Unsteady Flow Modeling Using Transient Rotor–Stator Interface

Based on experimental investigation of unsteady flow phenomena in centrifugal compressor, conducted in LPI (SPbSPU), including the measurements of high frequency pressure and hot-wire probes, numerical calculation was conducted with the aid of commercial ANSYS CFX12. The object was a model of industrial compressor, tested in full range of mass flows (from maximum to the onset of surge). Unsteady turbulent flows were calculated with URANS, turbulence model - SST-Menter. Region between the impeller and diffuser was calculated with Transient Method option. Time discretization Δ = 12 μsec. Sequential 20 revolutions of rotors were calculated, also LES model were used. Unsteady calculation results demonstrated reasonable agreement with experimental data both in meridional, and radial sections concerning the character of “jet – wakes” propagation, distribution of velocities in diffuser, and clearly showed three-dimensional flow conditions and reverse zones on the diffuser walls. “Frozen” velocity distributions during rotating stall demonstrated possibility of unsteady flow prediction with the aid of ANSYS CFX12. CFD results comparison with experimental data showed reasonable agreement for distributions of total pressures in diffuser, as well total and static characteristics of impeller and diffuser.