Wind Effects on Air-Cooled Condensers: Wind-Tunnel 2-D Flow Fields for Base Case, Wind Screens, and Louvers

2017 ◽  
Author(s):  
Ryan S. Parker
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Flow Field ◽  
Mitigation Measures ◽  
Horizontal Wind ◽  
Base Case ◽  
Hot Wire ◽  
Horizontal Wind Speed ◽  
Air Cooled Condensers ◽  
Wind Tunnel Measurements

Detailed 2-axis hot-wire anemometry measurements were conducted around a scale Air-Cooled Condenser (ACC) model within an atmospheric boundary layer wind-tunnel. The measurements were taken for the “standard” flow field, as well as the effects of using partial wind screens and louvers as mitigation measures. This provides a representation of the complex 2-D flow field present underneath an operating ACC when subjected to various speed cross winds. Optimal ACC operation is achieved when all fans generate a uniform flow pattern into the plenum chamber of the ACC, and this is dependent on the speed and direction of the air at the inlet. The wind-tunnel measurements support the assertion that wind screens reduce the horizontal wind speed directly downstream; however, this comes with a marked increase in turbulence. The results suggest a wind-screen covering a smaller portion (6% tested) of the ACC inlet may be more beneficial than the more common 50% coverage.

scholarly journals Comparison of Large Eddy Simulations of a convective boundary layer with wind LIDAR measurements

2012 ◽  
Vol 8 (1) ◽  
pp. 83-86 ◽  
Author(s):  
J. G. Pedersen ◽  
M. Kelly ◽  
S.-E. Gryning ◽  
R. Floors ◽  
E. Batchvarova ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Geostrophic Wind ◽  
Large Eddy Simulations ◽  
Horizontal Wind ◽  
Convective Boundary ◽  
Horizontal Wind Speed ◽  
Large Eddy ◽  
Lidar Measurements ◽  
Wind Lidar

Abstract. Vertical profiles of the horizontal wind speed and of the standard deviation of vertical wind speed from Large Eddy Simulations of a convective atmospheric boundary layer are compared to wind LIDAR measurements up to 1400 m. Fair agreement regarding both types of profiles is observed only when the simulated flow is driven by a both time- and height-dependent geostrophic wind and a time-dependent surface heat flux. This underlines the importance of mesoscale effects when the flow above the atmospheric surface layer is simulated with a computational fluid dynamics model.

scholarly journals Wind profile correction algorithm based on Atmospheric Boundary Layer stability profile

2021 ◽  
Author(s):  
Francisco Albuquerque Neto ◽  
Vinicius Almeida ◽  
Julia Carelli
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Wind Profile ◽  
Horizontal Wind ◽  
Boundary Layer Stability ◽  
Correction Algorithm ◽  
Horizontal Wind Speed ◽  
Study Region ◽  
Profile Correction ◽  
Wind Profiles

<p>In recent years, the use of radar wind profilers (RWP) at airports has grown significantly with the aim of supporting decision makers to maintain the safety of aircraft landings and takeoffs.</p><p>The RWP provide vertical profiles of averaged horizontal wind speed and direction and vertical wind velocity for the entire Atmospheric Boundary Layer (ABL) and beyond. In addition, RWP with Radio-Acoustic Sounding System (RASS) are able to retrieve virtual temperature profiles in the ABL.</p><p>RWP data evaluation is usually based on the so-called Doppler Beam Swinging method (DBS) which assumes homogeneity and stationarity of the wind field. Often, transient eddies violate this homogeneity and stationarity requirement. Hence, incorrect wind profiles can relate to transient eddies and present a problem for the forecast of high-impact weather phenomena in airports. This work intends to provide a method for removing outliers in such profiles based on historical data and other variables related to the Atmospheric Boundary Layer stability profile in the study region.</p><p>For this study, a dataset of almost one year retrieved from a RWP LAP3000 with RASS Extension is used for a wind profile correction algorithm development.</p><p>The algorithm consists of the detection of outliers in the wind profiles based on the thermodynamic structure of the ABL and the generation of the corrected profiles.</p><p>Results show that the algorithm is capable of identifying and correcting unrealistic variations in speed caused by transient eddies. The method can be applied as a complement to the RWP data processing for better data reliability.</p><p> </p><p>Keywords: atmospheric boundary layer; stability profile; wind profile</p>

