03.4 - Applied Aerodynamics
METHODICAL STUDIES OF THE POSSIBILITY TO APPLY A NUMERICAL METHOD WITH BUILD-IN EMPIRICAL CRITERIA FOR DETERMIMING THE LAMINAR-TO-TURBULENT TRANSITION ON THE CONE SURFACE AT HIGH MACH NUMBERS
N.V. Voevodenkoš, Y.G. Shvalevš; šTsAGI, Russia
At high supersonic flight velocities, a laminar-to-turbulent transition (LTT) in the boundary layer on the body surface has a significant effect on the aerodynamic characteristics of the aircraft. First of all, it affects on thermal processes, on the aerodynamic drag coefficient and on the lift-to-drag ratio of the aircraft. Therefore, when choosing a method for numerical simulation of the flow around aircraft at such modes, it is important that the method correctly simulates an LTT phenomenon. However, this is a very difficult task, even for the up-to-date computer technology and CFD methods. Due to the complexity of the phenomenon under consideration, along with numerical simulation, empirical methods have being developed that predict the LTT beginning and its length using simple formulas obtained as a result of generalization and analysis of large arrays of experimental data obtained both in wind tunnels and in flight experiments. However, empirical methods also have significant limitations and require methodological studies aimed at the methods validation, determining the applicability range and the methods accuracy.rnThis paper presents the results of methodical studies aimed at the investigation of the possibility to determine the LTT position using empirical criteria embedded in a numerical method based on the Euler equations solution and on the hypersonic small disturbance theory. The criteria of Simeonides and Berry were chosen as empirical formulas for determining LTT, their results are compared with experimental data. Methodical studies of LTT on the surface of cones with half-angles at the vertex ? = 0, 5 °, 10 ° and 20 ° in the range of Mach numbers M = 1.8 ÷ 10 at angles of attack ? = 0, 10 °, 20 °, 30 ° and Reynolds numbers Re = (3 ÷ 45) ? 106 were performed. The results of calculations using the numerical method with built-in empirical criteria are compared with experimental data obtained in high-speed ADT TsAGI T-116.rn