Skin Friction versus Fire Propagation

Flame Impingment;Vorticity Amplification Theory;Stagnation Point;Turbulent Intensity;Flame Impingement

Gibson, LaTosha ; Dr. William Roberts, Committee Member,Dr. Kevin Lyons, Committee Chair,Dr. Zhilin Li, Committee Member,Gibson, LaTosha ; Dr. William Roberts ; Committee Member ; Dr. Kevin Lyons ; Committee Chair ; Dr. Zhilin Li ; Committee Member

University:North Carolina State University

关键词: Flame Impingment;    Vorticity Amplification Theory;    Stagnation Point;    Turbulent Intensity;    Flame Impingement;   

Others  :  https://repository.lib.ncsu.edu/bitstream/handle/1840.16/530/etd.pdf?sequence=1&isAllowed=y

美国|英语

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【 摘 要 】

In examination of skin friction versus fire propagation, two methods of solution were of interest: (1) the viscous solution of the incompressible stagnation point velocity flow and (2) the Amplification Theory. For stagnation point velocity flow, the velocity is assumed to be zero at the stagnation point for the viscous solution. The Amplification Theory, however, deduces that the velocity is characterized by vortexes at the stagnation point. Therefore it was hypothesized that turbulence intensity through the Amplification Theory would render higher values for skin friction. The accounting of flame stretch was believed to have a small effect on the value of skin friction since the stretched laminar burning velocity is a product of the laminar burning velocity, and the pressure and temperature risen by a small power. Because of the direct correlation between the wall heat flux at the stagnation point and shear stress, the associated analytical heat flux equation utilizing the stagnation velocity gradient as a function of turbulent intensity was believed to be in a closer approximation to empirical values than the heat flux associated with the viscous solution for the incompressible stagnation point flow. Overall, the values from the viscous solution of the stagnation point velocity reported lower values than values of the K-epsilon solution involving premixed combustion. However, factoring stretch decreased the skin friction within the stagnation region. The empirical heat flux formula was shown to be in closer proximity to experimental values than the semi-analytical and theoretical heat flux solution.