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IEC TS 62882
Edition 1.0 2020-09
TECHNICAL
SPECIFICATION
colour
inside
Hydraulic machines – Francis turbine pressure fluctuation transposition
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IEC TS 62882
Edition 1.0 2020-09
TECHNICAL
SPECIFICATION
colour
inside
Hydraulic machines – Francis turbine pressure fluctuation transposition
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.140 ISBN 978-2-8322-8786-6
– 2 – IEC TS 62882:2020 © IEC 2020
CONTENTS
FOREWORD . 9
INTRODUCTION . 11
1 Scope . 12
2 Normative references . 13
3 Terms, definitions, symbols and units . 13
3.1 General terms and definitions . 13
3.2 Units . 13
3.3 Overview of the terms, definitions, symbols and units used in this document . 14
3.3.1 Subscripts and symbols . 15
3.3.2 Geometric terms and definitions . 16
3.3.3 Physical quantities and properties terms and definitions . 17
3.3.4 Discharge, velocity and speed terms and definitions . 17
3.3.5 Pressure terms and definitions . 18
3.3.6 Specific energy terms and definitions. 18
3.3.7 Height and head terms and definitions . 19
3.3.8 Power and torque terms and definitions . 20
3.3.9 Efficiency terms and definitions . 21
3.3.10 General terms and definitions relating to fluctuating quantities . 21
3.3.11 Fluid dynamic and scaling terms and definitions . 24
3.3.12 Dimensionless terms and definitions . 24
4 Description of pressure fluctuation phenomena. 25
4.1 General . 25
4.2 Pressure fluctuations overview . 30
4.3 General description of draft tube flow in Francis turbines . 32
4.4 Detailed description of pressure fluctuation phenomena . 34
4.4.1 Mode 1: Pressure fluctuation in high load . 34
4.4.2 Mode 2: Pressure fluctuation in best operation range. 35
4.4.3 Mode 3: Pressure fluctuation in upper part load . 35
4.4.4 Mode 4: Pressure fluctuation in part load . 36
4.4.5 Mode 5: Pressure fluctuation in deep part load . 38
4.4.6 Modes 6.a and 6.b: Rotor-stator interaction (RSI) pressure fluctuation. 39
5 Specifications of pressure fluctuation measurement and analysis . 41
5.1 General . 41
5.1.1 Overview . 41
5.1.2 Purpose of the measurements . 41
5.1.3 Procedures and parameters to record . 42
5.1.4 Locations of pressure fluctuation test transducers . 43
5.1.5 Data acquisition for pressure fluctuation measurements . 44
5.1.6 Transducers and calibration . 45
5.2 Pressure fluctuation on a model turbine . 45
5.2.1 General . 45
5.2.2 Homology and limitations . 46
5.2.3 Detailed procedures. 46
5.3 Special requirements and information for a prototype turbine . 48
5.3.1 General . 48
5.3.2 Source of information . 48
5.3.3 Important aspects . 48
5.4 Analysis, presentation and interpretation of results . 49
5.4.1 General . 49
5.4.2 Time-domain analysis . 49
5.4.3 Frequency-domain analysis . 50
5.4.4 Non-dimensional frequency and pressure . 50
5.4.5 Presentation and interpretation of pressure fluctuations . 50
6 Identification of potential resonances in test rig and prototype . 51
6.1 General . 51
6.2 Identify resonance in test rig . 53
6.3 Possible resonance and self-excited pressure fluctuation in prototype . 53
6.3.1 General . 53
6.3.2 Draft tube vortex related resonances and self-excited pressure
fluctuation in prototype . 53
6.3.3 Rotor-stator interaction (RSI) related resonance . 55
6.3.4 Resonance with fluctuation modes not treated in this document . 55
7 Transposition method and procedure . 56
7.1 General . 56
7.2 Parameters influencing transposition . 56
7.2.1 Model test head . 56
7.2.2 Thoma number . 56
7.2.3 Froude number . 57
7.3 Relevant quantities for transposition . 57
7.3.1 Fluctuation frequency . 57
7.3.2 Fluctuation amplitude . 57
7.4 Transposable types of fluctuations . 57
7.5 Statistical analysis of model and prototype transposition accuracy . 58
8 Mitigations . 59
8.1 Draft tube vortex phenomena . 59
8.1.1 General . 59
8.1.2 Draft tube fins . 59
8.1.3 Draft tube with a central column . 60
8.1.4 Air admission . 61
8.1.5 AVR or PSS parameter tuning . 62
8.2 Runner inter-blade vortex. 63
8.3 Blade interaction . 63
8.4 Operation restriction . 63
Annex A (informative) Example of pressure fluctuation records . 64
Annex B (informative) Typical pressure fluctuation transducers parameters for model
test . 83
Annex C (informative) Pressure transducer dynamic calibration . 84
C.1 Fast valve opening method . 84
C.2 Rotating valve method . 84
C.3 Electrical spark method . 85
Annex D (informative) Proposed remote pressure measurement fluctuation correction . 86
D.1 General . 86
D.2 Correction method theory . 86
D.3 Measuring and estimating tube frequency response . 87
– 4 – IEC TS 62882:2020 © IEC 2020
D.4 Pressure fluctuation correction . 89
D.5 Limitations . 92
Annex E (informative) Forced response analysis for Francis turbines operating in part
load conditions. 93
E.1 General . 93
E.2 Systematic methodology based on detailed modelling of hydroelectric power
plant .
...