1、<p><b>　　附錄A</b></p><p>　　Research on pulse output model digital vortex flow meters</p><p>　　The vortex flow meter is widely used in different fields due to its flexibility to v

2、arious media, non-mobile parts, simple structure and long life etc. However, it has poor performance when operating at low flow rate where the Signal-to-Noise ratio is very small or even the signal is submerged by the no

3、ise. The traditional analog vortex flow meter has benefits of steady signal, high accuracy and good real time in the regular flow range, while it also has a disadvantage of weak signal difficult t</p><p>　　B

4、ased on the previous efforts a pulse output model digital vortex flow meter is developed successfully, which inherits the advantages of the analog one and make up its shortage mentioned above. The digital vortex flow met

5、er with its double-core structure that means a couple of CPUs made up of DSP and MSP430 identifies the vortex signals from noises by the frequency spectrum analyzing algorithm in DSP at low flow rate where the analog one

6、 is not accurate, or even can’t work. Meanwhile it works o</p><p>　　This dissertation consists of theory, hardware/software design and experiment. The main point includes:</p><p>　　1.The scheme

7、 called double-channel work model of the pulse output model digital vortex flow meter is designed. The principle is a switch of two different methods to detect the vortex signal. That is using spectrum analysis of digita

8、l signal at low flow rate and frequency counting like analog vortex flow meters in the regular flow range. The critical criterion of the switch point is the uncertainty of the frequency.</p><p>　　2.A pulse o

9、utput model digital vortex flow meter is developed successfully. The flow meter is studied respectively at DN25 and DN50 pipelines of the water flow experiment facility and DN50 and DN100 pipelines of the gas flow experi

10、ment facility that locate at Process Detect & Control Laboratory in Tianjin University. And the data shows that the digital flow meter has the property of a better lower limit than the analog one and a bigger range r

11、atio of 1:28.5～41.3. </p><p>　　Masses of experiments on the digital vortex flow meter have been carried out at the water flow experiment facility and the gas flow experiment facility of Tianjin University re

12、spectively. The result shows that the pulse output model digital vortex flow meter has a satisfying lower limit that increases the range ratio effectively, strong ability and good real time and thus it is of great practi

13、cability.</p><p>　　The 21st century is the century information, information and materials and new technology as the main pillar of society from the human revolution is industrialization era to information er

14、a, as the perception, acquisition, conversion, processing and transmission of information technology and the indispensable testing instrument, has become an important technology and computer equivalent and daily life and

15、 production of all fields. Along with the rapid development of science and technology, indus</p><p>　　After continuous efforts, and technical workers have developed pyretic and various characteristics of flo

16、w meter. According to the measuring method and the structure of the classification method, will be divided into differential pressure meter flowmeter, volumetric flowmeter, fluid flow, ultrasonic vibration flowmeter, mas

17、s flowmeter, insert flowmeter open-channel flow and other flowmeter, 11 kinds . The research of the vortex flowmeter belongs to the hydrodynamic vibration flowmeter are widely</p><p>　　Vortex flowmeter is ac

18、cording to the fluid velocity of vibration frequency and the corresponding principle of work. As early as in 1878 straw Strophe published about fluid velocity relationship with the vibration frequency, straw, vortex fre

19、quency is said to stop features of similar size and the velocity of the relationship. People in the early vortex research mainly is the purpose of prevention. Vortex flow vibration phenomenon for measuring the study bega

20、n in the 1950s, such as wind meter and</p><p>　　Vortex flowmeter is a fluid vibration flowmeter, set in the fluid flow vortex happened (resistance from vortex happen) alternately on both sides of the body pr

21、oduces regular vortex, the spiral called Carmen vortex, swirling in spiral happen asymmetrical body downstream, vortex flowmeter is arranged by measuring the vortex frequency and realization of flow measurement.</p>

22、;<p>　　Vortex flowmeter by sensors and switches two parts. Sensors (including vortex flow resistance occurs, components, instrument) such as table, converter including pre-amplifier, filtering plastic circuit, D/A

23、 transformation circuit, output interface circuit, terminals, bracket and shields, etc. In recent years, intelligent flowmeter is the microprocessor, communications and other functions that are installed in converter mod

24、ule.</p><p>　　According to the detection means, vortex flowmeter stress can be divided, capacitive and thermal type, type of ultrasonic vibration, strain, and photoelectric and fiber, etc. Among them, stress

