多段翼附壁效应环量控制RANS气动特性分析OA

Combining traditional high lift devices with circulation control is expected to improve the takeoff and landing performance of aircraft.Based on the Reynolds averaged Navier-Stokes(RANS)method,the 2D NLR-7301 2-segment airfoil was taken as the research object.The circulation control was applied to the main element and the flap respectively,and the effects of jet positions,heights,and momentum coefficients on the aerody-namic characteristics of the multi-segment airfoil were systematically investigated.The results show that,the position of the jet determines the basic aerodynamic force.For a too far backward jet position,the Coanda sur-face will be too small to yield the wall attachment effect.Conversely,for a too far forward jet position,signifi-cant separation will easily happen on the lower surface,to reduce the lift-enhancement effect.The lift coeffi-cient generally increases with the decrease of the jet height and the increase of the momentum coefficient,but there is a nonlinear effect by multiple parameters.A smaller jet height can bring a better lift increasement.For high jet heights,the jet velocity is low,to weaken the entrainment effect and potentially cause circulation con-trol failure of the main element.For the circulation control of either the main element or the flap of NLR-7301,0.03 is an appropriate momentum coefficient,and further increase will cause significant separation of the lower surface,and reduce the efficiency of lift-enhancement.From the perspective of pressure distribution,the circu-lation control can elevate the suction peak at the leading edge of the main element,and improve the upper sur-face suction and lower surface pressure.At the same time,the entrainment effect of the main element jet flow helps to eliminate the boundary layer separation at the trailing edge of the flap.Furthermore,the circulation control can still effectively enhance the aerodynamic performance of the wing under 3D conditions.However,its control effect is affected by the spanwise flow and gradually diminishes from the wing root to the tip.The a-bove conclusions provide a reference for the design of the circulation control of multi-element airfoils.In practi-cal applications,numerical optimization is required to find the optimal combination of control parameters,in view of both lift and drag characteristics.