Dynamics and kinetics of gas-phase and multiphase detonations
Stanford University
Abstract
A basic understanding of detonation structure is critical to problems ranging from Type Ia supernova explosions to hydrogen explosion safety and hypersonic propulsion. This talk will focus on two related research problems: the origin of detonation cellular structure and the drag and vaporization of liquid droplets upon shock impact. High-speed microscopic jetting exceeding several km/s is theoretically studied, modeled, and analyzed in gaseous detonation. The jets deliver energy to produce and sustain an overdriven shock that defines the shape and size of detonation cells. The jets arise along with vorticity generated at points of shock intersection and are subsequently transported in a stagnation flow configuration after shock collision. Jetting provides a discrete energy transfer and focusing mechanism essential for sustaining global detonation propagation and cellular structures for the observed mixtures. The jetting also raises a range of interesting scientific questions concerning reaction kinetics, molecular transport, and gas dynamics under non-equilibrium thermodynamic conditions. In the area of shock-droplet interaction, we propose a coupled drag and vaporization model describing the simultaneous momentum and energy transfers from the post-shock gas, leading to acceleration and non-equilibrium heating and vaporization of the droplet mass behind a shock.
About the speaker
Dr. Hai Wang is Professor of Mechanical Engineering at Stanford University. Prior to his appointment at Stanford, he was the Northrop Chair in Engineering and Professor of Aerospace and Mechanical Engineering at USC. He received his Ph.D. in Fuel Science from Penn State in 1992. He was a Professional Research Staff at Princeton University from 1994 to 1996 before starting his faculty career at the University of Delaware. He is best known for his work on the mechanisms of PAH and carbon formation in reacting flows and development of chemical kinetic models for fuel pyrolysis and combustion. He has made contributions in the application of ab initio quantum chemistry and reaction rate theory in chemical kinetics. He developed stochastic methods for detailed modeling and uncertainty quantification. He contributed to the transport theories of nanoparticles and large molecules, atmospheric heterogeneous chemistry, and nanomaterials synthesis and its applications in solar cells and lithium-ion batteries. His current research projects include high-speed propulsion, detonation, combustion and propellant chemistry, phonons and their effects on electron quantum tunneling in layered materials, and battery chemistry. He was the recipient of the AIAA Propellant and Combustion Award in 2018, and the Humboldt Research Award in 2019. He is a Fellow of ASME and an inaugural Fellow the Combustion Institute. He served as the Co-Editor-in-Chief of Progress in Energy and Combustion Science from 2014 to 2024. He is currently the President of the Combustion Institute, an international, non-profit, educational and scientific society.
