Invite Speaker I:
"Title:Dynamic Combustion and Response Characteristics of a Novel Combined Solid Rocket Motor Regulated by a Pintle Valve"
Abstract
Thrust regulation has been a major challenge to the solid rocket motor. The dynamic combustion and response characteristics of a novel combined solid rocket motor regulated by a pintle valve are numerically studied in this paper. The results show that as the flow regulation ratio increases, the combustion zone moves towards the burning surface, which enhances gas-solid heat transfer and leads to larger regression rate. With the movement of the pintle valve, the flow and combustion processes near pintle valve and pre-combustion chamber is strongly intensified. Meanwhile, the location of the maximum degree of the mixing moves towards the burning surface, which causes the regression rate to increase from 4.96 mm·s-1 to 13.03 mm·s-1 with movement of the pintle valve from 0.70 s to 0.76 s. With the flow regulation ratio increasing from 1.6 to 4.0, the response time of pressure decreases by 50% while the regulation ratios of the thrust and the regression rate reach 3.35 and 2.11, respectively. When the regulation ratios increase, the average heat release rate gradually increases since the increase of the regulation ratio intensifies the mixing and oxidation reactions between the species. In addition, during the full-scale flow regulation of the oxidizer-rich gas, the specific impulse efficiency ranges from 81% to 88%. It is found that there exists an optimum regulation ratio to obtain the maximum specific impulse efficiency. Based on the results, it is possible to regulate the regression rate and the thrust of the combined solid motor simultaneously. This work provides better insight into dynamic combustion and response characteristics of solid motor under flow regulation.
Bio-Sketch
Dr. Shuyuan Liu has been working as Associate Professor in School of Astronautics, Northwestern Polytechnical University since 2019. Dr. Liu obtained his Ph.D. degree from Department of Mechanical Engineering, The Hong Kong Polytechnic University in 2017 and continued working as a Post-doctoral fellow until 2019. Dr. Liu’s research area mainly include flow, heat transfer and combustion processes involved in solid and ramjet rocket motors. He has published more than 30 academic papers in combustion and thermal engineering-related quality journals and secured National Natural Science Foundation of China and other programs.
Shuyuan Liu
Associate Professor of Northwestern Polytechnical University, China
Invite Speaker II:
"Title:Meniscus-guided 3D Nanoprinting of Optoelectronic Devices"
Abstract
Exploiting a femtoliter liquid meniscus formed on a nanopipette is a powerful approach to spatially control mass transfer or chemical reaction at the nanoscale. Here, a nanoprecision 3D printing is developed for organic–inorganic metal halide perovskites. The method is based on guiding evaporation-induced perovskite crystallization in mid-air using a femtoliter ink meniscus formed on a nanopipette, resulting in freestanding 3D perovskite nanostructures with a preferred crystal orientation. Stretching the ink meniscus with a pulling process enables on-demand control of the nanostructure's diameter and hollowness, leading to an unprecedented tubular-solid transition. This approach generates 3D red, green, and blue (RGB) perovskite nanopixels with ultrahigh integration density. We show that the 3D form of these nanopixels enhances their emission brightness without sacrificing their lateral resolution, thereby enabling the fabrication of high-resolution displays with improved brightness. Furthermore, 3D pixels can store and encode additional information into their vertical heights, providing multilevel security against counterfeiting. It is expected that the method has the potential to create freeform perovskite nanostructures for customized optoelectronics.
Bio-Sketch
Chen Mojun, Assistant Professor in Smart Manufacturing Thrust at the Hong Kong University of Science and Technology (Guangzhou), Affiliate Assistant Professor in Mechanical and Aerospace Engineering at the Hong Kong University of Science and Technology. He obtained his master's degree from the Department of Modern Mechanics at the University of Science and Technology of China, and his PhD from the Department of Mechanical Engineering at the University of Hong Kong. His research areas include micro/nano 3D printing technology, optoelectronic devices, micro/nano robots, and wearable devices. Chen Mojun has published over 20 papers in peer-reviewed journals in the field of advanced manufacturing and materials (4 cover papers), including Advanced Materials (front cover), Nano Letters, ACS Nano, Advanced Functional Materials, and Small (frontispiece). He has been granted one US patent. As a core member, he has participated in several projects funded by the Hong Kong Research Grants Council (RGC) on the research of meniscus-guided and electrohydrodynamic micro/nano 3D printing technology. He has received the 2019-2020 Outstanding PhD Thesis Award (Department of Mechanical Engineering, University of Hong Kong), the Best Poster Award at the University of Hong Kong Electronic Materials and Devices Seminar, the Young Researcher Award at the Fourth International Experimental Fluid Dynamics Conference (only 3 winners), the Outstanding Paper Award at the Ninth National Experimental Fluid Dynamics Conference, and his supervised students has received honors such as the 2024 3MT champion. Currently, he serves as a young editor for eScience (impact factor: 42.9), leads a National Natural Science Foundation of China Youth Project, several Guangdong provincial and municipal natural science foundation projects, and horizontal projects from relevant enterprises and institutions.
Mojun Chen
Assitant Professor of The Hong Kong University of Science and Technology (Guangzhou), China
Invite Speaker III:
"Title:Aeroelastic Phenomena of High-aspect-ratio Flexible Wings and Flow Controls "
Abstract
The aerodynamic performance and structural safety of high-aspect-ratio flexible wings, such as high-altitude long-endurance (HALE) unmanned aerial vehicles (UAVs), helicopter rotors and wind turbine blades, can be dramatically affected once serious aeroelastic phenomena occur, namely flutters. In this study, experimental investigations are performed to understand the mechanism of fluid-structure interactions on a 3D high-aspect-ratio beam-shell elastic wing with an aspect-ratio of 7.5 at Reynolds numbers from 1.82×〖10〗^4 to 1.58×〖10〗^5 in steady flight conditions and with gust disturbances. The forces at the wing root, bending and torsion deformations, as well as the flow field are simultaneously measured using load cell, FBG, strain gauges, digital image correlation (DIC) and particle image velocimetry (PIV). Bio-inspired leading-edge protuberances, passive morphing via a bistable structure, and active blowing techniques are employed to control the aeroelastic phenomena. With these techniques, the flight regime with flutters can be greatly contracted, amplitudes of limit cycle oscillations (LCO) can be reduced, and gust alleviation can be achieved.
Bio-Sketch
Dr. Lu Shen received his B.S. degree in Aeronautic and Astronautic Engineering from Shanghai Jiao Tong University in 2011 and M.S. and Ph.D. degrees from the Hong Kong Polytechnic University in Mechanical Engineering in 2014 and 2018. He is currently an assistant professor at Center for Turbulence Control in Harbin Institute of Technology, Shenzhen. His research focuses on experimental fluid mechanics, fluid-structure interactions, and flow control techniques.
Lu Shen
Assistant Professor of Harbin Institute of Technology, Shenzhen, China
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