An empirical model of velocity profiles for turbulent flow in smooth pipes

AIChE Journal ◽  
1980 ◽  
Vol 26 (2) ◽  
pp. 308-310 ◽  
Author(s):  
Michael A. Stein ◽  
David P. Kessler ◽  
Robert A. Greenkorn
Keyword(s):  
Turbulent Flow ◽  
Empirical Model ◽  
Velocity Profiles

Experiments on Backward-Facing Step Flows Preceding a Filter

2007 ◽  
Author(s):  
S. Yao ◽  
C. Krishnamoorthy ◽  
F. W. Chambers
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Separated Flow ◽  
Reynolds Numbers ◽  
Velocity Profiles ◽  
Step Height ◽  
Reattachment Point ◽  
Backward Facing Step ◽  
Air Filters ◽  
Air Filter

The resistance of automotive air filters alters upstream pressure gradients and thereby affects flow separation, the velocity distributions over the filter, and the performance of the filter. Air filters provide a resistance sufficient to alter flows, but not enough to make face velocities uniform. The backward-facing step flow is an archetype with a separation that resembles those found in automotive air filter housings. To gain insight to the problem of separation and filters, experiments were conducted measuring velocity fields for air flows in a 10:1 aspect ratio rectangular duct with a backward-facing step with and without the resistance of an air filter mounted downstream. The expansion ratio for the step was 1:2. The filter was mounted 4.25 and 6.75 step heights downstream of the step; locations both upstream and downstream of the nominal 6 step-height no-filter reattachment point. Experiments were performed at four Reynolds numbers between 2000 and 10,000. The Reynolds numbers were based on step height and inlet maximum velocity. The inlet velocity profiles at the step were developed. A Laser Doppler Anemometer (LDA) was used to measure velocity profiles and map separated regions between the step and the filter. The results indicate that the filter tends to decrease the streamwise velocity on the non-separated side of the channel and increase it on the separated, step, side compared to the no-filter flow. Non-separated flow tends to separate due to the deceleration and separated flow reattaches before the filter, whether the filter is placed at 4.25 or 6.75 step heights. The literature shows that without a filter the reattachment location depends on the Reynolds number in the laminar and transitional regimes, but is constant for turbulent flow. However, the area of the reversed flow may vary with Reynolds number for turbulent flow. With the filter at 4.25 step heights, the area of reversing flow is reduced significantly, and the Reynolds number has little effect on the main properties of the flow. With the filter at 6.75 step heights, the reversing flow area decreases as the Reynolds number increases though the reattachment point is fixed just upstream of the filter.

Study of Tabs in a Short Annular Diffuser With a Strong Swirling Flow

2014 ◽  
Author(s):  
D. J. Cerantola ◽  
A. M. Birk
Keyword(s):  
Turbulent Flow ◽  
Swirling Flow ◽  
Dynamic Pressure ◽  
Orientation Angle ◽  
Velocity Profiles ◽  
Back Pressure ◽  
Pressure Recovery ◽  
Axial Position ◽  
Projected Area ◽  
Annular Diffuser

Passive augmentation devices are typically added to diffusers to increase pressure recovery; however, applications such as infrared suppression exist where more uniform outlet velocity profiles are also desirable. Square tabs were added to a short annular diffuser system with diffuser effectiveness of 80% in strong swirling subsonic turbulent flow. The number, axial position, width, and height were varied for the tabs with a 135° orientation angle. Results showed that back pressure increased linearly with increasing tab projected area blockage but outlet velocity uniformity was maximum with 7% tab blockage. Tabs placed on the centre body base recovered more dynamic pressure than tabs placed downstream on the centre body with similar tab area blockage.

An Experimental Study and Analysis of Turbulent Film Tilted Pad Bearings

1974 ◽  
Vol 96 (1) ◽  
pp. 168-173 ◽  
Author(s):  
R. A. Burton ◽  
H. J. Carper ◽  
Y. C. Hsu
Keyword(s):  
Experimental Study ◽  
Turbulent Flow ◽  
Large Scale ◽  
Velocity Profiles ◽  
Working Fluid ◽  
Pressure Distributions ◽  
Aspect Ratios

Velocity profiles and pressure distributions are reported for turbulent flow under tilted pads in a large scale bearing model (6-ft shaft size, with air as the working fluid). Results are extended analytically to other bearing sizes and aspect ratios.

Experimental Study of Turbulent Flow Induced by Regular and Irregular Waves Above a Rock-Armored Slope

2014 ◽  
Author(s):  
Konstantina A. Galani ◽  
Giannis D. Dimou ◽  
Athanassios A. Dimas
Keyword(s):  
Experimental Study ◽  
Turbulent Flow ◽  
Velocity Profiles ◽  
Irregular Waves ◽  
Wave Crest ◽  
Regular Waves ◽  
Mean Velocity ◽  
Peak Period ◽  
Wave Trough ◽  
Wave Heights

The aim of the present work is the experimental study of the turbulent flow induced by waves above a physical model of a rock-armored slope of 1/3. The armor consisted of two layers of rocks with characteristic diameter D50 = 4.4cm. Measurements of the instantaneous velocity fields were conducted using an underwater planar PIV system. Four cases of incoming waves were tested, two cases of regular waves of 1st order Stokes theory with wave period of 1.134s and wave heights of 0.04m and 0.08m, respectively, and two cases of irregular waves, generated from a JONSWAP spectrum, with a peak period of 1.134s and significant wave heights of 0.04m and 0.08m, respectively. For the regular waves, the period-averaged velocity profiles show the existence of a strong undertow current heading towards deep water, while turbulence is not homogeneous with larger horizontal fluctuations. The phase-averaged horizontal velocity profiles present systematically larger values during wave trough passage than during wave crest passage. Furthermore, as the depth becomes smaller, the waveform loses its symmetry, with the wave trough becoming wider and the wave crest steeper. For the irregular waves, the mean velocity profiles show the existence of an undertow current weaker in magnitude than the one in the regular waves, while turbulence is still not homogeneous with larger horizontal fluctuations. For both wave cases, spanwise vorticity, which is generated at the rough surface of the rock-armored slope, is transported landward by the turbulent velocities.

scholarly journals NEAR-BOTTOM VELOCITIES IN WAVES WITH A CURRENT

1978 ◽  
Vol 1 (16) ◽  
pp. 82 ◽  
Author(s):  
W.T. Bakker ◽  
Th. Van Doorn
Keyword(s):  
Mathematical Model ◽  
Turbulent Flow ◽  
Velocity Distribution ◽  
Experimental Verification ◽  
Velocity Profiles ◽  
Horizontal Direction ◽  
Numerical Accuracy ◽  
A Current ◽  
Bottom Velocities

Bakker (1974) developed a mathematical model concerning the sand concentration and velocity distribution in an oscillatory turbulent flow, with or without resultant current. The flow is assumed to be uniform in horizontal direction. The present paper reports on an experimental verification of this theory. Furthermore, the numerical accuracy of the model has been investigated and diagrams are presented which enable the computation by hand of global velocity profiles.

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