Master of Science in Mechanical Engineering, Cleveland State University, 2015, Washkewicz College of Engineering

Design of the fluid flow and heat transfer components utilizing the Computational Fluid Dynamics (CFD) is relatively new yet cheaper and accurate method that becomes popular and reliable today. In this thesis, design of a heat exchanger using CFD analysis technique is considered. A key investigation of this devise is the selection of the tubes and connection them to inlet and outlet manifolds. Correctly selected tube size and tube cross section impacts the heat exchanger performance. Thermal and hydrodynamic performance of the flow in circular and elliptic tubes connected to the inlet and outlet manifolds have been computationally investigated for maximum Figure of Merit. The tube with high Figure of Merit is the one with high heat transfer rate and low pressure drop. The tube has four different configurations of the cross section: a circular tube and three elliptic tubes with aspect ratios = 0.75, 0.50, and 0.25. All tubes are constrained to have the same wetted perimeter and the length, thus have the same heat transfer area. The tube is a smooth straight tube that has the length of 0.3048 m (12 in.) and wetted perimeter of 0.0798 m (3.1416 in.). The tube wall thickness is negligible. The contribution of the inlet and outlet manifolds is examined. A wide range of Reynolds numbers is covered, Re =100 (laminar flow), 10,000 (transitional flow), and 20,000 (turbulent flow). ANSYS FLUENT commercial code has been utilized in this investigation. The code was validated matching with experimental correlations (for developing hydrodynamic and thermal flow) available in the literature. The CFD simulation results were in agreement with the experimental correlation within 5%. This investigation started with simulating 12 different flow conditions inside the tubes without manifolds: three sets with four different tube options (as stated above) in each set. Each set represents the different flow regime: laminar transitional and turbulent with set Reynold number value, as n (open full item for complete abstract)

Committee: Mounir Ibrahim PhD (Committee Chair); Majid Rashidi PhD (Committee Member); Asuquo Ebiana PhD (Committee Member) Subjects: Aerospace Engineering; Automotive Engineering; Mechanical Engineering; Nuclear Engineering; Petroleum Engineering

PhD, University of Cincinnati, 2002, Engineering : Aerospace Engineering

The performance of liquid fuel atomizer in gas turbine combustor has direct effects on flame stability, combustion efficiency, and pollutant emissions. Therefore, further understanding of the underlying physics of these atomizers is one of the primary requirements for advanced gas turbine combustor design. Simplex atomizers are commonly used in air-breathing gas turbine engines because they produce good atomization characteristics and are relatively simple and inexpensive to manufacture. Internal flow characteristics of simplex nozzles play a very important role on the atomizer performance. So it is of great practical interest to examine the relationships between internal flow characteristics, nozzle design variables, and important spray features. Part I of this dissertation revealed the detailed flow structure inside simplex atomizers through the DPIV and LDV study. The internal flow field is generally symmetric except very near the inlet slot plane. The velocity profiles are very similar at different axial locations within the swirl chamber. The discharge parameters were measured and used to examine the correlations from previous researchers. Detailed flow field information was linked with the discharge parameters to obtain more insight into the nozzle performance. The relationship between the internal flow characteristics and discharge parameters confirmed that the internal flow structure plays a very important role on the atomizer performance. Part II presents the internal flow structure of large-scale simplex nozzles at two different working-fluid/ambient-fluid density ratios. The effects of density ratio, Reynolds number and orifice geometry on the internal flow field were examined by using a 2-D LDV probe. At the higher density ratio, Reynolds number and orifice geometry has little impact on the internal flow field. At the lower density ratio, the orifice contraction angle has little effect on the internal flow field, whereas the expansion angle can significa (open full item for complete abstract)

Committee: Dr. San-Mou Jeng (Advisor) Subjects: Engineering, Aerospace