本文選題：軟顫振　切入點：流動控制　出處：《哈爾濱工業(yè)大學》2015年碩士論文

【摘要】：在交通需求日益增長的趨勢下,大跨橋梁取得了突飛猛進的發(fā)展。隨著跨度增大,橋梁在結構上變?yōu)橐环N柔性體系,對風荷載作用極為敏感。橋梁硬顫振是一種風致自激發(fā)散性振動并極易造成結構毀壞。軟顫振為漸發(fā)性顫振,沒有明顯的突發(fā)性顫振臨界點,振動表現(xiàn)為等幅彎扭耦合振動。因此,研究硬顫振、軟顫振及抑制橋梁風致顫振的流動控制方法對提高大跨橋梁的抗風設計水平和服役安全具有重大意義。本文采用CFD數值模擬方法研究了流線型橋梁主梁斷面硬顫振和軟顫振現(xiàn)象,并提出了采用主被動混合流動控制新方法抑制顫振。主要內容如下:建立蘇通大橋和桃花峪黃河大橋施工狀態(tài)下數值計算模型,采用CFD通用軟件FLUENT模擬兩座橋梁的靜力三分力系數及流場特性,考慮了不同模型比例、網格數量、時間步長和計算風速對計算結果的影響規(guī)律,并將模擬結果與風洞試驗結果進行對比分析,驗證計算結果精確性并選擇最優(yōu)網格計算模型和求解策略,為下一步計算橋梁的風致振動奠定基礎。利用強迫振動法和直接計算法計算不同攻角下兩座橋梁的顫振臨界風速,并比較兩種數值方法計算結果與風洞試驗結果的差異。直接計算法是利用FLUENT的用戶自定義函數(UDF)和動網格技術實現(xiàn)橋梁斷面的風致流固耦合振動模擬,結構振動響應采用四階Runge-Kutta方法求解,得到各攻角下不同風速的結構動力響應時程曲線,進而得到顫振臨界風速。同時,采用直接計算方法得到了兩座橋梁發(fā)生軟顫振現(xiàn)象的攻角和各攻角下發(fā)生軟顫振風速范圍。研究了不同響應狀態(tài)下的橋梁斷面尾流的旋渦脫落模式,解釋了其產生原因及與響應之間的關系。通過在橋梁節(jié)段模型底部施加控制板,利用主被動吹、吸氣相結合的流動控制方法抑制不同攻角下橋梁的顫振特性。對于非負風攻角,分析距斷面底部不同距離控制板控制效果的優(yōu)劣,并選擇最優(yōu)距離參數。對于被動方法控制效果不好的攻角采用主動吹、吸氣方法,對于確定距斷面底部距離的控制板,分析不同吹氣和吸氣速度對顫振特性的抑制效果,同時分析了相同吹、吸氣流量下不同吹、吸氣速度分布的控制效果。最后,通過斷面附近速度流線與渦量等值線圖揭示本文方法對顫振特性的控制機理。
[Abstract]:In the trend of increasing traffic demand, the long-span bridge has made rapid development. With the increase of span, the bridge becomes a flexible system in structure. The bridge hard flutter is a kind of wind-induced self-excited divergence vibration and can easily cause structural damage. The soft flutter is gradual flutter, and there is no obvious critical point of sudden flutter. The vibration is shown as the coupling vibration of equal amplitude, bending and torsion. Therefore, the hard flutter is studied. The methods of soft flutter and wind-induced flutter control are of great significance to the improvement of wind-resistant design and safety of long-span bridges. In this paper, the CFD numerical simulation method is used to study the hard fibrillation of the main girder section of streamlined bridges. Vibration and soft flutter, A new method of active and passive mixed flow control is proposed to suppress flutter. The main contents are as follows: the numerical calculation models of Sutong Bridge and Taohuayu Yellow River Bridge are established. The static three-point force coefficient and flow field characteristics of two bridges are simulated by CFD general software FLUENT. The effects of different model ratio, mesh number, time step size and calculated wind speed on the calculated results are considered. The simulation results are compared with the wind tunnel test results to verify the accuracy of the calculation results and to select the optimal grid computing model and solution strategy. The method of forced vibration and direct calculation are used to calculate the flutter critical wind speed of two bridges at different angles of attack. The results of the two numerical methods are compared with the results of the wind tunnel test. The direct calculation method is to simulate the wind-induced fluid-solid coupling vibration of the bridge section by using the user-defined function of FLUENT and the dynamic grid technology. The fourth order Runge-Kutta method is used to solve the structural vibration response. The time-history curves of the structural dynamic response under different wind speeds at different angles of attack are obtained, and the critical flutter velocity is obtained. The attack angles of soft flutter phenomena in two bridges and the range of soft flutter wind speed at each angle of attack are obtained by direct calculation method. The vortex shedding modes of cross-section wake under different response states are studied. By applying control panel at the bottom of the bridge segment model, the flutter characteristics of the bridge at different attack angles are restrained by using active and passive blowing and inspiratory flow control method. For the non-negative wind attack angle, the flutter characteristics of the bridge at different angles of attack are suppressed. The control effects of different distance control panels from the bottom of the section are analyzed, and the optimal distance parameters are selected. For the passive control methods, the active blowing and inspiratory methods are used to determine the distance from the bottom of the section. At the same time, the control effect of the same blowing rate, different suction flow rate and different suction velocity distribution on the flutter characteristics is analyzed. The control mechanism of flutter characteristics is revealed by using the contour diagram of velocity streamline and vorticity near the section.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U441.3

【參考文獻】

相關期刊論文 前2條

1 曹豐產,項海帆,陳艾榮;橋梁斷面的氣動導數和顫振臨界風速的數值計算[J];空氣動力學學報;2000年01期

2 劉高,強士中,王秀偉;主動控制翼板抑制懸索橋顫振的研究[J];應用力學學報;2002年04期

相關博士學位論文 前2條

1 徐楓;結構流固耦合振動與流動控制的數值模擬[D];哈爾濱工業(yè)大學;2009年

2 趙娜;超聲速流中機翼及壁板非線性顫振的主動控制方法研究[D];哈爾濱工業(yè)大學;2014年

相關碩士學位論文 前1條

1 張朝貴;橋梁主梁“軟”顫振及其非線性自激氣動力參數識別[D];同濟大學;2007年

，

本文編號：1658476