【摘要】：氣液兩相流動(dòng)廣泛存在于石油、化工、能源、動(dòng)力等多個(gè)領(lǐng)域,與單相流動(dòng)相比,氣液兩相流的流動(dòng)界面復(fù)雜多變,受相間作用力和速度滑移等因素影響。描述氣液兩相流動(dòng)的參數(shù)主要有流型、相分率、段塞流型下的液塞頻率、液塞長度、液塞速度等。對(duì)多相流流動(dòng)規(guī)律和機(jī)理的研究以及對(duì)氣液兩相流動(dòng)過程的設(shè)計(jì)、檢測、和控制都依賴于對(duì)其特征參數(shù)的準(zhǔn)確測量。鑒于多相流動(dòng)的復(fù)雜性和隨機(jī)性,對(duì)氣液兩相流參數(shù)的檢測至今依然是一個(gè)未能很好解決的難題。而高壓、強(qiáng)腐蝕、易燃易爆、快速流動(dòng)的兩相流系統(tǒng)的廣泛應(yīng)用對(duì)檢測方法提出了更高的要求,研究新一代氣液兩相流參數(shù)檢測的理論和裝置,不但有重要的科學(xué)意義,還具有廣泛的工程應(yīng)用價(jià)值。鑒于超聲波具有良好的穿透性、指向性以及非接觸性等特點(diǎn),本文以在管壁中多次往返傳播所形成的超聲波余振衰減譜為研究對(duì)象,提出了基于超聲回波原理的氣液兩相流非介入式測量的新方法。論文建立了氣液兩相流管道超聲場的預(yù)測模型,結(jié)合公式計(jì)算等方法模擬研究了超聲波在管壁中的傳播和衰減特性。研究了超聲波在傳播過程中的能量損失、聲能與傳播介質(zhì)質(zhì)點(diǎn)振動(dòng)幅值或者速度幅值之間的關(guān)系,開展了對(duì)超聲波傳播過程中衰減因素的分析。經(jīng)過模擬發(fā)現(xiàn)由管壁-液體所構(gòu)成的界面由于其透射作用較強(qiáng),相當(dāng)一部分聲能被液體吸收從而使得超聲回波衰減十分劇烈;而由管壁-氣體所構(gòu)成的界面由于其透射作用較弱,使得大部分的聲能被反射回了固體管壁使得管壁內(nèi)的超聲回波衰減十分緩慢。通過分析超聲的回波衰減特性即可判斷出探頭所在位置處管壁內(nèi)側(cè)接觸的介質(zhì)是氣還是液,進(jìn)而實(shí)現(xiàn)兩相流的非介入式測量。本文以空氣和水為工作介質(zhì),在氣-液兩相流試驗(yàn)環(huán)道上開展了超聲流型識(shí)別的試驗(yàn),測試管段水平布置,試驗(yàn)流型包括分層流、段塞流和環(huán)狀流。試驗(yàn)采用頻率為5MHz的超聲探頭,通過Olympus超聲發(fā)生器實(shí)現(xiàn)信號(hào)的發(fā)射和接收,采用泰克示波器對(duì)回波進(jìn)行監(jiān)測和記錄。探頭分別布置在管道頂部(12點(diǎn)鐘)、側(cè)面(3點(diǎn)鐘)以及底部(6點(diǎn)鐘)位置。經(jīng)試驗(yàn)發(fā)現(xiàn):對(duì)于分層流,頂部探頭和側(cè)面探頭所測得的結(jié)果基本一致,反映的是氣-固界面超聲回波特性,而底部位置的探頭,因其所處位置處的管壁內(nèi)側(cè)與液體接觸,故其超聲回波的衰減速率遠(yuǎn)高于頂部和側(cè)面探頭,反映的是液-固界面超聲回波特性;對(duì)于環(huán)狀流,由于管道內(nèi)壁周向被液膜覆蓋,故三個(gè)探頭所測結(jié)果均為液-固界面回波特征;對(duì)于段塞流,當(dāng)液塞頭部開始通過超聲探頭所在位置時(shí),頂部和側(cè)面的超聲探頭檢測到的結(jié)果會(huì)因管道內(nèi)介質(zhì)的變化而發(fā)生突變。根據(jù)采集的三個(gè)特征觀測點(diǎn)上的超聲回波數(shù)據(jù),提取信號(hào)的包絡(luò)面積,成功實(shí)現(xiàn)了流型的在線識(shí)別。構(gòu)建了一種基于超聲回波信號(hào)的段塞流參數(shù)檢測系統(tǒng),將兩個(gè)頻率相同的超聲探頭進(jìn)行配對(duì)分別進(jìn)行超聲波的發(fā)射和接收,并將二者緊靠布置在管道外壁同一截面上的12點(diǎn)鐘方向位置。另一對(duì)探頭按照相同方式布置于管壁上,兩對(duì)探頭之間相距3m,分別作為上下游回波測量裝置。當(dāng)液塞來臨時(shí),上下游的回波測量裝置可以檢測出發(fā)生回波衰減波形突變的時(shí)間差,即液塞通過兩對(duì)超聲探頭間距的時(shí)間間隔,進(jìn)而求出液塞速度。同樣可以根據(jù)單個(gè)接收探頭的超聲回波突變時(shí)間獲得液塞通過單個(gè)超聲接收探頭的時(shí)間,結(jié)合得到的液塞速度,根據(jù)時(shí)間速度法即可獲得液塞的長度。將測量結(jié)果與傳統(tǒng)差壓法所測結(jié)果進(jìn)行對(duì)比分析,二者結(jié)果基本一致。由于基于壁面回波測量方法的研究對(duì)象為在管壁內(nèi)傳播的超聲波,該方法不依賴管道內(nèi)的氣、液介質(zhì)的聲波特性,基本不受溫度、壓力、氣液組分等參數(shù)影響,無需聲速矯正,不受氣-液界面波動(dòng)干擾。
[Abstract]:The gas-liquid two-phase flow is widely existed in many fields such as petroleum, chemical industry, energy, power, etc. Compared with the single-phase flow, the flow interface of the two-phase flow of the gas liquid is complex and changeable, and is influenced by the factors such as the phase-to-phase force and the speed slip. The parameters of the two-phase flow of the gas-liquid are mainly the flow pattern, the phase fraction, the plug frequency of the slug flow, the length of the liquid plug, the speed of the liquid plug, etc. The study of the flow law and mechanism of the multiphase flow and the design, detection and control of the two-phase flow of the gas are dependent on the accurate measurement of the characteristic parameters. In view of the complexity and randomness of the multi-phase flow, the detection of the two-phase flow parameters of the gas liquid is still a difficult problem. The wide application of the two-phase flow system with high pressure, strong corrosion, inflammable and explosive and fast flow has put forward a higher requirement for the detection method, and studies the theory and the device of the two-phase flow parameter detection of a new generation of gas liquid, which not only has important scientific significance, but also has a wide application value. In view of the good penetration, directivity and non-contact characteristics of the ultrasonic wave, this paper presents a new method for non-interventional measurement of two-phase flow of gas liquid based on the principle of ultrasonic echo. In this paper, the prediction model of the ultrasonic field of the two-phase flow pipeline of the gas liquid is established, and the propagation and attenuation characteristics of the ultrasonic wave in the pipe wall are simulated by using the method of formula calculation and the like. The relationship between the energy loss, the acoustic energy and the vibration amplitude or the velocity amplitude of the propagation medium is studied, and the analysis of the attenuation factors in the process of ultrasonic propagation is carried out. it is found that the interface composed of tube wall-liquid