本文關(guān)鍵詞： 氣液兩相流 參數(shù)檢測(cè) 超聲波 編碼激勵(lì) 脈沖壓縮 測(cè)試系統(tǒng)　出處：《天津大學(xué)》2014年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：超聲檢測(cè)技術(shù)廣泛應(yīng)用與醫(yī)學(xué)、流體等的測(cè)量中,因超聲波在流體中傳播,不會(huì)破壞流體的流場(chǎng)與造成壓力損失,故超聲檢測(cè)技術(shù)擁有獨(dú)特的優(yōu)勢(shì)。同時(shí)超聲傳感元件可以安裝在管道外壁,也就能夠避免與流體相互接觸。本文主要針對(duì)應(yīng)用于氣液兩相流測(cè)量的超聲檢測(cè)技術(shù)的問(wèn)題進(jìn)行研究。在兩相流檢測(cè)中,超聲方法的應(yīng)用仍存在一些問(wèn)題。主要原因在于,超聲波傳播過(guò)程中,聲波路徑十分復(fù)雜,會(huì)產(chǎn)生多次反射造成波形的疊加,使超聲波信號(hào)頻率混雜、測(cè)量結(jié)果信噪比較低。課題包括以下幾方面工作:(1)為滿足兩相流過(guò)程參數(shù)的在線檢測(cè),通過(guò)研究編碼信號(hào)以及脈沖壓縮特性。采用線性調(diào)頻信號(hào)編碼激勵(lì)的方式,結(jié)合氣液兩相介質(zhì)分布及流動(dòng)特性實(shí)際,分析線性調(diào)頻信號(hào)時(shí)寬、帶寬對(duì)脈沖壓縮效果的影響,選擇適用于兩相流超聲測(cè)試技術(shù)的編碼信號(hào)形式。(2)設(shè)計(jì)了基于FPGA的線性調(diào)頻編碼激勵(lì)和脈沖壓縮信號(hào)技術(shù)結(jié)合的兩相流超聲測(cè)試系統(tǒng),實(shí)現(xiàn)編碼信號(hào)的發(fā)生、激勵(lì)、高速數(shù)據(jù)采集、數(shù)字脈沖壓縮算法,以及基于PCI總線的通訊等功能,為進(jìn)一步研究超聲編碼測(cè)試技術(shù)提供硬件平臺(tái)。(3)搭建實(shí)驗(yàn)測(cè)試平臺(tái),根據(jù)兩相流測(cè)試中的超聲衰減法基本原理對(duì)氣液兩相流中氣泡的參數(shù)進(jìn)行提取和修正。相關(guān)的實(shí)驗(yàn)結(jié)果表明,使用編碼激勵(lì)信號(hào)可以有效測(cè)量氣液兩相流中氣泡的參數(shù),并可以在不損失分辨率的基礎(chǔ)上提高系統(tǒng)的信噪比。驗(yàn)證了編碼激勵(lì)與脈沖壓縮技術(shù)應(yīng)用于氣液兩相流超聲檢測(cè)中的可行性。
[Abstract]:Ultrasonic testing technology is widely used in medicine and fluid measurement, because ultrasonic wave propagates in the fluid, it will not destroy the fluid flow field and cause pressure loss. Therefore, ultrasonic detection technology has a unique advantage, and ultrasonic sensing elements can be installed in the outer wall of the pipe. In this paper, the ultrasonic detection technology used in gas-liquid two-phase flow measurement is studied. There are still some problems in the application of ultrasonic method. The main reason is that in the process of ultrasonic wave propagation, the sound wave path is very complex, which will produce multiple reflections and cause the superposition of the waveform, which makes the frequency of ultrasonic signal mixed. The SNR of the measured results is low. The research includes the following work: 1) On-line detection to satisfy the parameters of two-phase flow process. By studying the characteristics of coded signal and pulse compression, the time-width of LFM signal is analyzed by using the encoding excitation mode of linear frequency modulation signal, combining with the distribution of gas-liquid two-phase medium and the actual flow characteristics. The effect of bandwidth on pulse compression. A two-phase flow ultrasonic testing system based on FPGA is designed, which combines the linear frequency modulation (LFM) coding excitation and pulse compression signal technology. The functions of coding signal generation, excitation, high-speed data acquisition, digital pulse compression algorithm, and communication based on PCI bus are realized. For the further study of ultrasonic coding testing technology provides a hardware platform. According to the basic principle of ultrasonic attenuation method in two-phase flow measurement, the bubble parameters in gas-liquid two-phase flow are extracted and corrected. The parameters of bubbles in gas-liquid two-phase flow can be effectively measured by using the coded excitation signal. The signal-to-noise ratio of the system can be improved without loss of resolution, and the feasibility of applying the coded excitation and pulse compression techniques to the ultrasonic detection of gas-liquid two-phase flow is verified.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：O359;TB553

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