Research on wake characteristics and HCWF blade number matching of a new coupled propeller

Abstract

For the purpose of wake energy recovery and hub vortex control in a new Coupled Propeller (CP), three hub cap with fins (HCWF) schemes with different blade numbers are designed for a specific multi-blade CP. A numerical investigation of the CP-HCWF system is conducted using the Large Eddy Simulation (LES) method. Firstly, the analysis focuses on the distribution of axial and tangential flow velocity characteristics of the CP. The wake spectral characterization analysis results reveal that the 10th-order component is equivalent to the 5th-order components within 0.7 R of the HCWF. However, beyond 0.7 R of the HCWF, the 10th-order component becomes more significant. Then, the influence of the HCWF blade number on the CP performance is further analyzed. Hydrodynamic efficiency, post-hub pressure recovery, wake energy recovery, and hub vortex elimination improve with increased HCWF blade numbers. The 10-blade HCWF demonstrates the best performance. Ultimately, the reliability of the numerical findings is verified through the model test. The efficiency variation with the fin number exhibits a consistent trend in the test and calculation results. It is suggested that the HCWF blade number is selected by considering the sum of the CP blades as a reference.