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Full-Text Articles in Mechanical Engineering
Ignition And Extinction Behavior Of Fuels In A Microcombustor, Pawan Sharma
Ignition And Extinction Behavior Of Fuels In A Microcombustor, Pawan Sharma
LSU Doctoral Dissertations
Conventional fuel testing device-CFR engine requires large quantities of fuels, which makes it unsuitable for research of small samples of fuels. This current study seeks to address this limitation by using an externally heated microcombustor as an alternative fuel testing device. Mainly three combustion behaviors have been observed inside a microcombustor: strong flames at higher flow rates, Flames with Repetitive Extinction and Ignition (FREI) at intermediate flow rates, and weak flames at marginal flow rates. In previous studies, weak combustion behavior has been proven suitable to study fuel properties from small samples of fuels. Microcombustor experiments typically rely on flame …
The Effects Of Asymmetric Micro Ratchets On Pool Boiling Performance, Lance Austin Brumfield
The Effects Of Asymmetric Micro Ratchets On Pool Boiling Performance, Lance Austin Brumfield
LSU Doctoral Dissertations
Nucleate boiling is an attractive method for achieving high heat flux at low superheat temperatures. It is frequently used for industrial applications such as heat exchangers and is being considered to cool advanced central processing units (CPU) which produce heat fluxes on the order of 1 MW/m2 and are becoming increasingly less efficient to cool via forced conduction of air. The issue with implementing nucleate boiling as a cooling mechanism lies in the difficulty of quantifying the numerous and complex mechanisms which control the process. A comprehensive nucleate boiling model has yet to be formulated and will be required in …
Steady And Unsteady Thermo-Strucural Simulation Of Thermally Actuated Micro- And Nano-Structures, Elham Maghsoudi
Steady And Unsteady Thermo-Strucural Simulation Of Thermally Actuated Micro- And Nano-Structures, Elham Maghsoudi
LSU Doctoral Dissertations
This dissertation provides a thermo-structural simulation for nano-scale and micro-scale structures with pinned and fixed boundary conditions which are either thermally positioned, buckled, or actuated. The study begins with simulating a pinned-pinned beam in micro-scale and nano-scale. The steady state thermo-structural equation is solved numerically using an implicit Finite Difference method implemented in Matlab to obtain the thermal positioning response, which is the thermally steady state center displacement, by adding a constant, time-independent heat flux to the structure. The results show the steady state thermal displacement of the system is a function of the geometry, pressure, material properties, and constant …
Flow Field And Heat Transfer Analyses Of Mechanical Seals, Zhaogao Luan
Flow Field And Heat Transfer Analyses Of Mechanical Seals, Zhaogao Luan
LSU Doctoral Dissertations
Mechanical seals are widely used in rotating equipment such as pumps, turbines and agitators to prevent leakage. One crucial factor for keeping seals reliable is the thermal behavior of the seal rings. The existing literature on thermal effects in seals primarily concentrates on the conduction of heat into the rings. Yet, a more complete analysis requires understanding of the flow field around the rings. In this dissertation, both the laminar and turbulent flows within the seal chamber are studied and their effects on the heat transfer in the seal rings are evaluated. Based on extensive sets of numerical simulations, heat …
Turbine Blade Tip Cooling And Heat Transfer, Hasan Nasir
Turbine Blade Tip Cooling And Heat Transfer, Hasan Nasir
LSU Doctoral Dissertations
Turbine blade tip leakage flow from blade pressure side to suction side over the tip surface increases the thermal loading to the blade tip, leading to a high local temperature and thus, is considered one of the primary sources of blade failure. Leakage flow can be reduced by using a recessed or squealer tip blade or by cooling the blade tip to incorporate film cooling. The performance of different recessed tip geometries were investigated and compared with plane tip performance. A transient liquid crystal technique was employed to measure detailed heat transfer coefficient distributions. Coolant injection from holes located on …