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Tuesday, August 11, 2020 | History

1 edition of Laminar boundary layer development downstream of a suction slot found in the catalog.

Laminar boundary layer development downstream of a suction slot

by Sabri Cigdem

  • 24 Want to read
  • 16 Currently reading

Published .
Written in English

    Subjects:
  • Mechanical engineering

  • The Physical Object
    Paginationp. ;
    ID Numbers
    Open LibraryOL25266139M

    About the development of swept laminar suction wings with full chord flap blowing flap deflexion flight tests fluid ground effect high lift increase installation investigations jet sheet jet-flap laminar boundary layer laminar flow leading edge lift coefficient lift increment limiting streamlines Mach number mass flow maximum lift. Roy, S. and Thakar, H.S., Compressible boundary layer flow with non-uniform slot injection (or suction) over (i) a cylinder and (ii) a sphere. Heat Mass Transfer. v Google Scholar [7]. Roy, S. and Saikrishnan, P., Non-uniform slot injection (suction) into steady laminar water boundary layer flow over a rotating sphere. Int. by: 4.

    Unsourced material may be challenged and removed. Boundary layer suction is a boundary layer control technique in which an air pump is used to extract the boundary layer at the wing or the inlet of an aircraft. Improving the air flow can reduce drag. Improvements in fuel efficiency have been estimated as high as 30%. influences the development of a boundary layer along a surface and in particular can prevent or at least delay separation of the viscous region. Several investigators [8 – 10] have studied the effect of slot suction (injection) into a laminar compressible boundary layer by considering the interaction.

    these is suction where mass is drawn away from the laminar boundary layer through porous walls or slots. If sufficient suction is applied and the boundary layer is not allowed to develop and grow normally, the boundary layer presumably will remain laminar; thus, the associated skin friction will be lower than that for turbulent flow. Another Cited by: Aircraft laminar flow control (LFC) from the s through the s is reviewed and the current status of the technology is assessed. Examples are provided to demonstrate the benefits of LFC for subsonic and supersonic aircraft. Early studies related to the laminar boundary-layer flow physics, manufacturing tolerances for laminar flow, and insect-contamination avoidance are discussed. LFC Cited by:


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Laminar boundary layer development downstream of a suction slot by Sabri Cigdem Download PDF EPUB FB2

Enter the password to open this PDF file: Cancel OK. File name:. Approved for public release; distribution in r boundary layer development downstream of a suction slot was investigated in a low velocity wind tunnel.

In order to observe the effect of suction on the boundary layer, detailed boundary layer profiles were measured at various stations upstream and downstream of a suction slot for different suction flow : Sabri Cigdem. Books. AIAA Education Series; Library of Flight; Progress in Astronautics and Aeronautics; The Aerospace Press; Browse All Books; Meeting Papers; Standards; Other Publications.

About; For Authors ; Vol Issue 6. No Access. Investigation of a Laminar Boundary-Layer Suction by: To this end, we study the variation in the downstream development of a laminar boundary layer as a function of blowing amplitude through a slot by carrying out numerical simulations of a two-dimensional, unsteady, spatially-developing laminar boundary layer.

For relatively weak blowing amplitudes, no separation is observed downstream of the by: 3. The problem of the flow of a laminar boundary layer into a suction slot has been examined experimentally in a low turbulence water channel.

A dimensional analysis is used to determine the variables that are important to the problem and these are found to be the slot Reynolds number and a new parameter that is introduced to describe the mean velocity gradient in the flow above the by: 1. Through a short perforated wall strip, local boundary layer suction is applied to a turbulent boundary layer to generate a quasi-laminar boundary layer with highintensity active turbulence.

The retransition begins with algebraic growth of streamwise streaks from immediately behind the : Masahito Asai, Yasufumi Konishi, Yuki Oizumi, Michio Nishioka.

The chordwise suction distribution, for which the crossflow Reynolds number at various chordwise stations is 40 percent higher than the corresponding local crossflow stability limit Reynolds number, can then be determined from calculations of the development and stability of the laminar boundary layer on swept laminar suction wings.

noise. A suction slot is present upstream of the throat and removes the boundary layer on the contraction wall, allowing a new undisturbed laminar boundary layer to grow on the nozzle wall.

