Download or read book Influence of Free stream Disturbances on Boundary layer Transition written by Bill Harvey and published by . This book was released on 1978 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influence of Free stream Disturbances on Boundary layer Transition written by William D. Harvey and published by . This book was released on 1978 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influence of Free stream Disturbances on Boundary layer Transition written by Bill Harvey and published by . This book was released on 1978 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influence of Measured Free stream Disturbances on Hypersonic Boundary layer Transition written by R. D. Wagner and published by . This book was released on 1969 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Mehod for the Prediction of the Effects of Free stream Disturbances on Boundary layer Transition written by J. A. Benek and published by . This book was released on 1973 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: A semiempirical expression for boundary-layer transition location is developed based on the concept of a critical ratio of inertial to viscous shearing stresses at laminar breakdown. Extensive comparisons between predicted and measured transition locations on a 10-deg included-angle cone at transonic speeds are shown with the data predicted to within 10%. Comparisons are also made with low subsonic and supersonic data which indicate the method is extendible to these flow regimes. (Author).
Download or read book Effects of Wind Tunnel Disturbances on Boundary layer Transition with Emphasis on Radiated Noise written by Samuel Ralph Pate and published by . This book was released on 1980 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Effects of wind tunnel free-stream disturbances on boundary-layer transition are reviewed. Experimental results show that free-stream disturbances dominate the transition process as determined by the experimentally measured transition Reynolds numbers on simple geometries (flat plates and sharp cones). Principal modes of disturbance are turbulence (u(tilde)/U infinity) and acoustic sound (p(tilde)/q infinity) at subsonic speeds; hole/slot acoustic resonance at transonic speeds (p(tilde)/q infinity); and tunnel wall turbulent-boundary layer radiated noise at supersonic-hypersonic speeds (p(tilde)/q infinity). Data correlations and resulting empirical equations that show the direct relationship between transition Reynolds numbers and free-stream disturbance levels are presented and discussed.
Download or read book Laminar turbulent Transition of Boundary Layer Influenced by Free stream Disturbances written by Pavel Jonáš and published by . This book was released on 1995 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Wind Tunnel Disturbances on Boundary layer Transition with Emphasis on Radiated Noise written by Samuel Ralph Pate and published by . This book was released on 1980 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Boundary Layer Transition at Supersonic Speeds written by E. R. Van Driest and published by . This book was released on 1961 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments carried out in the 12-inch supersonic wind tunnel to investigate the effect of three dimensional roughness elements (spheres) on boundary-layer transition on a 10-degree (apex angle) cone without heat transfer are described. The local Mach number for these tests was 2.71. The data show clearly that the minimum (effective) size of trip required to bring transition to its lowest Reynolds number varies power of the distance from the apex of the cone to the trip. Use of available data at other Mach numbers indicates that the Mach number influence for effective tripping is taken into account by a simple expression. Some remarks concerning the roughness variation for transition on a blunt body are made. Finally, a general criterion is introduced which gives insight to the transition phenomenon and anticipates effects of external and internal disturbances, Mach number transfer.
Download or read book Comments on Hypersonic Boundary layer Transition written by Kenneth F. Stetson and published by . This book was released on 1990 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Boundary Layer Receptivity to Freestream Disturbances and Its Role in Transition written by William S. Saric and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Method for the Prediction of the Effects of Free Stream Disturbances on Boundary Layer Transition written by J. A. Benek and published by . This book was released on 1973 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: A semiempirical expression for boundary-layer transition location is developed based on the concept of a critical ratio of inertial to viscous shearing stresses at laminar breakdown. Extensive comparisons between predicted and measured transition locations on a 10-deg included-angle cone at transonic speeds are shown with the data predicted to within 10%. Comparisons are also made with low subsonic and supersonic data which indicate the method is extendible to these flow regimes. (Author).
