Turbulent Boundary Layer and Flow Resistance on Plates Roughened by Wires

1976 ◽  
Vol 98 (4) ◽  
pp. 635-643 ◽  
Author(s):  
Y. Furuya ◽  
M. Miyata ◽  
H. Fujita
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Surface Resistance ◽  
Flow Resistance ◽  
Flow Direction ◽  
Roughness Element ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Secondary Currents ◽  
Pressure Drag

The flow resistance in a plate roughened by equally spaced wires at right angles to the flow direction was investigated experimentally by measuring the turbulent boundary layer developing along it. Measurements of pressure distribution around a roughness element revealed that the pressure drag accounts for a large portion of the surface resistance and remaining skin frictional part is almost equal to that of a smooth plate. Measurements were also made for plates having three-dimensional roughness. These plates were roughened by short wires in a staggered manner. In this case, the boundary layer was found to have a three-dimensional structure due to accompanying secondary currents.

scholarly journals Receptivity of a laminar boundary layer to the interaction of a three-dimensional roughness element with time-harmonic free-stream disturbances

1992 ◽  
Vol 242 ◽  
pp. 701-720 ◽  
Author(s):  
M. Tadjfar ◽  
R. J. Bodonyi
Keyword(s):  
Boundary Layer ◽  
Laminar Boundary Layer ◽  
Stokes Flow ◽  
Free Stream ◽  
Flow Direction ◽  
Roughness Element ◽  
Three Dimensional ◽  
Unsteady Motion ◽  
Time Harmonic ◽  
Tollmien Schlichting

Receptivity of a laminar boundary layer to the interaction of time-harmonic free-stream disturbances with a three-dimensional roughness element is studied. The three-dimensional nonlinear triple–deck equations are solved numerically to provide the basic steady-state motion. At high Reynolds numbers, the governing equations for the unsteady motion are the unsteady linearized three-dimensional triple-deck equations. These equations can only be solved numerically. In the absence of any roughness element, the free-stream disturbances, to the first order, produce the classical Stokes flow, in the thin Stokes layer near the wall (on the order of our lower deck). However, with the introduction of a small three-dimensional roughness element, the interaction between the hump and the Stokes flow introduces a spectrum of all spatial disturbances inside the boundary layer. For supercritical values of the scaled Strouhal number, S0 > 2, these Tollmien–Schlichting waves are amplified in a wedge-shaped region, 15° to 18° to the basic-flow direction, extending downstream of the hump. The amplification rate approaches a value slightly higher than that of two-dimensional Tollmien–Schlichting waves, as calculated by the linearized analysis, far downstream of the roughness element.

Three-Dimensional Structure of Pressure–Velocity Correlations in a Turbulent Boundary Layer

2015 ◽  
pp. 103-113
Author(s):  
Yoshitsugu Naka ◽  
Michel Stanislas ◽  
Jean-Marc Foucaut ◽  
Sebastien Coudert ◽  
Jean-Philippe Laval
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Three Dimensional Structure

0517 Three-dimensional structure of the linear disturbance in a turbulent boundary layer

2013 ◽  
Vol 2013 (0) ◽  
pp. _0517-01_-_0517-02_
Author(s):  
Masanari NAGASAKI ◽  
Taiki MISHIBA ◽  
Konosuke MATSUMOTO ◽  
Masaharu MATSUBARA
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Three Dimensional Structure ◽  
Linear Disturbance

Measurements of the Turbulent Boundary Layer in the Diffuser Behind an Axial Compressor

1987 ◽  
Vol 109 (3) ◽  
pp. 405-412 ◽  
Author(s):  
H. Pfeil ◽  
M. Go¨ing
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Flow Direction ◽  
Three Dimensional ◽  
Great Influence ◽  
Axial Compressor ◽  
One Stage ◽  
Dimensional Effects ◽  
Diffuser Flow ◽  
Outlet Flow

This paper presents boundary layer measurements in a diffuser behind a one-stage axial compressor for the case of nearly axial outlet flow direction from the blades. According to the results, three-dimensional effects caused by the compressor blading have a great influence on the character and development of the turbulent boundary layer and must be included in methods to predict the diffuser flow.

scholarly journals Measurements of the Turbulent Boundary Layer in the Diffuser Behind an Axial-Compressor

1986 ◽  
Author(s):  
H. Pfeil ◽  
M. Göing
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Flow Direction ◽  
Three Dimensional ◽  
Great Influence ◽  
Axial Compressor ◽  
One Stage ◽  
Dimensional Effects ◽  
Diffuser Flow ◽  
Outlet Flow

The paper presents boundary layer measurements in a diffuser behind a one-stage axial-compressor for the case of nearly axial outlet flow-direction from the blades. According to the results, three-dimensional effects caused by the compressor-blading have a great influence on the character and development of the turbulent boundary layer and must be included in methods to predict the diffuser flow.

