Design concept and aerodynamic characteristics of XTER TBCC inlet

The performance of inlets is critical to combined cycle engines. Aiming at the overall demand of Xiamen Turbine Ejector Ramjet (XTER), the design concept and design elements of the inward-turning Turbine Based Combined Cycle (TBCC) inlet for XTER are reviewed in detail. On this basis, flow structures and characteristics of the inlet are analyzed. Results show that either design elements or design constraints of the XTER inlet are coupled with each other, and the mass modulation mechanism is the core element, which is, however, difficult to design and makes the mutual restriction among design elements more complicated. Flow structures in the XTER inlet vary significantly with the increase of Mach number from 0 to 6. Nevertheless, the total mass flow rate remaines above 0.75, which meets the mass flow demand. The mass distribution mechanism also helps the flow mass varies smoothly during mode transitions. During the turbine-to-ejector transition at Mach 2.5, the total-pressure recovery coefficients of the ejector and scramjet increase steadily. Once the transition ends, the total-pressure recovery coefficient is close to or above 0.85. As to the ejector-to-scramjet transition at Mach 3-4.5, the mass flow rate of the inlet increases from 0.81 to 0.90. Moreover, the ejector tunnel maintains a high total-pressure recovery coefficient in the first 62.5% process, indicating that this tunnel still performs properly in the first half of mode transition process. Taken together, the XTER inlet it is capable of continuous normal operation in a wide speed range since its aerodynamic characteristics meet the demand of power system, i.e., the mass flow rate varies moderately in the full speed range and the tunnel performance transits smoothly in the mode transition process.