Operational and Mission Highlights :A Monthly Summary of Top Achievements, June 2022
Highlights are given in the following areas: Nuclear Security, Science, Technology and Engineering, Mission Operations, and, Community Relations.
42 ENGINEERING↗
SEARCH · Engineering Papers
Results for “engine operability”
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.
Operational and Mission Highlights: A Monthly Summary of Top Achievements
This Los Alamos National Laboratory newsletter provides highlights in the areas of nuclear security; science technology and engineering; mission operations; and community relations.
42 ENGINEERING↗
Apparatus for sensor failure detection and correction in a gas turbine engine control system
A gas turbine engine control system maintains a selected level of engine performance despite the failure or abnormal operation of one or more engine parameter sensors. The control system employs a continuously updated engine model which simulates engine performance and generates signals representing real time estimates of the engine parameter sensor signals. The estimate signals are transmitted to a control computational unit which utilizes them in lieu of the actual engine parameter sensor signals to control the operation of the engine. The estimate signals are also compared with the corresponding actual engine parameter sensor signals and the resulting difference signals are utilized to update the engine model. If a particular difference signal exceeds specific tolerance limits, the difference signal is inhibited from updating the model and a sensor failure indication is provided to the engine operator.
Spang, H. A., III↗
Operational and Mission Highlights. A Monthly Summary of Top Achievements, February 2021
The newsletter highlights achievements in the following areas: Nuclear Security; Science, Technology and Engineering; Mission operations; and Community Relations.
42 ENGINEERING↗
Advanced oxygen-hydrocarbon rocket engine study
A consistent engine system data base was generated for defining advantages and disadvantages, system performance and operating limits, engine parametric data, and technology requirements for candidate high pressure LO2/HC engine systems. Optimum LO2/HC engine power cycles were synthetized and representative conceptual engine design generated for a specified advanced surface to orbit transportation system.
Obrien, C. J.↗
Advanced oxygen-hydrocarbon Earth-to-orbit propulsion
Liquid oxygen/hydrocarbon (LO2/HC) rocket engine cycles for a surface to orbit transportation system were evaluated. A consistent engine system data base is established for defining advantages and disadvantages, system performance and operating limits, engine parametric data, and technology requirements for candidate engine systems. Preliminary comparisons of the engine cycles utilizing delivered specific impulse values are presented. Methane and propane staged combustion cycles are the highest LO2/HC performers. The hydrogen cooled LO2/methane dual throat engine was found to be the highest performing. Technology needs identified in the study include: high temperature turbines; oxidizer-rich preburners; LO2, methane, and propane cooling; methane and propane fuel-rich preburners; the HC fuel turbopump; and application of advanced composite materials to the engine system. Parametric sensitivity analysis data are displayed which show the effect of variations in engine thrust, mixture ratio, chamber pressure, area ratio, cycle life, and turbine inlet temperature on specific impulse and engine weight.
Obrien, C. J.↗
Recent tests on the Carter small reciprocating steam engines
The Jay Carter Enterprises (JCE) Paratransit Vehicle steam engine was tested over a range of conditions which might be experienced by the power converter subsystem of the Small Community Solar Thermal Power Experiment. Some difficulties were encountered getting the engine ready for testing. These difficulties were related to the five year dormancy of the entire system and to incomplete development work that had been going on at the time of cessation of steam engine work at JCE. Other difficulties were related to the fact that the particular expander being tested never ran before and possessed some manufacturing defects. Nevertheless, the engine was operated successfully and results of testing do verify results of computer simulations of the engine in regard to the effect of temperature and power level variations. Engine efficiency was good but generally lower than expected and performance dropped as testing continued. The effect of change in expansion ratio was not demonstrated because of deterioration in engine performance. Post-test inspection revealed numerous correctable defects.
Kiceniuk, T.↗
Effect of standing transverse acoustic oscillations on fuel-oxidant mixing in cylindrical combustion chambers
Vapor fuel-oxidant mixing is analyzed for standing transverse acoustic fields simulating those existing in screeching or screaming combustors. The additional mixing due to the acoustic field is shown to be a function of sound pressure and frequency, stream velocity, and turbulence. The effects of these parameters are shown graphically for a realistic range of combustor conditions. The fuel-oxidant ratio at various combustor stations is shown to have a cyclic fluctuation which is in phase with the pressure fluctuations. Possible mechanisms contributing to screech and scream are discussed.
