Laser absorption spectroscopy for investigation of hypersonic propulsion
Gessman, Isabella
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https://hdl.handle.net/2142/132628
Description
Title
Laser absorption spectroscopy for investigation of hypersonic propulsion
Author(s)
Gessman, Isabella
Issue Date
2025-10-07
Director of Research (if dissertation) or Advisor (if thesis)
Lee, Tonghun
Doctoral Committee Chair(s)
Lee, Tonghun
Committee Member(s)
Cai, Lili
Glumac, Nick
Panerai, Francesco
Department of Study
Mechanical Sci & Engineering
Discipline
Mechanical Engineering
Degree Granting Institution
University of Illinois Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
hypersonics
scramjets
laser diagnostics
laser absorption spectroscopy
Abstract
Advancements in scramjet technology have arisen from recent interest in hypersonic propulsion. Progress in ground-testing capabilities has accelerated this technological advancement, providing repeatable and controllable experimentation at lower costs than flight tests. A primary challenge of carrying out experiments in these ground test facilities is replicating exact conditions representative of the hypersonic flight environment. Generating high enthalpy conditions often produces a test gas with an altered chemical composition, which can influence combustion performance downstream. This dissertation first addresses this issue by characterizing the inflow gas in the ACT-II facility, using tunable diode laser absorption spectroscopy (TDLAS) to measure temperature and nitric oxide (NO) concentration. Another fundamental challenge associated with scramjet operation is achieving efficient fuel-air mixing and ignition within the short residence times of a scramjet combustor. Because thrust generation is strongly influenced by combustion performance, the next section of this dissertation details the development and demonstration of TDLAS sensors for combustion characterization. Simultaneous carbon monoxide (CO) and carbon dioxide (CO2) concentration measurements characterize combustion performance for different combustor geometries and fueling schemes. Finally, the last portion of the dissertation demonstrates a diagnostic for future scramjet applications. Water vapor absorption spectroscopy using a broad-bandwidth laser is demonstrated in a shock tube for temperature and pressure measurements in a simulated combustion environment. The work represents potential for an additional combustion product measurement in a scramjet.
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