Research On Hydrodynamics Of A Blended Wing Body Underwater Glider With Twin Tails For Shallow Water Applications

With the increasing number of offshore oil and gas development platforms and offshore wind farms,the demand for inspection work on the bottom structure of the platform is also increasing.It is urgent to develop underwater inspection equipment suitable for stable close observation in shallow water interference environment.Compared with the floating underwater vehicle,the crab like multi legged robot has more advantages in this task,but it still has the disadvantage of high energy consumption when it is moving in long distance.In this paper,by using the buoyancy control system,the crab like multi legged robot can be extended and transformed into an underwater glider,which can realize the glide motion with less energy consumption.Aiming at the problems of wave interference and limited vertical motion space in shallow water,the prototype model of underwater glider is designed by using wing body fusion shape to take into account the requirements of high lift drag ratio,relatively large driving force and sufficient load volume.At the same time,a pair of multi-functional tail rudders with switchable control mode are designed with reference to the swimming feet of sea crabs.In the case of no experimental prototype,the shallow water gliding performance and the tail rudder control function of the designed Underwater Glider will be tested and predicted mainly through the hydrodynamic researchAccording to the research background and task requirements,the shape and general layout design of the conceptual prototype of the wing body fusion twin tail rudder shallow water glider is carried out,and the main performance parameters of the prototype are given,and its dynamic modeling and hydrodynamic analysis are carried out.In order to verify the research method of hydrodynamic numerical simulation based on CFD,the standard model of SUBOFF submarine is taken as the verification object,and a variety of model pool experiments are simulated in the computational fluid dynamics software STAR-CCM+,some hydrodynamic coefficients are solved and compared with the experimental values or the solution values of panel method,the accuracy of different simulation methods is discussed,so as to determine the simulation solution of all hydrodynamic coefficients of underwater glider A variety of simulation conditions combination.A variety of simulation conditions are applied to two sets of underwater glider computational grid models which are built for the problem of tail rudder control mode switchover.A set of fixed hydrodynamic coefficients of the main hull of the underwater glider and two sets of switchable hydrodynamic coefficients under different tail rudder control modes are solved by least square method and Fourier series decomposition.Finally,According to the results of dynamic modeling and hydrodynamic coefficient solution,the motion simulation of the shallow water glider with dual tail rudders is studied by iterative solution of ordinary differential equations,and the gliding performance of the main hull,pitching rudder and heading rudder is analyzed.The results show that the current design of the blended wing body underwater glider can achieve the expected shallow water glide in its buoyancy regulation cycle,the glide path is smooth,and the speed is significantly higher than that of the classic revolving body underwater glider;the choice of the pitching rudder has a significant impact on the longitudinal section glide performance,which verifies the rationality of the solution of the hydrodynamic separation.By adjusting the pitching rudder,the navigation slope and speed can be changed to meet the demand for different sea conditions,the heading rudder has certain steering ability.