the SSME program, the engine has required a high level of manpower to support the performance of inspections, maintenance (scheduled and unscheduled) and operations (prelaunch and post-flight). As a consequence, the labor- intensive needs of the SSME provide a significant impact to the overall cost efficiency of the Space Transportation System (STS). One of the strategic goals of the SLI is to reduce cost by requiring the engine(s) to be easier (Le. less expensive) to operate and maintain. The most effective means of accomplishing this goal is to infuse the operability and maintainability features into the engine design from the start. This paper discusses some of the operational issues relevant to a reusable LOx/LH2 main engine, and the means by which their impact is mitigated in the design phase.

Ballard, Richard O.↗
NASA NTRS1986

Combustion engine system

A flow through catalytic reactor which selectively catalytically decomposes methanol into a soot free hydrogen rich product gas utilizing engine exhaust at temperatures of 200 to 650 C to provide the heat for vaporizing and decomposing the methanol is described. The reactor is combined with either a spark ignited or compression ignited internal combustion engine or a gas turbine to provide a combustion engine system. The system may be fueled entirely by the hydrogen rich gas produced in the methanol decomposition reactor or the system may be operated on mixed fuels for transient power gain and for cold start of the engine system. The reactor includes a decomposition zone formed by a plurality of elongated cylinders which contain a body of vapor permeable, methanol decomposition catalyst preferably a shift catalyst such as copper-zinc.

Houseman, John↗
NASA NTRS1991

Definition, technology readiness, and development cost of the orbit transfer vehicle engine integrated control and health monitoring system elements

An Integrated Control and Health Monitoring (ICHM) system was conceived for use on a 20 Klb thrust baseline Orbit Transfer Vehicle (OTV) engine. Considered for space used, the ICHM was defined for reusability requirements for an OTV engine service free life of 20 missions, with 100 starts and a total engine operational time of 4 hours. Functions were derived by flowing down requirements from NASA guidelines, previous OTV engine or ICHM documents, and related contracts. The elements of an ICHM were identified and listed, and these elements were described in sufficient detail to allow estimation of their technology readiness levels. These elements were assessed in terms of technology readiness level, and supporting rationale for these assessments presented. The remaining cost for development of a minimal ICHM system to technology readiness level 6 was estimated. The estimates are within an accuracy range of minus/plus 20 percent. The cost estimates cover what is needed to prepare an ICHM system for use on a focussed testbed for an expander cycle engine, excluding support to the actual test firings.

Cannon, I.↗
NASA NTRS2016

Hexapod Robot

The project I am working on at NASA-Johnson Space Center in Houston, TX is a hexapod robot. This project was started by various engineers at the Trick Lab. The goal of this project is to have the hexapod track a yellow ball or possibly another object from left to right and up/down. The purpose is to have it track an object like a real creature. The project will consist of using software and hardware. This project started with a hexapod robot which uses a senor bar to track a yellow ball but with a limited field of vision. The sensor bar acts as the robots "head." Two servos will be added to the hexapod to create flexion and extension of the head. The neck and head servos will have to be programmed to be added to the original memory map of the existing servos. I will be using preexisting code. The main programming language that will be used to add to the preexisting code is C++. The trick modeling and simulation software will also be used in the process to improve its tracking and movement. This project will use a trial and error approach, basically seeing what works and what does not. The first step is to initially understand how the hexapod works. To get a general understanding of how the hexapod maneuvers and plan on how to had a neck and head servo which works with the rest of the body. The second step would be configuring the head and neck servos with the leg servos. During this step, limits will be programmed specifically for the each servo. By doing this, the servo is limited to how far it can rotate both clockwise and counterclockwise and this is to prevent hardware damage. The hexapod will have two modes in which it works in. The first mode will be if the sensor bar does not detect an object. If the object it is programmed to look for is not in its view it will automatically scan from left to right 3 times then up and down once. The second mode will be if the sensor bar does detect the object. In this mode the hexapod will track the object from left to right or up and down. The hexapod will eventually be able to track the object moving its head and body in sync with on another and being able to rotate its body at 360 degrees. This is the plans and possible end results for the hexapod robot I will be working on during my summer internship at NASA Johnson Space Center. Since working on the hexapod project I have gained an increase interest in robotics. I enjoy the process of critical thinking. Also will working on this project I was challenged in a way that made more passionate to strive even more to become an engineer. I've learned that asking questions is an important part of the learning process. Also I learn that much more is accomplished when teamwork is applied.

Begody, Ericka↗
NASA NTRS2011

Spin Start Line Effects on the J2X Gas Generator Chamber Acoustics

The J2X Gas Generator engine design has a spin start line connected near to the turbine inlet vanes. This line provides helium during engine startup to begin turbomachinery operation. The spin start line also acts as an acoustic side branch which alters the chamber's acoustic modes. The side branch effectively creates 'split modes' in the chamber longitudinal modes, in particular below the first longitudinal mode and within the frequency range associated with the injection-coupled response of the Gas Generator. Interaction between the spin start-modified chamber acoustics and the injection-driven response can create a higher system response than without the spin start attached to the chamber. This work reviews the acoustic effects of the spin start line as seen throughout the workhorse gas generator test program. A simple impedance model of the spin start line is reviewed. Tests were run with no initial spin start gas existing in the line, as well as being initially filled with nitrogen gas. Tests were also run with varying spin start line lengths from 0" to 40". Acoustic impedance changes due to different spin start gas constituents and line lengths are shown. Collected thermocouple and static pressure data in the spin start line was used to help estimate the fluid properties along the line length. The side branch impedance model was coupled to a chamber impedance model to show the effects on the overall chamber response. Predictions of the spin start acoustic behavior for helium operation are shown and compared against available data.

Kenny, R. Jeremy↗