Non-Ideal Compressible-Fluid Dynamics Simulations With SU2: Numerical Assessment of Nozzle and Blade Flows for Organic Rankine Cycle Applications

The growing interests towards Organic Rankine Cycle (ORC) turbo-machinery calls for reliable and well-established simulation and design tools, including Computational Fluid Dynamics (CFD) software, accounting for non-ideal thermodynamic behaviour in close proximity to the liquid-vapour saturation curve and critical point, as well as two-phase properties. SU2, an open-source CFD solver originally developed at Stanford University, Palacios et al. (2013, 2014), was recently extended to deal with non-ideal thermodynamics, including state-of-the-art multi-parameter equations of state implemented in the FluidProp library, Colonna and van der Stelt (2004), and it is now in the process of becoming a reliable simulation tool for academic and industrial research on ORC machinery. The investigation of SU2 performances in connection with the numerical simulation of steady nozzle and turbine flows of interest for ORC applications are provided. Numerical simulations refer to both inviscid and viscous flow, with diverse thermodynamic (ideal gas, Van der Waal gas, Peng- obinson Stryjek-Vera, Span-Wagner multi-parameter equation of state) and turbulence (Spalart-Allmaras, SST-k) models. Considered geometries include straight axis planar nozzle, and a typical ORC turbine blade passage.