Keynote & Plenary Speakers

Abstract

This seminar will highlight two recent achievements in our research group regarding oblique detonation wave (ODW) initiation. First, we report on the influence of incoming boundary layer on the initiation characteristics of ODWs. This investigation, conducted with the in-house massively parallel block-structured finite volume solver PHAROS integrated with detailed chemistry, highlights the markedly different responses of abrupt and smooth ODWs to the presence of an incoming boundary layer and elucidates the underlying formation mechanisms. For ODWs induced by finite-length ramps, a unified initiation criterion is proposed that considers the free-stream Mach number, the dimensionless boundary-layer thickness, and the dimensionless ramp length. Building upon the above results, a concave-surface strategy for the active control of boundary layer separation induced by the ODW is proposed. Numerical results reveal the existence of an optimal curvature radius for the concave surface: this optimum markedly suppresses boundary-layer separation while simultaneously exploiting the thermal boundary layer to shorten the detonation initiation length. Second, we introduce, for the first time, an energy-deposition-assisted method for initiating ODWs on finite-length ramps at low Mach numbers. Numerical simulations are employed to investigate the localized gas heating effects inherent in the mimicked plasma-assisted initiation, with particular emphasis on the influence of deposition regimes (continuous versus pulsatile) and magnitudes (deposition power and single pulse energy) on ODW initiation characteristics. The results demonstrate that both continuous and pulsatile energy deposition can effectively facilitate on-wedge ODW initiation. As the deposition power or the pulse energy progressively increases, several modes emerge sequentially on the finite wedge, namely, failed initiation, various delayed initiation modes, and various direct initiation modes. By analyzing the spatiotemporal evolution of the key wave structure under single-pulse deposition, a critical pulse-repetition frequency required for sustained on-wedge ODW initiation has been obtained. This prediction is subsequently validated by employing multi-pulse regimes. When both deposition energy and pulse repetition frequency are taken into account, the minimum mean power required for pulsatile energy deposition is found to be approximately one order of magnitude lower than that for continuous one. We warmly invite experts and scholars to join us for a stimulating discussion.

Bio-Sketch

Professor Chih-Yung Wen received his Bachelor of Science degree in Mechanical Engineering from National Taiwan University in 1986. He subsequently earned his Master of Science and Doctor of Philosophy degrees in Aeronautics from the California Institute of Technology (Caltech), USA, in 1989 and 1994, respectively. He commenced his academic career at the Department of Mechanical Engineering, Da-Yeh University, where he was promoted to full Professor in 2002. During his tenure at Da-Yeh University, he held several key administrative positions, including Chairman of the Department of Mechanical and Vehicle Engineering and Provost.

In 2006, Professor Wen joined the Department of Aeronautics and Astronautics at National Cheng Kung University. In 2012, he was appointed Professor in the Department of Mechanical Engineering at The Hong Kong Polytechnic University. From 2019 to 2025, he served as Interim Head and subsequently Head of the Department of Aeronautical and Aviation Engineering. He currently holds the position of Chair Professor of Aeronautical Engineering and serves as Director of the Research Institute of Large Aircraft, Director of the Research Center of Uncrewed Autonomous Systems, and Associate Director of the Research Institute for Sports Science and Technology.

Professor Wen has authored or co-authored more than 300 scientific publications, including journal articles, conference proceedings, and book chapters, and is the holder of 14 patents. He is a Fellow of the American Society of Mechanical Engineers (ASME), the Royal Aeronautical Society (RAeS), and the Hong Kong Institution of Engineers (HKIE), as well as an Associate Fellow of the American Institute of Aeronautics and Astronautics (AIAA). Professor Wen is actively involved in professional and academic activities in the fields of Mechanical and Aerospace Engineering at both national and international levels and serves on several prominent professional boards and committees related to Aerospace Engineering.