Download or read book Observations on the Influence of Ambient Pressure on Boundary layer Transition written by J. Leith Potter and published by . This book was released on 1968 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: For at least 15 yrs it has been known that the Reynolds number characterizing transition form laminar to turbulent boundary-layer flow (based on local properties and wetted length to transition) may be influenced by the local unit Reynolds number or some still unidentified, related quantity under both subsonic and supersonic conditions. Because examples of this were available almost exclusively from wind tunnel work, and because of the possibility that free-stream disturbances were responsible, there has been uncertainty as to whether the so-called unit Reynolds number effect exists in atmospheric free flight. The study described in the report was conducted in a free-flight range, thereby circumventing 'wind tunnel effects, ' and it has resulted in a demonstration of the variation of transition Reynolds number with range pressure (or unit Reynolds number) under conditions of fixed Mach number and average wall temperature ratio. Some preliminary measurements of sound pressures in the range air are reported for comparison with published results for wind tunnels. (Author).
Download or read book The Effects of Acoustical Disturbances on Boundary Layer Transition written by Gabriel Miller and published by . This book was released on 1978 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The analysis of transition from laminar to turbulent flow on a flat plate has been the subject of numerous investigations. In the present work, emphasis has been placed on establishing a computational technique which can be utilized to develop a basic understanding of the effects of the propagation of acoustic waves into a boundary layer, and the ultimate effect of such disturbances on transition. The nonlinear system of unsteady compressible partial differential equations have been solved by a MacCormack predictor-corrector scheme which allows the effect of imposed disturbances to be tracked in time. The question of the mismatch in propagation velocity between Tollmein Schlichting and acoustic waves has been studied. The program indicates that while disturbances are propagating with the speed of sound in the inviscid flow, the waves well within the boundary layer are propagating at a speed on the order of the freestream velocity and thus the boundary layer is being excited by the classical Tollmein Schlichting waves. The analysis thus indicates that the effect of acoustical disturbances on transition is similar to the effect of other perturbations as experiments have indicated. (Author).
Download or read book Study of the Effect of Free stream Turbulence Upon Disturbances in the Pre transitional Laminar Boundary Layer written by James M. Kendall and published by . This book was released on 1982 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Part I: Hot wire anemometry has been employed to determine certain characteristics of the turbulence in the free-stream of a low-speed, low-turbulence wind tunnel and to study the influence on such turbulence upon the fluctuations within a flat-plate boundary layer. A technique was employed which provided information concerning the propagation speed of the disturbances and this was used as a means of classification as to type or cause. It was found that Tollmien-Schlichting waves did not possess significant energy until a Reynolds number considerably higher than that of the theoretical neutral point was attained and that the subsequent growth exceeded the prediction of linear analysis. Part II: Distributed roughness present upon an aerodynamic surface alters the laminar boundary layer mean velocity profile such as to increase the instability presented here of the profile distortion for the case of small roughness in a Blasius boundary layer. The roughnesses tested include a single protuberance at Reynolds numbers below 50, the interaction between two such elements, the interaction between one element and a multitude of others, and the distortion due to distributed roughness. (Author).
Download or read book Effects of Free stream Turbulence on Boundary Layer Transition written by Th Herbert and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influence of High Amplitude Noise on Boundary Layer Transition to Turbulence written by William Saric and published by . This book was released on 1998 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work completes a series of detailed experiments of boundary layers undergoing transition to turbulence with the major effort directed toward the most important issue facing the understanding of fundamental causes of transition, i.e., the receptivity to freestream disturbances. This problem is reviewed in detail by Saric et al. (1994). The present effort concentrates on leading-edge receptivity and receptivity of two-dimensional roughness. The effects of large-amplitude freestream noise is considered with the effort directed toward determining the limits of linear receptivity. Single-frequency and broad-band sound waves are used along with 2-D roughness elements to determine how the unstable waves are initiated. New data are presented on leading edge-receptivity that clarify some difficulties with previous experimental work. Comparisons with recent DNS are excellent. Data are also presented for nonlinear receptivity of 2-D roughness elements. It is shown that there is little difference between the single-frequency excitation and white noise in that the response is still keenly triggered by the amplitude of the individual mode. Thus a single frequency at 120 dB is more dangerous than white noise at 120 dB where the energy is distributed of many modes.
