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Monday, November 16, 2020 | History

2 edition of On the effect of boundary layer growth on the stability of compressible flows found in the catalog.

On the effect of boundary layer growth on the stability of compressible flows

Nabil M. El-Hady

On the effect of boundary layer growth on the stability of compressible flows

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  • 9 Currently reading

Published by National Aeronautics and Space Administration, Scientific and Technical Information Branch, For sale by the National Technical Information Service] in Washington, D.C, [Springfield, Va .
Written in English

    Subjects:
  • Boundary layer -- Mathematical models.,
  • Laminar flow -- Mathematical models.,
  • Stability -- Mathematical models.

  • Edition Notes

    StatementNabil M. El-Hady ; prepared for Langley Research Center under grant NSG-1645.
    SeriesNASA contractor report -- NASA CR-3474.
    ContributionsUnited States. National Aeronautics and Space Administration. Scientific and Technical Information Branch., Langley Research Center.
    The Physical Object
    Pagination44 p. :
    Number of Pages44
    ID Numbers
    Open LibraryOL17827299M

    Note presenting numerical solutions of quantities appearing in the Karman momentum equation for the development of a turbulent boundary layer in plane and in radial compressible flows along thermally insulted surfaces in tabular form for a rnage of Mach numbers from to Through use of the tables, approximate calculation of boundary-layer growth is reduced to routine arithmetic. A boundary layer is a thin region of fluid near a wall where viscous effects are important in determining the flow field. The boundary layer is a buffer region between the wall below and the inviscid free-stream above. Mathematically, its main pur. A theory for turbulent compressible boundary layer flow over a flat plate is presented, taking into account the effects of heat transfer on the conditions at the edge of the laminar sublayer. The skin friction equations are derived from the definition of boundary-layer momentum thickness and the momentum equation, from which von Karman's.


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On the effect of boundary layer growth on the stability of compressible flows by Nabil M. El-Hady Download PDF EPUB FB2

Get this from a library. On the effect of boundary layer growth on the stability of compressible flows. [Nabil M El-Hady; United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch.; Langley Research Center.].

On the effect of boundary layer growth on the stability of compressible flows - NASA/ADS The method of multiple scales is used to describe a formally correct method based on the nonparallel linear stability theory, that examines the two and three dimensional stability of compressible boundary layer by: 6.

On the effect of boundary layer growth on the stability of compressible flows. By N. El-Hady. Abstract. The method of multiple scales is used to describe a formally correct method based on the nonparallel linear stability theory, that examines the two and three dimensional stability of compressible boundary layer flows.

The method is Author: N. El-Hady. On the effect of boundary layer growth on the stability of compressible flows / By Nabil M. El-Hady, United States. National Aeronautics and Space Administration.

The base flow is the compressible laminar boundary layer with pressure gradien t. It contains all the physical properties as the dual effects of wall-heating and fav ourable pressure gradient. An analytical solution is derived for the two-dimensional, laminar, compressible, planar free jet.

The solution assumes constant pressure, specific heats, and unity Prandtl number and accounts for the effects of heat conduction and viscous dissipation in a self-consistent fashion. Exact closed-form expressions are provided for the streamwise and transverse velocities, temperature, vorticity.

On the effects of boundary-layer growth on flow stability: Authors: Gaster, M. Fluid Mechanics and Heat Transfer: Origin: STI: NASA/STI Keywords: Boundary Layer Stability, Flat Plates, Flow Stability, Orr-Sommerfeld Equations, Traveling Waves, Asymptotic Series, Flow Equations, Fluid Dynamics, Hydrodynamic Equations, Iterative Solution.

Stability of compressible boundary layer flow over indented surfaces is considered. Small surface indentations enhance certain flow instabilities. An increase in Mach number enhances further this behaviour.

Amplification for deepest case are locally up to 20 times larger than in flat plate. Boundary Layer in Compressible Fluids. Critical layer concept relative to hypersonic boundary layer stability. Leading Edge Bluntness and Slip Flow Effects in High Temperature Hypervelocity Flow Over a Flat Plate* *This research was partially supported by the Ballistic Systems Division, United States Air Force.

The Turbulent Boundary Layer in Compressible Flow W. CoP~, M.A., E., of the Engineering Division, N.P.L. Reports and Memoranda No. 28¢o* November, SummaryThe flow of a compressible gas past a fiat plate is investigated for a turbulent boundary layer. The. On the density ratio effect on the growth rate of a compressible mixing layer Physics of Fluids, Vol.

