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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Design and analysis of vortex generators on reengined Boeing 727-100QF center inlet S-duct by a reduced Navier-Stokes code

This paper describes the application of a three dimensional reduced Navier-Stokes code to perform design and analysis of vortex generators on a reengined Boeing 727-100QF center engine inlet S duct. This computer code with vortex generators modeling is shown to be cost-effective, accurate and easy to use to design the optimal vortex generators installed on a S-duct, predict its aerodynamic performance and provide the detailed flow field information.

Huang, Pao S.↗
NASA NTRS1990

Conceptual second-generation lunar equipment

The spring 1990 Introduction to Design class was asked to conceptually design second-generation lunar vehicles and equipment as a semester design project. The basic assumption made in designing second-generation lunar vehicles and equipment was that a network of permanent lunar bases already existed. The designs were to facilitate the transportation of personnel and materials. The eight topics to choose from included flying vehicles, ground-based vehicles, robotic arms, and life support systems. Two teams of two or three members competed on each topic and results were exhibited at a formal presentation. A clean-propellant powered lunar flying transport vehicle, an extra-vehicular activity life support system, a pressurized lunar rover for greater distances, and a robotic arm design project are discussed.

Source record↗
NASA NTRS1992

A study on vortex flow control on inlet distortion in the re-engined 727-100 center inlet duct using computational fluid dynamics

Computational fluid dynamics was used to investigate the management of inlet distortion by the introduction of discrete vorticity sources at selected locations in the inlet for the purpose of controlling secondary flow. These sources of vorticity were introduced by means of vortex generators. A series of design observations were made concerning the importance of various vortex generator design parameters in minimizing engine face circumferential distortion. The study showed that vortex strength, generator scale, and secondary flow field structure have a complicated and interrelated influence on the engine face distortion, over and above the initial geometry and arrangement of the generators. The installed vortex generator performance was found to be a function of three categories of variables: the inflow conditions, the aerodynamic characteristics associated with the inlet duct, and the design parameters related to the geometry, arrangement, and placement of the vortex generators within the outlet duct itself.

Anderson, Bernhard H.↗
NASA NTRS1992

A study on vortex flow control of inlet distortion in the re-engined 727-100 center inlet duct using computational fluid dynamics

Computational fluid dynamics was used to investigate the management of inlet distortion by the introduction of discrete vorticity sources at selected locations in the inlet for the purpose of controlling secondary flow. These sources of vorticity were introduced by means of vortex generators. A series of design observations were made concerning the importance of various vortex generator design parameters in minimizing engine face circumferential distortion. The study showed that vortex strength, generator scale, and secondary flow field structure have a complicated and interrelated influence on the engine face distortion, over and above the initial geometry and arrangement of the generators. The installed vortex generator performance was found to be a function of three categories of variables: the inflow conditions, the aerodynamic characteristics associated with the inlet duct, and the design parameters related to the geometry, arrangement, and placement of the vortex generators within the outlet duct itself.

Anderson, Bernhard H.↗
NASA NTRS1984

Performance tests for the NASA Ames Research Center 20 cm x 40 cm oscillating flow wind tunnel

An evaluation is presented of initial tests conducted to assess the performance of the NASA Ames 20 cm x 40 cm oscillating flow wind tunnel. The features of the tunnel are described and two aspects of tunnel operation are discussed. The first is an assessment of the steady mainstream and boundary layer flows and the second deals with oscillating mainstream and boundary layer flows. Experimental results indicate that in steady flow the test section mainstream velocity is uniform in the flow direction and in cross section. The freestream turbulence intensity is about 0.2 percent. With minor exceptions the steady turbulent boundary layer generated on the top wall of the test section exhibits the characteristics of a zero pressure gradient turbulent boundary layer generated on a flat plate. The tunnel was designed to generate sinusoidal oscillating mainstream flows. Experiments confirm that the tunnel produces sinusoidal mainstream velocity variations for the range of frequencies (up to 15 Hz). The results of this study demonstrate that the tunnel essentially produces the flows that it was designed to produce.

Cook, W. J.↗
NASA NTRS1990

Implications of Tracey's theorem to asynchronous sequential circuit design

Tracey's Theorem has long been recognized as essential in generating state assignments for asynchronous sequential circuits. This paper shows that Tracey's Theorem also has a significant impact in generating the design equations. Moreover, this theorem is important to the fundamental understanding of asynchronous sequential operation. The results of this work simplify asynchronous logic design. Moreover, detection of safe circuits is made easier.

