本文選題：對夾式止回閥 + 汽蝕現(xiàn)象�。� 參考：《蘭州理工大學(xué)》2017年碩士論文

【摘要】：對夾式止回閥作為自力式控制類閥門,能夠有效防止管路內(nèi)介質(zhì)倒流,泵及電機反轉(zhuǎn)等情況的發(fā)生。在國家大力發(fā)展智慧城市之際,其在樓宇自動化領(lǐng)域、水冷系統(tǒng)中起重要作用,然而國內(nèi)對于對夾式止回閥的理論研究缺失現(xiàn)象嚴重,依靠企業(yè)單獨試驗輔以經(jīng)驗總結(jié)已嚴重滯后于產(chǎn)品的更新發(fā)展步伐。本文以浙江省科技廳重大科技專項為依托,對應(yīng)用于系統(tǒng)流程的高可靠性的對夾式止回閥進行理論分析研究。本文詳細介紹對夾式止回閥的物理結(jié)構(gòu),描述對夾式止回閥的工作原理,重點分析流量與閥瓣開角之間的關(guān)系,并理論推導(dǎo)出相應(yīng)計算公式;對湍流狀態(tài)下流經(jīng)對夾式止回閥的流體進行三維靜態(tài)模擬,確定不同開度角下對夾式止回閥的流阻系數(shù)及速度壓力分布情況;為表征特性因素的瞬態(tài)變化規(guī)律,建立開啟過程二維動態(tài)模型,編譯UDF程序驅(qū)動運動部件及相關(guān)區(qū)域的瞬態(tài)變化,對閥門開啟過程進行監(jiān)控,分析不同時刻壓力速度變化情況,并對閥內(nèi)流場出現(xiàn)的旋渦現(xiàn)象進行初步探討。借鑒靜音止回閥閥內(nèi)流線設(shè)計,對對夾式止回閥閥內(nèi)流道進行動態(tài)模擬,選擇出最佳流線以改善閥體附近小渦的能量耗散,減弱止回閥開啟過程伴隨的汽蝕現(xiàn)象;閥門開啟過程中能量的耗散主要由兩方面構(gòu)成:其一,存在于閥瓣背水區(qū)域,表象為強烈的旋渦現(xiàn)象;其二,開啟過程閥前出現(xiàn)的水錘現(xiàn)象。為提升能量利用率進行結(jié)構(gòu)的優(yōu)化設(shè)計,并對優(yōu)化后的結(jié)構(gòu)進行動態(tài)數(shù)值分析,對比優(yōu)化前后特征曲線,驗證優(yōu)化結(jié)構(gòu)對縮小負壓區(qū)及防止水錘的有效性。通過上述對止回閥的優(yōu)化分析,對比實驗驗證結(jié)果表明:優(yōu)化閥內(nèi)流道后對夾式止回閥最佳開度角增長26°;結(jié)構(gòu)優(yōu)化后,止回閥在壓差開啟過程中,壓差平緩減小,防水錘效果明顯。閥內(nèi)流體旋度減小,旋渦數(shù)量及強度減弱,開啟過程中伴隨的振動與噪聲現(xiàn)象得到很好改善,閥門的流阻系數(shù)減小25%以上,提高閥門的流通量,為旋啟式止回閥系列產(chǎn)品的優(yōu)化設(shè)計提供參考。
[Abstract]:As an independent control valve, clamped check valve can effectively prevent medium backflow, pump and motor inversion in the pipeline.When the country develops the intelligent city vigorously, it plays an important role in the field of building automation, water cooling system. However, the theoretical research on the clamped check valve is seriously missing in our country.Depending on enterprises' individual test and experience summary, it has lagged behind the pace of product renewal and development.Based on the important science and technology project of Zhejiang Science and Technology Department, this paper makes a theoretical analysis and research on the high reliability check valve applied to the system flow.This paper introduces the physical structure of the clamped check valve, describes the working principle of the clamped check valve, analyzes the relationship between the flow rate and the valve disc opening angle, and deduces the corresponding calculation formula theoretically.The flow resistance coefficient and velocity and pressure distribution of clamped check valve at different opening angles were determined by three-dimensional static simulation of flow through the clamped check valve in turbulent state, in order to characterize the transient change law of characteristic factors, the flow resistance coefficient and velocity pressure distribution of clamped check valve were determined under different opening angles.The two-dimensional dynamic model of the opening process is established, and the transient changes of the moving parts and related regions driven by the UDF program are compiled. The valve opening process is monitored and the pressure and velocity changes at different times are analyzed.The vortex phenomenon in the valve flow field is discussed.Referring to the design of the inner flow line of the mute check valve, the dynamic simulation of the inner passage of the clamped check valve is carried out, and the optimum flow line is selected to improve the energy dissipation of the vortex near the valve body and to weaken the cavitation phenomenon accompanying with the opening process of the check valve.The energy dissipation during valve opening mainly consists of two aspects: first, it exists in the back water area of the valve disc, which appears as a strong vortex phenomenon; second, the water hammer phenomenon appears in front of the valve during the opening process.In order to improve the efficiency of energy utilization, the optimization design of the structure is carried out, and the dynamic numerical analysis of the optimized structure is carried out. Compared with the characteristic curves before and after the optimization, the effectiveness of the optimized structure in reducing the negative pressure area and preventing the water hammer is verified.Through the above optimization analysis of check valve, the result of contrast experiment shows that the optimum opening angle of clamped check valve increases by 26 擄after optimizing the flow channel of valve, and the pressure difference of check valve decreases gently during the process of differential pressure opening after structure optimization.The effect of waterproof hammer is obvious.The flow curl in the valve decreases, the number and intensity of the vortex weaken, the vibration and noise phenomenon accompanying in the opening process are improved very well, the flow resistance coefficient of the valve is reduced by more than 25%, and the flow flux of the valve is increased.It provides a reference for the optimization design of the series of rotary check valves.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TH134

【參考文獻】

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本文編號：1749113