本文關(guān)鍵詞： 突擴(kuò) 突跌 摻氣濃度 脈動壓強(qiáng) 模型試驗(yàn) 摻氣設(shè)施　出處：《昆明理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：我國蘊(yùn)含非常豐富的水利資源,隨著國家水電事業(yè)的快速發(fā)展,越來越多的高水頭泄水建筑物的設(shè)計(jì)和建設(shè),使得高速水力學(xué)問題越來越受到關(guān)注,高速水流的摻氣減蝕問題變得愈加重要,摻氣設(shè)施體形和來流水頭等因素對高速水流水力特性的改變就變得十分重要。雖然很多人對摻氣水流和脈動壓力的研究取得了一定的成績,但是在理論機(jī)理上的發(fā)展還是相對滯后,本文針對突擴(kuò)、突跌體形的摻氣設(shè)施進(jìn)行模型試驗(yàn),通過模型試驗(yàn)和理論分析的互相結(jié)合的方式,使用控制變量的研究方法,研究在不同流量、突擴(kuò)寬度、跌坎高度下泄槽中水流摻氣濃度分布以及變化規(guī)律、脈動總壓強(qiáng)的分布情況、時均壓強(qiáng)的變化、脈動壓強(qiáng)的特點(diǎn)等摻氣水流的水力特性。并且進(jìn)行分析和討論,得到以下成果:(1)通過控制變量法,改變流量、突擴(kuò)寬度、跌坎高度三種影響因素,對泄槽中不同水深、不同軸線處的摻氣濃度規(guī)律進(jìn)行對比分析,得出經(jīng)過突擴(kuò)、突跌型摻氣設(shè)施的水流,在泄槽中摻氣濃度的變化規(guī)律,影響泄槽中不同位置摻氣濃度的各種因素以及怎樣才能獲得良好的摻氣效果。(2)介紹了脈動壓強(qiáng)數(shù)據(jù)的分析和處理的方法,如何對脈動壓強(qiáng)數(shù)據(jù)進(jìn)行變異系數(shù)、偏態(tài)系數(shù)、峰度系數(shù)以及頻譜特性的處理以及這些數(shù)據(jù)所反映的規(guī)律。(3)基于脈動壓強(qiáng)數(shù)據(jù)處理上得出,泄槽中脈動總壓強(qiáng)的變化規(guī)律,在沖擊區(qū)脈動波動最大,沿程呈現(xiàn)出波動劇烈程度減弱,并在最后趨于穩(wěn)定的規(guī)律。而泄槽中時均壓強(qiáng)則是結(jié)合紊流特點(diǎn)呈現(xiàn)出先減小后增大的趨勢。(4)通過控制變量法來研究不同流量下、不同摻氣體形下泄槽中脈動壓強(qiáng)的變化規(guī)律,通過對比分析泄槽中脈動壓強(qiáng)的幅值、概率密度、頻譜特性等特點(diǎn),得出泄槽中水流脈動的變化規(guī)律。(5)分別對比不同摻氣設(shè)施下水槽中脈動壓強(qiáng)的幅值、頻譜的特點(diǎn),發(fā)現(xiàn)各種工況下?lián)綒馑鞯拿}動壓強(qiáng)基本符合高速水流低頻、高幅的特點(diǎn)。
[Abstract]:China is rich in water resources. With the rapid development of the national hydropower industry, more and more high-head drainage structures are designed and constructed, which makes the problem of high-speed hydraulics more and more concerned. The problem of air entrainment in high velocity flow becomes more and more important. The shape of aeration facilities and the first class factors of income have become very important to the change of hydraulic characteristics of high speed flow, although many people have made some achievements in the study of aeration flow and pulsating pressure. However, the development of theoretical mechanism is still lagging behind. In this paper, the model test is carried out for the aeration facilities with sudden expansion and sudden fall. Through the combination of model test and theoretical analysis, the research method of control variables is used. The distribution of aeration concentration, the distribution of total pulsating pressure, and the variation of average pressure in the channel with different flow rate, sudden expansion width and the height of falling ridge are studied. The characteristics of pulsating pressure and other hydraulic characteristics of aerated flow are analyzed and discussed, and the following results are obtained: 1) by controlling variable method, three factors affecting the flow rate, the width of sudden expansion, and the height of falling ridge are changed, and different water depths in the channel are obtained. The law of aeration concentration at different axes is compared and analyzed, and the variation law of aeration concentration in the vent is obtained through sudden expansion and sudden fall of air flow in aeration facilities. Various factors affecting aeration concentration at different locations and how to obtain good aeration effect are introduced in this paper. The methods of analyzing and processing pulsating pressure data, how to carry out variation coefficient and skewness coefficient of pulsating pressure data are introduced. The processing of kurtosis coefficient and spectrum characteristic and the law reflected by these data. Based on the data processing of pulsating pressure, it is concluded that the variation of total pulsating pressure in the vent is the most fluctuating in the impact zone. The fluctuation intensity decreases along the flow path and tends to be stable in the end, while the average pressure in the discharge tank shows a trend of first decreasing and then increasing according to the characteristics of turbulent flow) the control variable method is used to study the different flow rate. The variation law of pulsating pressure in different gas-doped discharge channels is analyzed by comparing the amplitude, probability density and spectrum characteristics of the pulsating pressure in the vent. The characteristics of amplitude and spectrum of pulsating pressure in flume under different aeration facilities are compared respectively. It is found that the fluctuating pressure of aerated flow basically accords with the characteristics of low frequency and high amplitude of high speed flow under various working conditions.
【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】：TV135.2

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