Characteristics of conical vortices and their effects on wind pressures on flat-roof-mounted solar arrays by LES

2020 ◽  
Vol 200 ◽  
pp. 104146
Author(s):  
Jingxue Wang ◽  
Qingshan Yang ◽  
Pham Van Phuc ◽  
Yukio Tamura
Keyword(s):  
Solar Arrays ◽  
Conical Vortices ◽  
Wind Pressures ◽  
Flat Roof

Comparisons of design wind pressures on roof-mounted solar arrays between wind tunnel tests and codes and standards

2020 ◽  
pp. 136943322096527
Author(s):  
Jingxue Wang ◽  
Qingshan Yang ◽  
Yi Hui
Keyword(s):  
Wind Tunnel ◽  
Experimental Results ◽  
Solar Panels ◽  
Wind Tunnel Tests ◽  
Pressure Equalization ◽  
Solar Arrays ◽  
Side Ratio ◽  
Design Values ◽  
Wind Pressures ◽  
Flat Roof

The current codes and standards concerning wind loads on roof-mounted solar panels are discussed and summarized. Wind pressures on flat- and slope-roof-mounted solar arrays obtained from wind tunnel tests are compared with the recommended design values in ASCE 7-16 and JIS C 8955: 2017. Different parameters, including building side ratio, aspect ratio and parapet height, are examined. Results show that the largest wind pressures on flat-roof-mounted solar panels of all zones in ASCE 7-16 tend to be 10% to 26% smaller than the experimental results when normalized tributary area An is larger than 103. Uplift wind forces on flat-roof-mounted solar panels in downstream regions obtained from experiments can be larger than the recommended values in JIS C 8955: 2017 for adverse wind, but downward force coefficients are basically smaller than those in JIS C 8955: 2017 for fair wind. 40% to 60% increase on the pressure equalization factor for slope-roof-mounted solar panels is suggested for the potential refinement of ASCE 7-16 based on this study. Meanwhile, proposed pressures of slope-roof-mounted solar panels in JIS C 8955: 2017 might be too conservative according of experimental results.

Mean wind pressures on flat roof corners affected by parapets: field and wind tunnel studies

1999 ◽  
Vol 21 (7) ◽  
pp. 629-638 ◽  
Author(s):  
Theodore Stathopoulos ◽  
Rajan Marathe ◽  
Hanqing Wu
Keyword(s):  
Wind Tunnel ◽  
Wind Pressures ◽  
Flat Roof

scholarly journals Fluctuating Wind Pressures due to the Conical Vortices on Flat Roofs

2001 ◽  
Vol 21 (1Supplement) ◽  
pp. 283-286
Author(s):  
Tetsuro TANIGUCHI ◽  
Yoshihito TANIIKE ◽  
Junko IKEUCHI
Keyword(s):  
Conical Vortices ◽  
Wind Pressures ◽  
Flat Roofs ◽  
Fluctuating Wind

WIND LOADS ON ROOFING SYSTEM AND PHOTOVOLTAIC SYSTEM INSTALLED PARALLEL TO FLAT ROOF

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Tetsuo Yambe ◽  
Yasushi Uematsu ◽  
Kosuke Sato
Keyword(s):  
Time History ◽  
Photovoltaic System ◽  
Pressure Equalization ◽  
Pv Systems ◽  
External Pressures ◽  
Wind Actions ◽  
Strong Winds ◽  
Wind Pressures ◽  
Flat Roof ◽  
Roofing System

Mechanically-attached waterproofing system has become popular in Japan. Being vulnerable to wind actions, especially to suctions, this roofing system is often damaged by strong winds. Similarly, photovoltaic (PV) systems installed on flat roofs are often damaged by strong winds, because the PV panels are subjected to large wind forces in an adverse wind. In order to reduce such damage to both systems, the authors propose to install the PV panels parallel to the flat roof with gaps between them, which may reduce the net wind forces on the PV panels due to the effect of pressure equalization. In addition, the wind pressures acting on the waterproofing system will decrease significantly. The present paper investigates the validity of the above-mentioned idea. The wind pressures underneath the PV panels, called ‘layer pressures’, are evaluated by a numerical simulation using the unsteady Bernoulli equation together with the time history of external pressures measured at many locations on the rooftop of a flat-roofed building model in a turbulent boundary layer. The results clearly indicate a significant reduction of wind forces acting on the PV panels as well as on the waterproofing system. The use of PV panels for reducing the wind pressures on waterproofing system is quite effective to the corner region of the roof, where very large suctions are induced in a diagonal wind.

LES study of wind pressure and flow characteristics of flat-roof-mounted solar arrays

2020 ◽  
Vol 198 ◽  
pp. 104096 ◽  
Author(s):  
Jingxue Wang ◽  
Pham Van Phuc ◽  
Qingshan Yang ◽  
Yukio Tamura
Keyword(s):  
Flow Characteristics ◽  
Wind Pressure ◽  
Solar Arrays ◽  
Flat Roof

Full-scale measurements of wind pressures on flat roof corners

1990 ◽  
Vol 36 ◽  
pp. 1063-1072 ◽  
Author(s):  
T. Stathopoulos ◽  
A. Baskaran ◽  
P.A. Goh
Keyword(s):  
Full Scale ◽  
Wind Pressures ◽  
Flat Roof

scholarly journals On the Use of the Cubic Translation to Model Bimodal Wind Pressures

2019 ◽  
Vol 15 (2) ◽  
pp. 20-32
Author(s):  
François Rigo ◽  
Thomas Andrianne ◽  
Vincent Denoël
Keyword(s):  
Bimodal Distribution ◽  
Wind Pressure ◽  
Wind Engineering ◽  
Pressure Data ◽  
Direct Evaluation ◽  
Translation Model ◽  
Background Turbulence ◽  
Wind Pressures ◽  
Non Gaussian ◽  
Flat Roof

Abstract The cubic translation model is a well know tool in wind engineering, which provides a mathematical description of a non-Gaussian pressure as a cubic transformation of a Gaussian process. This simple model is widely used in practice since it offers a direct evaluation of the peak factors as a function of the statistics of the wind pressure data. This transformation is rather versatile but limited to processes which are said to be in the monotonic region. For processes falling outside this domain, this paper describes an alternative which is based on the physics of the wind flow. First, it is shown, with a classical example of a flow involving corner vortices on a flat roof, that the pressure data which does not meet the monotonic criterion is in fact associated with a bimodal distribution. Then, the proposed approach is to decompose this data into the two governing modes (slow background turbulence and fast corner vortices) and apply the usual translation model to each of them.

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