双变循环发动机变几何分流环的设计及气动特性研究

In order to study the aerodynamic characteristics of the splitter segment in a dual variable cycle engine, a dual fan-blade variable splitter mechanism was designed. Moreover, the designed variable splitter profiles were optimized for three typical operating conditions of the dual variable cycle engine: Ma0.8, Ma2.35, and Ma4.0. CFD were conducted to investigate the flow fields within different splitter segments under various operating conditions. When operating in the turbofan mode with a splitter angle of 11.6°, the leading edge profile of the splitter with gradually increasing wall curvature radius from the end to the tail effectively mitigates the normal pressure gradient around the leading edge surface and the axial adverse pressure gradient within the passage. This configuration reduces the boundary layer thickness and suppresses flow separation. Meanwhile, when operating in the turbojet mode with a splitter angle of -31.8°, a concave surface in the form of conic is employed on the lower surface of the splitter. A smaller throat area enhances the kinetic energy of the airflow, counteracts the adverse pressure gradient, reduces separation area, and minimizes total pressure loss. Further investigations reveal that a smaller throat area is not always favorable, as it may result in a larger adverse pressure gradient, exacerbating airflow separation.