TURBINES, GAS - AFTER-BURNING↗
Analytical and Experimental Studies of a Divided-flow Ram-jet Combustor
Results of a theoretical and experimental study of the total pressure losses and combustion efficiencies associated with the divided-flow combustor are presented and comparisons made with the nondivided-flow combustor. The theoretical treatment indicated the range of primary-zone size, primary-zone air flow, and flame-holder pressure-loss coefficients over which the total-pressure loss through the divided-flow combustor was less than that through the nondivided-flow combustor. The experimental work indicated the range of fuel-air ratios, for a given size primary zone, over which the combustion efficiency in the divided-flow combustor was higher than that in the nondivided-flow combustor.
COMBUSTION - EFFECT OF ENGINE OPERATING CONDITIONS↗
Starting characteristics and combustion performance of magnesium slurry in 6.5-inch-diameter ram-jet engine mounted in connected-pipe facility
The starting characteristics and combustion performance of slurry type fuels, consisting of 50 percent magnesium powder in a hydrocarbon carrier, have been investigated in a flight-type, 6.5-inch-diameter ram-jet engine in a connected-pipe facility. Quick, dependable starting of the engine was obtained by the use of a disk which blocked part of the combustor area downstream of the flame holder. Acceptable performance was achieved with a short fuel-air mixing length by the development of a fuel-distribution control sleeve.
COMBUSTION - RAM-JET ENGINES↗
A study of the durability of beryllium rocket engines
An experimental test program was performed to demonstrate the durability of a beryllium INTEREGEN rocket engine when operating under conditions simulating the space shuttle reaction control system. A vibration simulator was exposed to the equivalent of 100 missions of X, Y, and Z axes random vibration to demonstrate the integrity of the recently developed injector-to-chamber braze joint. An off-limits engine was hot fired under extreme conditions of mixture ratio, chamber pressure, and orifice plugging. A durability engine was exposed to six environmental cycles interspersed with hot-fire tests without intermediate cleaning, service, or maintenance. Results from this program indicate the ability of the beryllium INTEREGEN engine concept to meet the operational requirements of the space shuttle reaction control system.
Paster, R. D.↗
Operational and Mission Highlights. A Monthly Summary of Top Achievements August 2021
Monthly newsletter highlights for areas including Nuclear Security, Science, Technology, and Engineering, Mission Operations and Community Relations. Information for selected media coverage is also included.
42 ENGINEERING↗
The effect of insulated combustion chamber surfaces on direct-injected diesel engine performance, emissions, and combustion
The combustion chamber of a single-cylinder, direct-injected diesel engine was insulated with ceramic coatings to determine the effect of low heat rejection (LHR) operation on engine performance, emissions, and combustion. In comparison to the baseline cooled engine, the LHR engine had lower thermal efficiency, with higher smoke, particulate, and full load carbon monoxide emissions. The unburned hydrocarbon emissions were reduced across the load range. The nitrous oxide emissions increased at some part-load conditions and were reduced slightly at full loads. The poor LHR engine performance was attributed to degraded combustion characterized by less premixed burning, lower heat release rates, and longer combustion duration compared to the baseline cooled engine.
Dickey, Daniel W.↗
An advanced intelligent control system framework
A reusable rocket-engine intelligent control system (RREICS) framework was developed to a define a control framework for rocket-engine systems that reduces the required engine maintenance, extends the useful operating life, and maximizes the probability of mission success. The RREICS framework defines a controller that handles a rocket engine cluster as a single system rather than as a collection of individual engines. This enables the controller to alter individual engine operations in response to engine performance or integrity degradations while maintaining the propulsion subsystem external parameters at the levels required for mission success. A simplified model of a three engine cluster and the associated propulsion subsystem controller is also described.
