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CONTENTS
Volume 34, Number 3, March 2022
 


Abstract
The present paper is focused on analyzing a set of Computational Fluid Dynamics (CFD) simulation data on reducing orthogonal peak base moment coefficients on a high-rise rectangular building with wings. The study adopts an aerodynamic optimization procedure (AOP) composed of CFD, artificial neural network (ANN), and genetic algorithm (G.A.). A parametric study is primarily accomplished by altering the wing positions with 3D transient CFD analysis using k-εturbulence models. The CFD technique is validated by taking up a wind tunnel test. The required design parameters are obtained at each design point and used for training ANN. The trained ANN models are used as surrogates to conduct optimization studies using G.A. Two single-objective optimizations are performed to minimize the peak base moment coefficients in the individual directions. An additional multiobjective optimization is implemented with the motivation of diminishing the two orthogonal peak base moments concurrently. Pareto-optimal solutions specifying the preferred building shapes are offered.

Key Words
Artificial Neural Network (ANN); computational fluid dynamics; genetic algorithm; high-rise building; multiobjective optimization; wind tunnel

Address
Rajdip Paul:Department of Civil Engineering, Hooghly Engineering & Technology College,
Vivekananda Rd, Pipulpati Post, Chinsurah, West Bengal-712103, Hooghly, India

Sujit Kumar Dalui:Department of Civil Engineering, Indian Institute of Engineering Science and Technology,
Shibpur, P.O. Botanic Garden, Shalimar, West Bengal-711103, Howrah, India

Abstract
Mobile sand barriers are a new type sand-retaining structure that can be moved and arranged according to the engineering demands of sand control. When only used for sand trapping, mobile sand barriers could be arranged in single row. For the dual purposes of sand trapping and sand stabilization, four rows of mobile sand barriers can be arranged in a staggered form. To reveal the effect of plane layout, the included angle between sand barrier direction and wind direction on the characteristics of flow fields and the sand control laws of mobile sand barriers, numerical computations and wind tunnel tests were conducted. The results showed that inflows deflected after passing through staggered arrangement sand barriers due to changes in included angle, and the sand barrier combination exerted successive wind resistance and group blocking effects. An analysis of wind resistance efficiency revealed that the effective protection length of staggered arrangement sand barriers approximately ranged from the sand barrier to 10H on the leeward side (H is sand barrier height), and that the effective protection length of single row sand barriers roughly ranged from 1H on the windward side to 20H on the leeward side. The distribution of sand deposit indicated that the sand interception increased with increasing included angle in staggered arrangement. The wind-breaking and sand-trapping effects were optimal when included angle between sand barrier direction and wind direction is 60°-90°.

Key Words
mobile sand barriers; numerical computation; plane layout; wind-sand two-phase flow; wind tunnel test

Address
Li Gao, Jian-jun Cheng, Bo-song Ding, Jia Lei, Yuan-feng An and Ben-teng Ma: College of Water Resources and Architectural Engineering, Shihezi University, Shihezi Xinjiang 832003, China

Abstract
Although mostly used in wind turbine market, single rotor wind turbines have problems with transportation and installation costs due to their large size. In order to solve such problems, multi-rotor wind turbine is being proposed; however, light weight design of multi-rotor wind turbine is required considering the installation at offshore or deep sea. This study proposes the systematic design process of the multi-rotor wind turbine focused on its supporting structure with simultaneous consideration of static and dynamic behaviors in an ideal situation. 2D and successive 3D topology optimization process based on the density method were applied to minimize the compliance of supporting structure. To realize the conceptual design obtained by topology optimization for manufacturing feasibility, the derived 3D structure was modified to have shell structures and optimized again through parametric design using the design of experiments and the response surface method for detail design of their thicknesses and radii. The resultant structure was determined to satisfy the stress and the buckling load constraint as well as to minimize the weight and the resultant supporting structure were verified numerically.

Key Words
design of experiment; light weight design; multi-rotor wind turbine; response surface method; topology optimization

Address
Hyeon Jin Park:Graduate school of Mechanical Engineering, Yonsei University

Min Kyu Oh:Graduate school of Mechanical Engineering, Yonsei University

Soonok Park:Department of Engineering Automotive, Dong Seoul University

Jeonghoon Yoo:School of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, 03722, Republic of Korea

Abstract
As wind turbine rotors increase, the overall loads and dynamic response become an important issue. This problem is augmented by the exposure of wind turbines to severe atmospheric events with unconventional flows such as tornadoes, which need specific designs not included in standards and codes at present. An experimental study was conducted to analyze the loads induced by a tornado-like vortex (TLV) on horizontal-axis wind turbines (HAWT). A large-scale tornado simulation developed in The Wind Engineering, Energy and Environment (WindEEE) Dome at Western University in Canada, the so-called Mode B Tornado, was employed as the TLV flow acting on a rigid wind turbine model under two rotor operational conditions (idling and parked) for five radial distances. It was observed that the overall forces and moments depend on the location and orientation of the wind turbine system with respect to the tornado vortex centre, as TLV are three-dimensional flows with velocity gradients in the radial, vertical, and tangential direction. The mean bending moment at the tower base was the most important in terms of magnitude and variation in relation to the position of the HAWT with respect to the core radius of the tornado, and it was highly dependent on the rotor Tip Speed Ratio (TSR).

Key Words
experimental test; HAWT; tornadoes; wind loads; wind turbine; WindEEE Dome

Address
Juan P. Lopez:Department of Civil and Environmental Engineering, University of Western Ontario, London, Ontario, Canada

Horia Hangan:Department of Civil and Environmental Engineering, University of Western Ontario, London, Ontario, Canada/ Department of Mechanical Engineering, Ontario Tech University, Oshawa, Ontario, Canada

Ashraf El Damatty:Department of Civil and Environmental Engineering, University of Western Ontario, London, Ontario, Canada


Abstract
The resiliency of electricity transmission and distribution lines towards natural and man-made hazards is critical to the operation of cities and businesses. The extension of these lines throughout the country increases their risk of extreme loading conditions. This paper investigates a unique extreme loading condition of a 100-year old distribution line segment that passes across a river and got entangled with a boom of a ship. The study adopts the Applied Elements Method (AEM) for simulating 54 cases of the highly deformable structural behaviour of the tower. The most significant effects on the tower's structural integrity were found to occur when applying the load with components in all three of the cartesian directions (i.e., X, Y and Z) with the full capacities of the four cables. The studied extreme loading condition was determined to be within the tower's structural integrity were found to occur when applying the load with components in all three of the cartesian directions (i.e., X, Y and Z) with the full capacities of the four cables. The studied extreme loading condition was determined to be within the tower

Key Words
applied element method; extreme loading; failure mechanism; lattice tower; structural dynamics

Address
Jason Ah Chin, Mauricio Garcia, Jeffrey Cote, Ellen Mulcahy, Jonathan Clarke and Ahmed Elshaer: Civil Engineering Department, Lakehead University, Thunder Bay, Canada


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