双向飞翼空天飞行器概念外形研究

Research on bi-directional flying wing space shuttle configuration

  • 摘要: 空天飞行器飞行速域宽,气动外形需同时考虑起飞高升力与超/高超声速高升阻比需求,给飞行器的气动布局设计带来很大难度。双向飞翼飞行器概念具有两个互相垂直的对称面,在亚声速时以大展弦比模态飞行,可获得足够的升力,超/高超声速时以小展弦比模态飞行,可尽量降低激波阻力,飞行模态转换的转换通过机身旋转90°实现,可能解决宽速域高升阻比设计矛盾。本文据此构建了一种双向飞行空天飞行器外形,并开展了CFD数值仿真。结果表明,与Sanger类常规布局的空天飞行器相比,双向飞翼概念外形的亚声速时最大升阻比为16,提升30%~50%;高超声速段升阻比性能基本相当,最大升阻比4,说明该外形是一种有潜力的空天往返飞行器方案。在此基础上,从飞行器技术实现角度,系统梳理了双向飞翼飞行器方案面临的三大技术难点,并提出了可行的解决途径或可能的攻关方向。针对飞行器纵向静不稳定度偏大问题,提出调整机身平面形状和剖面形状等,可使静不稳定度降低至10%以内;针对飞行模态转换控制困难问题,创新性地提出了一种基于非对称垂尾的控制方法,在飞行器两个飞行模态下各安置一片垂尾,在提供了足够的模态转换控制力矩的同时,改善了飞行器的横航向稳定性;针对发动机耦合设计问题,提出了一种新的涡轮和火箭发动机独立垂直布置的方法,降低了空天飞行器对组合动力技术的依赖性,有助于双向飞翼空天飞行器的早日实现。

     

    Abstract: The inconsistency between high-lift requirement at taking off and high lift-drag ratio requirement at supersonic/hypersonic flying often confuses aerospace shuttle designers. Bi-directional flying wing concept consists of a symmetric diamond planform. This wing flows with a high aspect ratio shape at subsonic speed, while changes its flying mode by rotating the aircraft 90° around vertical axis. It finally flows with a low aspect ratio shape at hypersonic speed. This concept is considered as a new way to overcome the design conflict between subsonic and hypersonic flight. By using the new concept, this paper constructed an aerospace shuttle. The CFD result shows that, compared with German TSTO vehicle, i.e., Sanger, the new concept aircraft has a 30%-50% higher lift-to-drag ratio at subsonic speed, reaching 16 while maintains a high lift-to-drag ratio at hypersonic speed, reaching 4. It has been indicated that bi-directional flying wing configuration is a potential option for space flight. Furthermore, three main problems have been pointed out in designing this new concept vehicle. These problems are longitudinal stability issue at subsonic speed, conversion disorders in changing flying model, and difficulties in coupling airframe and engine design, respectively. For each problem, one or more applicable solutions were proposed. Particularly, a new flying conversion mode was indicated by installing two asymmetrical vertical fins at the tail the fuselage to provide enough control moment and improve lateral stability for the aircraft. In addition, a new power plant, i.e., the installment of individual orthogonal engines in different direction was proposed to reduce the requirements of combined power. These means may contribute to the realization of the bi-directional flying wing concept.

     

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