Performance and control of a collective and cyclic pitch propeller for an underwater vehicle

Most of the underwater vehicles have control surfaces to enable manoeuvring. The problem with an underwater vehicle with control surfaces is operating it at low speed. At low speed, the control surfaces become inoperative as the magnitude of the generated lift relates to the water speed passing over the control surfaces. A novel device, which is a potential solution to this problem, is the collective and cyclic pitch propeller (CCPP). The CCPP can generate both axial and transverse thrusts in one device. The research focused on the performance of the CCPP and the performance of an underwater vehicle equipped with the CCPP. The information about the true performance of this CCPP has not been investigated. Assessing the true performance in a straight line of the CCPP was the first objective of this research. The development of the simulation program was the second objective of this research in order to assess the motion control of an underwater vehicle by using the CCPP. The performance in a straight line of the CCPP behind an underwater vehicle was assessed by using a captive test in the Towing Tank at the Australian Maritime College. In the experiment, the propeller was set at various pitch angles, and it was tested at various advance coefficients. Polynomial equations for estimating the thrust and the torque coefficients of the propeller with the collective pitch setting were established. In addition, the effects of the collective pitch, cyclic pitch, and advance coefficient related to the magnitude and direction of the transverse thrust were studied. Increasing the magnitude of the collective pitch setting caused the direction of the transverse thrust to rotate clockwise when looked at from aft. The magnitude of the transverse thrusts increased as the collective pitch setting increased. Different types of cyclic pitch setting affected the direction of the transverse thrust differently. Increasing the magnitude of the cyclic pitch setting raised the magnitude of the transverse thrust. According to the experimental information, the direction and the magnitude of the transverse thrust was found to be difficult to control manually. Hence a motion control system of an underwater vehicle equipped with the CCPP was developed in order to assist an operator to control the vehicle. The proportional integral derivative control law was used to develop the control system. The capability of the motion control system and the manoeuvrability of the underwater vehicle equipped with the CCPP were assessed by using a developed simulation program. In addition, the numerical simulation of an underwater vehicle equipped with the CCPP is an essential tool to develop the CCPP in the future. The simulation program was developed by using the mathematical model of a test underwater vehicle. Furthermore, the forces of the CCPP were modelled by using the experimental results and the performance prediction program. The simulation study has shown that the underwater vehicle equipped with the CCPP has flexible manoeuvrability, and controllability. The CCPP is capable of controlling an underwater vehicle in all directions. For further development, the free running test should be conducted in order to demonstrate the performance of the underwater vehicle and to verify the simulation program.