高超声速推进系统用单膨胀斜面喷管型面设计和流场模拟

基于特征线法,并考虑变比热的影响,开展了高超声速飞行器用单膨胀斜面喷管设计。利用CFD数值模拟技术,计算得到了设计状态和沿飞行轨迹其它飞行状态下的单膨胀斜面喷管内外流场和特性。结果表明,在设计状态马赫数5时,基于特征线法得到的单膨胀斜面喷管内流场分布符合设计要求,而在其它较低的飞行马赫数下,单膨胀斜面喷管处于过膨胀状态,并且过膨胀的程度随飞行马赫数的降低而愈加严重。在马赫数2.5时,喷管膨胀面气流已发生明显分离,喷管性能急剧恶化。为了提高低马赫数条件下单膨胀斜面喷管的性能,采用变几何结构(调节下斜板角度)或基于二次流控制的单膨胀斜面喷管是必须的。

Design Method and Flow Field Simulation of Single Expansion Ramp Nozzle

For hypersonic vehicles,the effect of nozzle aerodynamic characteristics on vehicles performance is serious.Based on Characteristic methods,considering effect of variable specific heat and boundary development,the methods and program to determine the contour of single expansion ramp nozzles for hypersonic vehicles were developed.With CFD numerical simulation technology,the nozzle flow field and aerodynamic characteristics were computed on design point and along flight trajectory.The results indicated that,at Mach 5,namely design point,the performance of designed single expansion ramp nozzles is perfect,but throughout much of the low-supersonic and mid-supersonic flight regimes,the performance was poor.Flow separation was observed on the expansion ramp at Mach 2.5.To improve off-design performance of single expansion ramp nozzles,variable geometry nozzle configuration should be adopted.