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September 26, 2022: Brian Bojko, US Naval Research Laboratory, 4:00 pm in 100 McBryde Hall "Development and Application of Solid Fuel Combustion Models"

  • 4:00 p.m.
  • 100 McBryde Hall 
  • Brian Bojko, U.S. Naval Research Laboratory
  • Faculty Host: Dr. Gregory Young

Abstract: The use of solid fuels in propulsion applications has gained increasing interest due to their ability to increase the specific impulse and range of a flight vehicle. However, the long hydrocarbon polymer chains that make up the solid fuel break down and undergo pyrolysis at various rates, devolving into different gaseous chemical compositions depending on the temperature, heat flux, and pressure within the combustor. Furthermore, the mass flux of the solid fuel is highly dependent on the heat release from the flame zone and vice-versa. This is a highly coupled event that defines the solid fuel combustion process. Initially, this talk will focus on the understanding of fundamental combustion processes of solid fuel combustion at various oxidizer compositions and mass fluxes. The canonical setup for this research is an opposed flow burner, where experimental and numerical studies are conducted to highlight the fundamental physics. Upon analyzing the small-scale combustion phenomena, the development of a flamelet progress variable (FPV) approach is described to demonstrate the translation of finite-rate kinetic effects to large-scale simulations in a computationally efficient approach. Including detailed chemistry mechanisms into multi-dimensional simulations are intractable due to the vast amount of computational power needed to solve the increasing number of partial differential equations (PDEs) and the numerically stiff reaction kinetics. Applying an FPV methodology reduces the total amount of PDEs to be solved and eliminates the numerical stiffness associated with combustion, enabling combustion simulations of flight vehicles at scale.

Bio: Brian Bojko received his doctorate in Aerospace Engineering from the University at Buffalo studying the effects of finite-rate chemistry in turbulent multiphase combustion scenarios including metal combustion, biomass combustion, and turbulent spray flames. He has worked for the Navy as a computational combustion research engineer for the past 5 years, where he currently works in the Laboratories for Computation Physics and Fluid Dynamics at the Naval Research Laboratory in Washington, D.C. Dr. Bojko has expertise in creating reduced order models of small-scale combustion phenomena for use in large-scale combustion simulations through techniques such as the flamelet progress variable approach. He is currently developing such models for the JENRE® Multiphysics framework, which is an in-house discontinuous Galerkin code for solving the compressible reacting Navier-Stokes equations.