Study on the Influence of Sharp / Blunt Fuselage on the Aerodynamic Performance of Supersonic Nacelle

At present, in the planning of supersonic civil aircraft, the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$^{\prime}\mathrm{N}+\mathrm{X}^{\prime}$</tex> generation planning developed by NASA has the most reference value. The cruise Mach number of supersonic civil aircraft proposed by NASA is about 1.8. Therefore, it is of great academic significance and engineering application value to consider the structural design and aerodynamic performance analysis of the fuselage and nacelle of supersonic civil aircraft in cruise state. In this paper, an axisymmetric inlet for supersonic civil aircraft is designed. The Mach number of the inlet at the design point is 1.75. The flow characteristics solving models of axisymmetric inlet, inlet with a sharp nose fuselage and inlet with a blunt nose fuselage were established. On the basis of verifying the accuracy of the solving model, the designed axisymmetric inlet was placed in the nacelle and installed on the sharp nose fuselage and blunt nose fuselage respectively. The effects of the inlet with a fuselage structure and the inlet without a fuselage structure on the aerodynamic performance of total pressure recovery coefficient and outlet total pressure distortion index were studied respectively. The flow field characteristics and formation mechanism of the internal and external flow of the inlet outer cover at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0^\circ$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2^\circ$</tex> angles of attack were analyzed. The results show that in the cruise state, the structure with fuselage will increase the internal flow loss and the total pressure distortion at the outlet, reduce the total pressure recovery coefficient of the inlet and increase the total pressure distortion index at the outlet. Under the interference of the fuselage, the low-energy fluid in the inlet deviates towards the first quadrant of the YZ plane. Under the condition of the angle of attack, the low-energy fluid in the first quadrant of the YZ plane is reduced. The deflection of the airflow makes the low-energy fluid more evenly distributed in the first quadrant and the fourth quadrant of the YZ plane. In the structure of the inlet without fuselage, the total pressure recovery coefficient of the designed axisymmetric inlet under the design point condition is 94.7 %, and the D (total pressure distortion index) is 0.237. In the structure of the inlet with fuselage, the total pressure recovery coefficient of the inlet installed on the sharp nose fuselage under the design point condition is 90.58 %, and the D is 0.242. The total pressure recovery coefficient of the inlet installed on the blunt nose fuselage under the design point condition is 89.6 %, and the D is 0.248. The research content of this paper provides a theoretical basis for the aerodynamic performance analysis and structural design of the nacelle inlet used in supersonic civil aircraft.