本文關(guān)鍵詞：軸流式止回閥關(guān)閉過程的可靠性數(shù)值模擬　出處：《北京工業(yè)大學(xué)》2012年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 軸流式止回閥 CFD 動(dòng)網(wǎng)格技術(shù) 可靠性 數(shù)值分析

【摘要】：止回閥作為管路系統(tǒng)中的關(guān)鍵部件，其性能優(yōu)劣、壽命長短、工作可靠度高低直接影響到泵機(jī)組及管道的安全。在對閥門進(jìn)行可靠性分析時(shí)，傳統(tǒng)可靠性試驗(yàn)方法往往需要耗費(fèi)大量的時(shí)間和金錢，既不經(jīng)濟(jì)且實(shí)現(xiàn)困難。所以必須探求新的試驗(yàn)方法，即利用目前較為成熟的液壓類產(chǎn)品的數(shù)值仿真技術(shù)，在試驗(yàn)前通過有效的建模仿真來減少試驗(yàn)次數(shù)、降低試驗(yàn)費(fèi)用等。 在閥門關(guān)閉過程中，往往很容易發(fā)生水擊問題；閥門的運(yùn)動(dòng)極其復(fù)雜，涉及到液動(dòng)力和彈簧力相互作用的流固耦合問題，，不能用簡單的方法反映其運(yùn)動(dòng)規(guī)律。本文以軸流式止回閥二維模型為研究對象，利用編程給定閥瓣運(yùn)動(dòng)的位移、速度、加速度和液動(dòng)力等參數(shù)之間的相互關(guān)系，與CFD進(jìn)行結(jié)合，從流場分析的角度分別對靜水條件下和停泵條件下的軸流式止回閥關(guān)閉過程進(jìn)行了數(shù)值模擬。并結(jié)合可靠性理論進(jìn)行閥門關(guān)閉過程中產(chǎn)品的可靠性數(shù)值分析，對未來開展針對液壓產(chǎn)品可靠性試驗(yàn)與評估提供可以借鑒的方法。論文的主要研究內(nèi)容如下： （1）UDF及動(dòng)網(wǎng)格技術(shù)很好的再現(xiàn)了二維軸流式止回閥在靜水條件和停泵條件下的非穩(wěn)態(tài)關(guān)閉過程。止回閥在關(guān)閉過程中，閥瓣瞬時(shí)響應(yīng)并關(guān)閉閥門；閥瓣運(yùn)動(dòng)速度先開始增加到最大速度，之后開始下降直至關(guān)閉。 （2）停泵后閥門關(guān)閉過程中，作用在閥瓣上的流體力先緩慢增加到某一值后波動(dòng)下降，下降過程緩慢；在閥門即將完全關(guān)閉時(shí)，流體力出現(xiàn)振蕩變化：流體力正反方向跳躍交替，且數(shù)值逐漸增大，最終流體力達(dá)到最大使閥門關(guān)閉。閥門關(guān)閉過程中，隨著閥瓣的移動(dòng)，閥內(nèi)流場一直在變化。流場壓力在閥瓣前后變化始終最大；閥門進(jìn)口端和出口端的壓差一直在增大；流體最大速度始終出現(xiàn)在閥瓣與閥體之間的流道中，在流體流經(jīng)閥瓣后，由于流速較大的原因產(chǎn)生了漩渦，并出現(xiàn)回流，但回流速度不大；由于閥瓣的運(yùn)動(dòng)引起閥瓣附近的流體出現(xiàn)漩渦，且湍動(dòng)能比下游流道出現(xiàn)的湍動(dòng)能大。 （3）運(yùn)用Monte Carlo法進(jìn)行可靠性概率分析和可靠性靈敏度分析，參考可靠性靈敏度分析結(jié)果，彈簧剛度、閥門直徑和閥瓣厚度對系統(tǒng)可靠度影響較大。其中增加彈簧剛度、降低閥瓣厚度，可以提高系統(tǒng)的可靠度，從而實(shí)現(xiàn)系統(tǒng)的優(yōu)化設(shè)計(jì)。
[Abstract]:Check valve as a key component in the pipeline system, its performance, life span, working reliability directly affect the pump unit and pipeline safety. In the valve reliability analysis. Traditional reliability test methods often cost a lot of time and money, which is not economical and difficult to realize. Therefore, we must explore a new test method, that is, using the more mature numerical simulation technology of hydraulic products. The effective modeling and simulation are used to reduce the number of experiments and reduce the cost of the tests before the experiment. In the process of valve closing, water hammer problem is always easy to occur. The movement of valve is extremely complex, which involves the fluid-solid coupling problem between hydraulic force and spring force, and can not be reflected by a simple method. In this paper, the two-dimensional model of axial flow check valve is taken as the research object. By programming the displacement, velocity, acceleration and hydrodynamic parameters of disc movement, the CFD is combined. From the point of view of flow field analysis, the closed process of axial flow check valve under static water condition and pump stop condition is numerically simulated, and the reliability numerical analysis of valve closure process is carried out by combining reliability theory. The main contents of this paper are as follows: (1) the methods of reliability test and evaluation for hydraulic products can be used for reference in the future. The UDF and dynamic grid technology can reproduce the unsteady state closure process of two-dimensional axial flow check valve under the condition of static water and stop pump. During the process of closing the valve, the valve disc can respond and close the valve. Disc motion increases first to maximum speed and then begins to decline until closed. (2) in the process of valve closing after pump stop, the flow force acting on the disc increases slowly to a certain value and then fluctuates and drops slowly; When the valve is about to be completely closed, the flow force oscillates: the flow force jumps alternately in the positive and negative directions, and the value increases gradually, finally the flow force reaches the maximum value to make the valve close. With the movement of the disc, the flow field in the valve is always changing. The pressure of the flow field always changes the most before and after the disc. The pressure difference between the inlet and outlet of the valve has been increasing; The maximum velocity of the fluid always appears in the passage between the disc and the valve body. After the fluid flows through the disc, the vortex is produced because of the high velocity of flow, and the reflux is not very fast. Because of the movement of the disc, the fluid around the disc appears whirlpool, and the turbulent kinetic energy is larger than that of the downstream passage. 3) using Monte Carlo method to analyze reliability probability and reliability sensitivity, referring to the result of reliability sensitivity analysis and spring stiffness. The valve diameter and disc thickness have great influence on the system reliability, in which increasing spring stiffness and reducing disc thickness can improve the reliability of the system and realize the optimal design of the system.
【學(xué)位授予單位】：北京工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：TH134

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