The unsteady process resulting from the interaction of upstream vortical structures with a downstream blade row in turbomachines can have a significant impact on the machine efficiency. The upstream vortical structures or disturbances are transported by the mean flow of the downstream blade row, redistributing the time-average unsteady kinetic energy (K) associated with the incoming disturbance. A transport model was developed to take this process into account in the computation of time-average multistage turbomachinery flows.
The model was applied to compressor and turbine geometry. For compressors, the K associated with upstream 2-D wakes and 3-D tip clearance flows is reduced as a result of their interaction with a downstream blade row. This reduction results from inviscid effects as well as viscous effects and reduces the loss associated with the upstream disturbance. Any disturbance passing through a compressor blade row results in a smaller loss than if the disturbance was mixed-out prior to entering the blade row.
For turbines, the K associated with upstream 2-D wakes and 3-D tip clearance flows are significantly amplified by inviscid effects as a result of the interaction with a downstream turbine blade row. Viscous effects act to reduce the amplification of the K by inviscid effects but results in a substantial loss. 2-D wakes and 3-D tip clearance flows passing through a turbine blade row results in a larger loss than if these disturbances were mixed-out prior to entering the blade row.