Academic Staff

BEng (National Taiwan University); MSc (Caltech, U.S.A.); PhD (Caltech, U.S.A.);

Fellow/ASME (American Society of Mechanical Engineering)

Fellow/RAeS (Royal Aeronautical Society)

Fellow/HKIE (Hong Kong Institute of Engineers)

Associate Fellow of AIAA

Associate Editor/AIAA Journal

Editor/Shock Waves Journal

Associate Editor/Journal of Advances in Aerodynamics

Homepage: https://www.polyu.edu.hk/researchgrp/cywen/index.php/en/pub.html

Area of Specialization

Aerothermodynamics and boundary layer transition of hypersonic/supersonic vehicles; Shock/droplet and shock/bubble interactions; Applications of DBD actuators on flow control; Experimental fluid mechanics and CFD; Numerical simulations and assessment of urban wind field and air pollution; Scramjet and Oblique Detonation Engines; Detonation; UAV/MAV technology research and development.

Short Description

Professor Wen received his Bachelor of Science degree from the Department of Mechanical Engineering at the National Taiwan University in 1986 and Master of Science and PhD from the Department of Aeronautics at the California Institute of Technology (Caltech), U.S.A. in 1989 and 1994 respectively. He worked at Caltech as a Research Fellow from February 1994 to July 1994 and then continued his teaching and research works at the Department of Mechanical Engineering at the Da-Yeh University, Taiwan. He was promoted to full professorship in February 2002. He had been the Chairman of the Department of Mechanical and Vehicle Engineering from August 1997 to July 2000, and the Provost from August 2004 to July 2006 in the Da-Yeh University, Taiwan. In August 2006, Professor Wen joined the Department of Aeronautics and Astronautics of the National Cheng Kung University (NCKU), Taiwan, before joining the Department of Mechanical Engineering, The Hong Kong Polytechnic University in 2012 as professor. He served as the associate head/research of ME department from May 2015 to October 2019. He is currently the Head and Chair Professor of Aeronautical Engineering of the Department of Aeronautical and Aviation Engineering, and the Associate Director of Research Institute for Sports Science and Technology. Professor Wen has authored and co-authored more than 300 scientific papers, conference papers and book chapters. He was also awarded 14 patents. Professor Wen, currently a HKIE Fellow and an AIAA Associate Fellow, actively engages in professional academic activities related to mechanical and aerospace engineering at both domestic and international levels. In addition, he serves as a member of, various key professional boards and bodies related to the Aerospace Engineering.

溫志湧教授於1986年在國立台灣大學機械工程學系取得工程學士學位，並於1989年及1994年在美國加州理工學院航空工程學系分別取得理學碩士及哲學博士學位。他於1994年2月至7月在美國加州理工學院擔任研究員，其後在台灣大葉大學機械工程學系繼續從事教學及研究工作，並於2002年2月獲取教授席。在大葉大學服務期間，他於1997年8月至2000年7月及2004年8月至2006年7月分別擔任機械與自動化工程學系系主任及教務長。溫教授於2006年8月加入台灣國立成功大學航空太空工程學系，之後，於2012年8月加入香港理工大學機械工程學系。他於2015年5月至2019年8月擔任機械工程學系研究副系主任，現在擔任航空及民航工程學系航空工程講座教授兼系主任及體育科技研究院副院長。溫教授是超過300篇科學論文、國際學術會議論文集及書籍章節的作者或合著者。他亦成功取得十四項專利。他現為香港工程師學會會士及美國航空太空學會的副院士，他亦積極參與國內外機械及航空航太工程有關的專業學術活動，並擔任多個與航空航太工程有關的專業學會及組織的成員。

 

Selected Research Project / Teaching & Learning Project

1. High-speed flow researches:

Studies on the fascinating high-speed flow promote the development of super- to hyper-sonic vehicles, such as Supersonic Combustion Ramjet (SCRamjet), aerospace shuttle, as well as various hypersonic vehicles. The research team led by Prof. Chih-Yung Wen at the Department of Mechanical Engineering of the university focuses on a few key elements in this field: 1) the interaction of the detached shock with rain droplet during the reentry of a space shuttle; 2) controlling of boundary layer transition during hypersonic flight; 3) non-equilibrium flow in and out of a hypersonic vehicle where the real-gas effect has to be considered; and 4) interpreting the mechanism of detonation and pursuing its accurate simulation.

