Numerical Investigation of Boundary Layer Transition Over Flat-Plate PDF Download
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Author: Kunlun Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
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Book Description
This paper presents two numerical cases of disturbed Navier-Stokes equations. In case 1, four order accuracy finite difference is used to investigate the evolution of negative frequency disturbance in Blasius boundary layer, results show us that negative frequency can reduce the streamwise wavelength of T-S wave, and accelerate the transition process. The effect of negative frequency lets to the breakdown of fluid structure becomes more significant. And, in the case two, two order accuracy finite volume method is used, Reynolds number is 900, and dimensionless frequency F is 86 in this case. Results present that the evolution process is more gradual in the positive frequency compare with the negative frequency in case 1. And the pressure contours clearly present a nonlinear interaction and break down process of two lambda vortexes.
Author: Kunlun Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
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Book Description
This paper presents two numerical cases of disturbed Navier-Stokes equations. In case 1, four order accuracy finite difference is used to investigate the evolution of negative frequency disturbance in Blasius boundary layer, results show us that negative frequency can reduce the streamwise wavelength of T-S wave, and accelerate the transition process. The effect of negative frequency lets to the breakdown of fluid structure becomes more significant. And, in the case two, two order accuracy finite volume method is used, Reynolds number is 900, and dimensionless frequency F is 86 in this case. Results present that the evolution process is more gradual in the positive frequency compare with the negative frequency in case 1. And the pressure contours clearly present a nonlinear interaction and break down process of two lambda vortexes.
Author: Yongxiang Wu
Publisher:
ISBN: 9783843952101
Category :
Languages : en
Pages : 0
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 232
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Book Description
This work focuses on instability mechanisms of high-speed boundary layers over flat plates and cones with a circular cross section. Supersonic transition investigations at Mach 2 and hypersonic transition investigations at Mach 8 are performed using Direct Numerical Simulations (DNS). At wind-tunnel conditions, these simulations allow for comparison with experimental measurements to verify fundamental stability characteristics. For the DNS of boundary-layer transition at Mach 2, the experimental studies by Kosinov et al. (1994) and Ermolaev et al. (1996) for a flat plate serve as reference and provide the physical conditions for the numerical setup. In these experiments, the weakly nonlinear regime of transition was studied resulting in the discovery of asymmetric subharmonic resonance triads. Scrutinizing the experimental data, reveals however the presence of another, possibly competing breakdown mechanism, in the experiments. Both mechanisms were addressed in detail in this work. To better understand geometrical influences, flat-plate and cylindrical geometries are studied under after-shock conditions of the conical investigations (experiments). This allows for a direct comparison with the results of the sharp cone to evaluate the influence of spanwise curvature and cone opening angle. The ratio of the boundary layer thickness to the spanwise radius is used to determine the importance of spanwise curvature effects. For a cone, in downstream direction the radius increases linearly while the boundary layer thickness stays almost constant. Hence, spanwise curvature effects are strongest close to the nose tip and decrease in downstream direction. Their influences on the secondary instability mechanisms provide some preliminary guidance in the design for future high-speed air vehicles.
Author: W. J. McCroskey
Publisher:
ISBN:
Category :
Languages : en
Pages : 40
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Book Description
The addition of heat to the boundary layer of an insulated flat plate by means of a point heat source at the leading edge has been found to delay the transition of laminar flow to turbulence. This paper describes an experimental investigation of the variation of transition Reynolds number on a roughened flat plate model with a heat source of strength, Q, spanning the leading edge. The present problem is compared with the problem of an aerodynamically heated boundary layer on an insulated flat plate. Transition Reynolds number was found to increase with increasing S over a range equivalent to a Mach number variation of 0
Author: Siegfried Wagner
Publisher: Springer Science & Business Media
ISBN: 3540450602
Category : Technology & Engineering
Languages : en
Pages : 334
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Book Description
The 24 papers presented at the international concluding colloquium of the German priority programme (DFG-Verbundschwerpunktprogramm) "Transition", held in April 2002 in Stuttgart. The unique and successful programme ran six years, starting April 1996, and was sponsored mainly by the Deutsche Forschungsgemeinschaft, DFG, but also by the Deutsches Zentrum für Luft-und Raumfahrt, DLR, the Physikalisch-Technische Bundesanstalt Braunschweig, PTB, and Airbus Deutschland. The papers summarise the results of the programme and cover transition mechanisms, transition prediction, transition control, natural transition and measurement techniques, transition - turbulence - separation, and visualisation issues. Three invited papers are devoted to mechanisms of turbulence production, to a general framework of stability, receptivity and control, and a forcing model for receptivity analysis. Almost every transition topic arising in subsonic and transonic flow is covered.
Author: H. F. Fasel
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Edward J. Hopkins
Publisher:
ISBN:
Category : Boundary layer
Languages : en
Pages : 36
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Book Description
Author: James R. Hall
Publisher:
ISBN:
Category : Boundary layer
Languages : en
Pages : 34
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Book Description
Author: Kyung Soo Yang
Publisher:
ISBN:
Category :
Languages : en
Pages : 184
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Book Description
Author: Tuncer Cebeci
Publisher: Elsevier
ISBN: 0323151051
Category : Technology & Engineering
Languages : en
Pages : 423
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Book Description
Analysis of Turbulent Boundary Layers focuses on turbulent flows meeting the requirements for the boundary-layer or thin-shear-layer approximations. Its approach is devising relatively fundamental, and often subtle, empirical engineering correlations, which are then introduced into various forms of describing equations for final solution. After introducing the topic on turbulence, the book examines the conservation equations for compressible turbulent flows, boundary-layer equations, and general behavior of turbulent boundary layers. The latter chapters describe the CS method for calculating two-dimensional and axisymmetric laminar and turbulent boundary layers. This book will be useful to readers who have advanced knowledge in fluid mechanics, especially to engineers who study the important problems of design.
