## 4 Analysis of Experimental Results
### Bearing Force Analysis
By comparing the fluctuating amplitudes of the three types of loads of a single blade, it can be observed that the fluctuating amplitude of the mixed load is significantly greater than that of the ice milling load, and the fluctuating amplitude of the ice milling load is significantly greater than that of the hydrodynamic load. The results show that the fluctuating amplitude of the single-blade mixed load increases significantly in the presence of water. According to the main fluctuating frequency determined in Figure 15, the fluctuating amplitude of the ice milling load and mixed load of the propeller and single blade under different inflow velocities, propeller rotational speeds, and cavitation numbers were extracted, and a column chart was drawn, as shown in Figure 16.  
Figure 16a,b show the main fluctuating amplitudes of the propeller thrust and torque during ice-propeller milling in air, as well as those in water under atmospheric pressure and decompression conditions. The fluctuating amplitudes of the BPF and APF were selected to analyze propeller thrust and torque, respectively. It can be observed from the figures that at the same propeller rotational speed and inflow velocity, the BPF fluctuating amplitude of the propeller thrust is the largest under atmospheric pressure, followed by that under the decompression condition, and the BPF fluctuating amplitude of the propeller axial force in air is the smallest. However, there are differences in the APF fluctuating amplitude of the propeller torque, and the difference in the torque fluctuating amplitude between the three states is small at low rotational speed and low inflow velocity. With the increase in rotational speed and inflow velocity, the difference in torque fluctuating amplitude is evident. During ice-propeller milling in air, the APF fluctuating amplitude of the propeller torque is the largest, followed by that in the decompression condition, and the BPF fluctuating amplitude of the propeller torque is the smallest under atmospheric pressure. Therefore, the axial excitation force of the propeller can be effectively reduced when the ice-going ship is sailing at low speeds with low rotational speed of the propeller in the ice zone. During ice-propeller milling in air, the higher the propeller rotational speed,  
the smaller the peak values of the axial force and torque (Figure 12), and the larger the BPF fluctuating amplitude of the axial force and the APF fluctuating amplitude of the torque. During ice-propeller milling in water under atmospheric pressure, with an increase in propeller rotational speed and inflow velocity, the advance coefficient increases and the BPF fluctuating amplitude of the propeller thrust increases, but the peak values of propeller thrust and torque (Figure 12) as well as the APF fluctuating amplitude of the torque decrease. During ice-propeller milling in water under the decompression condition, the smaller the number of cavitation, the smaller are the peak values of the propeller thrust and torque (Figure 12), but the larger the BPF fluctuating amplitude of the propeller thrust and the APF fluctuating amplitude of the torque. Figure 16: Fluctuating amplitudes of propeller and single-blade bearing force with different parameters: (**a**) fluctuating amplitude of \(T\); (**b**) fluctuating amplitude of \(Q\); (**c**) fluctuating amplitude of \(T_{X}\); (**d**) fluctuating amplitude of \(T_{T}\); (**e**) fluctuating amplitude of \(Q_{X}\); (**f**) fluctuating amplitude of \(Q_{Y}\). Figure 16c-f show the main fluctuating amplitudes of the single blade thrust and torque under three milling conditions. It can be observed from the figures that at the same propeller rotational speed and inflow velocity, the APF fluctuating amplitudes of the thrust and \(Y\)-direction torque of the single blade are the largest under the decompression condition, followed by that under atmospheric pressure, and the fluctuating amplitude is the smallest in air.