Investigation Of Flowfield Characteristics And Design Methodology Of Hypersonic Jaws Inlet

As the important component of scramjet, the hypersonic inlet not only provides the necessary air for the engine, but also compresses enough air to meet the needs of combustion, so its performance is a key factor to scramjet and airbreathing hypersonic vehicle. In 2005, Malo-Molina et al from U.S. Air Force Laboratory propose Jaws inlet, a kind of innovative inward turning inlet. Numerical simulation results indicate that Jaws inlet has better property compared to routine inlet. But now the foreign open literature does not dictate a detailed exposition on specific design method, the internal flow field of the Jaws inlet, a lot of problems need more thorough investigation.In present paper,the main objective is finding in a wide range of Mach number (Ma = 5,6,7), high-performance stream tracing Jaws inlet, which is suitable for air-breathing hypersonic vehicle inlet. A system investigation on streamline tracing Jaws inlet has been carried out using theoretical analysis, numerical simulation, wind tunnel experiments and other means.Inviscid basic flow field and design method of Jaws inlet was described in details. Jaws inlet was explored numerically and compared with a rectangular cross-section inlet in the same basic flow field. The performance and flow-field characteristic of Jaws inlet on different Mach number and attack angle was compared, and the effect of viscosity were also analyzed. The design method of streamline traced has been verified. In addition, compared to the rectangular cross-section, inlet performance of the Jaws inlet is insensitive to the angles of attack on design point; inlet has high mass capture and compression capability on off-design point; boundary layer growth of the develops slowly and shock boundary layer interaction is weak because of the diminished wetted area, and total pressure recovery coefficient is much higher.Because the presence of viscosity, a more suitable inlet design parameters are selected by numerical simulation, in order to solve the possible failure of design problems based on inviscid flow. Cebeci and Bradshaw's finite difference program is used to solve the two-dimensional compressible boundary layer equation, according to the achieved displacement thickness of the boundary layer, the 8-7 (the ramp in pitch plane is inclined at 8o to the free stream and in yaw plane is inclined at 7o to the free stream, yielding planar shocks).inlet internal profile is then corrected, and the inlet performance after correction is compared with uncorrected flow by numerical simulation. Jaws inlet with and without boundary layer correction were investigated using numerical simulation and hypersonic wind tunnel tests. Static pressure distribution along the centerline of the walls was measured. The performance of Jaws inlet on different Mach number and attack angle was compared, and the effect of boundary layer correction was also studied. The tunnel experimental data agree well with the numerical simulation. Especially at the wall before the lip, the static pressures almost have the same value. Although there is small deviation existing at inward contraction section, the pressure changing trends of the wall are consistent. The experimental results prove that the numerical simulation can reflect the pressure distribution with good reliability. In addition, boundary layer correction improves the total pressure recovery coefficient of Jaws inlet, reduce internal contraction ratio, and enhance the start performance. So the working range is enlarged, it has positive effect on the design of inlet.Using the proposed hypersonic propulsion/airframe integration design, based on Jaws inlet, shape design of an aircraft was studied. By numerical simulation, hypersonic vehicle's aerodynamic characteristics are analyzed; the design meets the technical requirements. Some try and bedding are carried out for the future engineering application of Jaws inlet.