Unsteady rotor force suppression of a pump-jet by stator actuated oscillating trailing edge flaps: A numerical study

Abstract

The unsteady rotor force is the main source of the pump-jet-shafting system vibration. The coupling between rotor rotation and stator wake results in the characteristic line spectra of rotor unsteady force. The actuated oscillating trailing edge flaps (AOTEF) is introduced to the stator. The secondary flow generated by AOTEF is used to suppress the unsteady rotor force. A numerical model is established based on the unsteady Reynolds averaged Navier-Stokes equation (URANS) method of the shear stress transport (SST k-ω) turbulence model, taking the SUBOFF and pump-jet propulsor with AOTEF as the research object. Aiming at suppressing unsteady force at rotor blade passing frequency (BPF), the expression of AOTEF harmonic oscillation law is given and optimized. Under the optimal control of the AOTEF, the hydrodynamic performance remains unaffected. At BPF, the axial unsteady force of the rotor and a single blade decrease by 15.6 dB and 14.8 dB, separately. Further analysis shows that the AOTEF can manipulate the stator wake and the velocity on the rotor inlet plane. The research results show that the AOTEF can significantly suppress the unsteady rotor force while maintaining the hydrodynamic performance, which will shed some light on controlling the unsteady force of the pump-jet.