Comments on Hypersonic Boundary-layer Transition


Book Description

This is a survey paper on the subject of hypersonic boundary-layer transition. Part 1 discusses boundary-layer stability theory, hypersonic boundary-layer stability experiments, and a comparison between theory and experiment. Part 2 contains comments on how many configuration and flow parameters influence transition. Part 3 discusses some additional general aspects of transition. Part 4 discusses problems of predicting transition and comments on three prediction methods. Part 5 contains some general guidelines for prediction methodology. Keywords: Boundary layer transition, Boundary layer stability, Hypersonic boundary layers.




Hypersonic Boundary Layer Transition Experiments


Book Description

New hypersonic wind tunnel data have been obtained to investigate boundary layer transition, with primary emphasis given to tip bluntness and angle of attack effects. The rearward displacement of transition on the cone frustum due to tip bluntness was found to be quite sensitive to free stream Mach number as well as the entropy layer swallowing by the boundary layer. At the highest Mach number obtained in these experiments (M = 9.3), the length of laminar flow could be extended to about nine times the length of laminar flow of a sharp cone at identical conditions. The sensitivity of the maximum rearward displacement of transition with free stream Mach number appeared to be primarily related to local Reynolds number reduction because of pressure losses across the bow shock. Low transition Reynolds numbers typically found on nosetips, extended onto the front portion of the cone frustum. It appears that the still unexplained low transition Reynolds numbers associated with blunt bodies in hypersonic flow includes not only the nosetip region, but the forward portion of the cone frustum. Transition location was found to be sensitive to small changes in angle of attack, and both the sharp and blunt tips produced a rearward movement of transition on the windward ray at small angles of attack. A low supersonic flared nozzle closely duplicated the hypersonic pressure and heat transfer distributions over the nose region of a blunt body.







Comments on Hypersonic Boundary-Layer Transition


Book Description

This is a survey paper on the subject of hypersonic boundary-layer transition. Part 1 discusses boundary-layer stability theory, hypersonic boundary-layer stability experiments, and a comparison between theory and experiment. Part 2 contains comments on how many configuration and flow parameters influence transition. Part 3 discusses some additional general aspects of transition. Part 4 discusses problems of predicting transition and comments on three prediction methods. Part 5 contains some general guidelines for prediction methodology. Keywords: Boundary layer transition, Boundary layer stability, Hypersonic boundary layers.




Comments on Hypersonic Boundary-Layer Transition


Book Description

This is a survey paper on the subject of hypersonic boundary-layer transition. Part 1 discusses boundary-layer stability theory, hypersonic boundary-layer stability experiments, and a comparison between theory and experiment. Part 2 contains comments on how many configuration and flow parameters influence transition. Part 3 discusses some additional general aspects of transition. Part 4 discusses problems of predicting transition and comments on three prediction methods. Part 5 contains some general guidelines for prediction methodology. Keywords: Boundary layer transition, Boundary layer stability, Hypersonic boundary layers.




Advances in Hypersonics


Book Description

These three volumes entitled Advances in Hypersonics contain the Proceedings of the Second and Third Joint US/Europe Short Course in Hypersonics which took place in Colorado Springs and Aachen. The Second Course was organized at the US Air Force Academy, USA in January 1989 and the Third Course at Aachen, Germany in October 1990. The main idea of these Courses was to present to chemists, com puter scientists, engineers, experimentalists, mathematicians, and physicists state of the art lectures in scientific and technical dis ciplines including mathematical modeling, computational methods, and experimental measurements necessary to define the aerothermo dynamic environments for space vehicles such as the US Orbiter or the European Hermes flying at hypersonic speeds. The subjects can be grouped into the following areas: Phys ical environments, configuration requirements, propulsion systems (including airbreathing systems), experimental methods for external and internal flow, theoretical and numerical methods. Since hyper sonic flight requires highly integrated systems, the Short Courses not only aimed to give in-depth analysis of hypersonic research and technology but also tried to broaden the view of attendees to give them the ability to understand the complex problem of hypersonic flight. Most of the participants in the Short Courses prepared a docu ment based on their presentation for reproduction in the three vol umes. Some authors spent considerable time and energy going well beyond their oral presentation to provide a quality assessment of the state of the art in their area of expertise as of 1989 and 1991.




Transition of the Hypersonic Boundary Layer on a Cone


Book Description

The document covers observations of transitions of the hypersonic boundary layer on a cone at M = 10. Transition independent of the unit Reynolds number was obtained. Blunt cone transition with a wide range of nose radii was examined. It was found possible to correlate transition on different blunt cones using a new bluntness parameter. (Author).