Numerical Investigation on Unsteady Separation Flow Control in an Axial Compressor Using Detached-Eddy Simulation

Abstract

Unsteady excitation has proved its effectiveness in separation flow control and has been extensively studied. It is observed that disordered shedding vortices in compressors can be controlled by unsteady excitation, especially when the excitation frequency coincides with the frequency of the shedding vortex. Furthermore, former experimental results indicated that unsteady excitation at other frequencies also had an impact on the structure of shedding vortices. To investigate the impact of excitation frequency on vortex shedding structure, the Detached-Eddy Simulation (DES) method was applied in the simulation of shedding vortex structure under unsteady excitations at different frequencies in an axial compressor. Effectiveness of the DES method was proved by comparison with URANS results. The simulation results showed a good agreement with the former experiment. The numerical results indicated that the separation flow can be partly controlled when the excitation frequency coincided with the unsteady flow inherent frequency. It showed an increase in stage performance under the less-studied separation flow control by excitation at a certain frequency of pressure side shedding vortex. Compared with other frequencies of shedding vortices, the frequency of pressure side shedding vortex was less sensitive to mass-flow variation. Therefore, it has potential for easier application on flow control in industrial compressors.

Investigation on the Flow Field Entropy Structure of Non-Synchronous Blade Vibration in an Axial Turbocompressor

“…However, there still exists a little difference. As depicted in literature [ 31 ], near the stall boundary, the interface of the incoming flow and tip leakage vortex is pushed to the leading edge of the neighboring blade. The increasing blockage at tip region is concentrated on the local suction side of the blade, rotating with the blade.…”

“…The unsteady flow field in the turbocompressor is solved by using the numerical solution of 3-D Navier-Stokes equations adopted by the commercial software CFX. The spatial discretization of the flow governing equations is employed on an upwind scheme, and second-order backward differencing is integrated for the time-accurate solution [ 31 ]. Boundary conditions imposed on the inlet consist of total pressure and total temperature.…”

Investigation on the Mechanism and Parametric Description of Non-Synchronous Blade Vibration

“…The unsteady flow field is solved by using the numerical solution of 3-D Navier-Stokes equations by the commercial software CFX. The spatial discretization of the flow governing equations is employed on a high-resolution scheme, and second-order backward differencing is integrated for the time-accurate solution [ 32 ]. The total pressure boundary condition is used at the inlet and the averaged static pressure boundary condition is set to the outlet with a constant rotor speed.…”

Advances in Mechanical Systems Dynamics

“…In the second paper [26], the flow separation in axial compressors is controlled by the unsteady (pressure) excitation, not only at the shredding vortex frequency (traditional method), but also at other frequencies, demonstrating the impact on the structure of shredding vortices.…”