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Old   May 13, 2013, 13:55
Default Transonic Inviscid Turbine Cascade
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Hey guys,

Iím trying to replicate the transonic, inviscid results of an inverse turbine blade design thesis. I have the original blade geometry, and have more or less copied the original mesh. The original geometry is discontinuous, leading to a passage shock at the discontinuity (Iíve attached geometry and Mach contour images). In the thesis, the ratio of back pressure to stagnation pressure is given as 0.65, so Iíve been using a pressure inlet and outlet and just picking pressures that correspond to that ratio. However, if Iím using lower pressures, i.e. Po = 100 kPa and Pback = 65 kPa, I donít get a shock at all. As I increase both pressures (Po = 10 000 kPa, Pback = 6 500 kPa), I am getting the shock, but itís upstream of the discontinuity (shown in the 3rd attached picture).

Iíd really appreciate any advice as to what I can do to improve these results. Thanks.
Attached Images
File Type: jpg Original.jpg (44.6 KB, 8 views)
File Type: jpg Mach Contours.jpg (36.6 KB, 5 views)
File Type: jpg Mach.jpg (51.3 KB, 7 views)
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Old   May 22, 2013, 10:20
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Just an update - I've managed to get what looks like a pretty good replica of the original results, using a stagnation pressure of 50 000 kPa and back pressure of 32 500 kPa. The shock appears to be occurring in the same place as the original work, and comparing upstream and downstream Mach numbers in both cases (0.483 vs. 0.478 and 0.819 vs 0.803) shows good agreement. Additionally, the mass flow through the passage has only 0.39% difference between the two cases.

However, if anyone has any ideas how I could get these results without having to use as high pressures, I would appreciate it.

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File Type: jpg Mach Contours.jpg (36.6 KB, 2 views)
File Type: jpg case8-mach.jpg (52.9 KB, 1 views)
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