25、 (also called the piezoelectric) vortex flowmeter with its fast response and strong signal, working temperature range wide, strong adaptability and high reliability etc, has become the main products vortex flowmeter type

26、. This vortex flowmeter, it is to test the lift in form stress testing devices, piezoel</p><p>　　As mentioned, vortex flowmeter has many advantages, and there are many problems to be solved, especially in th

27、e measurement of small flow, vortex useful signal is very weak, yi was drowned, low noise signal under the velocity measurement caused great difficulties. In order to solve this problem, the domestic and overseas scholar

28、s and scientific research institutions in research and application of various solutions, namely of digital signal processing method to solve, but most just stay in the re</p><p>　　In recent years, the vortex

29、 signal processing methods about the study many (such as wavelet method of adaptive LMS changes, etc), the algorithm of tianjin university professor zhang tao presided over the research of vortex sensor output signal for

30、 exploration of digital signal processing won great progress. Ling Qing master according to the signal features and vortex of signal processing method, the requirements for maximum likelihood estimation results in cycle

31、chart are put forward on the basi</p><p>　　Along with the Digital Signal Processor Digital Signal processing (DSP) technology, referred to the rapid development and wide application, make complex Signal proc

32、essing algorithm can achieve in hardware. DuanRuiFeng master a set of DSP and MSP430 microcontroller combination of the vortex digital signal processing system, using slack trapped cycle graph method for calculating the

33、vortex flowmeter signal frequency. Experimental results show that the vortex flow dual-core digital signal processin</p><p>　　This topic is on the basis of research achievements in domestic production, the v

34、ortex flowmeter is limited to simulate the vortex flowmeter, research and implementation of a practical pulse output type vortex flowmeter figures. The pulse output type digital vortex flowmeter using MSP430 MCU based on

35、 DSP and the twin CPU hardware structure, small flow in low velocity by DSP based on fast Fourier transform (FFT) form fast, referred to as the power spectrum estimation is proposed to measure vortex</p><p>

36、<b>　　附錄B</b></p><p>　　脈沖輸出型數(shù)字渦街流量計的研究</p><p>　　渦街流量計因其介質(zhì)適應(yīng)性強，無可動部件，結(jié)構(gòu)簡單、使用壽命長等諸多優(yōu)點，在許多行業(yè)得到了廣泛的應(yīng)用。而在低流速下，渦街測量就顯現(xiàn)出了它的不足，渦街信號的信噪比很低，有用信號幾乎被噪聲淹沒。普通的渦街流量計采用模擬信號處理方法，在正常流量范圍內(nèi)，渦街流量信號穩(wěn)定、測量準確

37、、實時性好；而在小流量下，渦街有用信號微弱、提取困難，導(dǎo)致實際測量下限比較高，量程比小，一般為10：1。</p><p>　　鑒于上述模擬渦街流量計具有的優(yōu)勢以及存在的不足，課題在前人研究成果的基礎(chǔ)上，研究并成功地實現(xiàn)了一臺實用的脈沖輸出型數(shù)字渦街流量計。該數(shù)字渦街流量計采用了基于DSP和MSP430單片機雙CPU的硬件結(jié)構(gòu)，在低流速小流量的情況下，由DSP實現(xiàn)頻譜分析算法來計算渦街信號頻率，有效地克服了模擬渦街

38、在小流量下測量精度不高甚至不能測量的問題；在正常流量范圍內(nèi)，由單片機對渦街信號前置放大電路輸出的方波進行計頻，具有常規(guī)模擬渦街在高信噪比的情況下測量準確、實時性好的優(yōu)點。</p><p>　　本文從原理分析、硬件軟件設(shè)計和實驗研究三方面來研究，主要內(nèi)容包括：</p><p>　　1.設(shè)計了脈沖輸出型數(shù)字渦街流量計的總體方案，尤其是采用了雙通道處理的方式，將低流量下數(shù)字信號處理的頻譜分析功能

39、和正常流量范圍內(nèi)智能渦街的計頻功能有機地結(jié)合起來，并引入了頻率不確定度的概念作為判斷渦街有用信號雙通道處理方法的依據(jù)。</p><p>　　2.成功實現(xiàn)了一臺脈沖輸出型數(shù)字渦街流量計。通過在天津大學(xué)過程檢測和控制實驗室的水流量實驗裝置上進行的25mm口徑和50mm口徑實驗研究，以及在氣體實驗裝置上進行的100mm和50mm口徑實驗研究的結(jié)果表明，本脈沖輸出型數(shù)字渦街流量計有效地降低了渦街的流量下限，使量程比顯著擴

