Wind effects on rough-walled and smooth-walled large cooling towers

2016 ◽  
Vol 20 (6) ◽  
pp. 843-864 ◽  
Author(s):  
XX Cheng ◽  
L Zhao ◽  
YJ Ge ◽  
R Dong ◽  
C Demartino
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Wind Tunnel ◽  
Flow Field ◽  
Atmospheric Boundary Layer ◽  
Model Test ◽  
Full Scale ◽  
Cooling Towers ◽  
Test Results ◽  
Wind Effects

Adding vertical ribs is recognized as a useful practice for reducing wind effects on cooling towers. However, ribs are rarely used on cooling towers in China since Chinese Codes are insufficient to support the design of rough-walled cooling towers, and an “understanding” hampers the use of ribs, which thinks that increased surface roughness has limited effects on the maximum internal forces that control the structural design. To this end, wind tunnel model tests in both uniform flow field with negligible free-stream turbulence and atmospheric boundary layer (ABL) turbulent flow field are carried out in this article to meticulously study and quantify the surface roughness effects on both static and dynamic wind loads for the purpose of improving Chinese Codes first. Subsequently, a further step is taken to obtain wind effects on a full-scale large cooling tower at a high Re, which are employed to validate the results obtained in the wind tunnel. Finally, the veracity of the model test results is discussed by investigating the Reynolds number (Re) effects on them. It has been proved that the model test results for atmospheric boundary layer flow field are all obtained in the range of Re-independence and the conclusions drawn from model tests and full-scale measurements basically agree, so most model test results presented in this article can be directly applied to the full-scale condition without corrections.

A new atmospheric boundary layer wind tunnel simulation methodology for wind effects on large cooling towers considering wind environment variations

2018 ◽  
Vol 22 (5) ◽  
pp. 1194-1210 ◽  
Author(s):  
XX Cheng ◽  
X Chen ◽  
YJ Ge ◽  
H Jiang ◽  
L Zhao
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Atmospheric Boundary Layer ◽  
Model Test ◽  
Test Results ◽  
Wind Effects ◽  
Simulation Methodology ◽  
Codes Of Practice ◽  
Wind Tunnel Simulation ◽  
Tunnel Model

The traditional atmospheric boundary layer wind tunnel model test practice employs wind fields, the flow characteristics of which are in accordance with the empirical formulae of the atmospheric turbulence presented in Codes of Practice and monographs. However, the empirical formulae presented in Codes of Practice and monographs cannot truthfully reflect the high variations of the realistic atmospheric turbulence which sometimes aggravates wind effects on structures. Based on model tests conducted in a multiple-fan actively controlled wind tunnel, it is found that most wind effects on large cooling towers change monotonically with the increase in free-stream turbulence, and the model test results are more unfavorable for a flow field of low turbulence intensity than for a flow field of high turbulence intensity with respect to the measured coherences. Thus, a new atmospheric boundary layer wind tunnel simulation methodology for wind effects on circular cylindrical structures is proposed to overcome the deficiency of the traditional atmospheric boundary layer wind tunnel model tests. The new simulation methodology includes the simulation of two realistic atmospheric boundary layer flow fields with the highest and the lowest turbulence intensities in the wind tunnel and the envelopment of model test results obtained in the two flow fields (e.g. the mean and fluctuating wind pressure distributions, the power spectral density, the coherence function, and the correlation coefficient). The superiority of the new atmospheric boundary layer wind tunnel simulation methodology over the traditional model test practice is demonstrated by comparing the model test results with the full-scale measurement data.

Effects of free-stream turbulence on wind loads on a full-scale large cooling tower

2017 ◽  
Vol 21 (10) ◽  
pp. 1437-1453 ◽  
Author(s):  
XX Cheng ◽  
J Dong ◽  
Y Peng ◽  
L Zhao ◽  
YJ Ge
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Atmospheric Boundary Layer ◽  
Turbulence Intensity ◽  
Cooling Tower ◽  
Free Stream ◽  
Wind Loads ◽  
Significant Feature ◽  
Wind Effects ◽  
Free Stream Turbulence

The high variability in turbulence is a significant feature of the realistic atmospheric boundary layer winds which might have strong effects on wind loads on structures submerged in atmospheric boundary layer. This article has been devoted to this matter of science which is of practical importance to wind-engineering design and research. First, the variation of the turbulence intensity of the atmospheric boundary layer flow has been studied using theoretical calculations and meteorological wind measurements. Second, the effects of free-stream turbulence on wind loads on circular cylindrical structures have been revealed at high Reynolds number and equivalent conditions based on field measurements and wind tunnel model tests for wind effects on a large cooling tower. Through these works, it is found that the turbulence intensity for the measured atmospheric boundary layer winds is highly variable due to the significant effect of the mean wind speed, which is not well represented by the traditional empirical formulae. Besides, the free-stream turbulence significantly influences the dynamic characteristics of wind effects on the cooling tower in most cases, and the wind effects for a flow field of high turbulence intensity are generally more unfavorable than those for a flow field of low turbulence intensity.

