Zonal hybrid RANS-LES simulation of a 1.5-stage turbine

This paper introduces a novel method to conduct zonal hybrid RANS-LES simulations of turbomachinery configurations and demonstrates its application to a 1.5-stage turbine. The method extends the classical mixing plane concept to provide bi-directional interface conditions between RANS and LES sub-domains. A rotational synthetic turbulence generator is combined with the mixing plane approach at the inlet of LES sub-domains. The method features the reconstruction of modeled turbulence quantities at the outlet of a LES sub-domain required by a downstream RANS sub-domain. The application to the 1.5-stage turbine displays the feasibility of the coupling interfaces to conduct an embedded LES in the confined space of the turbine's rotor. The flow analysis highlights predictive differences between the embedded LES and a reference pure RANS simulation in terms of secondary flow effects in the rotor sub-domain.