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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 631 records · Page 35

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NASA NTRS1937

Some experiments on the slipstream effect

The models designated "Torino 30, 31, 32" are horizontal tail surfaces of rectangular, triangular, and elliptical plan form and all of the same profile section. Tests were carried out with the object being to determine the effect of the propeller slipstream on the aerodynamical characteristics of the horizontal stabilizer. The results presented correspond to a first series of tests made without an interposed wing and in which the distance between the plane of the propeller disk and the tail was maintained constant.

Ferrari, C↗

NASA NTRS1990

Airframe structural optimization for maximum fatigue life

A methodology is outlined for optimization of airframe structures under dynamic constraints to maximize service life of specified fatigue-critical components. For practical airframe structures, this methodology describes the development of sensitivity analysis and computational procedures for constraints on the steady-state dynamic response displacements and stresses. Strain energy consideration is used for selection of structural members for modification. Development of a design model and its relation to an analysis model, as well as ways to reduce the dimensionality of the problem via approximation concepts, are described. This methodology is demonstrated using an elastic stick model for the MH-53J helicopter to show service life improvements of the hinge fold region.

D. P. Schrage↗

NASA NTRS1993

Superpatch

A design model geometry file format with topology information used for model geometry exchange in Computational Fluid Dynamics (CFD) grid generation is described. The first part describes the reason why this file format is necessary and what we want to achieve through the file format. The second part provides the information stored in the file format. The purpose of the publication is for broad dissemination of this file format and for the wide participation of testing.

Chou, Jin J.↗

NASA NTRS1995

Experimental results for a hypersonic nozzle/afterbody flow field

This study was conducted to experimentally characterize the flow field created by the interaction of a single-expansion ramp-nozzle (SERN) flow with a hypersonic external stream. Data were obtained from a generic nozzle/afterbody model in the 3.5 Foot Hypersonic Wind Tunnel at the NASA Ames Research Center, in a cooperative experimental program involving Ames and McDonnell Douglas Aerospace. The model design and test planning were performed in close cooperation with members of the Ames computational fluid dynamics (CFD) team for the National Aerospace Plane (NASP) program. This paper presents experimental results consisting of oil-flow and shadow graph flow-visualization photographs, afterbody surface-pressure distributions, rake boundary-layer measurements, Preston-tube skin-friction measurements, and flow field surveys with five-hole and thermocouple probes. The probe data consist of impact pressure, flow direction, and total temperature profiles in the interaction flow field.

Spaid, Frank W.↗

NASA NTRS1995

The lift-fan aircraft: Lessons learned

This report summarizes the highlights and results of a workshop held at NASA Ames Research Center in October 1992. The objective of the workshop was a thorough review of the lessons learned from past research on lift fans, and lift-fan aircraft, models, designs, and components. The scope included conceptual design studies, wind tunnel investigations, propulsion systems components, piloted simulation, flight of aircraft such as the SV-5A and SV-5B and a recent lift-fan aircraft development project. The report includes a brief summary of five technical presentations that addressed the subject The Lift-Fan Aircraft: Lessons Learned.

Deckert, Wallace H.↗

NASA NTRS1996

Third International Symposium on Magnetic Suspension Technology

In order to examine the state of technology of all areas of magnetic suspension and to review recent developments in sensors, controls, superconducting magnet technology, and design/implementation practices, the Third International Symposium on Magnetic Suspension Technology was held at the Holiday Inn Capital Plaza in Tallahassee, Florida on 13-15 Dec. 1995. The symposium included 19 sessions in which a total of 55 papers were presented. The technical sessions covered the areas of bearings, superconductivity, vibration isolation, maglev, controls, space applications, general applications, bearing/actuator design, modeling, precision applications, electromagnetic launch and hypersonic maglev, applications of superconductivity, and sensors.

Groom, Nelson J.↗

NASA NTRS1996

Third International Symposium on Magnetic Suspension Technology

Groom, Nelson J.↗

NASA NTRS1996

Determination of Shed Ice Particle Size Using High Speed Digital Imaging

A full scale model of an aircraft engine inlet was tested at NASA Lewis Research Center's Icing Research Tunnel. Simulated natural ice sheds from the engine inlet lip were studied using high speed digital image acquisition and image analysis. Strategic camera placement integrated at the model design phase allowed the study of ice accretion on the inlet lip and the resulting shed ice particles at the aerodynamic interface plane at the rear of the inlet prior to engine ingestion. The resulting digital images were analyzed using commercial and proprietary software to determine the size of the ice particles that could potentially be ingested by the engine during a natural shedding event. A methodology was developed to calibrate the imaging system and insure consistent and accurate measurements of the ice particles for a wide range of icing conditions.