New perspectives on the impulsive roughness-perturbation of a turbulent boundary layer

2011 ◽  
Vol 677 ◽  
pp. 179-203 ◽  
Author(s):  
I. JACOBI ◽  
B. J. McKEON
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Flow Field ◽  
Spectral Energy ◽  
Internal Layers ◽  
Hot Wire ◽  
Mean Velocity ◽  
Composite Maps ◽  
Downstream Flow ◽  
Near Wall

The zero-pressure-gradient turbulent boundary layer over a flat plate was perturbed by a short strip of two-dimensional roughness elements, and the downstream response of the flow field was interrogated by hot-wire anemometry and particle image velocimetry. Two internal layers, marking the two transitions between rough and smooth boundary conditions, are shown to represent the edges of a ‘stress bore’ in the flow field. New scalings, based on the mean velocity gradient and the third moment of the streamwise fluctuating velocity component, are used to identify this ‘stress bore’ as the region of influence of the roughness impulse. Spectral composite maps reveal the redistribution of spectral energy by the impulsive perturbation – in particular, the region of the near-wall peak was reached by use of a single hot wire in order to identify the significant changes to the near-wall cycle. In addition, analysis of the distribution of vortex cores shows a distinct structural change in the flow associated with the perturbation. A short spatially impulsive patch of roughness is shown to provide a vehicle for modifying a large portion of the downstream flow field in a controlled and persistent way.

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.

Hypersonic Wind-Tunnel Measurements of Boundary-Layer Transition on a Slender Cone

AIAA Journal ◽  
2016 ◽  
Vol 54 (4) ◽  
pp. 1250-1263 ◽  
Author(s):  
Katya M. Casper ◽  
Steven J. Beresh ◽  
John F. Henfling ◽  
Russell W. Spillers ◽  
Brian O. M. Pruett ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Boundary Layer Transition ◽  
Layer Transition ◽  
Hypersonic Wind Tunnel ◽  
Wind Tunnel Measurements

scholarly journals Hypersonic Wind-Tunnel Measurements of Boundary-Layer Pressure Fluctuations

2009 ◽  
Author(s):  
Katya Casper ◽  
Steven Beresh ◽  
John Henfling ◽  
Russell Spillers ◽  
Brian Pruett ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Pressure Fluctuations ◽  
Hypersonic Wind Tunnel ◽  
Wind Tunnel Measurements

The aeroacoustics of finite wall-mounted square cylinders

2017 ◽  
Vol 832 ◽  
pp. 287-328 ◽  
Author(s):  
Ric Porteous ◽  
Danielle J. Moreau ◽  
Con J. Doolan
Keyword(s):  
Boundary Layer ◽  
Experimental Study ◽  
Reynolds Number ◽  
Wind Tunnel ◽  
Three Dimensional ◽  
Flow Structures ◽  
Hot Wire ◽  
Radiated Noise ◽  
Aspect Ratios ◽  
Square Cylinders

This paper presents the results of an experimental study that relates the flow structures in the wake of a square finite wall-mounted cylinder with the radiated noise. Acoustic and hot-wire measurements were taken in an anechoic wind tunnel. The cylinder was immersed in a near-zero-pressure gradient boundary layer whose thickness was 130 % of the cylinder width, $W$. Aspect ratios were in the range $0.29\leqslant L/W\leqslant 22.9$ (where $L$ is the cylinder span), and the Reynolds number, based on width, was $1.4\times 10^{4}$. Four shedding regimes were identified, namely R0 ($L/W<2$), RI ($2<L/W<10$), RII ($10<L/W<18$) and RIII ($L/W>18$), with each shedding regime displaying an additional acoustic tone as the aspect ratio was increased. At low aspect ratios (R0 and RI), downwash dominated the wake, creating a highly three-dimensional shedding environment with maximum downwash at $L/W\approx 7$. Looping vortex structures were visualised using a phase eduction technique. The principal core of the loops generated the most noise perpendicular to the cylinder. For higher aspect ratios in RII and RIII, the main noise producing structures consisted of a series of inclined vortex filaments, where the angle of inclination varied between vortex cells.

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