Numerical Investigation Of Effects Of Multiple Parameters On Characteristics Of Slender Delta Wing Rock

Wing rock is an important dynamic characteristic problem that should be focused on when an aircraft is flying at the high angle of attack.A lot of experiments and numerical studies have been carried out in and abroad,and great progress has been made in the research of delta wing rock.Whereas the shape of the leading edge,the position of the roll axis and the trailing edge of the jet flow have not been focused on the dynamic characteristics of the delta wing rock.In this text,the rocking motion of the 80 ° swept delta wing with different leading edge shapes,roll axis positions and trailing edge jets have been simulated numerically,through three-dimensional unsteady NS equations and Euler's rigid body dynamics equations.Sensitive factors like leading edge shape,roll axis position,and trailing edge on the dynamic characteristics of the slender delta wing rock have been investigated.First of all,the establishment of the computing method and program within the numerical simulation of slender delta wing rock movement.Based on the control equations of the Roe scheme;the LU-SGS method with two time steps;rigid dynamic meshing technique;three-dimensional NS equations and the rigid body dynamics equations.The writer has developed computing program which is suitable for the rock movement of slender delta.In addition,based on the verification and validation of classic examples for the development of the calculation procedure,the computational results are identical to the results of the relevant literature,which verified the reliability of the computing method and programSecondly,the influence of the leading edge shape on the dynamic characteristics of the slender-delta wing rock.Three kinds of delta wing with different leading edge shapes have been investigated: upward sharpened,downward sharpened and double-sided sharpened leading edge.The results show that the upward sharpened is the smallest in the rocking bifurcation angle,weakest in the rocking rolling stability and the most unstable for large periodic oscillation.The double-sided sharpened in the middle.And the downward sharpened is the largest in the rocking bifurcation angle,the most stable in rock rolling stability,the most difficult to instability and the significant periodic oscillation.Thirdly,the influence of the roll axis position on the dynamic characteristics of the slender-delta wing rock.The delta-wing roll shaft at four different positions have been investigated.The results show that the higher the rolling axis is,the smaller the rocking bifurcation angle,the weaker the rocking stability,and the bigger the rocking amplitude is,with the most likely to form large periodical oscillation.Therefore,the low position of roll shaft is beneficial to enhance the lateral stability of the delta wing.Finally,the influence of the trailing edge jet on the dynamic behavior of the slender delta wing rock.Three kinds of trailing edge jet conditions have been investigated.The results show that within jet flow the rocking bifurcation angle is smaller,and the rocking stability is weaker,and it is more unstable to form a large periodical oscillation.The larger the velocity ratio of the jet flow is,the larger amplitude of the corresponding delta-wing rock is.The existence of the jet flow does not limit the occurrence of wing rock however weaken the lateral stability of the wing rock in advance.