15th European Conference on Turbomachinery Fluid dynamics & Thermodynamics

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Main Topic:

Basic Phenomena



Alessandro Colombo - University of Bergamo, Italy
Antonio Ghidoni - University of Brescia, Italy
Edoardo Mantecca* - University of Brescia, Italy
Gianmaria Noventa - University of Brescia, Italy
Stefano Rebay - University of Brescia, Italy
David Pasquale - Turboden S.p.A., Italy


This work aims to show the new capabilities implemented in an in-house Discontinuous Galerkin (DG) solver [1] for the CFD simulation of Organic Rankine Cycles’ (ORCs) turbine stages. The Reynolds averaged Navier–Stokes equations coupled with the two equations k-log(ω) turbulence model are solved to predict the flow features in a multi reference frame, where interfaces between fixed and rotating zones are treated with a mixing plane approach [2] and non-reflecting boundary conditions are used. The thermal pressure-explicit equation of state (EoS) of Peng-Robinson is used to accurately relate thermodynamic quantities and is supplemented by a polynomial description of the ideal gas contribution to the isobaric specific heat. The dynamic viscosity and thermal conductivity are computed with Chung’s model. The solver has been assessed with the computation of the flow field through an existing axial ORC turbine (2 stages) provided by Turboden. The working fluid is the linear siloxane MDM (C8H24O2Si3). In particular, the influence on the solution’s accuracy of different aspects will be investigated, which are: the polynomial degree of the solution’s approximation, the mesh spacing and the employed thermodynamic model. The predicted results will be compared with numerical data provided by Turboden, obtained with a commercial CFD code. [1] Bassi, F. and Botti, L. and Colombo, A. and Crivellini, A. and Franchina, N. and Ghidoni, A. Assessment of a high-order accurate Discontinuous Galerkin method for turbomachinery flows. International Journal of Computational Fluid Dynamics (2016) 30:307–328. [2] Saxer, A.P. and Giles, M.B. Quasi-three-dimensional nonreflecting boundary conditions for Euler equations calculations. Journal of Propulsion and Power, (1993) 9:263–271.


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