 

Both numerical and experimental platforms have been built and researches are proceeding based on them. The in-house CFD method has shown good performance in capturing shock waves and contact discontinuities in simulating compressible single- and multi-fluid problems and the method itself is under further development. Shock tube with shadowgraph visualization system has produced reliable shock/droplet interaction images which not only validated the numerical simulations but also facilitated other high-speed flow research. A boundary layer transition control strategy is conducted numerically on a Mach 6 flat-plate using heating or cooling strip, where an efficient way to stabilize the hypersonic boundary layer is obtained. Considering the vibrational nonequilibrium effect, a modified steady one-dimensional Zel’dövich-von Neumann-Doring detonation model has been proposed, which confirms its important role played in the detonation cell size change. Via extensive numerical simulation on detonation, the vibrational relaxation in the chemical reaction has also been testified to be a crucial mechanism.

     
Fig.1 Shock tube facility and high-speed Schlieren image system for shock/droplet interaction research.

  
Fig.2 Ludwieg tube facility with SQRT(unit Re = 1.4~3.2 x 10^7 m^(-1)), Ma=4.0 and test time of 40 ms.

Fig.3 Numerical soot foils using four different vibrational energy/chemical reaction coupling models.

2. Applications of Plasma Actuators:

Plasma actuators have attracted considerable attention in the aerospace industry due to their features of simple mechanism, easy maintenance, low cost and fast response, and they can be formed to various shapes of vehicles. The plasma actuator ionizes the gas molecules and forms the plasma. Electric field induces the motion of plasma and results in the ionic wind which alters the velocity profile inside the boundary layer through the particle collisions and finally changes the aerodynamic characteristics of the vehicle. The research team experimentally investigated the effects of Dielectric Barrier Discharge (DBD) plasma actuators on the aerodynamics of a slender delta wing. The leading edge vortex breakdown locations under both symmetric and asymmetric control forms and various control frequencies are summarized. The aerodynamic response to the controls suggests that the DBD plasma actuator is a promising technique for delta wing maneuvering. More investigations on the delta wing maneuvering will be conducted in the near future.

Fig. 4. Smoke flow visualization results show the typical LEV structure in the transverse cross-section: (a) baseline case; (b) symmetric control case; and (c) asymmetric control (starboard-controlled) case. (α = 36°; Re = 50 000).

3. Unmanned Aerial Vehicle (UAV) and Micro Aerial Vehicle (MAV)

Wilderness search and rescue entails performing a wide-range of work in complex environments and large regions. Given the concerns inherent in large regions due to limited rescue distribution, UAV-based frameworks are a promising platform for providing aerial imaging. The research team led by Prof. Chih-Yung Wen developed an all-in-one camera-based target detection and positioning system and integrated it into a fully autonomous UAV. It is capable of on-board, real-time target identification, post-target identification and location and aerial image collection for further mapping applications. A UAV communication relay solution was also developed by the research team to extend the communication range and bypass obstacles in complex environments. In the application of tail-sitter vertical take-off and landing (TVOL) UAV, a hardware-in-loop simulation environment is established which is capable of real-time dynamic simulation and supports a robot operating system (ROS)-based open-source autopilot. An independent ROS package is well prepared for data communication between a simulator and flight control computer. 2016 Taiwan UAV competition champion is awarded to Prof. Wen’s team. In the MAV field, autonomous control is well realized on a four-wing flapping MAV by which the clap and fling mechanism was proven to play a key role in the lift generation. The understanding of MAV structure and aerodynamics has promoted the designing of flapping MAVs.

Fig.5 Photos of a fixed-wing UAV and a tail-sitter VTOL