Aerodynamic Characteristics Of Flying Vehicle With Autorotating Rotor In Flight Mode

Since the beginning of 21 st century,the traffic,the law enforcement and rescue of city,the large-scaled and farmed agriculture,and the military transportation offer adequate support for the design and research of a flying vehicle.The vehicle with autorotating rotor is becoming an important direction of the development on the strength including jump takeoff,spot landing,landing after engine-failure in flight,simple structure and low cost.The aerodynamic characteristics of flying vehicle with autorotating rotor in two typical flight conditions is focused by method of theory,CFD and test.The dynamic model in gyroplane level flight consists of all the configurational parts’ aerodynamic models.The autorotating rotor aerodynamic model is made up of the blade flapping model,the inflow model,and the thrust and torque.The flapping model and the thrust and torque of the rotor are calculated by blade element theory(BET)and momentum theory(MT),and a Glauert form and Drees coefficients is selected for the rotor inflow model.The models of propeller,fuselage and tails are built,too.Eventually,a gyroplane level flight dynamic model is assembled.The performance and aerodynamic characteristics of the one-three-scaled flying vehicle in level flight will be investigated by the proposed gyroplane model.The dynamic model is a guidance for design and a prediction of performance parameters of the flying vehicle.These parameters would be the initial conditions of numerical simulation of flow field around the one-three-scaled flying vehicle in level flight.The numerical simulation method of unsteady flowfiled past the autorotating rotor is proposed and validated against Niemi test,whose accuracy is 85%.Then the method of flowfield of the flying vehicle,or gyroplane,is proposed and validated against VPM M16 flying test,whose accuracy is 80%.The unsteady flowfields past autorotating rotor,body(including the tails),propeller,rotor-propeller,rotor-body,propeller-body,and the overall vehicle of the one-third flying vehicle are simulated,alternately.Their fluid characteristics are investigated and numerical results are compared so that the interaction principles among them are concluded and the interaction coefficient between rotor and propeller-body in the overall vehicle flowfield is quantified.The interaction coefficient is introduced in the one-three flying vehicle dynamic model in level flight for the enhancement of performance prediction.The response model of autorotating rotor considering the rapid blade-pitch increase(RBPI)is derived,then validated against the NACA experiment data.The jump takeoff model taking account of the effect of RBPI and ground is built and validated against the test data from a one-eighth-scaled flying vehicle with the autorotating rotor,whose accuracy can reach up to 95%.Gathering the statistical data of PMSE and MHE between simulation results of the four simplified models and test data,the effect of RBPI,ground and the induced velocity on jump takeoff performance is quantitated.The conclusion is that RBPI could be neglected in the design and quick performance estimation of the jump takeoff system.Meanwhile,the induced velocity distribution of the test rotor is derived that it is a linear then parabola time function at the same radial stand station and a linear function of the radial stand position at the same time.Finally,the performances of the 1/3 and the prototype of the flying vehicle in level flight are calculated by the jump takeoff dynamic model,which is good for performance parameters prediction and design of the jump takeoff system.The ordinary jump takeoff system doesn’t work for a flying vehicle prototype with a compact size and a large rotor and duct propeller disk loading.A new kind of jump takeoff solution,called ‘jump takeoff with flywheel’,is recommended to the prototype.The system of jump takeoff with flywheel for prototype is designed.A model for calculating the flywheel inertial is built based on the constraint,which is the anti-torque affected by the flywheel and has to be offset by the rudder.Then,a non-zero advanced ratio jump takeoff model of flying vehicle with large rotor disc loading and flywheel is established on the basis the jump takeoff model in Chapter 4.The proposed model is used for analyzing the influence of flywheel to jump takeoff performance of prototype,selecting a flywheel making the jump takeoff performance of prototype best,and finally,calculating the jump takeoff performance of prototype.Jump takeoff with flywheel is easy to make the gyroplane being jump takeoff instead of running,especially one with transmission.