Loss Measurement Strategy in ORC Supersonic Blade Cascades

Abstract

In the framework of Organic Rankine cycle (ORC) power systems, significant non-ideal gas effects typically take place in processes occurring within the cycle components. The flow non-ideality is of paramount importance for turbo-expander, whose design demands the application of advanced computational approaches, based on non-ideal compressible fluid dynamics (NICFD), to avoid misleading performance predictions. The validation of both low-fidelity and advanced aerodynamic methods based on state-of-the-art thermodynamic fluid models is therefore crucial but still limited, due to the lack of experimental benchmark data focused on ORC turbine losses. To fill this gap, an experimental campaign has been launched at Politecnico di Milano on a supersonic linear cascade representative of an ORC stator vane, with the aim of providing a reference for numerical simulations. This paper describes the devised measurement strategies conceived and implemented to investigate the flow-field established within the blade channels and downstream the planar row, particularly in the trailing edge region, and to retrieve the total pressure losses through the cascade with a relatively high spatial resolution, as they are the main outcomes of the experiments.