In order to investigate the transient hydrodynamic characteristics of water-jet propulsion with a screw mixed pump during the startup period and to overcome the difficulties in measuring the transient process parameters over a very short period of time, a method based on a flume experiment combined with computational fluid dynamics (CFD) is proposed. The thrust and torque of the pump-jet propulsion according to mooring status at different rotational speeds were measured by the test, which provided a group of data for the boundary and initial conditions of the numerical calculation of the user-defined function (UDF). Consecutive changes in the parameters of the water-jet propulsion dynamics can be captured from the numerical simulation of the startup process with the UDF. Thus, the transient hydrodynamic characteristics of water-jet propulsion according to time or rotation speed were obtained. The results show that the relationship between the thrust or torque of the water-jet propeller and pump rotational speed is close to the quadratic functions. The energy characteristic parameters of screw mixed water-jet pump, such as the flow rate, head, shaft power, and efficiency, rapidly increase and decrease and then remain relatively stable.

Wind turbine gearbox is a key component to transmit power in wind turbine driveline. It is necessary for gearbox to have high reliability and durable quality, and so, it is obviously important to analyze the reliability of key components and the root of common failure. By means of RomaxWIND software, gearbox simulation model was built which is based on the flexible FE structures. Considering the effects of flexible FE structures, such as housing and ring gear, and capturing system effects, analysis is performed to estimate the performance of components under 20 years’ LDD, and the bearing and gear report were generated. Gear mesh misalignment is one of the major gearbox failure causes. In view of it, three different models were built for the analysis of mesh misalignment, the result reveal that the effect of flexible FE structures should not be ignored.