發(fā)布時(shí)間：2018-05-17 21:39

  本文選題：水擊現(xiàn)象 + 經(jīng)典水擊理論��； 參考：《昆明理工大學(xué)》2017年碩士論文

【摘要】：國內(nèi)外學(xué)者開始研究水擊是從19世紀(jì)開始的,至今已經(jīng)有了100多年的歷史。這種發(fā)生在有壓管道中的水力現(xiàn)象,具有很大的危害,是水電站及泵站中不可避免的。管道中高低交替的水擊壓強(qiáng)可能會引起管道的劇烈震動(dòng)、噪音、變形,嚴(yán)重時(shí)甚至?xí)构艿乐苯颖选ｋm然水擊現(xiàn)象已經(jīng)有了 100多年的研究歷史,但其經(jīng)典理論依然有可改進(jìn)的地方。想要得到更為符合實(shí)際和精準(zhǔn)的研究結(jié)果,就需要對經(jīng)典水擊理論進(jìn)行探討,這樣才能為后面的研究內(nèi)容打下夯實(shí)的基礎(chǔ)。本論文首先對經(jīng)典水擊理論進(jìn)行了詳細(xì)的介紹,包括對水擊現(xiàn)象及其分類進(jìn)行了介紹分析,而后對經(jīng)典水擊理論的基本微分方程組進(jìn)行了詳細(xì)的推求,進(jìn)而在推求過程中提出自己的想法,即經(jīng)典水擊理論并沒有考慮管道內(nèi)流體的流速水頭,這可能會對計(jì)算結(jié)果產(chǎn)生一定的影響。本文針對這一問題,重新推導(dǎo)了運(yùn)動(dòng)方程及連續(xù)性方程,并使用特征線法對此方程組進(jìn)行數(shù)值計(jì)算,在FORTRAN平臺上進(jìn)行編程,并繪制了末端斷面水擊壓強(qiáng)隨時(shí)間的變化特性曲線。計(jì)算結(jié)果雖然好于經(jīng)典水擊理論,也與國外類似的試驗(yàn)結(jié)果相符合,但并沒有改善經(jīng)典水擊理論計(jì)算結(jié)果衰減性過慢的情況。然后本文選取隨流體一起運(yùn)動(dòng)的有限控制體建立的微元體,使用動(dòng)量定理及質(zhì)量守恒定律嚴(yán)謹(jǐn)推求并創(chuàng)建了完整的一維非恒定流基本微分方程,附加初始條件,進(jìn)而推導(dǎo)出用于水擊計(jì)算的運(yùn)動(dòng)方程及連續(xù)性方程,結(jié)合液體彈性方程及管壁彈性方程,組成了新的數(shù)學(xué)模型。在數(shù)值計(jì)算方法的選取上,由于特征線法在此數(shù)學(xué)模型上使用過于繁瑣,故本文選取了差分法對其進(jìn)行計(jì)算,建立了差分方程并給出了邊界條件和初始條件,在Matlab平臺上進(jìn)行編程計(jì)算,最終同樣繪制了末端斷面水擊壓強(qiáng)隨時(shí)間的變化規(guī)律曲線圖。最后,本文對以上兩種計(jì)算結(jié)果與經(jīng)典水擊理論進(jìn)行了對比分析,發(fā)現(xiàn)建立的第二個(gè)數(shù)學(xué)模型最符合國外類似試驗(yàn)結(jié)果,也改善了經(jīng)典水擊理論水擊壓強(qiáng)衰減過慢的情況,從而證明了本文創(chuàng)立的數(shù)學(xué)模型的準(zhǔn)確性。本文的探求內(nèi)容對經(jīng)典水錘理論進(jìn)行了完善,在學(xué)術(shù)研究上有理論意義,還為工程實(shí)例的計(jì)算提供了更為豐富的參考信息。
[Abstract]:Scholars at home and abroad began to study water hammer in the 19 th century, which has a history of more than 100 years. This kind of hydraulic phenomenon occurring in the pressure pipeline has great harm and is inevitable in the hydropower station and pumping station. The alternating high and low water hammer pressure in the pipeline may cause the pipe to vibrate, noise, deform and even burst directly. Although the phenomenon of water hammer has been studied for more than 100 years, its classical theory can still be improved. In order to obtain more practical and accurate research results, it is necessary to discuss the classical water hammer theory, so as to lay a solid foundation for the later research. In this paper, the classical water hammer theory is introduced in detail, including the water hammer phenomenon and its classification, and then the basic differential equations of the classical water hammer theory are deduced in detail. Then the author puts forward his own idea that the flow velocity head of the fluid in the pipe is not considered in the classical water hammer theory, which may have a certain influence on the calculation results. In this paper, the equations of motion and continuity are rederived, and the equations are numerically calculated by the method of characteristic line, and programmed on the FORTRAN platform, and the characteristic curves of the variation of water hammer pressure on the end section with time are plotted. Although the calculated results are better than the classical water hammer theory and are in agreement with similar experimental results abroad, it does not improve the slow attenuation of the calculated results of the classical water hammer theory. Then, the differential equations of one-dimensional unsteady flow are derived by using momentum theorem and the law of conservation of mass, and the initial conditions are attached to the differential equations of one-dimensional unsteady flow, which are established by the finite control body moving with the fluid, and the momentum theorem and the law of conservation of mass are used in this paper. Furthermore, the equations of motion and continuity for water hammer calculation are derived, and a new mathematical model is formed by combining the elastic equations of liquid and the elastic equations of pipe wall. In the selection of numerical calculation method, because the characteristic line method is too complicated to be used in this mathematical model, the difference method is selected to calculate it in this paper, the difference equation is established and the boundary conditions and initial conditions are given. By programming on Matlab platform, the curve of water hammer pressure changing with time at the end section is also plotted. Finally, by comparing the above two results with the classical water hammer theory, it is found that the second mathematical model is the most suitable for similar test results abroad, and it also improves the situation that the water hammer pressure attenuation is too slow in the classical water hammer theory. Thus, the accuracy of the mathematical model established in this paper is proved. The content of this paper improves the classical water hammer theory, has theoretical significance in academic research, and provides more abundant reference information for the calculation of engineering examples.
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TV732.4

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本文編號：1902945