Numerical investigation on the mechanism of cascade unsteady force control based on pre-stator actuated oscillating trailing edge flaps

Unsteady force caused by rotor - stator interaction is one of the main excitation sources of impeller machinery vibration. To suppress the unsteady force, the stator wakes are conducted by the secondary flow generated by stator actuated oscillating trailing edge flaps (AOTEF). The unsteady Reynolds averaged Navier-Stokes equation (RANS) method based on the shear transport turbulence k-ω model and the improved delayed detached eddy simulation (IDDES) method are employed to numerically study a single cascade with AOTEF. The results show that the AOTEF oscillating phase angle determines the phase relationship between the stator wake and the rotor blade, and then affects the strength of the interaction between the stator wake and the rotor blade. Under the optimal phase of AOTEF, the rotor unsteady force decreases by 3 dB at rotor-stator blade passing frequency. The AOTEF significantly rises the peak value of the stator wake deficit. The amplitude of stator wake vorticity is significantly weakened by AOTEF, and the vortex shedding phase is regulated by AOTEF actuating phase. This study provides a new idea for the vibration and noise reduction of turbomachinery.