Search

When examining the history of wind engineering, it is evident that many full-scale/model test comparisons have found noticeable differences between the results. Although understanding the causes of these differences is important for practical purposes, limited numerical and experimental conditions have often resulted in subjective explanations for full-scale/model test comparisons without scientific validation. To address this issue, this article suggests the use of the computational fluid dynamics technique or the multiple-fan actively controlled wind tunnel technique to quantitatively reveal the adverse effects that impact the reliability of the traditional atmospheric boundary layer wind tunnel tests for a large cooling tower, including not only the widely acknowledged influences (Reynolds number effects and turbulent flow characteristics effects) but also the non-stationarity effects that have potential influences. Established on the novel proposition, a new research scheme for future full-scale/model test wind effects comparisons for large cooling towers has been formulated based on the numerical or physical simulations of the sinusoidal flow fields. Using the Pengcheng cooling tower as a case study, the research recognized the very significant impact of Reynolds number effects, the non-stationarity effects that cannot be ignored, and the negligible effects of turbulent flow characteristics. [ABSTRACT FROM AUTHOR]

To protect large cooling towers against strong winds, wind tunnel model tests have traditionally been undertaken. As typical circular cylindrical structures, simulations of high Reynolds number (Re) effects are indispensable on scale models of large cooling towers to validate the truthfulness of test results. However, two issues currently exist that hinder the effectiveness of high Re effects simulation: (1) the mean wind pressure distribution at high Re is usually utilized as the sole simulation target, and the simulation results are not typically checked for other dynamic wind effects that are equally important; and (2) it is not clear whether the wind effects obtained and generalized by other researchers for small-sized cooling towers can be used as simulation targets for large cooling towers. In light of these issues, a new method for the simulation of high Re effects that takes into account real simulated dynamic wind effects is proposed in this study and compared with the traditional simulation method, which only considers the simulation of the mean wind pressure distribution. By comparing the wind effects measured on a 167 m-high large cooling tower with those obtained on small-sized cooling towers, the irrationality of treating the wind effects measured on small-sized cooling towers as high Re effects simulation targets for large cooling towers is demonstrated. With these findings, future model tests are expected to reproduce more realistic wind effects on large cooling towers. [ABSTRACT FROM AUTHOR]

A new research scheme for a full-scale/model test comparison is proposed for effectively validating the wind tunnel pressure measurement technique in this article. With the new research scheme and using quantifiable data, future full-scale/model test comparisons are expected to reasonably disclose the main problem with the traditional atmospheric boundary layer wind tunnel pressure measurement technique with regard to the Reynolds number (Re) effects, the aero-elastic effects and the flow characteristic effects. Based on the engineering background of the Peng-cheng cooling tower, it was quantified by using the new research scheme that the average relative errors of the mean wind pressure coefficients are 52.39%, 1.87% and 35.91% for the Re effects, the aero-elastic effects and the flow characteristic effects, respectively. In view of the fluctuating wind pressure coefficients, the average relative errors are 97.58%, 21.14% and 20.20% for the Re effects, the aero-elastic effects and the flow characteristic effects, respectively. These suggest that Re effects are extremely significant for pressure measurement model tests of circular cylindrical structures, and flow characteristic effects are noticeable too. They should be mitigated using effective approaches, i.e., increasing the model surface roughness and placing the actively controlled devices at the beginning of the wind tunnel's working section, respectively. Additionally, the key field measurement technique adopted (i.e., the calculation of the reference static pressure) and details of manufacturing the aero-elastic pressure measurement model for the present study are also expounded in the article for reference. [ABSTRACT FROM AUTHOR]