Investigations of Ship Airwakes Using Concurrent Computations and Experiments

2021 ◽  
Author(s):  
David Farish ◽  
Dhuree Seth ◽  
Regis Thedin ◽  
Sven Schmitz
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Atmospheric Boundary Layer ◽  
Particle Image Velocimetry Data ◽  
Full Scale ◽  
Large Eddy Simulations ◽  
Small Scale ◽  
Computational Techniques ◽  
Dynamic Interface ◽  
Large Eddy

Using computational techniques established in previous full-scale dynamic interface simulations, small-scale large eddy simulations of Embry-Riddle Aeronautical University's Boundary-Layer Wind Tunnel were conducted. The ultimate goal of the study is to serve as a useful point of validation for full-scale airwake data provided to flight simulators used to develop flight software and train rotorcraft pilots for shipboard operations. Cowdrey rods were used in the wind tunnel to develop the turbulence and sheared inflow similar to an atmospheric boundary layer. Hot-wire anemometry and particle image velocimetry data were compared to OpenFOAM large eddy simulation data. In uniform inflow conditions, it was found that despite the reduced Reynolds number of the scaled setup, the computational airwake data agreed quite well with larger-scale wind tunnel experiments and full-scale large eddy simulations of the same ship model, but showed less asymmetry spanwise across the flight deck. Comparisons of the experimental and computational simulated atmospheric boundary-layer inflow show good agreement in the time-averaged velocity profile and velocity contours along the ship's centerline. It was further found that the computations while capturing the major flow structures, overpredict the turbulence intensities and turbulent kinetic energy in the ship airwake. The present study provides some confidence that full-scale coupled atmospheric boundary layer/ship airwake solvers are accurate and can assist in improving dynamic interface simulations.

scholarly journals Full-Scale/Model Test Comparisons to Validate the Traditional ABL Wind Tunnel Simulation Technique: A Literature Review

2017 ◽  
Author(s):  
X.X. Cheng ◽  
J. Dong ◽  
Y. Peng ◽  
L. Zhao ◽  
Y.J. Ge
Keyword(s):  
Wind Tunnel ◽  
Literature Review ◽  
Model Test ◽  
Full Scale ◽  
Simulation Technique ◽  
Scale Model ◽  
Test Results ◽  
Wind Tunnel Simulation ◽  
Measurement Results ◽  
New Research

Full-scale/model test comparison studies to validate the traditional ABL wind tunnel simulation technique are reviewed. According to the literature review, notable discrepancies between full-scale measurement results and model test results were observed by most performed comparison studies, but the causes of the observed discrepancies were not revealed in a scientific way by those studies. In this regard, a new research scheme for future full-scale/model test comparison studies is proposed in this article, which utilizes the multiple-fan actively controlled wind tunnel simulation technique. With the new research scheme, future full-scale/model test comparison studies are expected to reasonably disclose the main problems with the traditional ABL wind tunnel simulation technique, and the technique can be improved correspondingly.

Development of Boundary Layer in CRIACIV in Florence (Prato) and Comparison with CFD

2016 ◽  
Vol 820 ◽  
pp. 359-364
Author(s):  
Marek Magát ◽  
Ivana Olekšáková ◽  
Juraj Žilinský
Keyword(s):  
Fluid Dynamics ◽  
Boundary Layer ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Atmospheric Boundary Layer ◽  
Comparison Of The Results

In this article are described the results from testing profile of atmospheric boundary layer in BLWT (Boundary layer wind tunnel) in Florence (Prato), Italy with emphasis on comparison of the results with simulations in CFD (Computational fluid dynamics) software OpenFoam. The values are compared with calculated values from EuroCode.

scholarly journals Simulations of the Atmospheric Boundary Layer in a Wind Tunnel with Short Test Section

2013 ◽  
Vol 5 (3) ◽  
pp. 305-314 ◽  
Author(s):  
Luciana Bassi Marinho Pires ◽  
Igor Braga De Paula ◽  
Gilberto Fisch ◽  
Ralf Gielow ◽  
Roberto Da Mota Girardi
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Atmospheric Boundary Layer ◽  
Test Section ◽  
Short Test
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