40、大，量程比達到1：28.5～41.3。將此數(shù)字渦街分別在天津大學(xué)水流量實驗裝置和氣體流量實驗裝置上做了量的實驗，結(jié)果表明本脈沖輸出型數(shù)字渦街流量計具有很低的測量下限，有效擴大了渦街的量程比，抗干擾能力強，實時性好，具有很高的實用價值。</p><p>　　21世紀是信息的世紀，以信息、材料和生物為主要支柱的新技術(shù)革命正將人類社會從工業(yè)化時代推向信息化時代，作為感知、采集、轉(zhuǎn)換、處理和傳輸各種信息不可缺少的檢測技術(shù)

41、和儀表，已成為與計算機同等重要的技術(shù)而深入日常生活及生產(chǎn)的所有領(lǐng)域。隨著科學(xué)技術(shù)的突飛猛進，工業(yè)生產(chǎn)得到不斷發(fā)展，對檢測技術(shù)又提出了許多新的要求，而新的檢測技術(shù)和儀表的出現(xiàn)又進一步推動了科學(xué)技術(shù)的發(fā)展，故檢測技術(shù)的發(fā)展程度決定了科學(xué)技術(shù)的水平，換句話說檢測技術(shù)和儀表是衡量現(xiàn)代科學(xué)技術(shù)水平高低的一個標志。這其中，作為檢測技術(shù)重要組成部分的流量計量由于與國民經(jīng)濟、國防建設(shè)、科學(xué)技術(shù)的密切關(guān)系，在經(jīng)濟發(fā)展中占有重要的地位。</p>

42、<p>　　經(jīng)過不斷的努力和探索，科技工作者已開發(fā)出種類繁多、各具特色的流量儀表。按照測量方法和結(jié)構(gòu)的分類方法，將流量計分成差壓式流量計、容積式流量計、流體振動式流量計、超聲流量計、質(zhì)量流量計、插入式流量計、明渠流量計和其他流量計共十一大類。本課題研究的渦街流量計屬于流體振動式流量計中應(yīng)用最為廣泛的一種。</p><p>　　渦街流量計是依據(jù)流體振動頻率與流速有對應(yīng)關(guān)系的原理進行工作的。早在1878

43、年斯特勞哈（Strophe）就發(fā)表了關(guān)于流體振動頻率與流速關(guān)系的文章，斯特勞哈數(shù)就是表示渦街頻率與阻擋體特征尺寸、流速關(guān)系的相似準則。人們早期對渦街的研究主要是防災(zāi)的目的。渦街流體振動現(xiàn)象用于測量研究始于20世紀50年代，如風(fēng)速計和船速計等，60年代末開始研制封閉管道流量計——渦街流量計。70、80年代渦街流量計發(fā)展異常迅速，開發(fā)出眾多類型阻流體及檢測方法的渦街流量計，并大量生產(chǎn)投放市場，像這樣在短短幾年時間內(nèi)就到達從實驗室樣機到批量生

44、產(chǎn)過程的流量計還絕無僅有。</p><p>　　渦街流量計是一種流體振動式流量計，在流體中設(shè)置旋渦發(fā)生體（阻流體），從旋渦發(fā)生體兩側(cè)交替地產(chǎn)生有規(guī)律的旋渦，這種旋渦稱為卡門渦街，旋渦列在旋渦發(fā)生體下游非對稱地排列，渦街流量計通過測量其旋渦產(chǎn)生的頻率而實現(xiàn)流量計量。</p><p>　　渦街流量計由傳感器和轉(zhuǎn)換器兩部分組成。傳感器包括旋渦發(fā)生體（阻流體）、檢測元件、儀表體等；轉(zhuǎn)換器包括前置放

45、大器、濾波整形電路、D/A轉(zhuǎn)換電路、輸出接口電路、端子、支架和防護罩等。近年來智能式流量計還把微處理器、顯示通訊及其他功能模塊亦裝在轉(zhuǎn)換器內(nèi)。</p><p>　　按檢測方式劃分，渦街流量計可分為應(yīng)力式、電容式、熱敏式、超聲式、振動式、應(yīng)變式、光電式和光纖式等。其中，應(yīng)力式（又稱為壓電式）渦街流量計以其響應(yīng)快、信號強、工作溫度范圍寬、現(xiàn)場適應(yīng)性強、可靠性高等優(yōu)點，已成為渦街流量計的主要產(chǎn)品類型。這種渦街流量計中，

