*3.1. Establishment of the Test Bed*

The test bed of waterjet propulsion system is shown in Figure 4. The test bed consists of two closed loops. The main function of the first loop is to ensure the water circulation of the test bed and provide the bottom speed. The main function of the second loop is to test the performance of the waterjet propulsion pump. The size and shape of impeller and guide vane in the test device are consistent with the numerical model. The head, flow rate, torque, and speed were tested to obtain the hydraulic performance of the waterjet propulsion pump. The pump is driven by a DC electromotor (Changchuan, Nanjing, Jiangsu, China) at speeds varying from 700 rev/min to 2400 rev/min and equipped with an auxiliary axial pump to regulate the flow rate. The test rig has two electromagnetic flowmeters (Shanghai Guanghua Instrument Co., Ltd., Shanghai, China) with an absolute accuracy of ±0.5%. These flowmeters are used to test the flow rate of the main circulation pipeline system and second circulation pipeline system. The head of the waterjet propulsion pump is measured by the differential pressure transmitter (Yokogawa Sichuan Instrument Co., Ltd., Chongqing, China) with an absolute accuracy of ±0.2%.

**Figure 4.** Test rig.