Broughton, Howard↗

NASA NTRS1997

Physics and Process Modeling (PPM) and Other Propulsion R and T: Materials Processing, Characterization, and Modeling; Lifting Models - Volume 1

This CP contains the extended abstracts and presentation figures of 36 papers presented at the PPM and Other Propulsion R&T Conference. The focus of the research described in these presentations is on materials and structures technologies that are parts of the various projects within the NASA Aeronautics Propulsion Systems Research and Technology Base Program. These projects include Physics and Process Modeling; Smart, Green Engine; Fast, Quiet Engine; High Temperature Engine Materials Program; and Hybrid Hyperspeed Propulsion. Also presented were research results from the Rotorcraft Systems Program and work supported by the NASA Lewis Director's Discretionary Fund. Authors from NASA Lewis Research Center, industry, and universities conducted research in the following areas: material processing, material characterization, modeling, life, applied life models, design techniques, vibration control, mechanical components, and tribology. Key issues, research accomplishments, and future directions are summarized in this publication.

Source record↗

NASA NTRS1999

Aviation System Analysis Capability Air Carrier Investment Model-Cargo

The purpose of the Aviation System Analysis Capability (ASAC) Air Cargo Investment Model-Cargo (ACIMC), is to examine the economic effects of technology investment on the air cargo market, particularly the market for new cargo aircraft. To do so, we have built an econometrically based model designed to operate like the ACIM. Two main drivers account for virtually all of the demand: the growth rate of the Gross Domestic Product (GDP) and changes in the fare yield (which is a proxy of the price charged or fare). These differences arise from a combination of the nature of air cargo demand and the peculiarities of the air cargo market. The net effect of these two factors are that sales of new cargo aircraft are much less sensitive to either increases in GDP or changes in the costs of labor, capital, fuel, materials, and energy associated with the production of new cargo aircraft than the sales of new passenger aircraft. This in conjunction with the relatively small size of the cargo aircraft market means technology improvements to the cargo aircraft will do relatively very little to spur increased sales of new cargo aircraft.

Johnson, Jesse↗

NASA NTRS1999

Short Duration Base Heating Test Improvements

Significant improvements have been made to a short duration space launch vehicle base heating test technique. This technique was first developed during the 1960's to investigate launch vehicle plume induced convective environments. Recent improvements include the use of coiled nitrogen buffer gas lines upstream of the hydrogen / oxygen propellant charge tubes, fast acting solenoid valves, stand alone gas delivery and data acquisition systems, and an integrated model design code. Technique improvements were successfully demonstrated during a 2.25% scale X-33 base heating test conducted in the NASA/MSFC Nozzle Test Facility in early 1999. Cost savings of approximately an order of magnitude over previous tests were realized due in large part to these improvements.

Bender, Robert L.↗

NASA NTRS1998

Development of an Active Twist Rotor for Wind: Tunnel Testing (NLPN97-310

The development of the Active Twist Rotor prototype blade for hub vibration and noise reduction studies is presented in this report. Details of the modeling, design, and manufacturing are explored. The rotor blade is integrally twisted by direct strain actuation. This is accomplished by distributing embedded piezoelectric fiber composites along the span of the blade. The development of the analysis framework for this type of active blade is presented. The requirements for the prototype blade, along with the final design results are also presented. A detail discussion on the manufacturing aspects of the prototype blade is described. Experimental structural characteristics of the prototype blade compare well with design goals, and preliminary bench actuation tests show lower performance than originally predicted. Electrical difficulties with the actuators are also discussed. The presented prototype blade is leading to a complete fully articulated four-blade active twist rotor system for future wind tunnel tests.

Cesnik, Carlos E. S.↗

NASA NTRS1999

Development and Validation of a Supersonic Helium-Air Coannular Jet Facility

Data are acquired in a simple coannular He/air supersonic jet suitable for validation of CFD (Computational Fluid Dynamics) codes for high speed propulsion. Helium is employed as a non-reacting hydrogen fuel simulant, constituting the core of the coannular flow while the coflow is composed of air. The mixing layer interface between the two flows in the near field and the plume region which develops further downstream constitute the primary regions of interest, similar to those present in all hypersonic air breathing propulsion systems. A computational code has been implemented from the experiment's inception, serving as a tool for model design during the development phase.

