本文選題：軟顫振　切入點(diǎn)：流動控制　出處：《哈爾濱工業(yè)大學(xué)》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(jìn)的發(fā)展。隨著跨度增大,橋梁在結(jié)構(gòu)上變?yōu)橐环N柔性體系,對風(fēng)荷載作用極為敏感。橋梁硬顫振是一種風(fēng)致自激發(fā)散性振動并極易造成結(jié)構(gòu)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(diǎn),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(fēng)致顫振的流動控制方法對提高大跨橋梁的抗風(fēng)設(shè)計(jì)水平和服役安全具有重大意義。本文采用CFD數(shù)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(nèi)容如下:建立蘇通大橋和桃花峪黃河大橋施工狀態(tài)下數(shù)值計(jì)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(shù)及流場特性,考慮了不同模型比例、網(wǎng)格數(shù)量、時間步長和計(jì)算風(fēng)速對計(jì)算結(jié)果的影響規(guī)律,并將模擬結(jié)果與風(fēng)洞試驗(yàn)結(jié)果進(jìn)行對比分析,驗(yàn)證計(jì)算結(jié)果精確性并選擇最優(yōu)網(wǎng)格計(jì)算模型和求解策略,為下一步計(jì)算橋梁的風(fēng)致振動奠定基礎(chǔ)。利用強(qiáng)迫振動法和直接計(jì)算法計(jì)算不同攻角下兩座橋梁的顫振臨界風(fēng)速,并比較兩種數(shù)值方法計(jì)算結(jié)果與風(fēng)洞試驗(yàn)結(jié)果的差異。直接計(jì)算法是利用FLUENT的用戶自定義函數(shù)(UDF)和動網(wǎng)格技術(shù)實(shí)現(xiàn)橋梁斷面的風(fēng)致流固耦合振動模擬,結(jié)構(gòu)振動響應(yīng)采用四階Runge-Kutta方法求解,得到各攻角下不同風(fēng)速的結(jié)構(gòu)動力響應(yīng)時程曲線,進(jìn)而得到顫振臨界風(fēng)速。同時,采用直接計(jì)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(fēng)速范圍。研究了不同響應(yīng)狀態(tài)下的橋梁斷面尾流的旋渦脫落模式,解釋了其產(chǎn)生原因及與響應(yīng)之間的關(guān)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(jié)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(fù)風(fēng)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(shù)。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(jī)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(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U441.3

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本文編號：1658476