Adding head opposing jets is a common flow control approach to reduce the aerodynamic heating of hypersonic vehicles with blunt-shape head. However, interests of present studies are mostly focused on surface heating reduction originate from opposing jets only on single-and-determinate free incoming conditions, rather than that under existence of freestream perturbations, to the best of knowledge. In this work, two-layers research structure is formed to investigate the jet design parameters on surface thermal uncertainty with occurrence of free incoming perturbations. In the inner layer, the Polynomial Chaos method is applied for quantifying the surface thermal uncertainty, including the mean value and the standard deviation, under free incoming perturbations. In the outer layer, the Variance Analysis method is employed to describe the jet geometry and flow parameters on surface thermal uncertainty. As a consequence, the parameters impact on the mean surface heating under perturbations are found similar to that in baseline freestream condition. Moreover, only jet entry diameter and total-pressure ratio of jet-to-freestream are important when it comes to the standard deviation of surface heating. This research is anticipated to be available of robust thermal-reduction optimization on hypersonic vehicles with blunt-shape head in a wide range of free incoming conditions for reference.

增加与头部相对的喷头是一种常见的流量控制方法，可以减少具有钝头形状的高超音速飞行器的空气动力加热。然而，目前的研究主要集中在减少表面加热上，这是由于相对射流仅在确定的自由进入条件下产生的，而不是在存在自由流扰动的条件下，据所知。在这项工作中，形成了两层研究结构来研究射流设计参数对表面热不确定性的影响，并产生自由进来的扰动。在内层，采用多项式混沌方法来量化在自由输入扰动下的表面热不确定性，包括平均值和标准偏差。在外层 采用方差分析法描述了表面热不确定性下的射流几何形状和流动参数。结果，发现参数对扰动下平均表面加热的影响类似于基线自由流条件下的影响。此外，关于表面加热的标准偏差，仅射流入口直径和射流与自由流的总压比很重要。预期该研究将对具有钝形头部的高超音速飞行器在各种自由进入条件下的鲁棒热减少优化提供参考。当涉及表面加热的标准偏差时，只有射流入口直径和射流与自由流的总压比才重要。预期该研究将对具有钝形头部的高超音速飞行器在各种自由进入条件下的鲁棒热减少优化提供参考。当涉及表面加热的标准偏差时，只有射流入口直径和射流与自由流的总压比才重要。这项研究有望在各种自由进入条件下对钝头形高超音速飞行器进行鲁棒的减热优化，以供参考。