Jacqueline Chen — Seminar

Event Date: November 8, 2018
Speaker: Jacqueline Chen
Speaker Affiliation: Distinguished Member of Technical Staff
Reacting Flows Department
Sandia National Laboratories
Sponsor: Aeronautics & Astronautics and Mechanical Engineering
Time: 4:30-5:30 p.m.
Location: WALC 1055 – Hiler Theater
Contact Name: Maria Longoria-Littleton
Contact Phone: +1 765 49-40015
Contact Email: mlongori@purdue.edu
Priority: Yes
School or Program: College of Engineering
College Calendar: Show

Seminar Topic: DNS of Turbulent Combustion in Complex Flows

Jacqueline Chen

 

Direct numerical simulation methodology and computing power have progressed to the point where it is feasible to perform DNS in mildly complex geometries representative of flow configurations encountered in practical combustors. These complex flows encompass effects of mean shear, flow recirculation, and wall boundary layers together with turbulent fluctuations which affect entrainment, mixing and combustion. Examples of recent DNS studies with complex flows relevant to gas turbine and internal combustion engines will be presented. These include sequential reheat combustion in the presence of mixed combustion modes – hydrogen/air autoignition and flame propagation in a rectangular duct-in-a-duct configuration [1], stabilization of a turbulent premixed ethylene/air flame behind a backwards facing step [2], and autoignition of a n-dodecane jet at diesel conditions [3]. In many of these complex flows there are regions of low-intensity turbulence with mean recirculation, flame-wall interaction in boundary layers, and shear generated turbulence interacting with ignition kernels or a flame brush. The mean shear and boundary layer provide sources of turbulence generation which interact with the flame brush. These complex flows may induce different turbulence-chemistry interactions from those observed in isotropic decaying or forced homogeneous turbulence. New numerical diagnostics have been developed to understand the mixed combustion regimes based on extensions of the chemical explosive mode analysis (CEMA) [4]. Finally, prospects for computation of complex flows at the exascale will be discussed.