Design And High Speed Wind Tunnel Test Of Morphing Wing Model Based On Intelligent Structure

Morphing aircraft can be adapted to different environments and perform various missions by changing the aerodynamic shape of the vehicle,which is considered as an important direction for the future development of the aircraft.The weight,volume,and working environment of the vehicle are extremely stringent requirements for the design of the vehicle.With its high energy density and high output strain,Shape Memory Alloy is considered as one of the best driving components of the morphing aircraft.Taking the deflection of trailing edge as the design target,the experiment and modeling of mechanical properties of shape memory alloy,morphing wing's design and high-speed wind tunnel test,numerical simulation of the morphing wing under Fluid-Solid interaction and a series of research work were carried out.The specific research contents of this paper:Firstly,the mechanical properties of shape memory alloys were tested and modeled.The stress-strain curves of shape memory alloys at room temperature and high temperature were obtained by tensile test.The maximum recoverable strain of the shape memory alloy was tested.The relationship between recovery stress and pre-strain,heating temperature and recovery strain of shape memory alloy was tested in detail.Because of the error of Tanaka series constitutive model in large pre-strain,the recovery stress model of shape memory alloy was established by fitting the experimental data in this paper.Secondly,the design work of morphing wing model was developed.The operating principle of the bias-type shape memory alloy actuator was described in detail,and the principle experiment was carried out.A cantilever(or so-called flexible section)deflection structure of trailing edge was proposed.Driven by SMA and biased by flexible section,reciprocating deflection of wing model was realized.Based on the recovery stress model of shape memory alloy,the mechanical model of the deformation structure was established,and the key dimensions of the flexible structure were optimally selected.The finite element model of the wing was established.Based on the Nastran simulation,the deflection displacement of the flexible section and stress of flexible joints and shape memory alloys were obtained.The overall strength of the model was checked,which verifies the rationality and feasibility of the model design.The finite element model also provides the structure calculation model for the Fluid-Solid interaction simulation.The morphing wing model was designed and manufactured,and the ground test was carried out.Thirdly,experimental study on the morphing wing in the high speed wind tunnel was carried out.By means of VMD,PSI and PSP measurement,the deflection angle of the trailing edge and pressure distribution of the upper and lower wing surface were obtained.Experimental conditions: Ma=0.4~0.8,angle of attack a =0°~6°.The change rule of the deflection angle of the trailing edge with the AOA and the Maher number was analyzed.The variation of upper wing surface's pressure distribution of two stable states(before and after deflection)was analyzed.The aerodynamic yields after deflection were evaluated.The dynamic change rule and hysteretic characteristics of the upper wing surface's pressure distribution in the process of deformation were studied.The influence of the trailing edge deflection on the flow acceleration,the position change of the shock and the separation of the trailing edge flow was analyzed.The change of pressure distribution of the lower wing surface and were analyzed by PSP results.Fourthly,the Fluid-Solid interaction numerical simulation of the morphing wing model was developed.The deflection angle of trailing edge and the pressure distribution before and after deformation was calculated.The calculated results are in agreement with the experimental results.The flow structure of wing was described.At the same time,the change of aerodynamic coefficient was analyzed.