Band, Chinmayi2022-08-292022-08-292022-05https://hdl.handle.net/11299/241276University of Minnesota M.S. thesis. May 2022. Major: Mechanical Engineering. Advisor: Vinod Srinivasan. 1 computer file (PDF); viii, 81 pages.The effects of shear-thinning non-Newtonian liquid on droplet diameter distributionsgenerated using a Counterflow atomizer were studied. Aqueous solutions of Sodium Carboxymethyl cellulose (SCMC) salt of 0.5%, 1%, 1.5% and 2% by weight were considered for experiments, with corresponding zero shear viscosity values of 13.8 mPas, 28.2 mPas, 508 mPas and 1280 mPas. Droplet diameters were measured using a Particle Digital Image Analysis technique combined with diffuse back illuminated shadowgraphs. Flow visualization in the near-field of the nozzle exit was used to gain insight into the flow patterns inside the nozzle near the exit plane, and to explain far-field droplet distribution statistics. Tree-like spray structure similar to effervescent atomization was observed for test solutions with higher weight concentrations. During secondary atomization, droplets connected with thin filaments were observed, indicating a probable existence of extensional stresses in the fluid. At lower concentrations of solutions, the spray emerged as a plume of droplets that are shed from a liquid film on the inner wall of the nozzle discharge tube, accompanied by a gas core. The variation of the Sauter Mean Diameter in the axial and radial directions indicated that the filaments in the near field are sheared by the gas flow, and undergo secondary atomization, leading to small droplet diameters and a more uniform distribution as we proceed downstream.enAtomizationCounterflow AtomizerFlow VisualizationNon-Newtonian liquidsSodium Carboxymethyl cellulose (CMC)ViscoelasticityThesis or Dissertation