Rebagay, Rachel Lauren (2017-08). Heated Shock Tube Design and Characterization for Liquid Fuel Combustion Experiments. Master's Thesis.
Studying the combustion properties of liquid fuels and low vapor pressure fuels is important for power generation, propulsion, and aviation. Determining these properties, requires facilities like heated shock tubes that can ensure the fuel can remain in the vapor phase during combustion experiments. To better study the properties of liquid fuels, modifications were made to the high-pressure shock tube at Texas A&M University using custom heating jackets from BriskHeat Corporation and heating tapes controlled by temperature controllers to heat the facility to temperatures up to 150?C. Experiments were conducted to ensure the driven section of the shock tube, where combustion measurements are collected, was kept at uniform temperatures to prevent speeding up or slowing down of the shock wave as it passes through the test mixture. A stoichiometric methane-oxygen mixture in 98% argon was used to validate the heated facility for high-temperature gas mixtures, and an n-nonane, 4% oxygen mixture was used to validate the heated facility for liquid fuel mixtures. These results were compared to previous studies of the same mixtures. Temperature uniformity experiments resulted in a ?1?C temperature distribution for the 10 feet closest to the measurement location of the driven section for 50?C, 75?C, and 100?C set point temperatures. A temperature distribution of ?2?C was achieved for the 150?C maximum operating temperature of the facility. Ignition delay time measurements were made for the stoichiometric methane-oxygen mixture over a temperature range of 1784 K to 2134 K at 1.13 atm using an OH* diagnostic. These results matched well with previous studies of the same methane mixture, hence validating that the heated shock tube performs as well as it did for such mixtures prior to heating it. Ignition delay time measurements were also made for the n-nonane mixture over a temperature range of 1320 K to 1444 K at 1.7 atm, and these aligned well with previous studies of the same mixture. Therefore, the heated shock tube was validated for use with both gas and liquid baseline fuel mixtures, giving confidence that it will perform as intended for all future studies of low vapor pressure fuels.