can be absorbed by the liquid so that the attenuation of the ultrasonic echo is very severe due to the strong transmission effect of the interface, and the interface composed of the tube wall and the gas is weak due to its transmission effect, such that most of the sound can be reflected back into the solid wall such that the attenuation of the ultrasonic echo in the tube wall is very slow. by analyzing the echo attenuation characteristics of the ultrasonic, the medium which is in contact with the inside of the tube wall at the position of the probe is judged to be gas or liquid, and the non-interventional measurement of the two-phase flow is realized. In this paper, air and water are used as working medium, and the test of ultrasonic flow pattern recognition is carried out on the gas-liquid two-phase flow test loop. The test tube section is arranged horizontally. The test flow pattern includes stratified flow, slug flow and annular flow. The ultrasonic probe with a frequency of 5MHz is used to transmit and receive the signal through the Olympus ultrasonic generator, and the echo is monitored and recorded by the Tick oscilloscope. The probes are arranged at the top of the pipe (12 o 'clock), the side (3 o' clock) and the bottom (6 o 'clock) position, respectively. It is found that for stratified flow, the results of the top probe and the side probe are basically consistent, reflecting the ultrasonic echo characteristics of the gas-solid interface, and the probe at the bottom position is in contact with the liquid at the inner side of the tube wall at the position at which it is located, Therefore, the attenuation rate of the ultrasonic echo is much higher than that of the top and the side probes, reflecting the ultrasonic echo characteristics of the liquid-solid interface; for the annular flow, because the inner wall of the pipeline is covered by the liquid film in the circumferential direction, the results measured by the three probes are liquid-solid interface echo characteristics; and for the slug flow, When the head of the liquid plug begins to pass through the position of the ultrasonic probe, the results detected by the ultrasonic probe at the top and the side will change due to the change in the medium in the pipeline. according to the collected ultrasonic echo data on the three characteristic observation points, the on-line identification of the flow pattern is successfully realized. A segment plug flow parameter detection system based on an ultrasonic echo signal is constructed, and the two ultrasonic probes with the same frequency are paired to transmit and receive ultrasonic waves respectively, and the two ultrasonic probes are arranged in close proximity to the 12 o' clock direction position arranged on the same section of the outer wall of the pipeline. The other pair of probes are arranged on the pipe wall in the same way, and the distance between the two pairs of probes is 3m, which is used as the upstream and downstream echo measuring devices respectively. when the liquid plug is used for temporary, the echo measuring device at the upstream and downstream can detect the time difference of the change of the echo attenuation waveform, that is, the time interval of the liquid plug passing through the interval of the two pairs of ultrasonic probes, and then the liquid plug speed is obtained. and the length of the liquid plug can be obtained according to the time speed method according to the time of the ultrasonic echo mutation time of the single receiving probe to obtain the time of the liquid plug through a single ultrasonic receiving probe and combining the obtained liquid plug speed. The result of the measurement is compared with that of the conventional differential pressure method, and the results are basically the same. Since the research object based on the method of wall echo measurement is the ultrasonic wave propagating in the pipe wall, the method does not rely on the acoustic wave characteristics of the gas and liquid medium in the pipeline, and is not affected by the parameters such as temperature, pressure, gas liquid component, etc., and does not need sound speed correction, and is not disturbed by the fluctuation of the gas-liquid interface.
【學(xué)位授予單位】：中國石油大學(xué)(華東)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TQ021.1

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本文編號(hào)：2330988