OpenFOAM Turbo Tools: From General Purpose CFD to Turbomachinery Simulations

OpenFOAM is an established object-oriented library for Computational Continuum Mechanics, with emphasis on CFD. It implements physical models of fluid flow, structural analysis, heat and mass transfer using equation mimicking, with unstructured polyhedral mesh support and massive parallelism in domain decomposition mode. In order to use OpenFOAM in turbomachinery CFD, its “general purpose” capabilities are enhanced with turbo-specific features, related to physics of rotating regions and rotor-stator interfaces. Handling for geometric simplifications of multi-blade and multi-stage rotating machines are implemented, including simple stage interfaces, non-equal pitch of blade passages, pitch-wise cyclicity and mixing plane averaging. In this paper we describe the implementation of turbomachinery-specific features in OpenFOAM, in the spirit of object orientation and C++. Emphasis is given to the basic functionality of turbo tools, software layout in OpenFOAM, numerical formulation of stage interfaces and their place in overall code design. The paper is concluded with examples of turbomachinery simulations, illustrating the capability of turbo tools on industrial cases of incompressible and compressible turbomachinery flows.