本文使用邊界層流場中三維方柱橫風向強制振動實驗,探討高層建築風擺現象對於其所受風力特性的影響。實驗以流場特性、橫風向振幅及振頻為控制條件，量測方柱模型的風力係數、頻譜與相關長度等氣動力性質。實驗結果顯示橫風向強制振動對於順風向風力影響並不明顯，對於橫風向風力則有密切的關聯性。振頻與渦散頻率接近時，二者間會發生共振現象，振幅較大則進一步發生鎖定現象。擾動性昇力係數及相關尺度隨共振現象的發生而增大。增大紊流強度會減弱渦散強度及強制振動所引發的共振與鎖定現象。Wind tunnel experiments were conducted to study the aerodynamics of a 3-D square cylinder under forced vibration. Turbulent boundary layers, vibration amplitude and frequency were chosen as controlled parameters to investigate the wind load characteristics, such as drag and lift coefficients, force spectra and spatial Correlation of wind loads. Experimental results indicate that the acrosswind vibration affects strongly on the lift force and casts little influence on the drag force. When the frequency of forced vibration closes to the vortex shedding frequency, synchronization of these two occurs. Increasing the vibration amplitude, the vortex shedding frequency will "lock-in" to the vibration frequency and the lift coefficient and force length scale would subsequently increase. Presence of turbulence would weaken the vortex shedding intensity, diminish the synchronization and lock-in phenomenon.
關聯:
力學：中國力學學會期刊=The Chinese Journal of Mechanics 13(1)，頁33-44
