Browsing by Author "Jiang, Delin, 1992-"
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Item High-fidelity simulation of air-assisted atomization with inlet gas turbulence.(2021-11-03) Jiang, Delin, 1992-; Ling, Yue (Stanley)Atomization is the process for bulk liquids to disintegrate into small droplets, which is commonly seen in nature and and industrial applications. Airblast atomization is an air-assisted atomization approach and is widely used in gas turbine engines. It utilizes a high speed parallel gas stream to enhance the atomization of the bulk liquid. The velocity difference between the two fluids at the interface triggers a shear instability. The instability induces interfacial waves, which grow, roll up, and eventually break into ligaments and droplets. In order to optimize the design of airblast atomizers, it is crucial to have a comprehensive understanding of the effects of inlet gas turbulence on interfacial instability development, the primary liquid breakup mechanisms and the droplet statistics. In simulation, the turbulent velocity fluctuations are introduced in the gas inlet using a digital filtered method. A parametric study on the effect of inlet gas turbulence is studied using high-fidelity simulation. The the mass-momentum consistent volume of fluid method has been used to resolve the sharp interface. To characterize the topology evolution of the atomizing liquid jet, a novel skeletonization method has been developed.Item Three dimensional topology optimization with orthotropic material orientation design for additive manufacturing structures.(2017-08-02) Jiang, Delin, 1992-; Smith, Douglas E., 1962-Products produced with Additive Manufacturing often have anisotropic microstructures that form material layers are added during processing. Carbon fiber filled polymer deposited in beads with the Fused Filament Fabrication (FFF) process, for example, has been shown to have a highly anisotropic material response. This thesis considers the anisotropic behavior of FFF structures and presents a three dimensional topology optimization method that computes the best anisotropic material distribution and direction for minimum compliance of statically loaded AM structure. The optimization method is applied to single loaded problem, multiple loaded problem, and structures with regions of prescribed solid or void. Results show that printing the structures in different planes yields different minimum compliance of statically loaded AM structure. The opitmization method is applied to single loaded problem, and structures with regions of prescribed solid or void. Results show that printing the structures in different planes yields different minimum compliance, and that the lowest overall compliance is achieved when the applied load vector is parallel to the plan of material orientation. Furthermore, the preferred material orientation generally follows the outer contour of the dense material region for each layer.