Preliminary Study On Integrated Aerodynamic Characteristics Of The Aircraft/engine Based On Thrust-vectoring Technique

Aircraft/engine integration is the inevitable development trend for the modern and future fighters. The aim of the integration is the study of the interaction between the aircraft and engine, in order to reduce the adverse effects and get a better aircraft/engine matching performance. The highly blended fuselage layout and high efficient thrust-vectoring technique are the main tendency for the future fighter and unmanned aircraft which has high stealth performance. Based on the analysis of one-dimensional flow, CFD numerical simulation, the article has a preliminary study on the integrated aircraft/engine aerodynamic performance of a class of the future concept fighter.First, reference to a model of one advanced concept fighter and it’s aerodynamic performance of aircraft engine integration, by adding the incident angle of wing, blending wing-to-fuselage and nozzle-to-afterbody, the model has been improved. Reference to computing program for the mixed exhaust turbofan engine steady-state performance under the thrust requirement of the aircraft, this article determines the specific cross-sectional performance parameters of the engine and the basic dimensions of its propulsion systems flow path; then designs a stealth supersonic bump inlet basing on relevant design program and a relatively better aerodynamic performance axisymmetric nozzle using a geometric approximation method.Second, the article gives a preliminary research on the aerodynamic performance of the modified aircraft model with the CFD numerical simulation, and the analysis of its lift and drag characteristics. Moreover, the article researches the aerodynamic performance of the engine and the integrated installation of aircraft/propulsion system of, and also compares the flow field analysis with and without the engine installation. The results show that there is obvious shock wave drag and friction drag on the fuselage and wing, a large eddy and low static pressure area on the bottom of the fuselage, and a large drag at the bottom of the fuselage without the installation of the engine. After the installation of the engine, the total lift and drag of the fighter are increased, the drag at the bottom is diminished obviously, but the flow coefficient of the inlet, the total pressure recovery coefficient of the nozzle and the installed thrust of the engine are reduced.Then, this paper proposes a practical scheme of fluidic thrust-vectoring, analyses the aerodynamic performance of the aircraft and the propulsion systems of the engine under the process of thrust-vectoring, and studies the mutual interference flow mechanism of the aircraft/engine integration flow field. The results show that the thrust loss and the drag at the bottom increases after the jet thrust-vectoring. By influencing the static pressure distribution of the fuselage upper- and down-surface, the thrust-vectoring changes the lift and drag of aircraft fuselage, and it has less influence of the inlet and forebody.Last, for the requirements of future aircraft integration, this paper designs a new kind of three-dimensional nozzle, which is also called conformal nozzle, and analyzes the aerodynamic performance of internal flow and the aerodynamic characteristics under aircraft afterbody/nozzle integration. The results show that the new kind nozzle has little difference with the axisymmetric nozzle about the performance of internal flow, but in the terms of afterbody/nozzle integration, it has better aerodynamics characteristics. This nozzle reduces the drag of fuselage effectively, so as to realize the increase of the aircraft’s thrust. The conformal nozzle strengthens the mix of airflow after the nozzle exit section, shortens the hot core of the jet wake and enhances the aircraft stealth performance.