Wind effects on a full-scale cooling tower in velocity fields of different non-stationary levels

Author(s):  
X. X. Cheng ◽  
L. Zhao ◽  
Y. J. Ge ◽  
G. Wu
2012 ◽  
Vol 35 ◽  
pp. 120-139 ◽  
Author(s):  
J.Y. Fu ◽  
J.R. Wu ◽  
A. Xu ◽  
Q.S. Li ◽  
Y.Q. Xiao
Keyword(s):  

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
H. C. R. Reuter ◽  
D. G. Kröger

Cooling tower inlet losses are the flow losses or viscous dissipation of mechanical energy affected directly by the cooling tower inlet design, which according to the counterflow natural draft wet-cooling tower performance analysis example given in Kröger (Kröger, 2004, Air-Cooled Heat Exchangers and Cooling Towers: Thermal-Flow Performance Evaluation, Pennwell Corp., Tulsa, OK), can be more than 20% of the total cooling tower flow losses. Flow separation at the lower edge of the shell results in a vena contracta with a distorted inlet velocity distribution that causes a reduction in effective fill or heat exchanger flow area. In this paper, a two-dimensional (axi-symmetric) computational fluid dynamic (CFD) model is developed using the commercial CFD code ANSYS FLUENT, to simulate the flow patterns, loss coefficients and effective flow diameter of circular natural draft cooling tower inlets under windless conditions. The CFD results are compared with axial velocity profile data, tower inlet loss coefficients and effective diameters determined experimentally by Terblanche (Terblanche, 1993, “Inlaatverliese by Koeltorings,” M. Sc. Eng. thesis, Stellenbosch University, Stellenbosch, South Africa) on a cylindrical scale sector model as well as applicable empirical relations found in Kröger, determined using the same experimental apparatus as Terblanche. The validated CFD model is used to investigate the effects of Reynolds number, shell-wall thickness, shell wall inclination angle, fill loss coefficient, fill type, inlet diameter to inlet height ratio and inlet geometry on the flow patterns, inlet loss coefficient and effective diameter of full-scale cooling towers. Ultimately, simple correlations are proposed for determining the cooling tower inlet loss coefficient and inlet effective flow diameter ratio of full-scale cooling towers excluding the effect of rain zones and the structural supports around the cooling tower entrance.


1975 ◽  
Vol 97 (1) ◽  
pp. 9-38 ◽  
Author(s):  
J. E. Cermak

Wind has always had a strong influence, both unfavorable and favorable, upon man and his activities. Within the last decade needs for treatment of wind effects from an engineering point-of-view have increased tremendously. Losses due to wind ($500,000,000 in property damage, 240 deaths and 2600 injuries annually), increased demand and concern for human comfort, serious attempts to control air pollution, and the development and expansion of energy-production capabilities have resulted in applications of engineering to problems for which a body of knowledge has only started to emerge in the United States. The primary elements of this body of knowledge are found in the disciplines of meteorology, fluid mechanics, aerodynamics, and structural mechanics—organizing this knowledge to form a coherent subject-matter base for wind engineering is a real challenge for fluids engineers. The objectives of this review are to establish an initial subject-matter base for wind engineering, to demonstrate current capabilities and deficiencies of this base for an engineering treatment of wind-effect problems, and to indicate areas of research needed to broaden and strengthen the subject-matter base. Focusing of subject matter for wind engineering is accomplished through a historical summary of relevant scientific and technological material, an examination of information on wind characteristics, and a review of current capabilities for physical modeling of winds and wind effects in the laboratory. Current methods and capabilities in wind engineering are demonstrated by a review of problems related to atmospheric advection and dispersion of air pollutants, wind forces on buildings and structures, and control of winds. Research needs are specified separately for each area reviewed -wind characteristics, simulation of the wind, atmospheric transport of air pollutants, wind forces, and wind control. Physical modeling of boundary-layer-type winds and wind effects by measurements on small-scale models placed in long-test-section, meteorological wind tunnels currently provides the most reliable source of data for wind engineering. Coordinated measurements on full-scale systems and their small-scale models are necessary for continued confirmation of similarity for the laboratory data and for development of new modeling capabilities. In particular, development of a tornado simulator is an urgent need to support structural design for nuclear-power-plant facilities. Intensive analytical investigations of three-dimensional, thermally-stratified, turbulent boundary layers; separation of turbulent, unsteady flows; turbulent shear flow over bluff bodies; and interacting turbulent flows with a variety of turbulence characteristics are needed to ensure future progress in wind engineering. These investigations are needed to provide a framework for correlation of both laboratory and full-scale data, to support efforts to develop numerical modeling as a practical tool, and to develop a better understanding of the physical processes involved. These flow problems represent formidable frontiers of turbulent fluid motion. Therefore, investigations in the fluid-mechanics laboratory coupled with measurements on full-scale systems are expected to be the primary sources of information for wind engineering in the immediate future.


2016 ◽  
Vol 20 (6) ◽  
pp. 843-864 ◽  
Author(s):  
XX Cheng ◽  
L Zhao ◽  
YJ Ge ◽  
R Dong ◽  
C Demartino

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.


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