Unsteady Compressor Performance Assessment Using Euler Solvers

Although the use of 3D CFD simulations has become common practice, 2D and quasi-3D through-flow tools are still used to quickly assess compressor performance. These tools rely on semi-empirical models and correlations to account for complex flow features such as flow deviation and losses. The purpose of this paper is to describe the methodology that led to the development of FENICE1-PC/2D (Fast Euler Numerical Integrator for Compressor Evaluation). FENICE-PC/2D is an unsteady Euler solver which allows the prediction of complete compressor maps (i.e. forward, stalled and reversed flow). The tool offers the user the choice to run as a 2D flow solver, or as a quasi-2D solver. The latter relies on the principles of the well-established ‘parallel compressors’ technique [1], with cross flow (mass flow exchange between sectors) for the modelling of asymmetric flow fields. In particular, this paper presents the capabilities of both versions of FENICE, highlighting advantages and limitations where appropriate. The tool has been implemented in FORTRAN and verified adopting different compressor geometries. The verification was performed by imposing inlet total pressure and total temperature distortions, to assess the effect of the circumferential mass redistribution on the compressor’s overall performance. For the specific case of total pressure distortion, a comparison against available 3D CFD results was also carried out to verify the circumferential trends of various flow properties. Moreover, the total pressure distortion was used as a trigger to force the C106 compressor into stall and investigate the stall region. The study has showed that both FENICE-PC and FENICE-2D can be used effectively during the compressor preliminary design and development phase to study asymmetric and axisymmetric phenomena, hence avoiding the complexity and computational overhead associated with full 3D CFD simulations.