Optimization Of Aero And Hydro-dynamic Performance Of Cycloidal Propeller For Transmedia Purpose

The trans-medium vehicle is a multi-functional vehicle that can fly in the air,sail on the free surface and underwater,which has broad application prospects.A key issue in the design of trans-medium vehicle is the design of propellers suitable for both water and air environments.How to simultaneously meet the multiple working conditions and complex propulsion requirements in water and air,whilst avoiding the redundant design of "two sets of propellers separately for water and air" and increasing the number of aircraft Payload space is the key to propeller design.Due to its excellent maneuverability and adaptability to multiple working conditions,the cycloidal propeller is very suitable for cross-medium navigation.Based on the above background,this dissertation further proposes to increase the hydrodynamic performance of the cycloidal propeller in the water and in the air by adding flaps.First,the computational fluid software STAR-CCM+ is used to perform two-dimensional calculations on the three-blade cycloidal propeller.The blade airfoil is selected from the D section airfoil of the NSRDC experimental propeller,and the accuracy of the calculation model is verified by comparison with the experimental results.On this basis,the three-blade propeller with the basic airfoil NACA0012 is calculated,and the influence of flaps on the hydrodynamic performance of the cycloidal propeller is quantitatively studied.Secondly,the study on the hydrodynamic performance of cycloidal propeller under different flap parameters including the flap rotation pattern,the relative length of the flap and the flap rotation amplitude are conducted.Three different rotation patterns are calculated,namely the anti-virtual camber pattern,the sinusoidal pattern,and the superposition of these two patterns.The results show that for the conditions studied in this paper,when the flaps rotate according to the anti-virtual camber pattern,it is beneficial to offset the side thrust.When the advance coefficient J=1.0,the side thrust is reduced by 98%.When rotating according to the sinusoidal pattern,it is helpful to improve the efficiency of the propeller when the advance coefficient is high.When the advance coefficient J=1.0 and 1.2,the efficiencies are increased by 3.86% and 50% respectively.After the superimposed motion pattern,the two effects can be achieved at the same time.When the advance coefficient J=1.2,the efficiency is increased by43.5%,and the side thrust coefficient is reduced by 88.89%.Then,on the basis of the superposition of the two types of patterns,the influence of the relative length and the rotation amplitude of the flap is studied respectively.Finally,the influence of flap parameters including the fixed angle of flap and the pattern of flap rotation on the hovering efficiency of the cycloidal propeller is studied.The study found that for the conditions studied in this paper,comparing the hovering efficiency under the same paddle disk load,the hovering efficiency is higher when the flaps are fixed at an angle of 5°clockwise or rotate according to the superimposed pattern.