MIGRATION IN A LAMINAR SUSPENSION BOUNDARY LAYER MEASURED BY THE USE OF A TWO-DIMENSIONAL LASER–DOPPLER ANEMOMETER

1972 ◽  
pp. 385-403
Author(s):  
S.L. LEE ◽  
S. EINAV
Keyword(s):  
Boundary Layer ◽  
Laser Doppler Anemometer ◽  
Laser Doppler ◽  
Two Dimensional

An Experimental Investigation of Throughflow Velocities in Two-Dimensional Fluidized Bed Bubbles: Laser Doppler Anemometer Measurements

1994 ◽  
Vol 116 (3) ◽  
pp. 605-612 ◽  
Author(s):  
M. Gautam ◽  
J. T. Jurewicz ◽  
S. R. Kale
Keyword(s):  
Fluidized Bed ◽  
Fluidized Beds ◽  
Gas Flow ◽  
Sampling Technique ◽  
Laser Doppler Anemometer ◽  
Laser Doppler ◽  
Two Dimensional ◽  
End Effects ◽  
Convective Component ◽  
Bubble Phase

Detailed nonintrusive measurements have been made to determine the throughflow velocity in isolated fluidized bed bubbles. In air-fluidized beds, the throughflow component has been rather neglected and measurements of the visible bubble flow alone have, therefore, failed to clarify the overall distribution of gas flow between the phases. A single component fiber optic laser Doppler anemometer was used to map the fluid flow through a bubble rising in a two-dimensional bed. The bed was fluidized at a superficial velocity slightly higher than incipient. The conditioned sampling technique developed to characterize the periodic nature of the bubble phase flow revealed that the throughflow velocity in two-dimensional beds increases linearly with increasing distance from the distributor, thereby enhancing the convective component in the interphase mass transfer process. Bubble growth was accounted for and the end-effects were minimized. Dependence of the bubble throughflow on the elongation of the bubble was observed thus confirming the theoretical analysis of some previous investigators. However, experimental evidence presented in this paper showed that the existing models fail to accurately predict the convective component in the bubble phase of two-dimensional fluidized beds.

The Departure from Equilibrium of Turbulent Boundary Layers

1968 ◽  
Vol 19 (1) ◽  
pp. 1-19 ◽  
Author(s):  
H. McDonald
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Kinetic Energy ◽  
Stress Distribution ◽  
Boundary Layers ◽  
Turbulent Boundary Layers ◽  
Two Dimensional ◽  
Pressure Distributions ◽  
Momentum Integral ◽  
State Examination

SummaryRecently two authors, Nash and Goldberg, have suggested, intuitively, that the rate at which the shear stress distribution in an incompressible, two-dimensional, turbulent boundary layer would return to its equilibrium value is directly proportional to the extent of the departure from the equilibrium state. Examination of the behaviour of the integral properties of the boundary layer supports this hypothesis. In the present paper a relationship similar to the suggestion of Nash and Goldberg is derived from the local balance of the kinetic energy of the turbulence. Coupling this simple derived relationship to the boundary layer momentum and moment-of-momentum integral equations results in quite accurate predictions of the behaviour of non-equilibrium turbulent boundary layers in arbitrary adverse (given) pressure distributions.

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