Nemeth, ED↗
Orbit transfer vehicle engine study. Phase A: Continuation (study results)
Studies included: selection of boost pump designs for low NPSH operation and generation of associated programmatic data; evaluation of OTV engine operation at intermediate thrust levels and impact on programmatics; and assessments of OTV engine operation at idle-mode thrusts under conditions experienced during aerobraking maneuvers of the ABOTV. As a result of the studies, it was recommended that the original OTV boost pump designs be used without change for low NPSH operation. Intermediate thrust operation is feasible for both the expander cycle and staged combustion cycles.
Source record↗
ERBS fuel addendum: Pollution reduction technology program small jet aircraft engines, phase 3
A Model TFE731-2 engine with a low emission, variable geometry combustion system was tested to compare the effects of operating the engine on Commercial Jet-A aviation turbine fuel and experimental referee broad specification (ERBS) fuels. Low power emission levels were essentially identical while the high power NOx emission indexes were approximately 15% lower with the EBRS fuel. The exhaust smoke number was approximately 50% higher with ERBS at the takeoff thrust setting; however, both values were still below the EPA limit of 40 for the Model TFE731 engine. Primary zone liner wall temperature ran an average of 25 K higher with ERBS fuel than with Jet-A. The possible adoption of broadened proprties fuels for gas turbine applications is suggested.
Bruce, T. W.↗
High-Temperature Solid Lubricants Developed by NASA Lewis Offer Virtually "Unlimited Life" for Oil-Free Turbomachinery
The NASA Lewis Research Center is capitalizing on breakthroughs in foil air bearing performance, tribological coatings, and computer analyses to formulate the Oil-free Turbomachinery Program. The program s long-term goal is to develop an innovative, yet practical, oil-free aeropropulsion gas turbine engine that floats on advanced air bearings. This type of engine would operate at higher speeds and temperatures with lower weight and friction than conventional oil-lubricated engines. During startup and shutdown, solid lubricant coatings are required to prevent wear in such engines before the self-generating air-lubrication film develops. NASA s Tribology Branch has created PS304, a chrome-oxide-based plasma spray coating specifically tailored for shafts run against foil bearings. PS304 contains silver and barium fluoride/calcium fluoride eutectic (BaF2/CaF2) lubricant additives that, together, provide lubrication from cold start temperatures to over 650 C, the maximum use temperature for foil bearings. Recent lab tests show that bearings lubricated with PS304 survive over 100 000 start-stop cycles without experiencing any degradation in performance due to wear. The accompanying photograph shows a test bearing after it was run at 650 C. The rubbing process created a "polished" surface that enhances bearing load capacity.
DellaCorte, Christopher↗
Training Artemis Astronauts to Explore the Moon
To prepare for human exploration of the Moon in the mid-2020s, NASA is developing a program to provide geoscience and planetary science classroom training and geologic eld training to astronauts and other mission personnel. The Artemis geoscience training plan builds on a long legacy: NASA has trained astronauts in geology, planetary science, and geological eld work for more than 50 years. From ~1965-1972, the geology focus for astronauts included orbital Earth observations during the early NASA missions, but the endgame was preparation for the Apollo missions to the Lunar surface [see Phinney (2015), NASA-SP-2015-626; Lofgren et al.(2011);Schmitt, et al. (2011); and El Baz (2011), all from GSA SP483]. From the mid 1970s through2017, the primary purpose for geoscience training was to prepare astronauts to observe theEarth and document a wide variety of Earth processes from orbital platforms (Skylab, SpaceShuttle and International Space Station). Astronaut observations of Earth from the InternationalSpace Station remain an important activity today, but the prospect of exploration of the lunar surface through the Artemis Program lends additional purpose to the geoscience content and eld experiences that we provide the astronauts. We recently completed the geology and eld training with Astronaut Class 22 and are now planning both focused eld exercises and simulations for future Artemis crews, as well as the accompanying classroom lessons on lunar and planetary sciences. The training we offer extends beyond the astronaut office – we partner across operational and engineering organizations at NASA and provide eld work exercises and opportunities to personnel in the Flight Operations Directorate (responsible for the overall training and certification), as well as the exploration Extravehicular Activity Oce (developing spacewalk suits and tools). These partnerships contribute to building a common language and sense of purpose, and also help to ensure that NASA’s geoscience training and science operations are fully integrated with the teams and systems responsible for getting the next generation of astronauts to the surface of the Moon.
Artemis↗