Flaring in the upstream oil and gas industry generates black carbon, which adversely affects human health and is an important positive climate forcer. Experiments were performed to investigate soot formation and oxidation within these large, flare-type, turbulent, nonpremixed, buoyant flames. An optical measurement technique combining simultaneous auto-compensating Laser-Induced Incandescence (LII) and Elastic Light Scattering (ELS) measurements was used to measure the instantaneous soot volume fraction (fv), primary particle diameter (dp), and mean aggregate radius of gyration (Rgm1) of soot black carbon within an optical probe volume. Measurements were completed on two comparable turbulent buoyant flames emanating from a 50.8 mm diameter pipe (lab-scale flare) with and without an internal turbulence generating grid. Centreline profiles of fv, dp, and Rgm1 were determined within rigorously quantified uncertainties obtained via Monte Carlo analysis. Results show that, for the conditions investigated, internal pipe turbulence has only a minor effect on the soot formation trends within the flame, suggesting that internal turbulence is likely less important than other factors when modelling and predicting soot formation in flare flames. iii Acknowledgements Foremost, I would like to thank my supervisor Prof. Matthew Johnson and co-supervisor Dr. Brian Crosland for supporting me continuously throughout my master's research and helping me out by answering my never-ending questions. With their guidance, I was able to conclude my research and present this thesis. I could not have imagined having better advisors and mentors for my master's research.