Measurements of soot sublimation and oxidation at high temperatures in a shock tube

Willhardt, Colton Dean

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https://hdl.handle.net/2142/120184 Copy

Description

Title

Measurements of soot sublimation and oxidation at high temperatures in a shock tube

Author(s)

Willhardt, Colton Dean

Issue Date

2023-05-05

Director of Research (if dissertation) or Advisor (if thesis)

Glumac, Nick G

Department of Study

Mechanical Sci & Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• soot
• sublimation
• oxidation
• surface mass loss
• shock tube
• spectroscopy
• emission
• light

Abstract

Understanding the optical emission of a conventional fireball is of importance to the defense community for developing remote sensing techniques to aid in strategic responses. Soot is a condensed phase particulate present in many combustion environments including fireballs and contributes significantly to optical emission. Soot has been studied extensively in lower temperature regimes less than 4000K, but little work has been done at the higher temperatures that can be expected in a fireball. In a fireball soot mixes into layers of high temperature gases vaporizing the particles on the order of microseconds. To better understand optical emissions in these environments it is necessary to make measurements of soot properties at these temperatures. Local soot concentrations are dependent on particle surface reactivity, which is significant in the relevant temperature regime, so measurements of surface reaction rates are necessary. Soot emission is dependent on particle temperature, and surface reactions contribute to the energy balance on the particle, necessitating measurements of particle temperature. Products of surface reactions will contribute to local emissions, requiring measurements of gaseous surface reaction products. Here, a heterogeneous shock tube is used to shock soot particles at temperatures of 3000-7000K in gas mixtures of Argon and 2. At these temperatures, the surface of the soot particle sublimates and oxidizes, decaying the particle over time. Particle temperature measurements are made, and it is shown that the soot temperature will never exceed its sublimation temperature of ~4000K in gas hotter than the soot sublimation temperature. Sublimation and oxidation reaction rates are measured with emission signal decay, extending previous measurements in the literature, and parameters are fit to sublimation and oxidation models. Gaseous products are identified by emission spectroscopy, and relative concentrations are measured over time.

Graduation Semester

2023-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2023 Colton Willhardt

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