This study investigates the modulation of initial wind field structure on the relationship between the size and intensity of a simulated vortex.A series of idealized experiments are conducted by varying the radius of ...This study investigates the modulation of initial wind field structure on the relationship between the size and intensity of a simulated vortex.A series of idealized experiments are conducted by varying the radius of maximum wind(RMW)and shape parameter of the initial vortices.The size–intensity relationship is quantified by the linear regression coefficient of the azimuthally-averaged gale-force wind radius against the maximum wind during the development stage,reflecting the degree of size expansion at the same intensity increment.The regression coefficient increases with increased RMW and decreased,with the RMW being the primary constraint.The effect of lowering on the elevation of the regression coefficient gradually stands out when the initial RMW is large.Enlarging the RMW leads to a secondary circulation with a horizontally elongated structure,which retards the intensification while promoting size expansion,thus substantially enhancing size expansion as the vortex intensifies.Broadening the wind field outside the RMW by reducing results in abounding convection in the outer region,which promotes size expansion.Based on the axisymmetric tangential wind tendency and Sawyer–Eliassen equations,when the RMW is large,the active convection in the outer region can weaken the radial inflow induced by the eyewall heating in the inner region,thus retarding the intensification by reducing the radial imports of vorticity near the RMW.展开更多
A downburst is a strong downdraft generated by intense thunderstorm clouds,producing radially divergent and highly destructive winds near the ground.Its characteristic scales are expressed through random variations in...A downburst is a strong downdraft generated by intense thunderstorm clouds,producing radially divergent and highly destructive winds near the ground.Its characteristic scales are expressed through random variations in jet height,velocity,and diameter during an event.In this study,a reduced-scale parked wind turbine is exposed to downburst wind fields to investigate the resulting extreme wind loads.The analysis emphasizes both the flow structure of downbursts and the variations of surface wind pressure on turbine blades under different jet parameters.Results show that increasing jet velocity markedly enhances the maximum horizontal wind speed,while greater jet height reduces the horizontal wind speed and shifts the peak velocity closer to the jet center.Increasing jet diameter primarily affects the radial position of the maximum horizontal wind speed.For the wind turbine,the maximum equivalent stress and blade displacement increase almost linearly with jet velocity,but exhibit the opposite trend with jet diameter.Specifically,as jet velocity rises from 10 m/s to 20 m/s,the surface pressure coefficient at the blade tip increases by approximately 4.5 times.Changes in jet diameter indirectly alter the turbine’s relative position within the wind field,leading to variations in wind load direction and exposure area.Conversely,increasing jet height extends the dissipation path of the downdraft,thereby reducing the intensity of the airflow acting on the blades.For example,when jet height increases from 0.3 m to 1.2 m,the surface pressure coefficient at the blade tip decreases by nearly 50%.展开更多
基金This study is supported by the National Natural Science Foundation of China(Grant Nos.42175073 and 41975071).
文摘This study investigates the modulation of initial wind field structure on the relationship between the size and intensity of a simulated vortex.A series of idealized experiments are conducted by varying the radius of maximum wind(RMW)and shape parameter of the initial vortices.The size–intensity relationship is quantified by the linear regression coefficient of the azimuthally-averaged gale-force wind radius against the maximum wind during the development stage,reflecting the degree of size expansion at the same intensity increment.The regression coefficient increases with increased RMW and decreased,with the RMW being the primary constraint.The effect of lowering on the elevation of the regression coefficient gradually stands out when the initial RMW is large.Enlarging the RMW leads to a secondary circulation with a horizontally elongated structure,which retards the intensification while promoting size expansion,thus substantially enhancing size expansion as the vortex intensifies.Broadening the wind field outside the RMW by reducing results in abounding convection in the outer region,which promotes size expansion.Based on the axisymmetric tangential wind tendency and Sawyer–Eliassen equations,when the RMW is large,the active convection in the outer region can weaken the radial inflow induced by the eyewall heating in the inner region,thus retarding the intensification by reducing the radial imports of vorticity near the RMW.
基金the National Natural Science Foundation of China(Grant Nos.52276197, 52166014)Gansu Province Key Research and Development Program—Industrial Project(Grant No.23YFGA0069).
文摘A downburst is a strong downdraft generated by intense thunderstorm clouds,producing radially divergent and highly destructive winds near the ground.Its characteristic scales are expressed through random variations in jet height,velocity,and diameter during an event.In this study,a reduced-scale parked wind turbine is exposed to downburst wind fields to investigate the resulting extreme wind loads.The analysis emphasizes both the flow structure of downbursts and the variations of surface wind pressure on turbine blades under different jet parameters.Results show that increasing jet velocity markedly enhances the maximum horizontal wind speed,while greater jet height reduces the horizontal wind speed and shifts the peak velocity closer to the jet center.Increasing jet diameter primarily affects the radial position of the maximum horizontal wind speed.For the wind turbine,the maximum equivalent stress and blade displacement increase almost linearly with jet velocity,but exhibit the opposite trend with jet diameter.Specifically,as jet velocity rises from 10 m/s to 20 m/s,the surface pressure coefficient at the blade tip increases by approximately 4.5 times.Changes in jet diameter indirectly alter the turbine’s relative position within the wind field,leading to variations in wind load direction and exposure area.Conversely,increasing jet height extends the dissipation path of the downdraft,thereby reducing the intensity of the airflow acting on the blades.For example,when jet height increases from 0.3 m to 1.2 m,the surface pressure coefficient at the blade tip decreases by nearly 50%.
