Keywords

LAS, WMS, Speciation, Detonation, Aluminum Additive, Shock Tube

Abstract

Tunable diode lasers are widely used and are known to be great options for continuous wave lasing applications. Because of their stability and spectral selectivity, they have become an important diagnostic tool for modern combustion research. Previous combustion research, particularly those focused on solid and hybrid rocket systems, have shown that the interaction of aluminum with a reacting flow can greatly affect the dynamics and the thermochemical properties of the surrounding gas, therefore understanding the effects of aluminum-laden flows is critical for the advancement of these propulsion systems. However, due to the high degree of optical interference, high temperatures, and multiphase reactions, these aluminum-laden environments are very difficult to study. To overcome these challenges a three-color tunable diode laser diagnostic instrument, using the wavelength modulation spectroscopy (WMS) technique, was developed through this research effort. This work focuses on the hardware development of this sensor and acquisition of real-time gas temperature and H2O and CO concentrations. The diagnostic instrument targets two H2O absorbing transitions at 7185.59 cm-1 and 6806.03 cm-1 and one CO absorbing transition at 2008.52 cm-1. The H2O lasers were scanned at 25 kHz and modulated at 1 MHz, while the CO laser was scanned at 5 kHz and modulated at 200 kHz. The laser sensor was initially utilized to measure the chemical compositions of gas products through a shock tube to verify the accuracy of the sensor. After this initial testing, the diagnostic system was applied across a detonation tube facility to study the effects of burning aluminum in a reactive flow. In order to quantify the effects of aluminum reaction with the detonative flow, measurements from the aluminum-laden detonations were compared with non-aluminum detonation cases that used the same initial thermodynamic conditions. This research improves the understanding of the effects of aluminum combustion in propulsion systems.

Completion Date

2026

Semester

Spring

Committee Chair

Vasu, Subith

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Mechanical and Aerospace Engineering

Format

PDF

Document Type

Dissertation

Identifier

DP0053292

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