Numerical modeling of core compressor discharge for a windmilling aero engine

A gas turbine engine’s ability to relight in flight depends heavily on the combustion chamber’s inlet conditions. These conditions are dictated by the core compression system located immediately upstream of the combustor, but such conditions during windmill have not been thoroughly investigated and are not commonly available in the literature. In this paper, an entire high pressure ratio axial compressor is modelled using scale adaptive simulation. Real windmilling inlet conditions extracted from altitude test facility data are used as boundary conditions. The implications of steady vs. unsteady modelling and the use of different interface modelling approaches are investigated. A description of the discharge flow-field is given in terms of flow statistics, turbulent quantities, and dominant dynamic modes. The discharge flow-field is dominated by small scale structures resulting from leading edge separation in the last stator (OGV), with little influence of the upstream stages on the stator flow-field dynamics. The study has shown that, while an unsteady analysis is required, reduced order models allowing for a decoupled analysis of the last stage flow dynamics may be sufficient in future studies seeking to characterize combustor inlet conditions for inflight relight