Abstract ........................................................ 1
Table of contents .............................................. 11
List of figures ................................................ iv
List of tables ................................................. vi
Abbreviations ................................................. vii
Nomenclature ................................................... ix
1 Introduction ................................................. 1
2 Hypersonic Vacuum Wind Tunnel Göttingen ...................... 2
3 Load Estimation .............................................. 4
3.1 Balance Concepts ........................................ 5
4 Balance Principle, Design and Dimensioning ................... 7
4.1 Boundaries, Limitations ................................. 8
4.2 Determination of Forces and Moments ..................... 9
4.3 Balance Frame Material ................................. 10
4.4 Balance Frame Dimensioning ............................. 11
4.4.1 Normal Force Transducer ......................... 11
4.4.2 Tangential Force Transducer ..................... 16
4.4.3 Local Strain at Strain Gauge Positions .......... 30
4.5 Strain Gauges .......................................... 31
4.5.1 Strain Gauge Selection .......................... 31
4.5.2 Adhesion of the Strain Gauges ................... 32
4.5.3 Strain Gauge Circuitry .......................... 33
4.5.4 Balance Circuitry and Connectors ................ 34
4.6 Power Supply and Operating Parameters .................. 35
4.6.1 Amplifiers ...................................... 38
4.6.2 Settings ........................................ 40
4.7 Thermal Control and Monitoring ......................... 40
4.8 Attaching Balance Adapters and Insertion into Support
Frame .................................................. 43
5 Calibration ................................................. 45
5.1 Balance Linearity ...................................... 47
5.2 Balance Resolution ..................................... 47
5.3 Calibration Error ...................................... 48
5.4 Zero-Point Stability in Reference to Hysteresis ........ 48
5.5 Zero-Point Stability ................................... 48
5.6 Response Time .......................................... 49
5.7 Mutual Component Independency of Force Transducers ..... 50
5.8 Comparison to Analytical Estimation .................... 50
6 Installation and Adjustment in V2G .......................... 51
6.1 Handling High Angles of Attack ......................... 54
7 Application of Force Measurement Technique .................. 56
7.1 Operating Conditions ................................... 56
7.1.1 Test Matrix and Configuration ................... 56
7.1.2 Description of Flow Characterisation ............ 58
7.1.3 Flow Characterisation Results ................... 59
7.2 Force Measurement ...................................... 65
7.2.1 Experimental Setup .............................. 65
7.2.2 Experimental Process ............................ 67
7.2.3 Determination of Aerodynamic Coefficients ....... 69
8 Possible Improvements of V2G Force Measurement Technique .... 73
8.1 Improvements for Current Balance ....................... 73
8.2 Improvements for New Balances .......................... 73
8.3 Accuracy Improvements due to Well-Designed Test
Articles ............................................... 73
9 Summary, Outlook ............................................ 75
10 Acknowledgements ............................................ 76
11 References .................................................. 77
Appendix A - General Facts, Figures and Tables ................. 81
Appendix В - Balance Circuitry ................................. 84
Appendix С - SCILAB Code for Analytical Estimation ............. 91
Appendix D - DEWESOFT Settings ................................ 116
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