RESEARCH ON A NEW TRANSITION CONTROL TECHNOLOGY BASED ON THREE-DIMENSIONAL ELEMENTS

Three-dimensional discrete roughness, with a wide application prospect, will become a new type of boundary layer transition induction and control technology. To eliminate the transition position lag and cross-flow transition difficulty for 2-D roughness, a new fixed transition technology based on discrete roughness elements has been developed. The shape parameters of roughness elements of rough spots are calculated. A fast curing, easy molding, grinding and difficult deformation formula is presented and the high precision manufacturing technology for discrete roughness elements is established. Using 2-D airfoil and 3-D wing-body combination models, through pressure and force test, sublimation and infrared imaging methods, the transition and additional drag characteristics are verified by wind tunnel tests. The scale effect of diameter d, height k and spacing l of the elements on the transition characteristics is studied by numerical simulation. The results show that the new discrete roughness has the advantages of a small additional drag, high transition location accuracy and reliable performance. The accomplishment of this project provides a new way for fixed transition wind tunnel experiment and important reference for the further transition mechanism research.