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چكيده انگليسي :

80 Cfd simulation of plume dispersion and rise from stack or chimney in atmospheric scale Mehdi Jahangiri Mehdi Jahangeri@yahoo com April 14 2010 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiM Saghafian Assist Prof Supervisor Saghafian@cc iut ac irAbstractIn this project numerical study of dispersion and rise of smoke plume and distribution of pollutantconcentration on the ground level in 3 D and unsteady condition has been done Also spread of plume withtime and distance from stack has been investigated Because of high temperature difference between smokeplume and environmental air buoyancy force is considered In this project k and k RNGturbulence models are used too Atmospheric conditions are applied as temperature and velocity changeswith altitude in wind flow entrance Reaction between smoke plume and environmental air is ignored Themesh has been smaller where there are intense concentration gradients In order to reduce the calculation timeand because of symmetrical geometry the solution domain is halfed In comparison between achieved resultsfor smoke plume distribution from numerical solution and Gaussian model a few difference are seen whichare caused by supposition that are used for achievement of Gaussian model The results of smoke plume riseare compared with experience relations too which have a good agreement with each other Numericalsimulation predicts the smoke plume rise just less than experience amounts So the amount of pollutionconcentration on the ground level in numerical simulation just over than Gaussian model The amount ofsmoke plume rise in stable and unstable atmosphere states is minimum and maximum ordinary So pollutionconcentration in ground level in stable and unstable atmosphere states is maximum and minimum ordinary Also values of the ground level concentration of air pollutants were evaluated as a function of wind speed intwo cases Results of ground level concentration in two conditions of wind speed show that in a light windspeed maximum ground level is occurred in far away from stack rather than strong wind speed In twoconditions of wind speed rise of plume compared with together Results show that in a light wind speed theplume will rise much more than in a strong wind Consequently the height of rise is a function of the windspeed and in particular is inversely proportional to the wind speed In near of stack that smoke plume isdominated there is a few difference between rise of plume from k RNG turbulence model and kturbulence model By increase of distance from stack and increase of buoyancy force effect rather thanmomentum of smoke plume plume rise difference between k RNG turbulence model and kturbulence model increased In low distance from stack results of k RNG turbulence model is similarBrriggs equation and results of k turbulence model is similar Fay equation By increase of distance fromstack results of k RNG turbulence model and k turbulence model are similar to Briggs equation Key WordsSmoke plume simulation Stack Chimney Atmospheric condition Plume rise anddispersion Ground level concentration

جهانگيري، مهدي

شبيه سازي عددي پخش و صعود دود خروجي از دودكش در مقياس اتمسفريك

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