46、它把檢測元件受到的升力以應(yīng)力形式作用在壓電檢測元件上，轉(zhuǎn)換成交變的電荷信號，經(jīng)電荷放大、濾波、整形后得到旋渦信號。壓電傳感器響應(yīng)快、信號強、工藝性好、制造成本低，但是對振動比較敏感。</p><p>　　正如前面所述，渦街流量計具有諸多優(yōu)點，同時又有許多亟待解決的問題，特別是在測量小流量時，渦街有用信號非常微弱，易被噪聲信號淹沒，給低流速下的測量造成了很大困難。針對這一問題，國內(nèi)外學(xué)者及科研機構(gòu)紛紛研究并提出各種

47、解決方案，即應(yīng)用數(shù)字信號處理的方法解決，但大部分只是停留在方法上的研究，而沒有將高效率的算法應(yīng)用于實際服務(wù)于生產(chǎn)。</p><p>　　目前，國內(nèi)生產(chǎn)的渦街流量計還限于應(yīng)用模擬電路的方法對渦街信號進行處理（稱為模擬渦街流量計），這樣解決不了低信噪比條件下的問題，導(dǎo)致下限太高，量程比只能達到1：10，遠低于理論量程1：100。國外也只有Yokogawa公司、Rosemount公司和ABB公司研發(fā)出了應(yīng)用數(shù)字信號處理

48、的方法處理渦街信號的渦街，即數(shù)字渦街流量計，但是具體的技術(shù)并不公開。</p><p>　　近幾年，關(guān)于渦街信號處理方法的研究很多（如小波變化法、自適應(yīng)LMS算法等），由天津大學(xué)張濤教授主持研究的對渦街傳感器輸出信號進行數(shù)字信號處理方面的探索獲得了很大的進展。凌箐碩士根據(jù)渦街信號的特點及其對信號處理方法的要求，借鑒最大似然譜估計方法的研究成果，在周期圖法的基礎(chǔ)上提出了更適用于渦街頻率估計的松弛陷波周期圖法，并進行了

49、仿真實驗。該方法兼有高頻率分辨率和高計算效率的特點，有很強的抗復(fù)雜噪聲干擾的能力。吳鵬碩士基于子波變換消噪原理，結(jié)合流量測量特定要求，提出了一種適用于渦街流量傳感器信號處理的單支重構(gòu)濾波方法，同時給出了濾波級數(shù)的選取方法，這種計數(shù)方法能夠有效地擴大渦街流量傳感器的量程下限。但是，以上兩種方法由于算法本身的復(fù)雜性，使得計算量龐大、實時性無法得到保證，難以應(yīng)用于實際。</p><p>　　隨著數(shù)字信號處理（Digit

50、al Signal Processor，簡稱DSP）技術(shù)的飛速發(fā)展及廣泛應(yīng)用，使得復(fù)雜的信號處理算法得以在硬件上實現(xiàn)。段瑞峰碩士研究了一套DSP和MSP430單片機相結(jié)合的雙核結(jié)構(gòu)的數(shù)字渦街信號處理系統(tǒng)，采用松弛陷波周期圖法計算渦街流量計信號的頻率。實驗結(jié)果表明，這種雙核式數(shù)字渦街流量信號處理系統(tǒng)可以有效地降低測量下限（25mm口徑渦街測量下限可達0.323m3/h），實現(xiàn)數(shù)據(jù)處理的實時性。</p><p>　　

51、本課題是在前人研究成果的基礎(chǔ)上，針對國內(nèi)生產(chǎn)的渦街流量計還限于模擬渦街流量計的現(xiàn)狀，研究并實現(xiàn)了一臺實用的脈沖輸出型數(shù)字渦街流量計。這種脈沖輸出型數(shù)字渦街流量計采用基于DSP和MSP430單片機雙CPU的硬件結(jié)構(gòu)，在低流速小流量的情況下，由DSP實現(xiàn)基于快速傅里葉變換（fast Fourier transform，簡稱FFT）的功率譜估計算法，以測得渦街信號頻率并進行實時的脈沖輸出；當流量在正常流量范圍內(nèi)，則采用模擬電路進行渦街信號的預(yù)