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Volume 28, Number 5, May 2019

This paper describes the application of a novel virtual prototyping methodology to wind turbine blade design. Numeric modelling data and experimental data about turbine blade geometry and structural/dynamical behaviour are combined to obtain an affordable digital twin model useful in reducing the undesirable uncertainties during the entire turbine lifecycle. Moreover, this model can be used to track and predict blade structural changes, due for example to structural damage, and to assess its remaining life. A new interactive and recursive process is proposed. It includes CAD geometry generation and finite element analyses, combined with experimental data gathered from the structural testing of a new generation wind turbine blade. The goal of the research is to show how the unique features of a complex wind turbine blade are considered in the virtual model updating process, fully exploiting the computational capabilities available to the designer in modern engineering. A composite Sandia National Laboratories Blade System Design Study (BSDS) turbine blade is used to exemplify the proposed process. Static, modal and fatigue experimental testing are conducted at Clarkson University Blade Test Facility. A digital model was created and updated to conform to all the information available from experimental testing. When an updated virtual digital model is available the performance of the blade during operation can be assessed with higher confidence.

Key Words
wind turbine; digital twin; finite element method; composite materials; modelling and simulation; design

Alessandro Baldassarre: Department of Mechanical and Aeronautical Engineering MAE, Clarkson University,
8 Clarkson Avenue, Potsdam, NY 13699-5725, USA
Alessandro Ceruti: Department of Industrial Engineering DIN, University of Bologna, Viale del Risorgimento 2, 40136 Bologna, Italy
Daniel N. Valyou: School of Engineering, Clarkson University, 8 Clarkson Avenue, Potsdam, NY 13699-5725, USA
Pier Marzocca:School of Engineering, Aerospace Engineering and Aviation, RMIT University, Bundoora VIC 3083, Australia

For super long-span bridges, the aerodynamic forces induced by the flow passing the box girder should be considered carefully. And the Reynolds number sensitively of aerodynamic characteristics is one of considerable issue. In the study, a numerical study on the Reynolds number sensitivity of aerodynamic characteristic (flow pattern, pressure distribution and aerodynamic forces) of a twin-box girder were carried out using large eddy simulation (LES) with the dynamic Smagorinsky–Lilly subgrid model. The results show that the aerodynamic characteristics have strong correlation with the Reynolds number. At the leading edge, the flow experiences attachment, departure, and reattachment stages accompanying by the laminar transition into turbulence, causing pressure plateaus to form on the surface, and the pressure plateaus gradually shrinks. Around the gap, attributing that the flow experiences stages of laminar cavity flow, the wake with alternate shedding vortices, and turbulent cavity flow in sequence with an increase in the Reynolds number, the pressures around the gap vary greatly with the Reynold number. At the trailing edge, the pressure gradually recovers as the flow transits to turbulence (the flow undergoes wake instability, shear layer transition-reattachment station), In addition, at relative high Reynolds numbers, the drag force almost does not change, however, the lift force coefficient gradually decreases with an increase in Reynolds number.

Key Words
Reynolds numbers effects; LES; twin-box girder; pressure distribution; aerodynamic forces

Shujin Laima, Wenli Chen and Hui Li: Key Lab of Smart Prevention and Mitigation for Civil Engineering Disasters of the Ministry of Industry and Information, Harbin Institute of Technology, Harbin 150090, China;
Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education, Harbin Institute of Technology, Harbin 150090, China;
School of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China
Buchen Wu and Chao Jiang:School of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China

