A study of snow drifting on a flat roof during snowfall based on simulations in a cryogenic wind tunnel

2019 ◽  
Vol 188 ◽  
pp. 269-279 ◽  
Author(s):  
Shengguan Qiang ◽  
Xuanyi Zhou ◽  
Kenji Kosugi ◽  
Ming Gu
Author(s):  
Chenhui Yu ◽  
Fei Liao ◽  
Haibo Ji ◽  
Wenhua Wu

With the increasing requirement of Reynolds number simulation in wind tunnel tests, the cryogenic wind tunnel is considered as a feasible method to realize high Reynolds number. Characteristic model-based adaptive controller design method is introduced to flow field control problem of the cryogenic wind tunnel. A class of nonlinear multi-input multi-output (MIMO) system is given for theoretical research that is related to flow field control of the cryogenic wind tunnel. The characteristic model in the form of second-order time-varying difference equations is provided to represent the system. A characteristic model-based adaptive controller is also designed correspondingly. The stability analysis of the closed loop system composed of the characteristic model or the exact discrete-time model and the proposed controller is investigated respectively. Numerical simulation is presented to illustrate the effectiveness of this control method. The modeling and control problem based on characteristic model method for a class of MIMO system are studied and first applied to the cryogenic wind tunnel control field.


2019 ◽  
Vol 162 ◽  
pp. 74-87 ◽  
Author(s):  
Zhixiang Liu ◽  
Zhixiang Yu ◽  
Fu Zhu ◽  
XiaoXiao Chen ◽  
Yi Zhou

2020 ◽  
pp. 136943322096527
Author(s):  
Jingxue Wang ◽  
Qingshan Yang ◽  
Yi Hui

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.


1988 ◽  
Author(s):  
Yutaka Yamaguchi ◽  
Hideki Kaba ◽  
Shizuyuki Yoshida ◽  
Nobumitsu Kuribayashi

1997 ◽  
Vol 34 (1) ◽  
pp. 34-42 ◽  
Author(s):  
Keisuke Asai ◽  
Hiroshi Kanda ◽  
Tetsuya Kunimasu ◽  
Tianshu Liu ◽  
John P. Sullivan

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