Analysis Of Heat Transfer Characteristics Of Flame Impinging To A Plane Surface Perpendicular To Flame Jet Axis

This thesis work consists a Flame jet impingement which is used in industrial heating and melting, aerospace applications also in safety research etc. to obtain high heat transfer rates. Jet impingement is generally used where high convective heat transfer rates are required. A theoretical analysis of laminar flame impinging perpendicularly on a flat surface has been developed to predict the influences of jet Reynolds number, ratio of plate separation distance to nozzle diameter and equivalence ratio on the Nusselt number. The analysis is based on numerical solution of the governing differential equations for conservation of mass, momentum and energy. Ethane, Propane, Acetylene, Hydrogen, Nitrogen and Oxygen have been considered as fuel and oxidizer respectively. It has been observed that the heat flux distribution for perpendicular plate is increasing with an enhancement on velocity gradient. The heat flux is higher for Nitrogen as compared to other fuels. The local heat flux decreases with an increase in heating height. A fuel rich mixture increases the plate heat flux. The average Nusselt number, Nu increases with an increase in jet Reynolds number, Re and separation distance. The average Nusselt number, Nu decreases with equivalence ratio. The increase in Nu is profound at higher values of Re. The conclusions and future scope has been manifested at the end of the work. Nomenclatures Cp specific heat D sphere or cylinder diameter d nozzle diameter G mass of gas flowing per second per unit cross-sectional area of gas stream h enthalpy per unit mass of mixture 117 International Journal of Engineering Research & Technology (IJERT) Vol. 2 Issue 8, August 2013 IJ E R T IJ E R T ISSN: 2278-0181 www.ijert.org IJERTV2IS80228 578 hd atomic dissociation energy Ht total enthalpy K thermal conductivity Nu Nusselt number Pr Prandtl number Ra Rayleigh Number q heat flux qf firing rate R radial distance from stagnation point along impingement surface St Stanton number H/d dimensionless distance between nozzle and target surface T temperature U gas stream velocity or time averaged longitudinal velocity Y mass fraction of different species h inclination angle of impingement plate q density b velocity gradient (s_1) l dynamic viscosity m kinematic viscosity D change in particular quantity e emissivity ∅ Equivalence ratio X oxygen enrichment ratio b body or target e’ condition at outer edge of body eq equilibrium f frozen condition