Variable inlet of two dimensional scramjet engine

In order that scramjet engine can work reliably over a wide range of Mach number and attack angles, a multi-objective optimization design for two-dimensional variable inlet was established. Total pressure recovery coefficient, static pressure rise and drag coefficient were selected as objective functions to form the multi-objective optimization of the two-dimensional scramjet mixed compression inlet. Based on one-dimensional aerodynamics analysis method, a multi-objective genetic algorithm was employed to find Pareto solutions on the design-condition. Then for different Mach numbers and angles of attack, optimal variable inlets, of which partial compression angles, angle and length of cowl and inlet height were variable, were obtained. The correctness of theoretical analysis was confirmed by simulations, and several conclusions were achieved. Firstly, the engine could work efficiently through a wide envelop of mach numbers and angles of attack by employing the optimal variable inlets. Secondly, the alterable inlet height makes the engine start and work steadily in both ramjet and scramjet mode. Thirdly, with the high mach number as the design mach number, the engine performance is improved by variable inlet design.