Modeling and numerical study of waterjet thrust stem (jet surf)

The ever-increasing expansion of marine recreation using water recreational equipment is one of the important fields of attention in the marine industry. Optimizing and upgrading the appropriate propulsion system for this type of marine device is one of the most important factors of updating and innovation, which leads to the strengthening of the marine economy and related engineering services. Motorized surfboard or so-called jet surf is one of these devices. The water jet is the most important part of the jet surf propulsion system. Limited research has been done on the design and analysis of the water jet system. In this research, the modeling and optimal design of the rotor and stator of the waterjet system related to the propulsion of the motorized surfboard are discussed. According to the limitations of engine selection, rotational speed, and engine design conditions, the appropriate rotor and stator were selected for the waterjet system. Also, the appropriate shape and dimensions of the system inlet channel were modeled in 4000 rounds. The relevant model was tested and the optimization results led to the maximum functional efficiency of Jet Surf being selected for the design. Their results and analysis show that in the 8-blade rotor and 10-blade stator, more thrust force is produced at 3500 rpm, but less torque is needed in the 6-blade rotor and 8-blade stator. Also, by using the trust diagram obtained for the system, it was determined that the ratio of the trust factor to the rotor revolution for this designed waterjet is about 15 and the efficiency of the whole system was 54%.