Theoretical Studies Of Boundary Layer Receptivity
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Total Pages | : 85 |
Release | : 2004 |
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This report results from a contract tasking Moscow Institute of Physics and Technology as follows. To predict boundary-layer transition in a rational way and capture its sensitivity to freestream noise, turbulence, surface roughness. steps/gaps/waviness. etc. a toolbox combining receptivity theory with nonlinear Parabolized Stability Equations and Direct Navier-Stokes Simulation is needed. This project addresses this need with theoretical modeling of high speed boundary-layer receptivity to acoustic disturbances as they interact with 3D roughness elements and waviness. The effort is basic. theoretical research on receptivity. Using the multiple-modes method, a compact and computationally robust algorithm providing fast calculations of receptivity characteristics will be developed. This algorithm will be integrated into a computational module that can be linked with a standard stability solver. Receptivity calculations will be made for the conditions relevant to future experiments in the new high Reynolds-number. Mach-6. quiet Ludwieg' tube of Purdue University. This will help to formulate recommendations for design of receptivity experiments and interpretation of the data. The results of the project can also be applied at the component level to assess laminar flow control concepts.
Author | : J. D. Crouch |
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Total Pages | : |
Release | : 1994 |
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Author | : Meelan Choudhari |
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Total Pages | : |
Release | : 1994 |
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Author | : Mohsen Jahanmiri |
Publisher | : LAP Lambert Academic Publishing |
Total Pages | : 64 |
Release | : 2013 |
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ISBN | : 9783659364518 |
Receptivity is the process which describes how environmental disturbances (such as gusts, acoustic waves or wall roughness) are filtered by a boundary layer and turned into downstream growing waves. It is closely related to the identification of initial conditions for the disturbances and requires knowledge of the characteristics of the specific external forcing field. Due to important role of receptivity theory in transition process of boundary layers, quite a few research works have been carried out in past few decades. This research review report tries to highlight the major research activities in this field of study that includes: the theory, different types of receptivity, its effect in three-dimensional boundary layers and receptivity at high speeds.
Author | : National Aeronautics and Space Administration (NASA) |
Publisher | : Createspace Independent Publishing Platform |
Total Pages | : 80 |
Release | : 2018-06-04 |
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ISBN | : 9781720705826 |
Experimental and theoretical studies of low speed leading edge boundary layer receptivity to free-stream vorticity produced by upstream wires normal to the leading edge are discussed. Data include parametric variations in leading edge configuration and details of the incident disturbance field including single and multiple wakes. The induced disturbance amplitude increases with increases in the leading edge diameter and wake interactions. Measurements agree with the theory of M. E. Goldstein.Kogan, M. N. and Shumilkin, V. G. and Ustinov, M. V. and Zhigulev, S. V.Langley Research CenterVORTICITY; FREE FLOW; FLAT PLATES; BOUNDARY LAYERS; LEADING EDGES; WAKES; LOW SPEED; NONUNIFORMITY; WIRE
Author | : Meelan Choudhari |
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Total Pages | : 44 |
Release | : 1995 |
Genre | : Boundary layer |
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Author | : National Aeronautics and Space Adm Nasa |
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Total Pages | : 26 |
Release | : 2018-10-23 |
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ISBN | : 9781729112342 |
Direct numerical simulations (DNS) of the acoustic receptivity process on a semi-infinite flat plate with a modified-super-elliptic (MSE) leading edge are performed. The incompressible Navier-Stokes equations are solved in stream-function/vorticity form in a general curvilinear coordinate system. The steady basic-state solution is found by solving the governing equations using an alternating direction implicit (ADI) procedure which takes advantage of the parallelism present in line-splitting techniques. Time-harmonic oscillations of the farfield velocity are applied as unsteady boundary conditions to the unsteady disturbance equations. An efficient time-harmonic scheme is used to produce the disturbance solutions. Buffer-zone techniques have been applied to eliminate wave reflection from the outflow boundary. The spatial evolution of Tollmien-Schlichting (T-S) waves is analyzed and compared with experiment and theory. The effects of nose-radius, frequency, Reynolds number, angle of attack, and amplitude of the acoustic wave are investigated. This work is being performed in conjunction with the experiments at the Arizona State University Unsteady Wind Tunnel under the direction of Professor William Saric. The simulations are of the same configuration and parameters used in the wind-tunnel experiments. Reed, Helen L. Unspecified Center ...
Author | : Ian John Sobey |
Publisher | : OUP Oxford |
Total Pages | : 350 |
Release | : 2000 |
Genre | : Mathematics |
ISBN | : 9780198506751 |
One of the major achievements in fluid mechanics in the last quarter of the twentieth century has been the development of an asymptotic description of perturbations to boundary layers known generally as 'triple deck theory'. These developments have had a major impact on our understanding of laminar fluid flow, particularly laminar separation. It is also true that the theory rests on three quarters of a century of development of boundary layer theory which involves analysis, experimentation and computation. All these parts go together, and to understand the triple deck it is necessary to understand which problems the triple deck resolves and which computational techniques have been applied. This book presents a unified account of the development of laminar boundary layer theory as a historical study together with a description of the application of the ideas of triple deck theory to flow past a plate, to separation from a cylinder and to flow in channels. The book is intended to provide a graduate level teaching resource as well as a mathematically oriented account for a general reader in applied mathematics, engineering, physics or scientific computation.
Author | : Xiaolin Zhong |
Publisher | : |
Total Pages | : 46 |
Release | : 2007 |
Genre | : Aerodynamics, Hypersonic |
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The objective of this research project is to compare our numerical simulation solutions with available experimental or theoretical results on hypersonic boundary layer receptivity and stability; and to conduct extensive DNS studies on the flow mechanisms of hypersonic boundary layer receptivity and stability. During the three-year period, we have conducted extensive DNS studies on the receptivity of hypersonic boundary layer flows over a sharp wedge, a flat plate, a blunt cone, and the FRESH aeroshell. DNS studies are compared with Stetson's 1984 stability experiment on Mach 7.99 flow over a blunt cone, and Maslov's leading-edge receptivity experiment on Mach 5.92 flow over a flat plate. Our numerical studies have been validated to be of high accuracy and led to further understanding of hypersonic boundary layer receptivity mechanism. Such understanding can lead to better tools for the prediction and control of high-speed boundary layer transition.
Author | : Thorwald Herbert |
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Release | : 1993 |
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