Carty, Atherton A.↗

NASA NTRS1999

Alterations in Skeletal Muscle Function with Microgravity, and the Protective Effects of High Resistance Isometric and Isotonic Exercise

Exposure to microgravity or models designed to mimic the unloaded condition, such as bed rest in humans and hindlimb unloading (HU) in rats leads to skeletal muscle atrophy, a loss in peak force and power, and an increased susceptibility to fatigue. The posterior compartment muscles of the lower leg (calf muscle group) appear to be particularly susceptible. Following only 1 wk in space or HU, rat soleus muscle showed a 30 to 40% loss in wet weight. After 3 wk of HU, almost all of the atrophied soleus fibers showed a significant increase in maximal shortening velocity (V(sub 0)), while only 25 to 30 % actually transitioned to fast fibers. The increased V(sub 0), was protective in that it reduced the decline in peak power associated with the reduced peak force. When the soleus is stimulated in situ following HU or zero-g one observes an increased rate and extent of fatigue, and in the former the increased fatigue is associated with a more rapid depletion of muscle glycogen and lactate production. Our working hypothesis is that following HU or spaceflight in rats and bed rest or spaceflight in humans limb skeletal muscles during contractile activity depend more on carbohydrates and less on fatty acids for their substrate supply. Baldwin et al. found 9 days of spaceflight to reduce by 37% the ability of both the high and low oxidative regions of the vastus muscle to oxidize long-chain fatty acids. This decline was not associated with any change in the enzymes of the tricarboxylic acid cycle or oxidation pathway. The purpose of the current research was to establish the extent of functional change in the slow type I and fast type H fibers of the human calf muscle following 17 days of spaceflight, and determine the cellular mechanisms of the observed changes. A second goal was to study the effectiveness of high resistance isotonic and isometric exercise in preventing the deleterious functional changes associated with unloading.

Fitts, R. H.↗

NASA NTRS2000

An Overview of Unsteady Pressure Measurements in the Transonic Dynamics Tunnel

The NASA Langley Transonic Dynamics Tunnel has served as a unique national facility for aeroelastic testing for over forty years. A significant portion of this testing has been to measure unsteady pressures on models undergoing flutter, forced oscillations, or buffet. These tests have ranged from early launch vehicle buffet to flutter of a generic high-speed transport. This paper will highlight some of the test techniques, model design approaches, and the many unsteady pressure tests conducted in the TDT. The objectives and results of the data acquired during these tests will be summarized for each case and a brief discussion of ongoing research involving unsteady pressure measurements and new TDT capabilities will be presented.

Schuster, David M.↗

NASA NTRS2000

Advanced Engineering Environments for Space Transportation System Development

There are significant challenges facing today's launch vehicle industry. Global competition, more complex products, geographically-distributed design teams, demands for lower cost, higher reliability and safer vehicles, and the need to incorporate the latest technologies quicker, all face the developer of a space transportation system. Within NASA, multiple technology development and demonstration projects are underway toward the objectives of safe, reliable, and affordable access to space. New information technologies offer promising opportunities to develop advanced engineering environments to meet these challenges. Significant advances in the state-of-the-art of aerospace engineering practice are envisioned in the areas of engineering design and analytical tools, cost and risk tools, collaborative engineering, and high-fidelity simulations early in the development cycle. At the Marshall Space Flight Center, work has begun on development of an advanced engineering environment specifically to support the design, modeling, and analysis of space transportation systems. This paper will give an overview of the challenges of developing space transportation systems in today's environment and subsequently discuss the advanced engineering environment and its anticipated benefits.

Thomas, L. Dale↗

NASA NTRS1994

Hypersonic Nozzle/Afterbody Experiment: Flow Visualization and Boundary Layer Experiments

This study was conducted to experimentally characterize the flow field created by the interaction of a single-expansion-ramp-nozzle (SERN) flow with a hypersonic external stream Data were obtained from a generic nozzle/afterbody model in the 3.5-Foot Hypersonic Wind Tunnel of the NASA Ames Research Center in a cooperative experimental program involving Ames and the McDonnell Douglas Aerospace. The model design and test planning were performed in close cooperation with members of the Ames computational fluid dynamics (CFD) team for the National Aero-Space Plane (NASP) program. This paper presents experimental results consisting of oil-flow and shadowgraph flow-visualization photographs, afterbody surface-pressure distributions, boundary-layer rake measurements, and Preston-tube skin-friction measurements.

Keener, Earl R.↗

NASA NTRS1997

Closed-Loop Hybrid Flight Management Systems

The objective of our research is to develop a methodology for the modeling, design, verification of flight management systems for the next generation of airspace operations. The overall point of view taken is shown schematically by a block diagram.

Meyer, George↗