Signal processing and experimental technology in ultrasonic flow measurement [Elektronische Ressource] / submitted by Yaoying Lin

Lin Chin-Cheng

Informations

• Publié par: universitat_duisburg-essen
• Publié le: 01 janvier 2004
• Nombre de lectures: 13
• Langue: English
• Poids de l'ouvrage: 1 Mo

Extrait

Signal Processing and Experimental Technology in
Ultrasonic Flow Measurement
Department 12—Mechanical Engineering
University of Duisburg—Essen
Granted Dissertation for Acquisition of Academic Degree of
Doctor of Engineering
Submitted by M. Sc. Yaoying Lin
from Pingxiang, China
Date of oral examination: 30. November, 2004
Chariman: Prof. Dr.-Ing. D. Wissussek
Experts: Prof. Dr.-Ing. V. Hans
Prof. Dr.-Ing. R. Tracht
Prof. Dr.-Ing. L. WangPreface
Preface
This dissertation records all research work I have done in the past two years since I came to
Germany and studied under the supervision of Professor Dr. Hans at the University of
Duisburg-Essen.
First I must give special thanks to my supervisor, Professor Dr. Hans, for his help with my
research work even after his retirement. That he is strict in research will be forever
remembered by me and influence my future work. His optimistic character also helped me
through the difficult period of time.
I’d like to thank Professor Dr. Tracht for taking time out of his tight schedule to review my
dissertation. The discussion with him benefits both this dissertation and me myself so much
that I will never forget. I must thank Professor Dr. Wang, at CDHK of Tongji University,
Shanghai for his support and encouragement. It is he who gave me this chance to finish this
dissertation in Germany.
I should also thank my colleagues in the Institute of Measurement and Control for their
cooperation and friendly help.
Another special gratitude owes to my husband, from whom I always get support and
understanding.
September 2004, in Essen
Yaoying LinContents
Contents
1 Introduction .................................................................................................................................. 1
2 Technologies in flow measurement............................................................................................. 4
2.1 Classification of flowmeters ................................................................................................ 4
2.1.1 Extractive energy approach ......................................................................................... 4
2.1.2 Additive energy approach............................................................................................ 6
2.2 Characteristics of ultrasonic flowmeters ............................................................................ 10
3 Experimental setup and basic principle...................................................................................... 12
3.1 Cross correlation measurement 12
3.1.1 Setup .......................................................................................................................... 12
3.1.2 Complex modulation................................................................................................... 14
3.1.3 Demodulation ............................................................................................................. 15
3.2 Vortex measurement .......................................................................................................... 17
4 Hilbert Transform ...................................................................................................................... 19
4.1 Negative and positive frequencies ..................................................................................... 19
4.2 Analytic signal ................................................................................................................... 19
4.3 Concept of Hilbert Tranform ............................................................................................. 20
4.4 Electronic Hilbert Transform ............................................................................................. 21
4.5 Software realization of Hilbert Transform......................................................................... 21
4.6 Results of the software....................................................................................................... 22
4.7 An improved CCF of amplitude demodulation by Hilbert Transform software ............... 23
4.8 Undersampled Hilbert Transform ...................................................................................... 26
4.8.1 Cross correlation measurement .................................................................................. 26
4.8.2 Vortex measurement .................................................................................................. 28
5 Kalman Filter ............................................................................................................................. 31
5.1 Theoretical model description............................................................................................ 31
5.2 Kalman Filter. .................................................................................................................... 32
5.3 Extended Kalman Filter ..................................................................................................... 33
5.4 EKF in phase demodulation............................................................................................... 34
5.5 The result of demodulation using EKF32 .......................................................................... 37
5.5.1 Phase demodulation ................................................................................................... 37
5.5.2 Amplitude demodulation ........................................................................................... 39
5.6 The algorithm of EKF24 .................................................................................................... 40
IContents
5.7 Amplitude demodulation ................................................................................................... 41
5.8 Vortex measurement .......................................................................................................... 42
5.8.1 Fully developed flow...................................................................................................43
5.8.2 Disturbed flow.............................................................................................................44
6 Analog signal processing in flow measurement .........................................................................47
6.1 Frequency shifting...............................................................................................................47
6.2 Mathematical justification.................................................................................................. 47
6.3 Amplitude modulation ....................................................................................................... 48
6.4 Application in vortex measurement and ccf measurement ................................................ 49
7 A combination of vortex flow meter with cross correlation method......................................... 52
7.1 Theorectical background.................................................................................................... 52
7.2 Measurement results .......................................................................................................... 53
7.3 Analysis.............................................................................................................................. 56
7.4 Influnence of bluff body size on the characteristic of the modulation in vortex flow
measurement ................................................................................................................................. 58
8 Inclination of bluff body in vortex flow measurement ............................................................. .61
8.1 Measurement background ...................................................................................................61
8.2 Ratio=1............................................................................................................................... 63
8.3 Ratio=2............................................................................................................................... 65
8.4 Ratio=3............................................................................................................................... 66
8.5 Rectangular bluff body....................................................................................................... 68
9 Disturbed flow measurement ..................................................................................................... 73
9.1 Fully developed flow and disturbed flow .......................................................................... 73
9.2 Technologies in disturbed flow measurement ................................................................... 74
9.3 Forms of disturbed flow..................................................................................................... 76
9.4 Vortex measurement in disturbed flow ............................................................................. 77
9.4.1 One bend..................................................................................................................... 77
9.4.2 Two 90° bends in plane.............................................................................................. 78
9.4.3 Two 90° bends out of plane........................................................................................ 81
9.5 Cross correlaton measurement in disturbed flow.........................................