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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.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1959

Performance of Two Boron-Modified S-816 Alloys in a Turbojet Engine Operated at 1650 F

S-816+B and modified S-816+B cast cobalt-base alloys were evaluated as turbine-bucket materials at 16500 F. Stress-rupture and tensile data obtained from these alloys had indicated satisfactory strength for engine operation at 1650 F. Although both alloys exhibited a limited ductility in room-temperature laboratory impact tests, there was a significant increase in impact resistance in the 1650 F tests. Bucket failures began after 10 hours of engine testing and continued at various intervals during the 107.5-hour test. Bucket lives were short relative to the predicted lives based on stress-rupture considerations (280 hr for S-816+B and 1750 hr for modified S-816+B). No significant difference was apparent in the performance of the two alloy groups. The primary cause of bucket failures in both alloys was mechanical fatigue. Impact damage occurred as a direct result of bucket tip fatigue failures and was a secondary cause of bucket failures. The impact of small pieces of fractured bucket tips on surrounding buckets caused a relatively large amount of impact damage to buckets of both alloys. The amount of impact damage from induced fractures at the bucket midspan, which provided relatively large failed fragments, was no greater than that which occurred as a result of tip failures.

Waters, William J.↗
NASA NTRS1969

Seismographic recording of large rocket engine operation

Recording equipment for rocket engine vibration is adaptable to determining the structural strength of building materials. This seismographic system is portable and is capable of measuring displacements in the direction of three mutually perpendicular axes.

Dalins, I.↗
NASA NTRS1956

Effect of Engine Operating Variables on Combustor-inlet Parameters

Studies of the fundamental processes of combustion are usually concerned with wide ranges of investigation of individual processes. In general, each fundamental combustion process may be studied in an environment that is most suited to its evaluation and possibly unrelated basically to any practical application. The majority of the data presented in volume I of this series concern the fundamental aspects of combustion as functions of the individual occurrence of various contributing processes. In a jet engine, however, the various fundamental combustion processes may occur simultaneously and may interact. Furthermore, the engine environment usually does not permit independent variation of single combustion parameters, since specified operating conditions impose specific values on the parameters. In volume II, data are presented to show the effect of operating conditions on the over-all combustion process in different combustion components. To show the effect of operating conditions, it is necessary to specify the range of these conditions within which combustion components may operate. Therefore, this chapter presents only the operating conditions that might be required in the primary combustors and afterburners of typical current turbojet engines. (Corresponding information on ram-jet engines is presented in ch. xisi.) This chapter is not intended to serve as an explanation of engine operation. The operating conditions of the combustion components are presented in terms of total pressures and temperatures at the primary-combustor and afterburner inlets, reference velocities and outlet total temperatures of the primary combustors, and velocities at the plane of the flameholder in the afterburners. The data are presented to relate the operating regions of typical current turbojet combustion components to flight altitudes, Mach numbers, and modes of engine operation. Specifically, data are presented for the combustion parameters of the primary combustor and afterburner of three turbojet engines having rated compressor total-pressure ratios of 5, 8, and 12 under full-throttle conditions. Operational data for the primary combustor also include part-throttle operation at 70, 80, and 90 percent of rated engine speed and windmifling operation. The range of flight conditions includes altitudes from sea level to 65,000 feet and flight Mach numbers from zero to 1.6.

Jones, A. W.↗
NASA NTRS1939

Engine Operation in Flight for Minimum Fuel Consumption

Engine and airplane performance data have been gathered from various sources and analyzed to determine indications of the most economical methods of flight operation from a consideration of fuel expenditure. The analysis includes the influence of such facts as fuel-air ratio, engine speed, engine knock, altitude, cylinder cooling, spark timing, and limits of cruising brake mean effective pressure. The results indicate that the cheapest power is obtained with approximately correct mixture at low engine speed and highest permissible manifold pressure. If more power is desired, the methods of obtaining it are, in order of fuel economy: (a) increasing the engine speed and maintaining safe cylinder temperatures by cooling; (b) retarding the spark or cooling further to permit higher manifold pressure; and, (c) riching the mixture. The analysis further shows that the maximum time endurance of flight occurs at the air speed corresponding to minimum thrust horsepower required and with minimum practicable engine speed. Maximum mileage per pound of fuel is obtained at slightly higher air speed. The fuel-air ratio should be approximately the theoretically correct ratio in both cases. For an engine equipped with a geared supercharger, as in the example presented, and with knock as the limiting condition, a comparison of operation at sea level and at 6,000 feet shoes flight at altitude to be more economical on the basis of both range and endurance.

