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Wind load is the designed control load for super-large cooling tower (SLCT) structures. Studies on wind resistance of those structures have focused mainly on normal winds, not on the influe...

The load–response correlation method has been recognized by the wind engineering community as a useful equivalent static wind load calculation method for structural design of quasi-static structures against strong winds. However, it has been found that the load–response correlation method is less effective to non-linear systems and in situations where load processes are non-Gaussian, such as large cooling towers subjected to strong winds. To validate the applicability of the load–response correlation method to large cooling towers, an aero-elastic model has been designed for a 215-m-high cooling tower in this article, which can simultaneously produce wind loads and wind-induced displacements of the structure according to wind tunnel model tests. Using data measured on the aero-elastic model, the exact results of correlation coefficients between wind loads and structural responses are obtained and validated by a non-linear finite element analysis. By comparing the correlation coefficients measured on the scaled model to the results based on the load–response correlation calculation, it is found that the correlations are much stronger for the load–response correlation calculation than those for the exact wind tunnel measurement. The explanation for this observation is that the non-linearity of the real structure and the non-Gaussian feature of the actual wind loads can weaken the correlations between the wind loads and the structural responses.

Recent measurement results indicate that the wind-induced response of super-large cooling tower (include super-large cooling tower in wet-cooling-systems and super-large cooling tower in dry-cooling-systems) exhibit remarkable non-stationary feature. In this study, wind-induced response signals of a typical super-large cooling tower under real Reynolds number and turbulent conditions were collected based on field measurement. Meanwhile, some other super-large cooling towers were measured to verify the research in this paper. On these bases, non-stationary and non-Gaussian features of wind-induced response of super-large cooling tower were studied. And evolutionary power spectral density of wind-induced response of super-large cooling tower were analyzed. Furthermore, the resonance effect were discussed by studying proportion of resonance component in wind-induced response. Finally, the extreme response and damping ratios considering non-stationary feature of wind-induced effect were obtained in this paper. The results show that the wind-induced response of super-large cooling tower is characterized by stable frequency evolution characteristics and non-stationary evolution characteristics in intensity aspect. Some detailed research conclusions can provide references for wind resistance safety design of super-large cooling tower and disaster prevention study of similar tall thin-walled structure.

Mean/fluctuating wind pressure distributions on an actual large cooling tower (167-meter high) have been obtained and compared to previous results of other cooling towers. The agreement of mean wind pressure distributions is good. But the fluctuating wind pressure coefficients on the large cooling tower are much smaller than those on cooling towers of smaller sizes over the full range. It is assumed that the differences have resulted from the discrepancy of the turbulence intensity of the incoming flow, which is proven true according to wind tunnel model tests. Besides, it is found that most wind pressure signals produced by transducers around the throat section of the actual large cooling tower are of non-Gaussian distributions and they are not likely to be caused by the organized large-scale vortices according to the spatial correlation analyses. The upcoming flow of unsteady speed and direction in the engineering field might be an explanation for the phenomena. Two different methodologies (the traditional Davenport methodology and the complete probability methodology) are adopted to calculate the peak factors, in which the complete probability methodology is appropriate for non-Gaussian distributions. Studies about the spectral characteristics of wind-induced pressures on the actual large cooling tower are also included in this paper, and results show some differences from the previous study.

Summary Herein, by a case study on a 5-MW wind turbine system developed by Nanjing University of Aeronautics and Astronautics, the wind field simulation and wind-induced vibration characteristics of wind turbine tower-blade coupled systems is analyzed. First, the blade-nacelle-tower-basis integrated finite element model with centrifugal forces induced by rotational blades is established. Then, based on a harmony superposition method and the modified blade element-momentum theory, the fluctuating wind field of tower-blade coupled systems is simulated, which considers wind shear effect, tower shadow effect, rotational effect, blade-tower dynamic and model interaction effects. Finally, the wind-induced dynamic responses and wind vibration coefficients of the wind turbine tower-blade coupled structure are discussed through the ‘consistent coupled method’ previously proposed by us. The results indicate that the wind-induced responses of a large wind turbine tower-blade coupled structure present complicated modal responses and multimode coupling effect. Additionally, the rotational effect would amplify aerodynamic loads on blades with high frequency, wind-induced dynamic responses and wind vibration coefficients of wind turbine tower. The centrifugal force effect could also amplify natural vibration frequency of the tower-blade coupled system and reduce the wind-induced dynamic responses and wind vibration coefficients of wind turbine tower. The research could contribute to wind-resistant design of structure for a large-scale wind turbine tower-blade system. Copyright © 2014 John Wiley & Sons, Ltd.

The current work describes a novel technique for wind turbine rotor optimization. The aerodynamic design and optimization of wind turbine rotor can be achieved with different methods, such as the semi-empirical engineering methods and more accurate computational fluid dynamic (CFD) method. The CFD method often provides more detailed aerodynamics features during the design process. However, high computational cost limits the application, especially for rotor optimization purpose. In this paper, a CFD-based actuator disc (AD) model is used to represent turbulent flow over a wind turbine rotor. The rotor is modeled as a permeable disc of equivalent area where the forces from the blades are distributed on the circular disc. The AD model is coupled with a Reynolds Averaged Navier–Stokes (RANS) solver such that the thrust and power are simulated. The design variables are the shape parameters comprising the chord, the twist and the relative thickness of the wind turbine rotor blade. The comparative aerodynamic performance is analyzed between the original and optimized reference wind turbine rotor. The results showed that the optimization framework can be effectively and accurately utilized in enhancing the aerodynamic performance of the wind turbine rotor.

The rigid pressure measurement and aero–elastic vibration measurement were performed to the largest exhaust cooling tower in Asia. Through analyses, the surface wind pressure distribution, multitower proportional coefficient, and wind-induced vibration coefficient of the exhaust cooling towers from the most unfavorable wind direction were obtained. On this basis, finite-element software and self-made repreprocessing and postprocessing programs were employed to analyze the ultimate load-carrying capacity and overall and local stabilities of exhaust cooling tower in three conditions, which include (1) no opening, (2) opening without strengthening, and (3) opening with different strengthening schemes, then the ultimate load-carrying capacity of exhaust cooling tower during construction under different load combinations was also analyzed. For cooling tower with opening, obvious stress aggregation was found near the opening, and the minimum safety factor for local stability of the tower throat area was...