Numerical Study Of Airfoil Transonic Buffet Characteristics

In order to improve the aerodynamic characteristics of wings in transonic flight and expand the available range of attack angle,the typical airfoil and wing body combination was numerically simulated in this paper.The main aerodynamic characteristics and flow structure of transonic buffeting process was analyzed.And a preliminary research on the suppression method of buffeting was carried out.Firstly,the numerical simulation of NACA0012 airfoil and ONERA M6 wing were carried out and compared with experimental data.The result showed that the simulation method can simulate the airfoil flow accurately.The criterion used to predict the buffet onset angle was valid and its prediction result is credible.Secondly,steady numerical simulation and unsteady numerical simulation based on the variable flow condition method and dynamic mesh method were used to investigated the aerodynamics of typical airfoil under different attack angles.The aerodynamic characteristics of the airfoil changing with attack angle was analyzed.The results achieved by these numerical simulation methods were similar to each other,but the specific values was slightly different.Thirdly,the 3D steady numerical simulation of wing body combination was investigated.The wing body combination aerodynamic characteristics with the variation of flow attack angle and the buffet onset angle were predicted using four buffeting prediction criterion.The results showed that the initial buffet attack angle of wing body combination predicted by lift curve,reversal in shock movement,pitching moment curve,tailing edge pressure deviation and wing surface streamlines methods were 4 deg.Then,the unsteady numerical simulation on the wing body combination at a fixed attack angle and continuous variation of attack angle showed that the unsteady numerical simulation of the fixed angle does not appear unsteady aerodynamic phenomenon;Five kinds of buffet onset angle criterion were used to predict the initial buffeting angle of wing body combination at continuous variation of attack angle investigation.The deviation of other four kinds of initial buffet prediction method of attack angle was less than 0.22 deg,except the trailing edge pressure line method which the deviation was 1.02 deg.In addition,the initial buffet attack angle obtained by the unsteady numerical simulation were 4.24 deg greater than the steady numerical simulation.Finally,the influence of the microtab which was installed at the trailing edge of the airfoil on the initial buffeting angle of the airfoil and the dynamics of the wing was investigated by numerical simulation.The results show that: for the three airfoils investigated in this paper,the initial angle of attack was increased by 0.5 deg under the specific flow Maher number.The buffet onset angle of ONERA M6 wing increased 1 deg in a specific flow Maher number when the microtab was installed.