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Wieting, A. R.

Publications and source records attributed to Wieting, A. R..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Adaptive finite element analysis of hypersonic laminar flows for aerothermal load predictions

The use of an adaptive mesh refinement procedure for analyzing hypersonic laminar flows with application to aerothermal load predictions is described. The adaptation procedure, which uses both quadrilateral and triangular elements, is implemented with the multistep Galerkin-Runge-Kutta scheme. Elements that lie in regions of strong gradients are refined based on indicators to obtain better definition of flow features. The effectiveness of the adaptive procedure is demonstrated by modeling Mach 11.7 flow over a 15-deg ramp. Numerical results are compared with predictions of strong interaction theories and experimental data. Surface quantities such as heating rates and pressure loads, critical for the effective design of high-speed vehicles, are found to be in good agreement with experimental values.

Ramakrishnan, R.↗
NASA NTRS1988

Studies of aerothermal loads generated in regions of shock/shock interaction in hypersonic flow

Detailed measurements of heat transfer and pressure distribution have been made in the present study of the aerothermal characteristics of regions of two-dimensional shock/shock interaction generated by the incidence of single and multiple shocks onto the bow shock ahead of a spanwise cylinder. For transitional flows, the measurements demonstrated a large increase in the aerothermal loads with increasing Mach number that cannot be predicted by simple phenomenological models. The studies with multiple incident shocks demonstrate that the largest aerothermal loads are generated on the cylinder when the shocks coalesce before they are incident on the bow shock.

Holden, M. S.↗
NASA NTRS1985

Structures and materials technology issues for reusable launch vehicles

Projected space missions for both civil and defense needs require significant improvements in structures and materials technology for reusable launch vehicles: reductions in structural weight compared to the Space Shuttle Orbiter of up to 25% or more, a possible factor of 5 or more increase in mission life, increases in maximum use temperature of the external surface, reusable containment of cryogenic hydrogen and oxygen, significant reductions in operational costs, and possibly less lead time between technology readiness and initial operational capability. In addition, there is increasing interest in hypersonic airbreathing propulsion for launch and transmospheric vehicles, and such systems require regeneratively cooled structure. The technology issues are addressed, giving brief assessments of the state-of-the-art and proposed activities to meet the technology requirements in a timely manner.

Dixon, S. C.↗
NASA NTRS1985

Structures and materials technology issues for reusable launch vehicles

Projected space missions for both civil and defense needs require significant improvements in structures and materials technology for reusable launch vehicles: reductions in structural weight compared to the Space Shuttle Orbiter of up to 25 percent or more, a possible factor of 5 or more increase in mission life, increases in maximum use temperature of the external surface, reusable containment of cryogenic hydrogen and oxygen, significant reductions in operational costs, and possibly less lead time between technology readiness and initial operational capability. In addition, there is increasing interest in hypersonic airbreathing propulsion for launch and transmospheric vehicles, and such systems require regeneratively cooled structure. The technology issues are addressed, giving brief assessments of the state-of-the-art and proposed activities to meet the technology requirements in a timely manner.

Dixon, S. C.↗
NASA NTRS1984

Modification of NASA Langley 8 foot high temperature tunnel to provide a unique national research facility for hypersonic air-breathing propulsion systems

A planned modification of the NASA Langley 8-Foot High Temperature Tunnel to make it a unique national research facility for hypersonic air-breathing propulsion systems is described, and some of the ongoing supporting research for that modification is discussed. The modification involves: (1) the addition of an oxygen-enrichment system which will allow the methane-air combustion-heated test stream to simulate air for propulsion testing; and (2) supplemental nozzles to expand the test simulation capability from the current nominal Mach number to 7.0 include Mach numbers 3.0, 4.5, and 5.0. Detailed design of the modifications is currently underway and the modified facility is scheduled to be available for tests of large scale propulsion systems by mid 1988.

Kelly, H. N.↗
NASA NTRS1984

Modification of NASA Langley 8 Foot High Temperature Tunnel to provide a unique national research facility for hypersonic air-breathing propulsion systems

A planned modification of the NASA Langley 8-Foot High Temperature Tunnel to make it a unique national research facility for hypersonic air-breathing propulsion systems is described, and some of the ongoing supporting research for that modification is discussed. The modification involves: (1) the addition of an oxygen-enrichment system which will allow the methane-air combustion-heated test stream to simulate air for propulsion testing; and (2) supplemental nozzles to expand the test simulation capability from the current nominal Mach number to 7.0 include Mach numbers 3.0, 4.5, and 5.0. Detailed design of the modifications is currently underway and the modified facility is scheduled to be available for tests of large scale propulsion systems by mid 1988.

Kelly, H. N.↗
NASA NTRS1983

Aerothermal environment in control surface gaps in hypersonic flow - An overview

Experimental and analytical research by the NASA Langley Research Center to develop an understanding of the fluid and thermal environment in control surface gaps such as the spanwise gap of the wing elevon and chordwise gap of a split elevon configuration typical of the Space Shuttle are summarized. Although the experimental and analytical studies were initiated too late to significantly impact the basic Shuttle design they do provide a fundamental understanding of the basic fluid/thermal environment in control surface gaps and help to establish a firm data base for future vehicle design.

