Keesee, Charles Lewis (2019-11). Laminar Flame Speed and Markstein Length Measurements of Various Multi-Component Liquid Fuels With Detailed Uncertainty Analysis. Doctoral Dissertation.
Thesis
New laminar flame speed experiments have been conducted for various traditional and alternative kerosene-based liquid fuels. These fuels included: Jet-A, RP-1, Diesel Fuel #2, Syntroleum S-8, Shell GTL, and n-decane. Understanding the combustion characteristics of these fuels is an important step in developing new chemical kinetics mechanisms that can be applied to real fuels. The precise composition of these fuels is known to change from sample to sample. Additionally, their low vapor pressures cause uncertainties in their introduction into gas-phase mixtures, hence leading to uncertainty in the mixture equivalence ratio. Multiple methods were implemented to help reduce and quantify the experimental uncertainty of these mixtures. One of these was an in-situ absorption technique. The diagnostic utilized a 3.39-um HeNe laser in conjunction with Beer's Law. Other techniques included finding better syringes to inject the fuel to ensure all of the fuel entered the vessel. Also improved were the methods to fill the vessel switching from solely relying on the partial pressure to include measuring the mass of fuel injected. This addition also allowed for back-calculating the molecular weight of the injected fuel to verify the liquid fuel had vaporized and was behaving as an ideal gas. The resulting spherically expanding, laminar flame experiments were conducted over a range of equivalence ratios from ? = 0.7 to ? = 1.5 at initial conditions of 1 atm and 403 K (all fuels except DF #2). Overall, the fuels showed similar behavior with all fuels having a peak flame speed between 56 cm/s and 60 cm/s, at an equivalence ratio between ? = 1.15 and ? = 1.25. While this peak value is richer than typically seen in literature, it is shown that the average fuel molecule used throughout these studies is inconsistent. Therefore it is suggested that using fuel mole fraction as opposed to equivalence ratio is a better parameter when comparing results from different data sets. Analysis also showed a strong linear correlation between Markstein length and equivalence ratio. This was used to help verify the accuracy and acceptability of some of the data points.
