进气道的功能是捕捉并压缩来流，为燃烧室提供合适的气流，保证发动机稳 定工作。为了适应对高超声速飞行器机动性的新需求，本文针对二元进气道在正 攻角的不起动问题展开了数值研究。 为了便于设计用于研究的进气道基准构型，本文发展了考虑进气道长度和唇 罩内角限制的二元进气道无粘波系拉格朗日优化方法，以最大总压恢复为优化目 标获得进气道的波系配置。优化过程中发现，斜激波强度接近有利于获得最大的 总压恢复。 基于上述波系配置设计进气道的基准构型，在该构型的基础上，首先数值考 察了不同肩部膨胀波分布对进气道在正攻角下的不起动过程的影响，发现肩部膨 胀波通过抑制分离区的增长可拓宽进气道不起动边界，而膨胀波过于集中或分散 都不利于保持正攻角下进气道起动状态，而当临界不起动攻角时的分离点位置接 近膨胀圆弧的起点时，对不起动边界的提升作用最明显。 其次，改变唇罩构型，研究了内压缩偏转角分配、压缩激波数量和唇口激波 与上壁面交汇点位置的影响，发现交汇点位置对不起动没有明显影响，而增加内 压缩激波数量能降低内压缩激波强度，从而有效地避免、甚至抑制上壁面的分离， 进而提升不起动临界攻角，而均匀分配偏转角能使多道内压缩激波的强度最大限 度地降低，从而使不起动边界更大幅度的拓宽。 最后，从宽高比和侧切两个角度，初步研究了三维效应对二元进气道不起动 的影响。在宽高非常小时，侧壁边界层挤占内流通道，提高增压能力的同时使进 气道更容易不起动，此时增加宽高比可以提升不起动临界攻角；随着宽高比的增 加，侧壁边界层在对不起动的负面影响逐渐降低，再进一步宽高比增加会削弱角 区高速流的作用，使得进气道更容易不起动，因此，随着宽高比的增加，不起动 边界先提高后下降。而减小侧板遮挡率使得进气道的侧面溢流加强，侧壁面激波 边界层干扰减弱，进而减小分离区，提升不起动边界。

The function of the inlet is to capture and compress the incoming flow to provide suitable airflow for the combustion chamber and ensure the stable operation of the engine. In order to meet the new requirements of maneuverability of hypersonic vehicles, a numerical study on the unstart phenomenon of the two-dimensional inlet at positive angle of attack is carried out in this paper. In order to facilitate the design of the basic configuration of the inlet for the study, the Lagrange optimization of shock waves for a two-dimensional hypersonic inlet by limiting the cowl internal angle and inlet length was developed in this paper. The wave system configuration of the basic inlet was obtained with the maximum total pressure recovery as the optimization objective. During the optimization process, it is found that the equal oblique shock strength is beneficial to obtain the maximum total pressure recovery. Based on the above basic configuration, the influence of different shoulder expansion wave distributions on the unstart process of the inlet at the angle of positive attack was investigated numerically. It was found that the shoulder expansion wave could widen the unstart boundary of the inlet by inhibiting the growth of the separation area, while too concentrated or dispersed expansion waves were not conducive to maintaining the starting state of the inlet at the angle of positive attack. When the separation point is close to the starting point of the expansion arc, the increase in the critical angle of attack of unstart is most apparent. Secondly, by changing the configuration of the cowl, the Influence of the distribution of deflection angle of internal compression, the number of compression shock waves, and the intersection position of the cowl shock and the upper wall surface are studied. It is found that the intersection position has no obvious influence on the movement, and increasing the number of internal compression shock waves can reduce the intensity of internal compression shocks, to effectively avoid or even inhibit the separation of the upper wall and then improve the critical angle of attack of unstart. The uniform deflection angle distribution can reduce the intensity of compression shock waves to the maximum so the unstart boundary can be widened more greatly. Finally, the three-dimensional effect on the unstart of the two-dimensional inlet is studied from aspect ratio and side cut. When the width and height are very small, the side wall boundary layer chokes the inner flow channel, improving the compression ability and making the inlet easier to unstart. Therefore, increasing the width and height ratio can improve the critical angle of attack of unstart. With the increase in aspect ratio, the negative impact of the side wall boundary layer gradually decreases; however, the further increase in aspect ratio will weaken the effect of high-speed flow in the corner region, making it easier for the inlet to unstart. Therefore, with the increase in aspect ratio, the unstart boundary will first increase and then decrease. With the decrease of the side plate shielding ratio, the side overflow of the inlet is strengthened, the separation area is reduced, and the unstart boundary is increased.