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2015 年 09 月 02 日
Seminar - Micro-Meso Swirling Combustion Chambers: concepts, projects and future developments by Dr. Angelo Minotti

Date: 02 September 2015 (Wednesday)

Time: 11:00 am – 12:00 pm

Venue: EF305, The Hong Kong Polytechnic University

Abstract:

The definition of “micro” keeps changing with the introduction of smaller and smaller power or thrust devices. Up to 15 years ago "micro" for a rocket meant typically thrust ~ O(1) N. A more current definition would now classify "micro" thrusts in the of order O(1), μN to O(1) mN. Microthrusters were associated with the development of micro- and nano-satellite concepts, in which satellites are conceived as capable of performing in the same or similar manner as conventional satellites within a much smaller package/weight by using MEMS technology. MEMS (Micro Electrical Mechanical System) technology is applicable to most or all combustion/propulsion systems, subject to restriction(s) posed by the physical laws that rule scaling.

The case for MEMS applied to chemical combustion/propulsion is based on scaling laws: for instance, in a microrocket, thrust T scales with area, while weight W scales with volume. Thus shrinking the combustor will increase the T/W ratio, a very attractive trend. However, the scaling laws should hold also throughout the range of physical effects that contribute to the working of a complete thruster or combustor system. This means, for instance, that viscosity will play an increasingly important role as size gets smaller, and that the simple isentropic expressions adopted in sizing rocket engines and gas turbines apply less and less as the dimensions shrink. Another fundamental issue is the low residence time inside the microcombustion chamber and therefore how to increase the combustion efficiency without chemical strategies, such as catalysis, in order to reduce manufacturing complexity and costs.

The goal of this seminar is to present the potentiality of micro-meso combustion chambers based on swirling motion as a solution to the above challenges. The outcomes of many, national and international, research projects are reported, together with possible future developments. These projects investigate the physics of swirling combustion chambers fed by H2, CH4, C3H8 and blends of CH4-H2 showing how such kind of technology might be adopted for energy production (replacing batteries) and/or propulsion for micro-nanosatellites manoeuvres.

Bio-sketch:

Prof. Minotti’s research interests are primarily in fluid dynamics, cold and reacting, and in the Dual Use Technology. He focuses, inter alia, on IR radiative heat transfer, real gas behaviour, numerical fluid dynamics, hydrocarbons combustion and micro-meso swirling combustion chambers. Prof. Minotti has two Master Degrees (Mechanical Engineering and Astronautics Engineering), a Master of Science (Space Transportation Systems) a PhD (Theoretical and Applied Mechanics) and a Postdoc (Aerospace Propulsion).

Following the above, he was appointed as Assistant Professor in Space Propulsion (2011-2013) at the Dept. of Mechanics and Aerospace Engineering of the Sapienza University of Rome. As of 2013 he is Assistant Professor in Space Systems at the Dept. of Astronautics, Electrics and Energetics Engineering and Professor of Dual Use and Arms Control at the School of Aerospace Engineering.

He has been involved in, and has managed, many national and international research projects and collaborates with the Italian Government on issues related to national and international security.