Recent advances and prospects in hypersonic inlet design and intelligent optimization.

As the "respiratory tract" of the air breathing engine, the hypersonic inlet plays the role of compressing, decelerating, and pressurizing flow. However, research on the traditional inlet design is mainly based on gas dynamics theory and experience, which not only leads to a long design period but also fails to ensure the performance of the inlet at non-design points under broad working conditions. In recent years, with the further development of flow physics, a variety of advanced inlet design methods have been proposed, and a large number of valuable data have been accumulated by applying high-fidelity computational fluid dynamics numerical simulation and ground wind tunnel tests. A new generation of machine learning technologies, typically represented by deep learning, is developing vigorously. By building a deep neural network structure and using data-driven methods to carry out model training, it can realize typical feature extraction automatically, efficiently, and accurately, which is helpful to deeply explore the hidden flow mechanism between data and establish a fast prediction model of inlet performance. The optimal inlet design scheme can be obtained by applying the performance intelligent prediction model and the multi-objective intelligent evolution algorithm. This paper provides a detailed overview of the latest progress in inlet design by applying traditional ideas, expounds the basic principles and typical applications of some representative and prospective machine learning methods, and especially reports the current research status of the combination of machine learning and inlet. Finally, the future development trends and potential applications of several research directions are summarized. [ABSTRACT FROM AUTHOR]