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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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7 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Numerical and physical aspects of aerodynamic flows III; Proceedings of the Third Symposium, California State University, Long Beach, CA, January 21-24, 1985

The present symposium considers hydrodynamic stability and turbulent transition, transition calculations in three-dimensional flows, a quasi-simultaneous finite difference approach for strongly interacting flows, the significance of the thin layer Navier-Stokes approximation, unsteady airfoil boundary layers, predictions and experiments on airfoils at low Reynolds numbers, and a comparison of interactive boundary layer and thin layer Navier-Stokes procedures. Also discussed are a viscous-inviscid interaction method for computing unsteady transonic separation, massive separation and dynamic stall on a cusped trailing edge airfoil, the computation of turbulent separated flows over wings, an iterative scheme for three-dimensional transonic flows, and the computation of three-dimensional flows with shock wave/boundary layer interaction. Many of the papers in this symposium were abstracted previously (cf., A85-42951).

Cebeci, T.↗
NASA NTRS1985

Symposium on Numerical and Physical Aspects of Aerodynamic Flows, 3rd, California State University, Long Beach, CA, January 21-24, 1985, Proceedings

Among the topics discussed are hydrodynamic stability and turbulent transition, separated flow simulations employing finite difference methods, a quasi-simultaneous finite difference approach for strongly interacting flow, the Newton solution of coupled Euler and boundary layer equations, multielement airfoil aerodynamics, vorticity dynamics, the significance of the thin layer Navier-Stokes approximation, a comparison of interactive and Navier-Stokes calculations of separating boundary layer flows, and a Navier-Stokes analysis for the mechanism of shock wave/boundary layer interactions. Also discussed are transonic interactions of unsteady vortical flows, boundary layers on oscillating airfoils, a laser-interferometer skin friction meter, flow over surface-mounted semibluff bodies, computations for spinning and spin-stabilized supersonic projectiles, transition calculations in three-dimensional flows, the effect of projectile boattailing in transonic flow, flow characteristics of a body of revolution at incidence, the influence of the boundary layer on the leading edge flow of a swept wing, and an interactive scheme for three-dimensional transonic flows.

Source record↗
NASA NTRS1990

Aeronautical facility requirements into the 2,000's

This paper delineates and speculates upon aeronautical systems, trends, and requirements into the 2,000's and indicates ground facility capability enhancements which are needed to support these devlopments. New facility capabilities required include (1) higher Reynolds number at low speeds especially for the high-lift and vortex hazard problems, (2) low-disturbance, high-speed aerodynamic and hypersonic propulsion facilities for transition and mixing studies, (3) large-scale and relatively long test-time hypersonic propulsion tunnels to allow multidisciplinary integration, (4) a large-scale, high-speed acoustics facility for en route noise minimization, (5) a large-scale ballistic range for planetary entry studies, and (6) development of advanced (full simultaneous 3-space and time) nonintrusive instrumentation for CFD transition/turbulence modeling/code validation and interacting flow physics determination.

Beach, H. L., Jr.↗
NASA NTRS2002

High-Glass-Transition-Temperature Polyimides Developed for Reusable Launch Vehicle Applications

Polyimide composites have been traditionally used for high-temperature applications in aircraft engines at temperatures up to 550 F (288 C) for thousands of hours. However, as NASA shifts its focus toward the development of advanced reusable launch vehicles, there is an urgent need for lightweight polymer composites that can sustain 600 to 800 F (315 to 427 C) for short excursions (hundreds of hours). To meet critical vehicle weight targets, it is essential that one use lightweight, high-temperature polymer matrix composites in propulsion components such as turbopump housings, ducts, engine supports, and struts. Composite materials in reusable launch vehicle components will heat quickly during launch and reentry. Conventional composites, consisting of layers of fabric or fiber-reinforced lamina, would either blister or encounter catastrophic delamination under high heating rates above 300 C. This blistering and delamination are the result of a sudden volume expansion within the composite due to the release of absorbed moisture and gases generated by the degradation of the polymer matrix. Researchers at the NASA Glenn Research Center and the Boeing Company (Long Beach, CA) recently demonstrated a successful approach for preventing this delamination--the use of three-dimensional stitched composites fabricated by resin infusion.

