Flow impingement on a perforated plate at an angle of attack

Nomenclature

A

= model constant

D

= diameter of the aperture

E_γ1, E_γ2

= intermittency destruction terms

F₁, F₂

= blending functions in the SST model

p

= pressure

P_k

= production term for the turbulent kinetic energy

P_γ1, P_γ2

= intermittency production terms

P_Π,t

= production term for the transition-onset Reynolds number

S

= absolute value of the shear strain rate

U_o

= average fluid velocity passing through the aperture

u

= local velocity

u_i

= velocity component in the i-direction

${\mathit{u}}_{\mathit{i}}^{\mathit{\prime }}$

= fluctuating velocity component

x_i

= Cartesian coordinate

Greek symbols

Π

= turbulent adjunct function

α

= SST model constant

β₁, β₂

= SST model constants

γ

= damping factor

ε

= turbulence dissipation

κ

= turbulent kinetic energy

μ

= molecular viscosity

μ_turb

= turbulent viscosity

ν

= kinematic viscosity

ρ

= fluid density

σ

= Prandtl-number-like diffusion coefficient

ω

= specific rate of turbulence dissipation

1. Introduction

Perforated media are frequently encountered in applications involving flow control, rectification of maldistributed flow, drag increase and speed brakes for aircraft flight control, reduction of jet noise, lift augmentation, attenuation of the onset of cavitation in liquid pipeline flows, insect control for greenhouse applications, automotive cooling systems and many others. These functions have been accomplished by application-specific perforated media. The particular function of interest here is the rectification of maldistributed flows. Such flows are created by geometrical variances such as bends and other pipe curvatures, valves, abrupt changes in cross section and many others. The most widely accepted means of rectifying maldistributed flows is by the judicial use of fluid resistances. In this regard, perforated plates have found frequent application. However, to the best of our knowledge, the available information about the fluid resistance of perforated plates is confined to flows which impinge perpendicularly on the plate surface. The goal of the present work is to investigate flows which impinge on the surface of flat perforated plates at an angle of attack.

In the situations to be considered here, flat perforated plates are positioned in rectangular ducts of various aspect ratios and at several angles of attack. Both laminar and...

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