Gopalakrishnan, S.↗
NASA NTRS1971

Quadratic performance index generation for optimal regular design.

Application of optimal control theory to practical problems has been limited by the difficulty of prescribing a performance index which accurately reflects design requirements. The task of deriving equivalent performance indices is considered in the present paper for a plant that is a completely controllable, scalar linear system with state feedback. A quadratic index is developed which leads to an optimal design performance satisfying some of the classical performance criteria.

Bullock, T. E.↗
NASA NTRS1974

Development and planning and design of equipment pumping generator of semiconductor lasers

The schematic of a multidimensional current pulse generator is studied. A MTKh-90 cold cathode thyratron is used as the current commutator. In the autooscillation mode on a frequency of 380 hertz the generator creates a current to 100 amps per pulse in a control resistance of 1 ohm. The pulse duration is regulated within the limits from 0.1 to 3.0 microseconds.

Popkov, A. V.↗
NASA NTRS1980

Effect of off-design operation of MHD generators on NO/x/ chemical kinetics

The purpose of this study is to provide a capability for determining the chemical kinetic behavior of one family of pollutants, the nitrogen oxides, in the flow of a coal-fired MHD generator facility. The method used in the study allows the prediction of the nonequilibrium concentration of the minor NO(x) species in a flow otherwise assumed in equilibrium. Consideration is given to the effect of preheat, stoichiometry, and oxygen enrichment of the NO(x) concentration. The effect of preheat and stoichiometry is found to have a significant influence on the NO(x) concentration at the exit of the radiant boiler.

Simmons, G. A.↗
NASA NTRS1983

Design Calculations for Thermoelectric Generators

Nine simplified analytic models based on average properties accurately predict heat rates for silicon/germanium thermoelectric generators. Solutions from simplified models were compared with those obtained using sophisticated numerical analysis. Maximum errors in calculated heat rate range from about 4 percent to about 0.2 percent. Models also used to calculate power delivered to load and thermodynamic efficiency.

Zeldin, B.↗
NASA NTRS1982

An Assessment of Alternate Thermal Protection Systems for the Space Shuttle Orbiter: Executive Summary - Volume 1

Alternate thermal protection system (TPS) concepts to the Space Shuttle Orbiter were assessed. Metallic, ablator, and carbon-carbon concepts which are the result of some previous design, manufacturing and testing effort were considered. Emphasis was placed on improved TPS durability, which could potentially reduce life cycle costs and improve Orbiter operational characteristics. Integrated concept/orbiter point designs were generated and analyzed on the basis of Shuttle design environments and criteria. A merit function evaluation methodology based on mission impact, life cycle costs, and risk was developed to compare the candidate concepts and to identify the best alternate. Voids and deficiencies in the technology were identified, along with recommended activities to overcome them. Finally, programmatic plans, including ROM costs and schedules, were developed for all activities required to bring the selected alternate system up to operational readiness.

Hays, D.↗
NASA NTRS1990

Human factors in the presentation of computer-generated information - Aspects of design and application in automated flight traffic

The man-machine interface and its influence on the characteristics of computer displays in automated air traffic is discussed. The graphical presentation of spatial relationships and the problems it poses for air traffic control, and the solution of such problems are addressed. Psychological factors involved in the man-machine interface are stressed.

Roske-Hofstrand, Renate J.↗
NASA NTRS2013

Next Generation Civil Transport Aircraft Design Considerations for Improving Vehicle and System-Level Efficiency

The future of aviation will benefit from research in aircraft design and air transportation management aimed at improving efficiency and reducing environmental impacts. This paper presents civil transport aircraft design trends and opportunities for improving vehicle and system-level efficiency. Aircraft design concepts and the emerging technologies critical to reducing thrust specific fuel consumption, reducing weight, and increasing lift to drag ratio currently being developed by NASA are discussed. Advancements in the air transportation system aimed towards system-level efficiency are discussed as well. Finally, the paper describes the relationship between the air transportation system, aircraft, and efficiency. This relationship is characterized by operational constraints imposed by the air transportation system that influence aircraft design, and operational capabilities inherent to an aircraft design that impact the air transportation system.

aircraft design↗