为满足航空发动机高空结冰试验的适航认证需求，本文提出了一种自由射流式高空结冰试验舱，并围绕其流场特性和结构优化展开研究。通过计算流体力学（CFD）方法，模拟了喷管射流在试验舱内的发展规律，重点分析了射流核心区长度和喷管与发动机间距对流场均匀性的影响。同时，将气动性能和结构约束纳入多学科优化框架，对喷管尺寸和舱体布局等关键参数进行了优化设计。结果表明，优化后的试验舱能够达到发动机高空结冰试验所需的温度（约-20℃）和压力（约101325 Pa）等环境指标，同时使发动机进口处的总压均匀度和速度均匀度分别提高了约5.6%和1.93%。优化设计使发动机进口流场的整体均匀度平均提高了3.76%，为提升航空发动机地面结冰试验能力提供了参考。

In order to meet the airworthiness certification requirements for high-altitude ice crystal icing tests of aero-engines, this paper proposes a free jet-based high-altitude ice crystal icing test chamber and conducts research on its flow field characteristics and structural optimization. Using computational fluid dynamics (CFD), the development of the jet flow in the test chamber was simulated, with a focus on analyzing the effects of the jet core length and the distance between the nozzle and the engine on the flow field uniformity. Additionally, aerodynamic performance and structural constraints were incorporated into a multidisciplinary optimization framework to optimize key parameters such as nozzle size and chamber layout. The results show that the optimized test chamber meets the environmental requirements for the engine and significantly improves the velocity and pressure uniformity at the engine inlet. This paper innovatively applies multidisciplinary design optimization methods to the design of the free jet ice crystal icing test chamber, providing a reference for enhancing the ground icing test capability of aero-engines.