A survey of lipids in arctic animals /

"Aero Medical Laboratory, Subcontract No. AF 33(038) 422-82049, E.O. No. 21-01-021.""April 1951."Includes bibliographical references (page 20).Mode of access: Internet

Survey of CFD applications for high speed inlets /

A comprehensive review of techniques and methods for applying computational fluid dynamics (CFD) analysis to high speed inlets and related flows is provided via an extensive literature survey of such applications. Topics covered include governing equations, numerical integration schemes, boundary conditions, gridding requirements, and turbulence models. Results of applications from the literature survey shed light on the relative success of the techniques being used throughout the industry. (AN)."Final Report for Period August 1992 - July 1994.""July 1994."Includes bibliographical references (pages 53-55).A comprehensive review of techniques and methods for applying computational fluid dynamics (CFD) analysis to high speed inlets and related flows is provided via an extensive literature survey of such applications. Topics covered include governing equations, numerical integration schemes, boundary conditions, gridding requirements, and turbulence models. Results of applications from the literature survey shed light on the relative success of the techniques being used throughout the industry. (AN).Mode of access: Internet

The effect of pressure gradients on transition zone length in hypersonic boundary layers /

Boundary layer transition was measured in zero, favorable, and adverse pressure gradients at Mach 8 using heat transfer. Models consisted of 7 degrees half angle forecones 0.4826 m long, followed by flared or ogive aft bodies 0.5334 m long. The flares and ogives produced constant pressure gradients. For the cases examined, favorable pressure gradients delay transition and adverse pressure gradients promote transition, but transition zone lengths are shorter in favorable pressure gradient. Results of the effect of adverse pressure gradient on transition zone lengths were inconclusive."Final Report for 06/01/90 - 12/01/93.""December 1993."Includes bibliographical references (pages 31-35).Boundary layer transition was measured in zero, favorable, and adverse pressure gradients at Mach 8 using heat transfer. Models consisted of 7 degrees half angle forecones 0.4826 m long, followed by flared or ogive aft bodies 0.5334 m long. The flares and ogives produced constant pressure gradients. For the cases examined, favorable pressure gradients delay transition and adverse pressure gradients promote transition, but transition zone lengths are shorter in favorable pressure gradient. Results of the effect of adverse pressure gradient on transition zone lengths were inconclusive.Mode of access: Internet

Characteristic based methods for the time-domain Maxwell equations /

Numerical procedures for solving the time-domain Maxwell equations based on the theory of characteristics were successfully developed. Both explicit and implicit methods were formulated by the time-central and spatial-windward algorithm to better describe wave motion. A new trapezoidal consistent implicit scheme was shown to be unconditionally stable for the linear initial value system and was able to generate numerical solutions comparable to those of the established explicit method. The formulation of the three-dimensional system including generalized coordinate system was completed but not explored. The present 2-D results on Cartesian frame demonstrated a potential for numerical efficiency improvement. Time-domain Maxwell equation, Trapezoidal consistent implicit scheme, Cartesian frame."Final Report for Period June 1990 - February 1991.""August 1993."Includes bibliographical references (pages 41-43).Numerical procedures for solving the time-domain Maxwell equations based on the theory of characteristics were successfully developed. Both explicit and implicit methods were formulated by the time-central and spatial-windward algorithm to better describe wave motion. A new trapezoidal consistent implicit scheme was shown to be unconditionally stable for the linear initial value system and was able to generate numerical solutions comparable to those of the established explicit method. The formulation of the three-dimensional system including generalized coordinate system was completed but not explored. The present 2-D results on Cartesian frame demonstrated a potential for numerical efficiency improvement. Time-domain Maxwell equation, Trapezoidal consistent implicit scheme, Cartesian frame.Mode of access: Internet

Characterization of the flowfield near a wrap-around fin at supersonic speeds /

A wall-mounted semi-cylindrical model fitted with a single wrap-around in (WAF) has been investigated numerically and experimentally, with the objective of characterizing the mean and turbulent flowfield near a WAF in a supersonic flowfield. Numerical and experimental results are used to determine the nature of the flowfield and quantify the effects of fin curvature on the character of the flow near WAFs. This research has been motivated by the need to identify possible sources of a high-speed rolling moment reversal observed in sub-scale flight tests. Detailed mean flow and turbulence measurements were obtained in the AFIT Mach 3 wind tunnel using conventional probes and cross-wire hot-film anemometry at a series of stations upstream of and aft of the fin shock/boundary layer interaction. Hot-film anemometry results showed the turbulence intensity and Reynolds shear stress in the fuselage boundary layer to be far greater on the concave side of the fin than on the convex side. Mean flow was also obtained in the AFIT Mach 5 wind tunnel using conventional pressure probes. Numerical results were also obtained at the test conditions employing the algebraic eddy viscosity model of Baldwin and Lomax. Correlation with experimental data suggests that the calculations have captured the flow physics involved in this complicated flowfield. The calculations, corroborated by experimental results, indicate that a vortex exists in the fin/body juncture region on the convex side of the fin. This feature is not captured by the oft-used inviscid methods, and can greatly influence the pressure loading on the fin near the root.Photocopy."Final Report : October 1, 1995 -- March 1, 1997.""February 1998."Includes bibliographic references (pages 8-1 to 8-8).A wall-mounted semi-cylindrical model fitted with a single wrap-around in (WAF) has been investigated numerically and experimentally, with the objective of characterizing the mean and turbulent flowfield near a WAF in a supersonic flowfield. Numerical and experimental results are used to determine the nature of the flowfield and quantify the effects of fin curvature on the character of the flow near WAFs. This research has been motivated by the need to identify possible sources of a high-speed rolling moment reversal observed in sub-scale flight tests. Detailed mean flow and turbulence measurements were obtained in the AFIT Mach 3 wind tunnel using conventional probes and cross-wire hot-film anemometry at a series of stations upstream of and aft of the fin shock/boundary layer interaction. Hot-film anemometry results showed the turbulence intensity and Reynolds shear stress in the fuselage boundary layer to be far greater on the concave side of the fin than on the convex side. Mean flow was also obtained in the AFIT Mach 5 wind tunnel using conventional pressure probes. Numerical results were also obtained at the test conditions employing the algebraic eddy viscosity model of Baldwin and Lomax. Correlation with experimental data suggests that the calculations have captured the flow physics involved in this complicated flowfield. The calculations, corroborated by experimental results, indicate that a vortex exists in the fin/body juncture region on the convex side of the fin. This feature is not captured by the oft-used inviscid methods, and can greatly influence the pressure loading on the fin near the root.Mode of access: Internet