6, No. 2 Linear stability analysis of density stratified parallel shear flows. There have been very few studies of nonlinear effects in the stability of compressible boundary layer flows and in this paper we address at least some aspects of the nonlinear theory relevant for modes on the upper-branch.

We show that the neutral modes are now governed by the properties of the compressible critical layer equation. The method of multiple scales is used to describe a formally correct method based on the nonparallel linear stability theory, that examines the two and three dimensional stability of compressible boundary layer flows.

The method is applied to the supersonic flat plate layer at Mach number The theoretical growth rates are in good agreement with experimental results. Boundary Layer Mach Number Transient Growth Neutral Stability Curve Supersonic Boundary Layer These keywords were added by machine and not by the authors.

This process is experimental and the keywords may be updated as the learning algorithm improves. The stability of compressible two- and three-dimensional boundary layers is reviewed. The stability of 20 compressible flows differs from that of incompressible flows in two important features: There is more than one mode of instability contributing to the growth of disturbances in supersonic laminar boundary layers and.

A study is conducted to investigate the effect of thermodynamic properties on the stability of compressible boundary layer flows. Both variable Prandtl number and variable C p show up to 25 percent variation in the growth rates when compared against results obtained when these parameters are held constant.

Two-dimensional Laminar Compressible Boundary- layer Programme for a Perfect Gas By C. Sells Reports and Memoranda No. * August, Summary. A computer programme has been written to solve the steady laminar two-dimensional boundary- layer equations for a perfect gas at given wall temperature, without wall suction.

The programme solves. The upper-branch linear and nonlinear stability of compressible boundary layer flows is studied using the approach of Smith and Bodonyi () for a similar incompressible problem.

The potential for transient growth in compressible boundary layers is studied. Transient amplification is mathematically associated with a non‐orthogonal eigenvector basis, and can amplify disturbances although the spectrum of the linearized evolution operator is entirely confined to the stable half‐plane.

Compressible boundary layer flow shows a large amount of transient growth over a. The resolvent formulation of McKeon & Sharma (J. Fluid Mech., vol.pp. –) is applied to supersonic turbulent boundary layers to study the validity of Morkovin’s hypothesis, which postulates that high-speed turbulence structures in zero-pressure-gradient turbulent boundary layers remain largely the same as their incompressible counterparts.

Supersonic zero-pressure-gradient turbulent boundary layers. Effect of wall cooling on the stability of compressible subsonic flows over smooth humps and backward-facing steps: Authors: Boundary Layer Stability, Compressible Flow, Subsonic Flow, Surface Cooling, Boundary Layer Control, Flow Equations, Laminar Boundary Layer, Laminar Flow, Mach Number, Shear Layers, Surface Defects it increases.

This paper represents a continuation of the work by Tempelmann et al. Fluid Mech., vol. b, pp. 5–37) on spatial optimal growth in incompressible boundary layers over swept flat present an extension of the methodology to compressible flow.

Also, we account for curvature effects. Figure 1. Growth of a boundary layer on a flat plate. The fundamental concept of the boundary layer was suggested by L. Prandtl (), it defines the boundary layer as a layer of fluid developing in flows with very high Reynolds Numbers Re, that is with relatively low viscosity as compared with inertia forces.

This is observed when bodies are. This second edition of the book, Modeling and Computation of Boundary-Layer Flows^ extends the topic to include compressible flows.

This implies the inclusion of the energy equation and non-constant fluid properties in the continuity and momentum : Hardcover. The effect of a laminar boundary layer on the stability of a plate in axial flow is discussed in Carpenter ().

It is shown that the presence of a boundary layer, no matter how thin, causes the effective flutter velocity to jump from U cf down to a lower velocity, similarly to the effect of damping.

An important difference, however, is that the boundary layer destabilizes Class B waves, whereas damping. Three-dimensional linear secondary instability theory is extended for compressible and high Mach number boundary layer flows. The small but finite amplitude compressible Tollmien-Schlichting wave effect on the growth of 3-D perturbations is investigated.

The focus is on principal parametric resonance responsible for the strong growth of subharmonic in low disturbance environment. Effects of Particulate Diffusion on the Compressible Boundary-Layer Flow of a Two-Phase Suspension Over a Horizontal Surface Ali J.