Three-Dimensional Structure of a Nominally Planar Turbulent Boundary Layer

1979 ◽  
Vol 101 (3) ◽  
pp. 326-330 ◽  
Author(s):  
Y. Furuya ◽  
I. Nakamura ◽  
H. Osaka
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Three Dimensional ◽  
Leading Edge ◽  
Turbulent Boundary Layers ◽  
Main Flow ◽  
The Other ◽  
Dimensional Structure ◽  
Spanwise Direction ◽  
Streamwise Vortices

This research is concerned with detailed experiments on spanwise nonuniformity of nominally planar turbulent boundary layers. Two procedures for eliminating spanwise nonuniformity are studied. One method is to remove the original, natural vortices by introducing additional ones arising from protuberances attached to the leading edge of a flat plate, and the other technique is by making the main flow entirely uniform. Effects of artificially controlled streamwise vortices on spanwise nonuniformity are examined. From these experiments, the process by which induced vortices cause nonuniformity of turbulent boundary layer characteristics in the spanwise direction is discussed.

On the evolution of a turbulent boundary layer induced by a three-dimensional roughness element

1992 ◽  
Vol 237 ◽  
pp. 101-187 ◽  
Author(s):  
P. S. Klebanoff ◽  
W. G. Cleveland ◽  
K. D. Tidstrom
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Laminar Boundary Layer ◽  
Roughness Element ◽  
Three Dimensional ◽  
Outer Region ◽  
Stream Velocity ◽  
Mean Velocity ◽  
Roughness Elements

An experimental investigation is described which has as its objectives the extension of the technical data base pertaining to roughness-induced transition and the advancement of the understanding of the physical processes by which three-dimensional roughness elements induce transition from laminar to turbulent flow in boundary layers. The investigation was carried out primarily with single hemispherical roughness elements surface mounted in a well-characterized zero-pressure-gradient laminar boundary layer on a flat plate. The critical roughness Reynolds number at which turbulence is regarded as originating at the roughness was determined for the roughness elements herein considered and evaluated in the context of data existing in the literature. The effect of a steady and oscillatory free-stream velocity on eddy shedding was also investigated. The Strouhal behaviour of the ‘hairpin’ eddies shed by the roughness and role they play in the evolution of a fully developed turbulent boundary layer, as well as whether their generation is governed by an inflexional instability, are examined. Distributions of mean velocity and intensity of the u-fluctuation demonstrating the evolution toward such distributions for a fully developed turbulent boundary layer were measured on the centreline at Reynolds numbers below and above the critical Reynolds number of transition. A two-region model is postulated for the evolutionary change toward a fully developed turbulent boundary layer: an inner region where the turbulence is generated by the complex interaction of the hairpin eddies with the pre-existing stationary vortices that lie near the surface and are inherent to a flow about a three-dimensional obstacle in a laminar boundary layer; and an outer region where the hairpin eddies deform and generate turbulent vortex rings. The structure of the resulting fully developed turbulent boundary layer is discussed in the light of the proposed model for the evolutionary process.

Multi-Plane Characterization of the Turbulent Boundary Layer

2018 ◽  
Author(s):  
Kadeem Dennis ◽  
Kamran Siddiqui
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Turbulent Flow ◽  
Flow Direction ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Wall Region ◽  
Turbulent Structures ◽  
Turbulent Flow Structure

The boundary layers are known for their significance in several engineering systems. In particular, the inner region of the turbulent boundary layer has been shown to play a significant role in controlling the dynamics of turbulent structures that are responsible for the transport of mass, heat and momentum. While substantial work has been done in the past to characterize the structure of turbulent flow in this region, the characterization of the three-dimensional turbulent flow structure is limited. This study reports a multi-plane particle image velocimetry (PIV) approach to investigate three-dimensional dynamics of the turbulent boundary layer in the near-wall region. Planar PIV is used to capture two-dimensional fluid velocity fields in several planes with respect to the fluid flow direction. These results are used to describe three-dimensional turbulent events given by key quantities such as mean and turbulent velocities and turbulent kinetic energy.

An experimental study of the mechanism of intermittent separation of a turbulent boundary layer

1984 ◽  
Vol 143 ◽  
pp. 153-172 ◽  
Author(s):  
Qing-Ding Wei ◽  
Hiroshi Sato
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Flow Field ◽  
Large Scale ◽  
Flow Direction ◽  
Quantitative Description ◽  
Three Dimensional ◽  
Field Measurements ◽  
Separation Region ◽  
Average Technique

A wind-tunnel investigation was made of the mechanism of separation of a two-dimensional turbulent boundary layer on a convex wall. The flow field was observed visually by using a large number of smoke wires arranged in various ways. Statistical quantities were obtained by newly developed direction-sensitive hot-wire probes and flow-direction meters. Smoke pictures show localized backflow spots in the separation region. They occur intermittently, grow downstream, merge with each other and eventually cover the whole flow field. Measurements of instantaneous flow direction show that velocity fluctuations in the separation region are strongly three-dimensional. The backflow factor, which is defined as the fraction of time of occurrence of backflow, is used for the quantitative description of the separation region. The role of large-scale ordered motions in the turbulent separation was investigated by use of the conditional sample and average technique. It was confirmed that a localized backflow is initiated by a large-scale low-speed lump of fluid which travels downstream.

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