Chuang, Kathy↗
NASA NTRS1999

NCV Flow Diagnostic Test Results

There were two objectives for this test. First, was to assess the reasons why there is approximately 1.5 drag counts (cts) discrepancy between measured and computed drag improvement of the Non-linear Cruise Validation (NCV) over the Technology Concept Airplane (TCA) wing body (WB) configurations. The Navier-Stokes (N-S) pre-test predictions from Boeing Commercial Airplane Group (BCAG) show 4.5 drag cts of improvement for NCV over TCA at a lift coefficient (CL) of 0. I at Mach 2.4. The pre-test predictions from Boeing Phantom Works - Long Beach, BPW-LB, show 3.75 drag cts of improvement. BCAG used OVERFLOW and BPW-LB used CFL3D. The first test entry to validate the improvement was held at the NASA Langley Research Center (LARC) UPV;T, test number 1687. The experimental results showed that the drag improvement was only 2.6 cts, not accounting for laminar run and trip drag. This is approximately 1.5 cts less than predicted computationally. In addition to the low Reynolds Number (RN) test, there was a high RN test in the Boeing Supersonic Wind Tunnel (BSWT) of NCV and TCA. BSV@T test 647 showed that the drag improvement of NCV over TCA was also 2.6 cts, but this did account for laminar run and trip drag. Every effort needed to be done to assess if the improvement measured in LaRC UPWT and BSWT was correct. The second objective, once the first objective was met, was to assess the performance increment of NCV over TCA accounting for the associated laminar run and trip drag corrections in LaRC UPWT. We know that the configurations tested have laminar flow on portions of the wing and have trip drag due to the mechanisms used to force the flow to go from laminar to turbulent aft of the transition location.

Cappuccio, Mina↗
NASA NTRS2021

Trends in Barrier Island Geomorphology Under Continuous Sea Level Rise: Padre Island from 1940-2020

Barrier islands serve an important role in shielding coastal areas from storm surges and wave erosion. Monitoring changes in a barrier island system helps determine the combined effect of sediment supply, aeolian sand transport, storms and sea level rise (SLR) on long-term island survival. Here we present and discuss changes to the southern end of Padre Island (TX),including a back-barrier active dune field, across 7 decades from 1941 - 2020. We have used aerial photos, satellite imagery, and field monitoring to map the decadal and seasonal geomorphological changes. We produced facies maps for each decade from 1970 to present, complemented with qualitative observations for 1941-1970, when aerial imagery was incomplete. We also used supervised classification to monitor monthly changes in the availability of sand for aeolian transport over a full seasonal cycle, to determine the role of the fluctuating water table on the sand budget of the active dune field. Results indicate that the southern end of Padre Island experienced significant change over the study period, transitioning from unvegetated dune fields and sand flats to expansive vegetated dunes, a tidal flat with microbial mats and a shrinking active dune field. Vegetated dunes, absent in 1970, now cover 14% of the study area. The active dune field shrunk from 12%coverage to 6%, with sand available for transport varying from 3% to 21% as the water table fluctuates throughout the year. The infrequently flooded back-island sand flat covering 40% of the study area has transitioned to a lower-lying tidal flat. Furthermore, extensive microbial mats and crusts have developed within the wind-tidal flat, in washover fans, and in low-lying interdune areas. All these early signs are consistent with a progressive drowning of the barrier island, an event we hypothesize was triggered by the sudden spread of vegetation along the back-beach dunes. Plant colonization then cut off sand supply from the beach to the back-barrier, and thus access to the primary source of sand to the system. Our findings highlight the contradictory role of vegetation in barrier islands, as they stabilize dunes and promote sand accretion at the back-beach, while also isolating the back-barrier from aeolian sediment sources, thus amplifying the effects of sea level rise in the absence of salt marshes and/or mangrove platforms.

K R Fisher↗