报告题目：Recent Observations in Premixed Flames and Droplet Impacts

报告人： Prof.Abhishek Saha

报告人单位：University of California

报告时间：Oct.25 (Thursday) 2:00pm-3:00pm

报告地点：B-518, Lee Shau Kee Building of Science and Technology

邀请人： Prof. Zhuyin Ren

Abstract:

The physics of flames and droplets are highly relevant in the areas of aero-propulsion, power generation, material synthesis and others. In this talk, I will share recent results and interpretations of recent studies related to these two areas.

In the first part, we will discuss some new results from Princeton’s constant-pressure expanding turbulent flame experiments conducted in normal and elevated pressures up to 25atm. First, I will discuss the role of Darrieus-Landau (DL), hydrodynamic, cellular flame-front instability in the propagation of turbulent flames, recognizing that the DL instability is promoted at high pressures. We will also highlight the role of preferential molecular diffusion in such interactions between cellular and turbulent flames. In the next part, we will focus on the dynamics of droplet impact on liquid films, in which first we will demonstrate that such impacts can result in two outcomes namely, bouncing and merging. Subsequently, we shall provide a regime diagram and scaling for the transitional boundaries. The merging outcome would be discussed in further details, focusing on the morphological evolution of a penetrating droplet inside the liquid pool after coalescence. We will show that the motion of such a droplet can be divided into three regimes, where inertia, capillary and viscous effects alternatingly play dominant roles to characteristically modulate the penetration process.

Bio:

Abhishek Saha is an Assistant Professor of Mechanical and Aerospace Engineering at University of California, San Diego. He received his PhD (2012) from Mechanical and Aerospace Engineering of University of Central Florida, with his dissertation recognized by the university-wide Outstanding Dissertation Award. Before joining UCSD, Prof. Saha was a research staff at Princeton University, working with Prof. C.K. Law’s group. Prof. Saha’s research experience encompasses areas of (1) dynamics of laminar and turbulent flames and (2) droplet dynamics in relation to power generation and propulsion. He has published extensively in leading journals, and is a recipient of the 2016 George H. Markstein Best Paper Award of the US-Eastern States Section Meeting of the Combustion Institute.