Wieting, A. R.↗
NASA NTRS1983

Experimental aerodynamic heating to simulated Shuttle tiles

The heat transfer to simulated Shuttle thermal protection system tiles was investigated experimentally using a highly instrumented metallic thin wall tile arranged with other metal tiles in a staggered tile array. Cold-wall heating rate data for laminar and turbulent flow were obtained in the Langley 8-Foot High-Temperature Tunnel at a nominal Mach number of 7, a nominal total temperature of 3300 deg R, free-stream unit Reynolds number from 340,000 to 2,200,000 per foot, and free-stream dynamic pressure of 1.8 to 9.1 psia. Experimental data are presented to illustrate the effects of flow angularity and gap width on both local peak heating and overall heating loads.

Avery, D. E.↗
NASA NTRS1983

Experimental aerodynamic heating to simulated shuttle tiles

The heat transfer to simulated shuttle thermal protection system tiles was investigated experimentally using a highly instrumented metallic thin wall tile arranged with other metal tiles in a staggered tile array. Cold-wall heating rate data for laminar and turbulent flow were obtained in the Langley 8-foot high temperature tunnel at a nominal Mach number of 7, a nominal total temperature of 3300 R, free-stream unit Reynolds number from 3.4 x 10 to the 5th power to 2.2 x 10 to the 6th power per foot, and free-stream dynamic pressure of 1.8 psia to 9.1 psia. Experimental data are presented to illustrate the effects of flow angularity and gap width on both local peak heating and overall heating loads.

Avery, D. E.↗
NASA NTRS1983

Aerothermal environment in control surface gaps in hypersonic flow: An overview

Experimental and analytical research to develop an understanding of the fluid and thermal environment in control surface gaps such as the spanwise gap of the wing elevon and chordwise gap of a split elevon configuration typical of the Space Shuttle are summarized. Although the experimental and analytical studies were initiated too late to significantly impact the Shuttle design they do provide a fundamental understanding of the basic fluid/thermal environment in control surface gaps and help to establish a firm data base for vehicle design.

Wieting, A. R.↗
NASA NTRS1982

Finite-Element Analysis of Forced Convection and Conduction

TAP2 thermal-analysis program was developed as part of research on finite element methodology for thermal analysis of convectively cooled structures, such as scramjet engines and hypersonic aircraft. Program simplifies computations when both structural and thermal analyses are required and is suited for thermal analysis of nuclear reactors and solar-panel heating systems.

Wieting, A. R.↗
NASA NTRS1982

Integrated finite element thermal-structural analysis with radiation heat transfer

An integrated approach for efficiently coupling thermal and stress analyses of structures with radiation heat transfer is presented. A new integrated one dimensional element based on a nodeless variable formulation is introduced. Lumped and consistent formulations of the nonlinear radiation heat transfer matrix are presented. The accuracy of the integrated approach is assessed by comparisons with analytical solutions and conventional finite element thermal-structural analyses. Results show that the nodeless variable thermal element yields accuracy equivalent to a higher order element but permits a common discretization with a lower order congruent structural element. The integrated element thus provides improved accuracy and efficiency of thermal stress analysis for structures with complex temperature distributions.

Thornton, E. A.↗
NASA NTRS1981

Computation of radiation view factors for surfaces with obstructed views of each other

Radiation calculations begin with a determination of view (or shape) factors describing the geometrical configuration of the exchanging surfaces. These viewfactor calculations can be very involved, time consuming and expensive. This paper describes the development of an algorithm for situations in which the view between two surfaces is obscured by one or more intervening surfaces. A technique based upon the combination of the Contour Integration and Double Area Integration methods and the acceleration techniques necessary for its efficient use are described. Numerical examples are given to demonstrate the use of the technique and to describe some of the problems inherent in treating radiation in enclosures.

Emery, A. F.↗
NASA NTRS1981

Integrated transient thermal-structural finite element analysis

An integrated thermal structural finite element approach for efficient coupling of transient thermal and structural analysis is presented. Integrated thermal structural rod and one dimensional axisymmetric elements considering conduction and convection are developed and used in transient thermal structural applications. The improved accuracy of the integrated approach is illustrated by comparisons with exact transient heat conduction elasticity solutions and conventional finite element thermal finite element structural analyses.

Thornton, E. A.↗
NASA NTRS1981

Integrated transient thermal-structural finite element analysis

An integrated thermal-structural finite element approach for efficient coupling of transient thermal and structural analysis is presented. New integrated thermal-structural rod and one dimensional axisymmetric elements considering conduction and convection are developed and used in transient thermal-structural applications. The improved accuracy of the integrated approach is illustrated by comparisons with exact transient heat conduction-elasticity solutions and conventional finite element thermal-finite element structural analyses. Results indicate that the approach offers significant potential for further development with other elements.

Thornton, E. A.↗
NASA NTRS1981

Finite element thermal analysis of convectively-cooled aircraft structures

The design complexity and size of convectively-cooled engine and airframe structures for hypersonic transports necessitate the use of large general purpose computer programs for both thermal and structural analyses. Generally thermal analyses are based on the lumped-parameter finite difference technique, and structural analyses are based on the finite element technique. Differences in these techniques make it difficult to achieve an efficient interface. It appears, therefore, desirable to conduct an integrated analysis based on a common technique. A summary is provided of efforts by NASA concerned with the development of an integrated thermal structural analysis capability using the finite element method. Particular attention is given to the development of conduction/forced-convection finite element methodology and applications which illustrate the capabilities of the developed concepts.

Wieting, A. R.↗