| The tip jet helicopter is drove by the reaction force produced by the high speed tip jet. This kind of helicopter has many advantages such as: fuselage simplified and compacted, empty weight lighted, because it does not need extra equipment to balance the anti-torque. The pressure jet rotor has been used widely as it is a typical driving system. Because the flow field and the aerodynamics of the rotor are influenced by the tip jet tremendously, the traditional method to calculate the rotor aerodynamics is not suitable. In this paper, a method to calculate the coupling aerodynamics of the pressure jet rotor’s inner flow and external flow has been built. This method also lays a technological foundation to design the pressure jet rotor. The main contents of this dissertation include as following:1) Firstly, the CFD computational models of the blade duct’s flow were built in this dissertation. The influences of some factors to the flow speed, pressure, temperature and the jet velocity of the duct, such as: the duct wall friction, the cross section shape of the tip nozzle, the total pressure of the duct entrance, the temperature of the air, and the speed of the rotor, has been analyzed deeply.2) Then the CFD computational models of the rotor blade’s external flow aerodynamics were built. Furthermore a method to study the coupling of the inner flow and the external flow has been established combined with the upper method. Through calculating a typical pressure jet rotor, it can be found that the influence of the coupling effect decreases the blade lift and increases the blade moment.3) Finally an engineering method to analyze the characteristics of the duct’s inner flow and the rotor’s external flow was put forward based on the CFD results. The validity and effectiveness of this method were proved, and it can be used to calculate the coupled aerodynamic characteristics of the pressure jet rotor quickly. |
PDF Full Text Request