Numerical Simulation Foraerodynamic Characteristics Ofasymmetric "Diamond Back" Wing At Low Reynolds Number

Because of the advantages of “Diamond back” wing on the side of folding pattern,structural configuration and aerodynamic characteristics, it has been used in designing airvehicle. In this paper, some questions about the aerodynamic characteristics of asymmetric“Diamond back” wing at low Reynolds number were studied by numerical simulation, theaim of this research was to provide reference for designing small UAV with the "Diamondback" wing.Firstly, a two-dimensional computational model based on the airfoil of E387withexperimental data was established, then the numerical method which can be used in this paperwere chosen and verified by numerical simulation. The results indicate that the TransitionSST turbulence model have high accuracy and creditability in solving the problem of flowingaround airfoil at low Reynolds number which is undemanding to stalling characteristics.Next, based on the geometry shape and design parameters of the “Diamond back” wing,the changes in aerodynamic parameters with the configuration parameters of “Diamondback”wing at low Reynolds number were simulated by two-dimensional computational modelwhich uses NACA6411airfoil. The simulation results indicate that the changes inaerodynamic characteristics along the spanwise of “Diamond back” wing are mainly causedby two reasons, one is the high-pressure and low-pressure region of the lower surface ofanterior airfoil which are formed by the high pressure around stagnation point at the leadingedge and the differential pressure between the upper and lower surface of the posterior airfoil,the other is differential pressure change between the upper and lower surface of posteriorairfoil caused by air blocking; Near the station of leading edge distance (x) between theanterior and posterior wing is about1.5times that of chord length of anterior airfoil, theinfluence of vertical height difference (H) to aerodynamic characteristics appear thephenomenon that change trend reversal; the combined influences of x and Htoaerodynamic characteristics are main reflected in the part of x less than1.5times that of chord length of anterior airfoil; One of effective optimization methods for “Diamond back”aerodynamic configuration is designing Hand the leading edge distance between the tipchord of the anterior and posterior wing rationally.Finally, a three-dimensional computational model of small UAV with asymmetric wingwas established, then the influences of the configuration parameters to the aerodynamiccharacteristics of small UAV were studied by numerical simulation. The results indicate thatthese influences are main reflect in rolling moment and yawing moment; the main reason tothe formation of fuselage rolling moment is the different pressure fields that locate at thedifferent installation sites where the wing contact to the fuselage; When the angle of attackand velocity of flow remain unchanged, the fuselage rolling moment only varies with theheight difference of left and right wing, and it is not affected by the angle of roll and dihedral;The rolling moment difference of left and right wing is affected by the dihedral and heightdifference of left and right wing, meanwhile, the dihedral has an inhibitory effect on therolling moment difference generated by the height difference of left and right wing; Thesynthesis looked that the rolling moments and yawing moments generated by heightdifference of left and right wing are relatively small, and it is possible to correct them.