1 Introduction .................................................. 1
1.1 Motivation .............................................. 1
1.2 Fundamental Aspects on Viscous Wakes and Potential
Effects of the Blade Rows ............................... 4
1.3 Periodical Unsteady Effects on the Blade Boundary
Layer Development ...................................... 11
1.4 Periodical Unsteady Profile Pressures and Blade
Pressure Forces ........................................ 14
1.5 Clocking of Turbomachinery Blade Rows .................. 15
1.6 Superposition of Wakes and Tip Leakage Flow ............ 18
2 Experimental Setup and Data Postprocessing .................. 21
2.1 Dresden Low-Speed Research Compressor .................. 21
2.2 Measurement Techniques and Data Postprocessing ......... 24
2.2.1 Probe Measurements within the Axial Gaps ........ 24
2.2.2 Flow Field Investigations with Laser-Doppler-
Anemometry ...................................... 26
2.2.3 Boundary Layer Investigations Using Surface-
Mounted Hot-Film Arrays ......................... 29
2.2.4 Measurement of Steady and Unsteady Profile
Pressure Distributions .......................... 32
2.2.5 Calculation of the Unsteady Blade Pressure
Force ........................................... 34
3 Flow Field Between the Blade Rows ........................... 37
3.1 Flow Field at Midspan .................................. 37
3.2 Flow Field Near Hub .................................... 40
4 Flow Field Within a Rotor Blade Row ......................... 42
4.1 Flow Field at Midspan .................................. 42
4.1.1 Time-Averaged Results, Design Point ............. 42
4.1.2 Periodical Unsteady Flow Field: Reference
Rotor-Stator Position, Design Point ............. 43
4.1.3 Sequence of Periodical Unsteady Flow Field,
Design Point .................................... 49
4.1.4 Periodical Unsteady Flow Field: Reference
Rotor-Stator Position, Operating Point Near
Stability Limit ................................. 50
4.2 Flow Field Near the Blade Tip (97.9% Channel Height) ... 52
4.2.1 Time-Averaged Results, Design Point ............. 52
4.2.2 Periodical Unsteady Flow Field: Reference
Rotor-Stator Position, Design Point ............. 53
4.2.3 Sequence of Periodical Unsteady Flow Field,
Design Point .................................... 58
4.2.4 Periodical Unsteady Flow Field: Reference
Rotor-Stator Position, Operating Point Near
Stability Limit ................................. 59
4.3 Flow Field at 91.7% Channel Height ..................... 62
4.3.1 Time-Averaged Results, Design Point ............. 62
4.3.2 Periodical Unsteady Flow Field: Reference
Rotor-Stator Position, Design Point ............. 63
4.4 Flow Field in the Outlet Plane of the Rotor Blade
Row .................................................... 64
4.5 Three-Dimensional View of the Flow Field ............... 66
5 Blade Boundary Layer ........................................ 69
5.1 Steady Flow Conditions ................................. 69
5.2 Fundamental Wake Influence on the Time-Resolved
Boundary Layer ......................................... 71
5.3 Boundary Layer Development on Stator 1, Suction Side,
Midspan ................................................ 73
5.3.1 Design Point .................................... 73
5.3.2 Operating Point Near the Stability Limit ........ 83
5.4 Boundary Layer Development on Stator 1, Pressure
Side, Midspan .......................................... 84
5.5 Boundary Layer Development on Stator 1, Suction Side,
Near Hub ............................................... 86
6 Profile Pressure Distributions .............................. 88
6.1 Time-Averaged Pressure Distribution on the Rotor and
Stator Blades .......................................... 88
6.2 Unsteady Pressure Distribution on the Rotor and
Stator Blades .......................................... 89
6.2.1 Stator 1 ........................................ 89
6.2.2 Stator 3 ........................................ 96
6.2.3 Stator 4 ........................................ 97
6.2.4 Rotor 1 ......................................... 97
6.2.5 Rotor 3 ......................................... 99
6.3 Frequency Contents of the Unsteady Profile
Pressures ............................................. 100
6.4 Influence of Clocking on the Unsteady Profile
Pressure .............................................. 102
7 Blade Pressure Forces ...................................... 108
7.1 Time-Averaged Blade Pressure Forces ................... 108
7.2 Comparison of Unsteady Profile Pressures and
Pressure Forces ....................................... 110
7.3 Unsteady Pressure Forces of Rotor and Stator Blades ... 111
7.3.1 Stator 1 ....................................... Ill
7.3.2 Stator 3 ....................................... 114
7.3.3 Rotor 1 ........................................ 115
7.3.4 Rotor 3 ........................................ 116
7.4 Frequency Contents of the Blade Pressure Forces ....... 117
8 Summary .................................................... 121
References .................................................... 126
Appendix ...................................................... 134
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