THE INVESTIGATION OF TIP CLEARANCE EFFECTS IN DUCTED ROTOR AERODYNAMIC CHARACTERISTICS USED IN UNMANNED AERIAL VEHICLES

摘要

The paper investigated the influence of tip clearanceon ducted fan aerodynamic characteristics based ontheoretical analysis and numerical simulation. Fromthe theoretical analysis, it proved that the rotor wasbeing off-loaded which could avoid flow separation.From the numerical simulation, with the increase oftip clearance, thrust coefficient was dropped greatly,especially when tip clearance was over 2%D whichwas less than the open rotor’s. As to powercoefficient, it was totally different, C_P of open rotorwas higher than ducted rotor’s. Although the powerneeded by tip clearance 3%D and 5%D was a littlelower than the other two, C_T/ C_P value was alsolower. For the tip clearance 5%D, C_T/ C_P wasalmost the same as open rotor.