Reuter, George↗
NASA NTRS2010

Using Web 2.0 Techniques in NASA's Ares Engineering Operations Network (AEON) Environment - First Impressions

The Mission Operations Laboratory (MOL) at Marshall Space Flight Center (MSFC) is responsible for Engineering Support capability for NASA s Ares rocket development and operations. In pursuit of this, MOL is building the Ares Engineering and Operations Network (AEON), a web-based portal to support and simplify two critical activities: Access and analyze Ares manufacturing, test, and flight performance data, with access to Shuttle data for comparison Establish and maintain collaborative communities within the Ares teams/subteams and with other projects, e.g., Space Shuttle, International Space Station (ISS). AEON seeks to provide a seamless interface to a) locally developed engineering applications and b) a Commercial-Off-The-Shelf (COTS) collaborative environment that includes Web 2.0 capabilities, e.g., blogging, wikis, and social networking. This paper discusses how Web 2.0 might be applied to the typically conservative engineering support arena, based on feedback from Integration, Verification, and Validation (IV&V) testing and on searching for their use in similar environments.

Scott, David W.↗
NASA NTRS1942

Aerodynamic Heat-Power Engine Operating on a Closed Cycle

Hot-air engines with dynamic compressors and turbines offer new prospects of success through utilization of units of high efficiencies and through the employment of modern materials of great strength at high temperature. Particular consideration is given to an aerodynamic prime mover operating on a closed circuit and heated externally. Increase of the pressure level of the circulating air permits a great increase of limit load of the unit. This also affords a possibility of regulation for which the internal efficiency of the unit changes but slightly. The effect of pressure and temperature losses is investigated. A general discussion is given of the experimental installation operating at the Escher Wyss plant in Zurich for a considerable time at high temperatures.

Ackeret, J.↗
NASA NTRS2018

Operability Engineering for the Europa Clipper Mission: Formulation Phase Results and Lessons

Operability is an important factor in both success and cost of space missions, but is difficult to quantify, and can suffer if not considered as part of early formulation and design. The Europa Clipper mission has taken a deliberate approach to infusing operability into the concepts and designs since early in the formulation phase. This paper reports on that approach to operability and the results thus far, as the Europa Clipper mission approaches its Preliminary Design Review. Definitions for operability and its various aspects are presented along with a description of the engineering and organizational approach taken to infusing operability into designs. A number of examples of operability requirements are shown, and key examples of trade studies and design decisions are described, along with influence on outcomes motivated by operability considerations. We find that support from management, empowerment of a cross-discipline Operability Working Group, consistent tracking of operability aspects over time, and broad infusion and participation in operability considerations are all significant factors in implementing operability. In particular, thoughtful and deliberate consideration of operability criteria has led to design decisions that include proper consideration of concerns related to the mission operations phase, and seem likely to provide better science results and mission outcomes.

Huh, Shin M.↗
NASA NTRS1991

Costs and benefits of lunar oxygen: Engineering, operations, and economics

Oxygen is the most commonly discussed lunar resource. It will certainly not be the easiest to retrieve, but oxygen's fundamental place in propulsion and life support guarantees it continued attention as a prime candidate for early in situ resource utilization (ISRU). The findings are reviewed of recent investigation, sponsored by NASA-Ames, into the kinds of technologies, equipment, and scenarios (the engineering and operations costs) that will be required even to initiate lunar oxygen production. The infrastructure necessary to surround and support a viable oxygen-processing operation is explained. Selected details are used to illustrate the depth of technology challenges, extent of operations burdens, and complexity of decision linkages. Basic assumptions, and resulting timelines and mass manifests, are listed. These findings are combined with state-of-the-art knowledge of lunar and Mars propulsion options in simple economic input/output and internal-rate-of-return models, to compare production costs with performance benefits. Implications for three realistic scales of exploration architecture - expeditionary, aggressive science, and industrialization/settlement - are discussed. Conclusions are reached regarding the contextual conditions within which production of lunar oxygen (LLOX) is a reasonable activity. LLOX appears less useful for Mars missions than previously hoped. Its economical use in low Earth orbit hinges on production of lunar hydrogen as well. LLOX shows promise for lunar ascent/descent use, but that depends strongly on the plant mass required.

Sherwood, Brent↗
NASA NTRS1994

Segmented Ion Engine Operation and Performance

The continuing trend toward smaller and smaller planetary spacecraft to enable the use of smaller, less expensive launch vehicles has motivated an examination of new approaches to reduce the size and mass of xenon ion propulsion systems for these new spacecraft. A system is proposed which is based on the use of a single 4x15-cm segmented ion thruster operated from a single internally redundant power processing unit. An engine input power throttling range of 380 to 4640 W is projected. The design and operation over a power range of 600 to 2400 W of a laboratory model segmented ion engine equipped with carbon-carbon grids is presented. There appear to be no problems associated with interactions with multiple ion sources operating from a single set of high voltage power supplies, neutralization of multiple ion sources from a single centrally located neutralizer, or operation of flat, thin carbon-carbon grids.

ion↗
NASA NTRS2001

Modeling of Multi-Tube Pulse Detonation Engine Operation

The present paper explores some preliminary issues concerning the operational characteristics of multiple-tube pulsed detonation engines (PDEs). The study is based on a two-dimensional analysis of the first-pulse operation of two detonation tubes exhausting through a common nozzle. Computations are first performed to assess isolated tube behavior followed by results for multi-tube flow phenomena. The computations are based on an eight-species, finite-rate transient flow-field model. The results serve as an important precursor to understanding appropriate propellant fill procedures and shock wave propagation in multi-tube, multi-dimensional simulations. Differences in behavior between single and multi-tube PDE models are discussed, The influence of multi-tube geometry and the preferred times for injecting the fresh propellant mixture during multi-tube PDE operation are studied.

