By Martin Kuntz and Florian Menter, CFX
During the last three and a half years, CFX has actively participated, as CFD software provider, in the European HPNURSA (High Performance Numerical Unsteady Rotor Stator Analysis) research project. The project, which started in 1998, recently closed with a workshop at the 21st IAHR meeting held in Lausanne, Switzerland in September 2002. Within the project, CFX worked closely with VA TECH HYDRO, as industrial end-user, and the Universities of Lausanne (EPFL) and Lyon (ECL) as academic partners.
The complexity of unsteady rotor-stator flows makes them highly computer intensive, as they require a transient simulation with sufficiently small time steps to resolve the unsteady features of the flow. Furthermore, the full 360-degree machine must generally be modelled, leading to multiple blades per row in the simulation. These demands increase CPU and memory requirements by at least an order of magnitude compared to steady-state simulations. If such computations are to be tractable for industrial users, the use of advanced computer and programming technologies is essential.
These issues have been addressed by the HPNURSA project, providing improvements to the unsteady time integration formulation, enhancements of the transient rotor-stator interface and the optimization of the parallel performance of CFX-TASCflow and CFX-5.