FSI in hydraulic machinery - Applying AcuSolve to identify hydrodynamic damping and hydroelastic instabilities

In order to assess the dynamic behaviour of submerged components of hydro turbines, the effect of the surrounding water flow must not be neglected. Hence, fluid-structure interaction (FSI) may play an important role. After summarizing FSI phenomena in hydraulic machinery and discussing suitable analysis procedures for FSI depending on the application, the presentation focuses on flow induced damping and hydroelastic instabilities. Due to the high fluid mass which is moving with the structure (added-mass effect), hydroelastic systems require strongly (iteratively) coupled solution procedures. Here, AcuSolve’s practical FSI turned out to be an efficient and accurate approach. Since flow induced damping effects may become one or two orders of magnitude higher than structural or material damping, hydrodynamic damping of a blade is investigated depending on the inflow velocity. For validating and evaluating the FSI procedure, results are compared to experimental data and a different FSI solver. Finally, a bypass valve at small opening is regarded including a complex turbulent flow field. The hydroelastic stability characteristic is investigated, and the critical inflow velocity is identified.

 

The Author

Björn Hübner
Development Engineer
Voith Hydro Holding GmbH & Co. KG