Physical Models for Supersonic Turbulent Boundary Layer Structure


Book Description

An experimental program was carried out to study the detailed structure of supersonic turbulent boundary layers. The experiments were designed to elucidate physical models and mechanisms that are particular to compressible turbulence, such as the effects of compressibility on the nature of the large- scale motions, the scaling laws for high Reynolds number supersonic turbulent flows, direct compressibility effects that cause the exchange of turbulence energy among the vorticity, entropy and sound modes, and the transport of heat and momentum by compressible turbulent motions. A description of the new optical experimental tools that were developed is included. (EDC).
















Turbulent Shear Layers in Supersonic Flow


Book Description

A good understanding of turbulent compressible flows is essential to the design and operation of high-speed vehicles. Such flows occur, for example, in the external flow over the surfaces of supersonic aircraft, and in the internal flow through the engines. Our ability to predict the aerodynamic lift, drag, propulsion and maneuverability of high-speed vehicles is crucially dependent on our knowledge of turbulent shear layers, and our understanding of their behavior in the presence of shock waves and regions of changing pressure. Turbulent Shear Layers in Supersonic Flow provides a comprehensive introduction to the field, and helps provide a basis for future work in this area. Wherever possible we use the available experimental work, and the results from numerical simulations to illustrate and develop a physical understanding of turbulent compressible flows.




Analysis of the Three-dimensional Compressible Turbulent Boundary Layer on a Sharp Cone at Incidence in Supersonic and Hypersonic Flow


Book Description

An analytical approach toward numerical calculation of the three-dimensional turbulent boundary layer on a sharp cone at incidence under supersonic and hypersonic flow conditions is presented. The theoretical model is based on implicit finite-difference integration of the governing three-dimensional turbulent boundary-layer equations in conjunction with a three-dimensional scalar eddy-viscosity model of turbulence. Comparison is made of present theory with detailed experimental measurements of the three-dimensional turbulent boundary-layer structure (velocity and temperature profiles), the surface streamline direction (obtained via an oil-flow technique) and surface heat-transfer rate.




The Structure of Turbulent Boundary Layers and Shock Wave Boundary Layer Interactions


Book Description

This report is the Final Technical Report for AFOSR Grant 89-0420, monitored by Dr James McMichael, for the period June 15, 1989 to October 14, 1992. Under this program, research was performed (1) to describe the structure of the large-scale motions in supersonic turbulent boundary layers, (2) to study the interaction of that turbulence with shock waves and strategies for controlling the interaction, (3) to differentiate between Mach and Reynolds number effects on turbulence structure in wall-bounded flows, and (4) to develop and implement new non-intrusive diagnostic techniques. The research is aimed at providing physical insight, and scaling information, for the development of turbulence models appropriate for supersonic shear layers. The primary experimental means used in these investigations were the Rayleigh scattering technique to study the instantaneous density field, the RELIEF line tagging method to study the instantaneous velocity field, and a dual hot-wire technique to obtain simultaneous velocity and density signals ... Boundary layers, Turbulence, Shock wave boundary layer interaction.




On the Coupling Between a Supersonic Turbulent Boundary Layer and a Flexible Structure


Book Description

A mathematical model and a computer code have been developed to fully couple the vibration of an aircraft fuselage panel to the surrounding flow field, turbulent boundary layer and acoustic fluid. The turbulent boundary layer model is derived using a triple decomposition of the flow variables and applying a conditional averaging to the resulting equations. Linearized panel and acoustic equations are used. Results from this model are in good agreement with existing experimental and numerical data. It is shown that in the supersonic regime, full coupling of the flexible panel leads to lower response and radiation from the panel. This is believed to be due to an increase in acoustic damping on the panel in this regime. Increasing the Mach number increases the acoustic damping, which is in agreement with earlier work. Frendi, Abdelkader Unspecified Center NAS1-19700; RTOP 537-06-37-20...