本文選題：長距離輸水 + 氣液兩相流　； 參考：《哈爾濱工業(yè)大學》2015年碩士論文

【摘要】：長距離輸水管道因氣水兩相流動狀態(tài)不斷轉(zhuǎn)變而產(chǎn)生的強烈壓力波動會誘發(fā)管道劇烈振動,引起管道連接部位的松動泄漏和整體結(jié)構(gòu)穩(wěn)定性的降低,甚至發(fā)生爆管現(xiàn)象。為了提高長距離輸水管道運行的安全性,并探究氣液兩相流不同流型下重力輸水和加壓輸水的管道振動特性,本文從氣液兩相流流型的基本理論出發(fā),基于兩相流體與管道的流固耦合作用,對長距離重力輸水和加壓輸水兩種方式在不同運行工況下的管道振動幅頻特性進行了研究。采用理論與試驗結(jié)合的方式,建立了氣液兩相流管道振動數(shù)學模型,理論分析了管道結(jié)構(gòu)屬性與氣液兩相流體流動特性對輸流管道系統(tǒng)振動固有特性的影響。選用有機玻璃管材搭建長距離輸水管道試驗平臺,通過調(diào)節(jié)氣泵進氣壓力控制進氣量在0~3.0m3/h之間并調(diào)節(jié)閥門控制流速在0.7~1.9m/s范圍內(nèi),同時模擬重力輸水和加壓輸水兩種方式的穩(wěn)態(tài)運行和關閥過渡過程工況。采用三向振動加速度傳感器對水平管道、45°上升管道、45°下降管道以及閥門部位進行穩(wěn)態(tài)條件下的振動響應檢測,獲得管道軸向和徑向振動加速度頻譜圖。使用關閥時間可控的電動球閥和氣動蝶閥進行過渡態(tài)試驗,研究關閥和事故水錘對管道振動幅頻特性的影響。理論和試驗結(jié)果表明,管道系統(tǒng)的固有頻率會隨著管徑或管材彈性模量的增大以及管長或管材密度的減小而提高。氣液兩相流含氣率的加大在提升管道系統(tǒng)固有頻率的同時也會提高水平管道的振動強度。在同一水流速下,水平管道軸向振動強度隨含氣率的增加而增大,于泡狀-段塞流過程增長速率最快,并在段塞流流型時達到最大。由于水平管道段塞流振動頻域較寬,極有可能發(fā)生管道共振,實際運行中應盡量避免該工況的出現(xiàn)。上升管彎頭由于連接耦合作用,振動強度大。下降管段的振動強度與管內(nèi)氣團的發(fā)展密切相關,應盡量避免非滿管流的產(chǎn)生。氣液兩相流過閥產(chǎn)生的局部擾動對上游近閥管段的徑向振動影響劇烈,使管道徑向振動向高頻區(qū)域發(fā)展,軸向振動受其影響較小�？礻P閥試驗中氣體的存在會降低管道中的水錘升壓,且含氣率越高其降低的幅度越大,但水錘波和管道振動的持續(xù)時間變長。這些對于長距離輸水管道的設計、改造及運行具有較大的參考意義。
[Abstract]:The strong pressure fluctuation caused by the continuous change of the gas-water two-phase flow state in the long distance water conveyance pipeline will induce the pipeline to vibrate violently, cause the loosening and leakage of the connection part of the pipeline, decrease the stability of the whole structure, and even cause the phenomenon of pipe burst. In order to improve the safety of long distance water conveyance pipeline and to explore the vibration characteristics of gravity water conveyance and pressurized water conveyance pipeline under different gas-liquid two-phase flow patterns, this paper proceeds from the basic theory of gas-liquid two-phase flow pattern. Based on the fluid-solid coupling between two-phase fluid and pipeline, the amplitude and frequency characteristics of pipeline vibration under different operating conditions were studied. A mathematical model for the vibration of gas-liquid two-phase flow pipeline is established by combining theory and experiment. The influence of pipeline structure properties and gas-liquid two-phase fluid flow characteristics on the natural vibration characteristics of pipeline system is analyzed theoretically. The plexiglass pipe is selected to build the test platform for long distance water conveyance pipeline. By adjusting the inlet pressure of the air pump to control the air intake between 0~3.0m3/h and the valve to control the flow rate in the range of 0.7~1.9m/s, At the same time, it simulates the steady operation of gravity water conveyance and pressurized water conveyance and the transient process of closing valve. The axial and radial vibration acceleration spectrum of horizontal pipeline is obtained by using three-direction vibration acceleration sensor to detect the vibration response of 45 擄descending pipeline and the position of valve under steady condition. The effect of shutoff valve and accident water hammer on the vibration amplitude-frequency characteristic of pipeline was studied by using electric ball valve and pneumatic butterfly valve with controllable closing time. The theoretical and experimental results show that the natural frequency of the pipe system increases with the increase of the diameter of the pipe or the elastic modulus of the pipe and the decrease of the length or density of the pipe. The increase of gas-liquid two-phase flow gas holdup can not only raise the natural frequency of pipeline system, but also increase the vibration intensity of horizontal pipeline. At the same water flow rate, the axial vibration intensity of horizontal pipeline increases with the increase of gas content, the fastest growth rate occurs in the bubbly slug flow process, and it reaches the maximum at the slug flow pattern. Due to the wide frequency domain of the slug flow vibration in the horizontal pipeline, it is very likely that the pipeline resonance will occur, which should be avoided in the actual operation. The vibration intensity of the riser elbow is high because of the coupling effect. The vibration intensity of the descending section is closely related to the development of the air mass in the pipe, and the non-full flow should be avoided as far as possible. The local disturbance caused by gas-liquid two-phase flow through the valve has a strong influence on the radial vibration of the upstream near valve section, which makes the radial vibration of the pipeline develop to the high-frequency region, and the axial vibration is less affected by it. The existence of gas in the fast closing valve test will reduce the pressure rise of water hammer in the pipeline, and the higher the gas content is, the larger the reduction range is, but the longer the duration of water hammer wave and pipeline vibration is. These are of great reference significance for the design, transformation and operation of long distance water conveyance pipeline.
【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】：TU991.3

【引證文獻】

相關會議論文 前1條

1 王振業(yè);;淺談長距離輸水管道設計中應注意的問題[A];2014年11月建筑科技與管理學術(shù)交流會論文集[C];2014年

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本文編號：1846660