Analysis Of The Aerodynamic Characteristics Of Propeller And Rotor

Propeller and rotor are important power components of aircraft.One is widely used in UAV and the other is unique to helicopter.UAV has received widespread attention from all over the world for their small size,low cost and easy manipulation,and it is developed vigorously in military and civilian fields with showing many kinds and large numbers.UAV mostly uses propeller to produce driving force to fly,mainly considering its low fuel consumption characteristics.At present,a development trend of military UAV is high altitude and long endurance,and the traditional propeller is no longer suitable for this kind.So it is necessary to study the aerodynamic characteristics of propeller so as to provide basis for selecting propellers for high altitude and long endurance UAV.The aerodynamic characteristics of helicopter rotor affect its flight performance directly.Rotor aerodynamic characteristics are usually divided into two states: hovering and forward flight.The quality of rotor is reflected by studying its flow field characteristics.Based on Fluent,three types of flow fields of propeller and rotor are simulated in this paper,and Pointwise software is used to divide the computational domain.The hovering flow fields of propeller and rotor are treated as steady,and the forward flight is treated as transient.The flow field of propeller is assumed incompressible due to its low flow and low rotation rate,and it is solved by the discrete method.Two flow fields of rotor are solved by coupling method with considering the compression effect of air flow in blade tip.Considering the complex motion of rotor in forward flight state,the dynamic grid technique under the control of UDF is applied to describe the motion.Finally,according to the characteristics of three kinds of flow fields,three numerical simulation methods that are suitable for their characteristics are established and solved.The reliabilities of each numerical methods are proved by test results or test examples.Then according to the established numerical simulation methods,three flow fields are solved.Results show that:(1)In a certain flow,there is an optimal blade angle and the corresponding best rotation rate to maximize the efficiency of the propeller.(2)In hovering state,the quality of the advanced blade is better than the basic blade due to its improved geometric shape in several aspects,including the increased blade width cooperated a tip tapper,the sweep position of tip leading edge advanced properly and the application of anhedral angle in blade tip.(3)In the forward flight,the aerodynamic load of the blade is asymmetrical in azimuth angles,and it changes constantly with the blade rotation.The leeward side pressure gradient of the retreating blade is larger,but the one and the negative pressure peak of the advancing blade are all smaller.And the tip vortex development of the advancing and retreating blade is also different.In this paper,the numerical simulation methods of three kinds of flow fields belonged to propeller and rotor are established,and the aerodynamic characteristics of the propeller and rotor are studied in each flow field.Basically,it involves the investigations of aerodynamic characteristics of propeller and rotor under typical operating conditions,which provides references for further deep research on aerodynamic characteristics of propeller and rotor.