The wind-induced vibration of stay cables of cable-stayed bridges, which includes rain-wind-induced vibration （RWIV） and dry galloping （DG）, has been studied for a considerable amount of time. In general, mechanic...The wind-induced vibration of stay cables of cable-stayed bridges, which includes rain-wind-induced vibration （RWIV） and dry galloping （DG）, has been studied for a considerable amount of time. In general, mechanical dampers or surface modification are applied to suppress the vibration. In particular, several types of surface-modification cable, including indentation, longitudinally parallel protuberance, helical fillet, and U-shaped grooving, have been developed. Recently, a new type of aerodynamically stable cable with spiral protuberances was developed. It was confirmed that the cable has a low drag force coefficient, like an indented cable, and that it prevented the formation of water rivulets on the cable surface. In this study, the stability for RWIV of this cable was investigated with various flow angles and protuberance dimensions in a wind-tunnel test. It was found that the spiral protuberance cable is aerodynamically stable against both RWIV and DG for all test wind angles. The effects of the protuberance dimensions were also clarified.展开更多
The unsteady Reynolds-averaged Navier-Stokes equations coupled with the k-co SST turbulence model are solved to obtain the steady and unsteady aerodynamic forces for airfoils and wings. The effects of vibration types ...The unsteady Reynolds-averaged Navier-Stokes equations coupled with the k-co SST turbulence model are solved to obtain the steady and unsteady aerodynamic forces for airfoils and wings. The effects of vibration types and amplitudes on aerody- namic forces of airfoils and wings are studied. The deformation characteristics of a swept wing induced by steady aerodynamic load are presented. It is found that for a vibrating elastic wing at small and medium incidences, its mean aerodynamic loads are almost the same as those obtained from the static one. On the contrary, at high incidences especially around the stall incidence, the vibration may change the mean values. In addition, the larger amplitude is, the larger discrepancy will be. For a swept wing, the steady aerodynamic loads usually lead to the ＂pitching down＂ effect on the wing tip which delays the stall compared with a rigid one; But this phenomenon dose not occur on a aeroelastic wing which can induce the separation ahead and trigger the stall. The above conclusions are in good agreement with the scatter characteristics of wind-tunnel data. The reason why the data obtained from wind tunnel and CFD are different is also analyzed. Meanwhile, it can be an explanation for scatter phe- nomenon of wind-tunnel data, especially for high incidence cases, which remains a puzzle so far.展开更多
The structure of parabolic condensers makes them susceptible to wind load because of their thin and large windward mirrors.In this paper,the wind pressure on a model of a condenser mirror(1:35)on multistorey flat roof...The structure of parabolic condensers makes them susceptible to wind load because of their thin and large windward mirrors.In this paper,the wind pressure on a model of a condenser mirror(1:35)on multistorey flat roofs is analysed via pressure measurement in a wind tunnel.The mean wind-pressure distribution law of flat-roof condenser mirrors(including the change law with working conditions and the maximum distribution characteristics)and the distribution law of fluctuating and extreme wind pressure are obtained.Furthermore,by comparison with the ground-based condenser distribution law,similarities and differences between the two are obtained.Research results show that the wind-pressure distribution law of flat-roof parabolic condenser mirrors is the same as those on the ground,but the mean wind-pressure coefficient(absolute value)is generally~30%smaller.Furthermore,the maximum effect is generally located at the windward mirror edge and the mirror is more susceptible to wind pressure in wind directions of 30°and 135°-150°.The results of this study can provide a theoretical reference for wind-resistant structure design and multistorey flat-roof condenser-related research.展开更多
文摘The wind-induced vibration of stay cables of cable-stayed bridges, which includes rain-wind-induced vibration （RWIV） and dry galloping （DG）, has been studied for a considerable amount of time. In general, mechanical dampers or surface modification are applied to suppress the vibration. In particular, several types of surface-modification cable, including indentation, longitudinally parallel protuberance, helical fillet, and U-shaped grooving, have been developed. Recently, a new type of aerodynamically stable cable with spiral protuberances was developed. It was confirmed that the cable has a low drag force coefficient, like an indented cable, and that it prevented the formation of water rivulets on the cable surface. In this study, the stability for RWIV of this cable was investigated with various flow angles and protuberance dimensions in a wind-tunnel test. It was found that the spiral protuberance cable is aerodynamically stable against both RWIV and DG for all test wind angles. The effects of the protuberance dimensions were also clarified.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11072199 and 10872171)
文摘The unsteady Reynolds-averaged Navier-Stokes equations coupled with the k-co SST turbulence model are solved to obtain the steady and unsteady aerodynamic forces for airfoils and wings. The effects of vibration types and amplitudes on aerody- namic forces of airfoils and wings are studied. The deformation characteristics of a swept wing induced by steady aerodynamic load are presented. It is found that for a vibrating elastic wing at small and medium incidences, its mean aerodynamic loads are almost the same as those obtained from the static one. On the contrary, at high incidences especially around the stall incidence, the vibration may change the mean values. In addition, the larger amplitude is, the larger discrepancy will be. For a swept wing, the steady aerodynamic loads usually lead to the ＂pitching down＂ effect on the wing tip which delays the stall compared with a rigid one; But this phenomenon dose not occur on a aeroelastic wing which can induce the separation ahead and trigger the stall. The above conclusions are in good agreement with the scatter characteristics of wind-tunnel data. The reason why the data obtained from wind tunnel and CFD are different is also analyzed. Meanwhile, it can be an explanation for scatter phe- nomenon of wind-tunnel data, especially for high incidence cases, which remains a puzzle so far.
基金supported by National Natural Science Foundation of China(grant number:51708478)the Natural Science Foundation of Hunan province(grant number:2020JJ5549)the State Key Laboratory of Marine Resource Utilization in South China Sea(MRUKF2021028).
文摘The structure of parabolic condensers makes them susceptible to wind load because of their thin and large windward mirrors.In this paper,the wind pressure on a model of a condenser mirror(1:35)on multistorey flat roofs is analysed via pressure measurement in a wind tunnel.The mean wind-pressure distribution law of flat-roof condenser mirrors(including the change law with working conditions and the maximum distribution characteristics)and the distribution law of fluctuating and extreme wind pressure are obtained.Furthermore,by comparison with the ground-based condenser distribution law,similarities and differences between the two are obtained.Research results show that the wind-pressure distribution law of flat-roof parabolic condenser mirrors is the same as those on the ground,but the mean wind-pressure coefficient(absolute value)is generally~30%smaller.Furthermore,the maximum effect is generally located at the windward mirror edge and the mirror is more susceptible to wind pressure in wind directions of 30°and 135°-150°.The results of this study can provide a theoretical reference for wind-resistant structure design and multistorey flat-roof condenser-related research.
