Numerical Study Of The High Speed Main Flow And Thrust Vectoring Interaction

The mission requirements for the new fighters are high maneuverability and short take-off and landing performance. When at high angles of attack, the flow conditions of the fighter will be much complex. The flow separation will become much serious and the aerodynamic control surfaces such as vertical tail are immerged into the wake flow. As a result, the efficiency of the aerodynamic control surfaces will be rapidly decreases or even lose control. Thus the thrust vectoring control technology must be used to satisfy the demand instead of the traditional techniques. As one of the key technologies in the design of the forth fighter, the thrust vectoring control technology has been studied in-depth by America since 1980's. It has been used successfully in the fourth generation fighters such as F-22 and F-35. The research measures include theoretical and computational analysis, scale model tests, flight simulators and flight simulation demonstration and so on. The interaction between main flow around aircraft model and vectoring jet flow is one of the main aspects of research work on thrust vectoring control technology. It should be noted that the jet effects of conventional nozzle jet and vectoring jet are much different. The former jet effect on the main flow is a weak disturbance. However the vectoring jet has strong interaction with main flow and results in significant effect on the aerodynamic characteristics of fighter. This interactive contribution to the aerodynamic behaviors strongly depends on nozzle/airframe configuration. Therefore in order to get more favorite vectoring jet effects, it should be carefully made airframe/propulsion integration design. The base of this kind of integration design is to understand the main flow/vectoring jet flow interaction and its physical mechanism.In this paper, numerical simulations are carried out studying the main flow/vectoring jet flow interaction for a simplified fighter configuration. In order to providing some guidance to the wind tunnel testing, the infections of the parameters such as Mach number of main flow, attack angle, nozzle deflection angle, Mach number, total pressure and total temperature of jet flow are summarized. The physical mechanism of the main flow/vectoring jet flow interaction is also analyzed.The thesis is divided into five chapters as follows:The first chapter is the introduction, in which, the research background of the thrust vectoring control technology is discussed. The development and the research methods of the thrust vectoring control technology are reviewed.In the second chapter, the numerical methods which used in this paper are introduced. The main content includes governing equations, numerical flux schemes, time marching methods, numerical boundary conditions and turbulence simulation methods. A developed RANS/LES turbulence model and its improved methods are also specified in detail.In the third chapter, validation for the improved RANS/LES turbulence model and code FLY3D is presented. The transonic flow past an aerofoil, flow around an aerofoil at a large angle of attack, flow over a circular cylinder at high Reynolds and supersonic sonic base flow are simulated. The simulated results are all consistent with the experimental data well, which indicates the applicability of the improved RANS/LES turbulence model and the code FLY3D.In the fourth chapter, the main flow/vectoring jet flow interaction of the simplified fighter configuration are studyed. The computational model, computational grid and boundary conditions are presented at first. Then the infections of the parameters such as Mach number of main flow, attack angle, nozzle deflection angle, Mach number, total pressure and total temperature of jet flow are system researched. Numerical simulation results show that for the simplified fighter configuration, the thrust vectoring jet effect on the high speed main flow is only effects on the aircraft components near the nozzle exit and have little effect on the aerodynamic characteristics of aircraft except at high angles of attack. However, the high speed main flow has strong interaction with thrust vectoring jet flow. With the increasing of the angle of attack and Mach number the decrease of thrust vectoring angle are increasing.The conclusion remarking is presented in the fifth chapter, and the future research works are also proposed.At last the references and acknowledgements are presented.