In order to examine the effects of different wind deflectors on the wind load distribution characteristics of extra-large cooling towers, a comparative study of the distribution characteristics of wind pressures on the surface of three large cooling towers with typical wind deflectors and one tower without wind deflector was conducted using wind tunnel tests. These characteristics include aerodynamic parameters such as mean wind pressures, fluctuating wind pressures, peak factors, correlation coefficients, extreme wind pressures, drag coefficients and vorticity distribution. Then distribution regularities of different wind deflectors on global and local wind pressure of extra-large cooling towers was extracted, and finally the fitting formula of extreme wind pressure of the cooling towers with different wind deflectors was provided. The results showed that the large eddy simulation (LES) method used in this article could be used to accurately simulate wind loads of such extra-large cooling towers. The three typical wind deflectors could effectively reduce the average wind pressure of the negative pressure extreme regions in the central part of the tower, and were also effective in reducing the root of the variance of the fluctuating wind pressure in the upper-middle part of the windward side of the tower, with the curved air deflector showing particularly. All the different wind deflectors effectively reduced the wind pressure extremes of the middle and lower regions of the windward side of the tower and of the negative pressure extremes region, with the best effect occurring in the curved wind deflector. After the wind deflectors were installed the drag coefficient values of each layer of the middle and lower parts of the tower were significantly higher than that without wind deflector, but the effect on the drag coefficients of layers above the throat was weak. The peak factors for the windward side, the side and leeward side of the extra-large cooling towers with different wind deflectors were set as 3.29, 3.41 and 3.50, respectively.

Key Words
extra-large cooling towers; wind deflector; fluctuating wind pressure; peak factor; pressure extremes; drag coefficient

S.T. Ke: Department of Civil Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;
State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China
P. Zhu: Tower college, China Information Consulting & Designing Institude Co, LTD, Nanjing 210019, China
Y.J. Ge: State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China

Non-synoptic winds have distinctive statistical properties compared to synoptic winds and can produce different wind loads on buildings and structures. The current study uses the new capabilities of the WindEEE Dome at Western University to replicate a stationary non-Gaussian wind event recorded at the Port of La Spezia in Italy. These stationary non-Gaussian wind events are also known as intermediate wind events as they differ from non-stationary non-Gaussian events (e.g., downbursts) as well as stationary Gaussian events (e.g., atmospheric boundary layer (ABL) flows). In the present study, the wind loads on a typical low-rise building are investigated for an intermediate wind event reproduced using a continuous radial impinging jet (IJ) at the WindEEE Dome. For the same building model, differences in wind loads between ABL and IJ are also examined. Wind loads on different surface zones on the building, as defined in the ASCE code for design loads, are also calculated and compared with the code.

Key Words
non-Gaussian; impinging jet; low-rise building; wind load; WindEEE Dome

Chowdhury Jubayer, Djordje Romanic and Horia Hangan: Wind Engineering, Energy and Environment (WindEEE) Research Institute, Western University, London, Ontario, Canada

Long-span bridge decks are often shaped as streamlined to improve the aerodynamic performance of the deck. There are a number of important shaping parameters for a streamlined bridge deck. Their effects on aerodynamics should be well understood for shaping the bridge deck efficiently and for facilitating the bridge deck design procedure. This study examined the effect of various shaping parameters such as the bottom plate slope, width ratio and side ratio on aerodynamic responses of single box streamlined bridge decks by employing unsteady RANS simulation. Steady state responses and flow field were analyzed in detail for wide range of bottom plate slopes, width and side ratios. Then for a particular deck shape Reynolds number effect was investigated by varying its value from 1.65x104 to 25x104. The aerodynamic response showed very high sensitivity to the considered shaping parameters and exhibited high aerodynamic performance for a particular combination of shaping parameters.

Key Words
streamlined bridge deck; bottom plate slope; width ratio; aerodynamic force coefficients; flow field; pressure distribution; Reynolds number; Side ratio; CFD and unsteady RANS

Md. N. Haque: Department of Civil Engineering, East West University, A/2 Jahurul Islam Avenue, Jahurul Islam City, Aftabnagar, Dhaka-1212, Bangladesh;
Department of Civil Engineering, Yokohama National University, 79-1, Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
Hiroshi Katsuchi, Hitoshi Yamada and Haeyoung Kim: Department of Civil Engineering, Yokohama National University, 79-1, Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan

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