Numerical unsteady flow analysis of a turbine stage with extremely large blade loads
2002 (English)In: Journal of turbomachinery, ISSN 0889-504X, Vol. 124, no 3, 429-438 p.Article in journal (Refereed) Published
This paper presents the detailed numerical analysis including parametric studies on the aerodynamic excitation mechanisms in a turbine stage due to the unsteady stator-rotor interaction, The work is part of the predesign study of a high-pressure subsonic turbine,for a rocket engine turbopump. The pressure level in such turbines can be remarkably high (in this case 54 MPa inlet total pressure). Hence, large unsteady rotor blade loads can be expected, which impose difficult design requirements, The parameter studies are performed at midspan with the numerical flow solver UNSFLO, a 2-D/Q3-D unsteady hybrid Euler/Navier-Stokes solver. Comparisons to 2-D and steady, 3-D results obtained with a fully viscous solver VOLSOL, are made. The investigated design parameters are the axial gap (similar to8-29 percent of rotor axial chord length) and the stator vane size and count (stator-rotor pitch ratio similar to1-2.75), For the nominal case the numerical solution is analyzed regarding the contributions of potential and vortical flow disturbances at the rotor inlet using rotor gust computations. It was found that gust calculations were not capable to capture the complexity of the detected excitation mechanisms, but the possibility to reduce excitations by enforcing cancellation of the vortical and potential effects has been elaborated. The potential excitation mechanism in the present turbine stage is found dominant compared to relatively small and local wake excitation effects. The parameter studies indicate design recommendations for the axial gap and the stator size regarding the unsteady rotor load.
Place, publisher, year, edition, pages
2002. Vol. 124, no 3, 429-438 p.
unsteady flow computation, forced response, turbomachinery, turbine, turbopumps, CFD, design, gust response, aerodynamics, prediction, forces
IdentifiersURN: urn:nbn:se:kth:diva-21745ISI: 000177013500015OAI: oai:DiVA.org:kth-21745DiVA: diva2:340443
QC 201005252010-08-102010-08-10Bibliographically approved