Wet Steam Test Case
This test case was established by RPMTurbo to examine wet steam effects on flutter analysis. Previously, there was no publicly avaliable experimental data or numerical solutions for unsteady wet steam flow due to harmonically oscillating profiles. The results were published at the 13th ISUAAAT at the University of Tokyo, Japan on 13 September 2012.
Geometry
The two-dimensional turbine geometry from Standard Configuration 11 was used. The chord length for the results shown here was increased by a factor of 3.0 to 0.2334 metres, so that the Reynolds numbers for the flow conditions were similar to those expected in an industrial steam turbine. The chord length for the results shown in the 2012 ISUAAAT paper was 0.0778 metres.
Flow Conditions
The flow conditions used for this test case are similar to the flow conditions at the last stage of a typical industrial steam turbine. The description of the flow conditions is given in the Table below. The first flow condition is pure steam vapour with no condensation, the second flow condition is high subsonic flow with condensation, and the third flow condition is transonic flow with condensation. The incoming turbulence for all conditions was assumed to be zero.
| Flow Condition | #1 | #2 | #3 |
|---|---|---|---|
| Inlet Total Pressure (kPa) | 13.0 | 13.0 | 13.0 |
| Inlet Total Temperature (K) | 400.0 | 324.2 | 324.2 |
| Inlet Inflow Angle (deg) | 15.2 | 15.2 | 15.2 |
| Inlet Total Quality | 1.0 | 0.9 | 0.9 |
| Outlet Pressure (kPa) | 9.75 | 9.75 | 7.5 |
Steady-State Solutions
A summary of the steady-state solutions are shown in the Table below. The Reynolds number is based on the flow conditions at the outlet. There are differences in the steady-state solutions shown here and those presented in the 2012 ISUAAAT paper. The differences occur on the suction side near the leading edge and are due to different Reynolds numbers.
| Flow Condition |
Outlet Mach Number |
Reynolds Number |
Polytropic Index |
Steam Quality Contours |
Mach Number Contours |
Pressure Plot | Profile Data |
|---|---|---|---|---|---|---|---|
| 1 | 0.663 | 380 000 | 1.308 |
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[Data] |
| 2 | 0.658 | 433 000 | 1.107 |
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[Data] |
| 3 | 0.915 | 469 000 | 1.109 |
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[Data] |
Unsteady Flow
The unsteady flow response due to the blade oscillating in a torsion mode is shown in the Table below. The centre of rotation for the torsion mode is 36.34% along the chord line. The frequency of the vibration for the results shown here is 70.66 Hz and the interblade phase angle is 0 degrees. The frequency was 212.0 for the results presented in the 2012 ISUAAAT paper. The frequency was changed in order to match the reduced frequency of the results presented in the 2012 ISUAAAT paper (shorter chord length). The reduced frequency is calculated based on full chord. The non-dimensional values were calculated using the maximum mode displacement divided by the chord length as the mode amplitude. Again there are differences in the unsteady solutions compared with the results in the 2012 ISUAAAT paper on the suction side near the leading edge because of different Reynolds numbers.
| Flow Condition |
Reduced Frequency |
Imag Unsteady Cp Plot |
Local Work Coefficient |
Data |
|---|---|---|---|---|
| 1 | 0.328 |
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[Data] |
| 2 | 0.380 |
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[Data] |
| 3 | 0.278 |
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[Data] |