Chamkha Department of Mechanical and Industrial Engineering, Kuwait University, P.O. BoxSafat, Kuwait. Boundary-Layer Stability and Transition W. Saric Arizona State University Tempe, USA Abstract Within the last five years, increased emphasis on secondary instability analysis along with the experimental observations of subharmonic instabilities have changed the picture of the transition process for boundary layers in low-disturbance.

Stability of Swept-Wing Boundary Layers Some of my early projects at Texas A&M dealt with the stability of the boundary layer on a swept wing, like those found on most commercial transports. Due to the swept angle of the leading edge, flow on these wings is three-dimensional and the pressure gradient across the wing results in a secondary flow.

The early stage of laminar-turbulent transition in a hypervelocity boundary layer is studied using a combination of modal linear stability analysis, transient growth analysis, and direct numerical simulation.

Modal stability analysis is used to clarify the behavior of first and second mode instabilities on flat plates and sharp cones for a wide range of high enthalpy flow conditions relevant. In physics and fluid mechanics, a boundary layer is the layer of fluid in the immediate vicinity of a bounding surface where the effects of viscosity are significant.

In the Earth's atmosphere, the atmospheric boundary layer is the air layer near the ground affected by diurnal heat, moisture or momentum transfer to or from the surface. On an aircraft wing the boundary layer is the part of the. T1 - Stabilisation of first-mode disturbances in compressible boundary-layer flows.

AU - Tunney, A. AU - Denier, J. PY - Y1 - N2 - The growth of inviscid, subsonic disturbances in an external, compressible boundary-layer flow is linked with the existence of generalised points of inflection in the base flow.

Fundamentals of Boundary Layers | Fluid Mechanics Grays's Paradox- Boundary Layer Effect (Explained) - Duration: Channel Flow of a Compressible Fluid. Boundary layer thickness.

The boundary layer thickness, δ, is the distance across a boundary layer from the walls to a point where the flow velocity has essentially reached the 'free stream' velocity.This distance is defined normal to the wall.

It is customarily defined as the point where: =at a point on the laminar boundary layers over a flat plate, the Blasius solution to the. A compressible supersonic confluent flow composed of boundary layers and mixing layers are studied by linear stability theory.

The flow is confined in a two-dimensional adiabatic channel. A slower flow lying in the center mixes with faster boundary layer flows on both sides and two mixing layers are evolved near the centerline.

Different unstable modes were discovered and the first mode was. In this paper, the hydrodynamic stability of the compressible boundary layer in chemical equilibrium was investigated using linearized Navier-Stokes simulations including a.

Numerical Methods for Hypersonic Boundary Layer Stability M. MALIK High Technology Corporation, P.O. BoxHampton, Virginia Received J revised Ma Various numerical methods for the solution of linear stability equations for compressible boundary layers are compared.

This study compares the mean and turbulent boundary layer velocity characteristics of surfaces covered with a marine biofilm with those of a smooth surface.

Measurements were made in a nominally zero pressure gradient, boundary layer flow with a two-component laser Doppler velocimeter at momentum thickness Reynolds numbers of to 19, in. The effect of compressibility on the structure of boundary layer needs study. The present effort is to study the stability behaviour of the supersonic and hypersonic boundary layers in the presence of adverse pressure gradients and free stream turbulence.

Compressible boundary layers have dominantly 2-D instabilities of Tollmein. The fluid flow phenomenon of boundary layer transition is a complicated and difficult process to model and predict. The importance of the state of the boundary layer with regard to vehicle design cannot be understated. compressible transient growth disturbances are simulated using a linear optimal disturbance solver as well as a CFD solver.

The data we will use to assess the linear stability of boundary layer flows will, in the majority of cases, be limited to the region of the boundary flow itself. In previous treatments of flow using the Taylor-Goldstein equation it is assumed that there is some point in the flow where a solid boundary .Even in subsonic flow, the effects of such variables as free-stream turbulence, surface curvature, pressure gradient, surface roughness, and surface temperature are known only qualitatively.

While the theory of laminar boundary-layer stability yields the conditions necessary for instability, it does not permit prediction of the transition point.turbulent boundary layer behavior is undoubtedly the Reynolds number.

For compressible flows, the Mach number becomes a further scaling parameter. Within the boundary layer, the flow is supersonic in the outer layer and subsonic near the wall, although the sonic line is .