Ebrahimi, Houshang B.↗
NASA NTRS1948

Altitude-Wind-Tunnel Investigation of Westinghouse 19B-2 19B-8, and 19XB-1 Jet-Propulsion Engines: Operational Characteristics - Part 1

An investigation was conducted in the NACA Cleveland altitude wind tunnel to determine the operational characteristics of the Westinghouse 19B-2, 19B-8, and 19XB-l jet-propulsion engines. The 19B engine is one af the earliest experimental Westinghouse axial flow engines. The 19XB-1 engine is an experimental prototype of the Westinghouse 15 series, having a rated thrust of 1400 pounds. Improvements in performance and operational characteristics have resulted in the 19XB-2B engine with a rated thrust of 1600 pounds. The operational characteristics were determined over a range of simulated altitudes from 5000 to 30,000 feet for the 19B engines and from 5000 to 35000 feet for the 19XB-l engine at airspeed from 20 to 380 miles per hour. The affects of altitude and airspeed on such operating characteristics as operating range, stability of combustion, starting, acceleration, and functioning of the fuel-control system are discussed. Damage to the engines that occurred during the investigation is also briefly discussed. The changes made in the combustion-chamber configuration to improve the operating we are described.

Fleming, William A.↗
DOE OSTI2024

Evaluation of the Performance and Exhaust Emissions of a 4 Cylinder CI Engine Operating With Dimethyl Ether (DME) and Propane Blends

In response to stringent emissions regulations and the need for higher efficiency engines, the utilization of DME and propane fuel blends in compression ignition (CI) engines has gained interest in the automotive industry. In this study, a range of DME-propane blends are explored in a CI combustion strategy at high injection pressures. A GT-Power model of a 2.2 L Hyundai CI engine was developed to facilitate evaluation of the impacts of variations of DME and propane blends at a light and medium engine speed-torque-load operating condition; specifically at 1500 rpm, 50 Nm and 2.84 bar brake mean effective pressure (BMEP); and 2000 rpm, 150 Nm, 8.53 bar BMEP speed-torque-load combination. Here, the GT-Power model was validated using Computational Fluid Dynamics (CFD) simulations. The results indicate that high diesel-like efficiencies can be achieved with a 100% DME mass substitution and up to 50% propane-DME blends could be implemented without a significant penalty on engine performance indicators. Significant brake specific nitrogen oxides (BSNOx) reductions were also observed along with reductions in carbon dioxide (CO2) and soot when leveraging these fuel blends.

computational fluid dynamics↗
NASA NTRS1976

Laser engines operating by resonance absorption

Basic tutorial article on the thermodynamic feasibility of laser engines at the present state of the art. Three main options are considered: (1) laser power applied externally to a heat reservoir (boiler approach); (2) internal heating of working fluid by resonance absorption; and (3) direct conversion of selective excitation into work. Only (2) is considered practically feasible at present. Basic concepts and variants, efficiency relations, upper temperature limits of laser engines, selection of absorbing gases, engine walls, bleaching, thermodynamic cycles of optimized laser engines, laser-powered turbines, laser heat pumps are discussed. Photon engines and laser dissociation engines are also considered.

Garbuny, M.↗
NASA NTRS2006

Thermodynamic Analysis of Dual-Mode Scramjet Engine Operation and Performance

Recent analytical advances in understanding the performance continuum (the thermodynamic spectrum) for air-breathing engines based on fundamental second-law considerations have clarified scramjet and ramjet operation, performance, and characteristics. Second-law based analysis is extended specifically in this work to clarify and describe the performance characteristics for dual-mode scramjet operation in the mid-speed range of flight Mach 4 to 7. This is done by a fundamental investigation of the complex but predictable interplay between heat release and irreversibilities in such an engine; results demonstrate the flow and performance character of the dual mode regime and of dual mode transition behavior. Both analytical and computational (multi-dimensional CFD) studies of sample dual-mode flow-fields are performed in order to demonstrate the second-law capability and performance and operability issues. The impact of the dual-mode regime is found to be characterized by decreasing overall irreversibility with increasing heat release, within the operability limits of the system.

Riggins, David↗