The suction slot is connected to the vacuum tank through a fast valve. The fast valve can be closed to allow a turbulent nozzle-wall boundary layer to by: Investigations of the asymptotic suction boundary layer. Jens H. Fransson Department of Mechanics, Royal Institute of Technology SE 44 Stockholm, Sweden Abstract An experimental and theoretical study on the e ect of boundary layer suction on the laminar-turbulent transition process has been carried out.

Both exper. of suction can prevent the boundary-layerflow from becoming fully turbulent. If transition is to be prevented by means of suction, it is essential that the suction should start in a region where the boundary layer is still in an undisturbed laminar condition.

The safest arrangement would be to start the suction at the leading edge. This might indeed beFile Size: 1MB. Numerical Study of Strong Slot Injection into a Supersonic Laminar Boundary Layer. Michele NapolitanoCited by: the viewpoint of classical non-interactive boundary-layer theory. Next, interactive boundary-layer theory is introduced in the context of un-steady separation.

This discussion leads onto a consideration of large-Reynolds-number asymptotic instability theory. We emphasise that a key aspect of boundary-layer theory is the development of singularities.

Development of boundary layer over a flat plate including the transition from a laminar to turbulent boundary layer. The fluid is streaming in from the left with a free stream velocity and due to the no-slip condition slows down close to the surface of the plate.

of the viscous region. Several investigators [11 - 13] have studied the effect of slot injection (suction) into a laminar compressible boundary layer over a flat plate by considering the interaction between the boundary layer and oncoming stream.

Uniform mass transfer in. boundary layer is laminar or turbulent. Thus, the larger the ball, the lower the speed at which a rough surface can be of help in reducing the drag. • Typically sports ball games that use surface roughness to promote an early transition of the boundary layer from a laminar to a turbulent flow are played over a Reynolds number range that isFile Size: 1MB.

In the suction case, the flow recovers from the immedi-ate rear of the slot. These features are also observed in three-dimensional views of the near-wall vortices. Introduction Wall blowing or suction through a spanwise slot in a tur-bulent boundary layer has been frequently employed due to its potential possibility for turbulence control.

Boundary layer tripping, i.e., forcing it from a laminar state into a turbulent state, is commonly used to fix the point of transition, to prevent laminar separation bubbles from occurring and to reduce the drag of bluff bodies at certain Reynolds numbers.

This forcing can be performed through various means: blowing/suction through a slot in Cited by: Suction is also an effective means of the boundary layer laminarization, which decreases friction losses (see Boundary Layer).

The effect of suction on the laminar boundary layer stability is due to decrease of the boundary layer thickness (a thinner boundary layer is less liable to turbulization) and also due to the changes in the velocity profile (it becomes more filled).

The ratio of momentum ux gain/loss due to the blowing/suction and momentum ux of the incoming boundary layer, ¾ D v w b=U 1 µ slot, iswhere µ slot is the momentum thickness without.

This book is organized into two main topics—boundary layer control for low drag, and shock-induced separation and its prevention by design and boundary layer control.

It specifically discusses the nature of transition, effect of two-dimensional and isolated roughness on laminar flow, and progress in the design of low drag Edition: 1. DNS study of discrete suction in a 3-D boundary layer downstream development of these disturbances and oversuction.

streamwise vortices outside the boundary layer. A suction/blowing slot.The investigation presented in this workshop is focused on the laminar-turbulent boundary layer transition on a two-dimensional airfoil, in particular at measuring the development and amplifica- tion of the Tollmien-Schlichting (TS) instabilities leading to transition.in the boundary layer of an external flow at high Reynolds number (see figure 1).

This flow structure could be caused by wall suction, slot injection, wall turning, etc. or in our problem by a small three-dimensional wall roughness. The Reynolds number is defined as: Re = Us L*/u, () where u is the kinematic viscosity of the fluid. This.