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Summary: Dynamic amplification effects caused by tower‐group interference is the most critical causes of wind‐induced destructions of super‐large cooling tower (SLCT), and four‐tower combinations are the most common tower‐group combining form. However, the dynamic amplification effects of SLCT of different four‐tower arrangements have not been studied systematically so far. The highest (220 m) SLCT in the world was taken as the target to conduct SLCT wind pressure measurement under 320 wind tunnel test conditions. Firstly, the stability performance under the design wind loads was analyzed. Then, the dynamic time‐history analysis was carried out, and the distribution characteristics of peak factors and values of extreme response were discussed. Furthermore, with a new concept parameter "tower‐group wind vibration coefficient" for the wind‐resistance design of SLCT, the distribution laws of two‐dimensional (2D), one‐dimensional (1D), and global tower‐group wind vibration coefficient were revealed under different four‐tower interferences. On these bases, we recommend the design parameters for wind‐resistance study of SLCT and the priority of four‐tower combination forms. The study showed that the dynamic effects of SLCT under different four‐tower arrangements were significantly different from each other and the tower‐group wind vibration coefficients proposed in this paper can reflect the interference effects of tower‐group more efficient than traditional design method. The results may become a useful database for the wind‐resistance design of SLCT and provide clues for the optimization of four‐tower arrangements in power plants. [ABSTRACT FROM AUTHOR]

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The wind loads distribution on the super-large cooling tower under the interference effect of tower group is very complicated. Particularly, energy distribution of fluctuation wind loads and extreme model is difficult to be predicted. However, accurate calculations of these two factors are the most direct ways for analysis of wind resistance dynamics of super-large cooling tower. The wind tunnel tests of the highest super-large cooling tower under five typical tower combinations (serial, rectangular, rhombus, L-shaped, and inclined L-shaped) with 320 working conditions were performed. On this basis, non-Gaussian and non-stationary properties of local wind pressure and overall force coefficient of super-large cooling tower were analyzed. Distribution laws of local wind pressure extremes and overall force coefficient extremes were discussed based on Hermite method and peak factor method. Key attention was paid to the mapping relationships of characteristic angles with local and overall aerodynamic force extremes. The effects of four-tower combination modes on fluctuation wind loads energy of super-large cooling tower were studied based on the power spectral density function, intrinsic mode function, and evolution power spectral density function. Besides, the estimation formulas of local wind pressure spectrum and overall pressure coefficient spectrum of super-large cooling tower under four-tower combination were proposed. It can be found that the extremes of local wind pressure and overall aerodynamic force could be predicted based on the linear relationship between characteristic angles and fluctuation wind loads. In addition, it is suggested to choose serial combination first, followed by inclined L-shaped, L-shaped, rhombus, and rectangular modes successively. [ABSTRACT FROM AUTHOR]

Different four-tower arrangements have a great impact on wind-induced response and stability performance of super-large cooling tower. However, a single indicator (eg., interference factor of overall wind load) cannot provide a comprehensive and objective evaluation of wind-resistance safety of cooling tower. Here five typical four-tower arrangements in engineering practice were experimented, namely, row, rectangular, rhombic, L-shape, and oblique L-shape arrangement. Wind tunnel tests for rigid body were performed to determine the wind loads distribution pattern on the surface of group tower under different four-tower arrangements. Finite element method was employed to analyze the internal force and deformation distributions under the design wind load of return period. The influence of different four-tower arrangements on wind load-induced response was discussed under different incoming wind angles. Then the local stability and overall buckling stability of the cooling tower were estimated, and the ultimate bearing capacities under different four-tower arrangements were compared considering geometric nonlinearity. Instead of using a uniform structural design standard for cooling towers group, the influence rule of different arrangements on wind-induced response and safety performance of the cooling tower group was summarized. [ABSTRACT FROM AUTHOR]

Group tower-related interference is one of the major causes of wind-induced damage of large cooling towers. The four-tower arrangements are the most common forms of the layout of group towers. In engineering practice, five arrangements are generally used, namely, single row, rectangular, rhombic, L-shaped, and oblique L-shaped. We performed wind tunnel tests on the rigid body to study the static, dynamic and extreme interference effects under these five arrangements. Then the computation formulas of interference factor that accounted for the wind directions under the five arrangements were proposed. The effects of four-tower arrangement on the distribution patterns of mean and pulsating wind pressures were discussed. The wind pressure signals at the typical measurement points of the cooling towers were subjected to decomposition and joint time-frequency analysis using mathematical statistics technique and Hilbert-Huang transform (HHT). The study shows that the maximum interference factors under the five arrangements were all higher than those under the layout of two towers. It is reasonable to use the extreme interference factor as the measure of the interference effects. The maximum positive pressure of the cooling towers was less affected by the interference effects related to four-towers, and the mean wind pressure were affected greatly in the regions of minimum negative wind pressure and leeward regions. The distribution patterns and values of pulsating wind pressures at the bottom and top of the cooling towers were significantly affected by the five arrangements of the cooling towers. Finally, based on comprehensive assessment of the interference effects of overall wind loads, arranging the four towers in a row was the best scheme, which was followed by the arrangements in oblique L-shaped pattern, L-shaped pattern, rhombic pattern and rectangular pattern successively. [ABSTRACT FROM AUTHOR]

Based on grey GM(1,1) model and BP artificial neural network, the grey-neural network joint model is established, which is used to predict the displacement and wind induced coefficients for large cooling towers. Using the joint model, the influence caused by little raw data is overcome. Furthermore the self-adaptability and predicting precision for wind-induced responses of large cooling towers are enhanced. Through comparative analysis of the wind-induced responses of domestic large hyperbolic cooling tower in aero-elastic model wind tunnel test, it can be found that the prediction results of wind-induced responses and wind vibration coefficients are in good agreement with the experimental results, which shows good validity and stability of the model, and then input parameters of refined research on wind induced response are predicted. The proposed method provide a new and effective idea for the refined research on wind effects of large cooling towers. [ABSTRACT FROM AUTHOR]