IMPACT ONTO THE BOUNDARY LAYER ON THE AIRFOIL OF A SMALL-SCALE AIRCRAFT SYSTEM WITH THE USE OF A WAVY SURFACE. PROBLEMS AND PROSPECTS (REVIEW)

A method is proposed to improve the aerodynamic performance of small-scale aircraft systems. The method is based on fundamental gas-dynamic phenomena, such as local separation of the boundary layer accompanied by the formation of the so-called separation bubbles, separation of the turbulent boundary layer, and flow stall from the leading edge of the airfoil, which change the entire flow structure around the body. Publications where the relationship of these phenomena is established and those that describe a control method eliminating the adverse consequences of flow separation with the use of a wavy surface of the airfoil are reviewed. The method is simple in implementation and offers many prospects. The areas of its applicability are determined, and the criteria of optimizing the wavy surface of the airfoil for particular operation conditions are provided. Results of investigations are reported, which show that the use of a wavy surface of wings or blades of flying vehicles can improve their aerodynamic characteristics. Various structural elements of the boundary layer are noted, such as local separation bubbles or a global separation region, and the criteria of their emergence are given, which assist in verification of numerical experiments.