超声速进气道出口弯段的阻力特性数值研究

Numerical Investigation on the Drags Trait of a Supersonic Inlet Curved Duct Near the Exit

推阻匹配设计是吸气式飞行器设计的核心问题,为了获取进气道的阻力特性并降低内流阻力,提高吸气式飞行器的总体性能,采用数值方法对超声速双侧布局进气道的冷流阻力特性开展研究,对比分析了不同转弯长度、转弯角度、扩张比下的弯段流态和阻力特性;获得了进气道内阻的分配比例及关键几何参数对弯段流场结构和进气道内阻的影响特性。结果表明:对于双侧布局的进气道,冷流条件下弯段内容易发生流动分离,存在较大的流动损失,在不产生溢流的情况下,弯段内阻占整个进气道内阻的大部分。分析发现,减小转弯角度或增加弯段扩张比均可降低进气道弯段内阻,而转弯长度与转弯半径相互影响,在给定的设计条件下,弯段内阻随转弯长度的增加先减小后增大。

The matching design of thrust and drag is the core issue in the design of air-breathing vehicles.In order to obtain the drag trait of the inlet and reduce the interior drag,and then improve the overall performance of the air-breathing vehicles,a study on the cold-flow drag trait of a supersonic,twin-duct inlet is conducted with a CFD method.By comparing the flow characteristics and drag trait of the inlets with different length,turning angle,divergence ratio of the curved ducts,drag allocation proportion of different parts of the inlet is acquired and effects of the geometric parameters on the flow structure and drag are attained.Results indicate that a flow separation will probably generate in the curved duct of a twin-duct inlet at a cold-flow condition,which results in a large loss of the flow.It is noted that the drag of the curved duct accounts for majority of the entire inlet when there is no spilled flow.The drag of the curved duct can be reduced by decreasing the turning angle or increasing the divergence ratio of the curved duct.However,due to the interrelationship between the curved ducts'length and turning radius,the drag of the curved duct firstly reduces and then turns to rising with the increment of the curved ducts'length at a fixed design condition.