scholarly journals Modeling of Turbulent Fluid Flow Over a Rough Wall With or Without Suction

2003 ◽  
Vol 125 (4) ◽  
pp. 636-642 ◽  
Author(s):  
G. Gre´goire ◽  
M. Favre-Marinet ◽  
F. Julien Saint Amand
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Fluid Flow ◽  
Rough Boundary ◽  
Two Dimensional ◽  
Turbulent Fluid Flow ◽  
Boundary Layer Suction ◽  
Zonal Model ◽  
Impermeable Wall ◽  
Logarithmic Law

The turbulent flow close to a wall with two-dimensional roughness is computed with a two-layer zonal model. For an impermeable wall, the classical logarithmic law compares well with the numerical results if the location of the fictitious wall modeling the surface is considered at the top of the rough boundary. The model developed by Wilcox for smooth walls is modified to account for the surface roughness and gives satisfactory results, especially for the friction coefficient, for the case of boundary layer suction.

Acoustic receptivity and evolution of two-dimensional and oblique disturbances in a Blasius boundary layer

2001 ◽  
Vol 432 ◽  
pp. 69-90 ◽  
Author(s):  
RUDOLPH A. KING ◽  
KENNETH S. BREUER
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Acoustic Wave ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Surface Waviness ◽  
S Wave ◽  
Boundary Layer Instability ◽  
Blasius Boundary Layer ◽  
Tollmien Schlichting

An experimental investigation was conducted to examine acoustic receptivity and subsequent boundary-layer instability evolution for a Blasius boundary layer formed on a flat plate in the presence of two-dimensional and oblique (three-dimensional) surface waviness. The effect of the non-localized surface roughness geometry and acoustic wave amplitude on the receptivity process was explored. The surface roughness had a well-defined wavenumber spectrum with fundamental wavenumber kw. A planar downstream-travelling acoustic wave was created to temporally excite the flow near the resonance frequency of an unstable eigenmode corresponding to kts = kw. The range of acoustic forcing levels, ε, and roughness heights, Δh, examined resulted in a linear dependence of receptivity coefficients; however, the larger values of the forcing combination εΔh resulted in subsequent nonlinear development of the Tollmien–Schlichting (T–S) wave. This study provides the first experimental evidence of a marked increase in the receptivity coefficient with increasing obliqueness of the surface waviness in excellent agreement with theory. Detuning of the two-dimensional and oblique disturbances was investigated by varying the streamwise wall-roughness wavenumber αw and measuring the T–S response. For the configuration where laminar-to-turbulent breakdown occurred, the breakdown process was found to be dominated by energy at the fundamental and harmonic frequencies, indicative of K-type breakdown.

Boundary Layers on a Rotating Rough Disk

1994 ◽  
Author(s):  
Ali Heydari ◽  
Ramin Miryan ◽  
Saeid Sharifi
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Parabolic Equations ◽  
Roughness Parameter ◽  
Rotating Disk ◽  
Turbulent Fluid Flow ◽  
Uniform Wall Temperature ◽  
Curve Fit ◽  
Uniform Wall ◽  
Finite Difference Solution

Abstract In this paper the turbulent fluid flow over a rotating disk with roughness is considered. The disk is assumed to be at uniform wall temperature. The surface roughness is assumed to influence the turbulent boundary layer by adding a roughness parameter height k. Boundary-layer approximation reduces the elliptic Navier-Stockes equations to parabolic equations, where the Keller-Cebeci method of finite-difference solution is used to solve the resulting system of partial-differential equations. The resulting curve-fit equations to the numerically calculated results for three regions of laminar, transition and turbulent flow is shown to be consistent to those obtained for flow over a flat plate or inside a circular cylinder. Calculations for various surface roughness parameters are made and results are presented.

An Investigation of two Turbulent Flows over Smooth and Rough Surfaces

1974 ◽  
Vol 16 (2) ◽  
pp. 71-78 ◽  
Author(s):  
W. K. Allan ◽  
V. Sharma
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Surface Roughness ◽  
Turbulent Boundary Layer ◽  
Turbulent Flows ◽  
Smooth Surface ◽  
Two Dimensional ◽  
Mean Velocity ◽  
Turbulent Boundary Layer Flow ◽  
Layer Flow

Experimental data for two-dimensional, low-speed, turbulent boundary layer flow has been used to verify the description of mean-velocity distributions proposed by Allan and to re-evaluate the entrainment function. The independence of pressure gradient and surface roughness as regards their effects on velocity profiles has been demonstrated. Boundary layer predictions agree with experimental data for a smooth surface, but further investigation is required for flow over a rough surface.

scholarly journals A combination application of tandem blade and endwall boundary layer suction in a highly loaded aspirated compressor outlet vane

2017 ◽  
Vol 232 (2) ◽  
pp. 129-143 ◽  
Author(s):  
Longxin Zhang ◽  
Songtao Wang
Keyword(s):  
Boundary Layer ◽  
Flow Control ◽  
Control Method ◽  
Three Dimensional ◽  
Full Potential ◽  
Two Dimensional ◽  
Suction Surface ◽  
Boundary Layer Suction ◽  
Flow Through ◽  
Highly Loaded

Aspirated compressor is a promising design concept to enhance the power density of the compression system; however, with regard to the rear stages of multistage aspirated compressor, the blade is fairly thin. Limited by the mechanical constraints, it seems impractical to implement the boundary layer suction on the blade suction surface. So the question arising is can we replace the blade suction surface with other feasible flow control methods without implementing extra device on the blade? To address this issue, a compound flow control method, composed of the endwall boundary layer suction and tandem blade, is proposed. The design philosophy is to utilize the EBLS to suppress the three-dimensional corner stall while to use the tandem blade to control the two-dimensional airfoil flow separation. The endwall boundary layer suction is barely implemented in the forward blade, whereas the corner flow in the rear blade is restrained by the flow through the gap between the forward and rear blades. The preliminary implement strategy of the compound flow control was presented and then applied in the design of a highly loaded aspirated compressor outlet vane. Three-dimensional numerical simulations were carried out to validate its effectiveness with different inlet boundary layer distributions. Both flow fields in the outlet vane and its loss characteristics were analyzed. The results show that, by applying the compound flow control, the outlet vane could not only achieve an aggressive loading without incurring large-scale separation at the design point but also have a considerable available incidence range. Due to the implement of the endwall boundary layer suction, the tandem blade can bring out its full potential in the two-dimensional flow control. Moreover, owing to the flow through the gap of the forward and rear blades, the aspiration flow rate required for the suppression of the three-dimensional corner stall can be reduced.

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