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Doctoral Thesis
DOI
10.11606/T.3.2016.tde-05012016-153925
Document
Author
Full name
Celso Luiz Felipini
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2015
Supervisor
Committee
Pimenta, Marcos de Mattos (President)
Altemani, Carlos Alberto Carrasco
Bistafa, Sylvio Reynaldo
Oliveira Junior, Silvio de
Vatavuk, Paulo
Title in Portuguese
Estudo do comportamento do escoamento em tochas de plasma térmico através de simulação numérica.
Keywords in Portuguese
Magnetohidrodinâmica
Mecânica dos fluídos
Método dos volumes finitos
Modelo MHD
Plasma térmico
Simulação numérica
Tocha de plasma
Turbilhonamento
Abstract in Portuguese
Esta tese apresenta um modelo matemático para simulação numérica do escoamento com turbilhonamento (swirl) em tochas de plasma térmico de arco não transferido que operam em corrente contínua, assim como os resultados obtidos com as simulações para estudo de casos. O modelo magneto-hidrodinâmico (modelo MHD) bidimensional permitiu simular a interação entre o escoamento e o arco elétrico usando uma configuração axissimétrica, que abrange as seguintes regiões: entrada do gás; interior da tocha; jato de plasma livre no ambiente. O modelo foi implementado num código numérico baseado no Método dos Volumes Finitos para a solução numérica das equações governantes. Para os estudos foram simulados casos com diferentes condições operacionais (vazão de gás; intensidade de corrente elétrica; gases plasmogênicos: ar e argônio; intensidade de turbilhonamento). A fim de verificar a qualidade do modelo, alguns resultados foram comparados com a literatura e apresentaram boa concordância: a maior diferença obtida entre valores de temperatura experimentais e valores calculados foi -10%, e a média das diferenças obtidas nas comparações foi de aproximadamente ±3,2%. Os perfis de temperatura e de velocidade obtidos para a região do arco e para o jato de plasma resultante permitiram o estudo do comportamento do escoamento na tocha de plasma em diferentes condições. Conclui-se que o modelo desenvolvido é apto à realização de investigações numéricas do escoamento em tochas de plasma e dos efeitos do turbilhonamento na interação arco/escoamento.
Title in English
Study of the flow behavior in thermal plasma torches through numerical simulation.
Keywords in English
Finite volume method
MHD model
Numerical simulation
Plasma torch
Swirl
Thermal plasma
Abstract in English
This thesis presents a mathematical model for numerical simulation of swirling flow in DC non-transferred arc thermal plasma torches, as well as the results obtained from simulations to case studies. The two-dimensional magnetohydrodynamic model (MHD model) allowed simulate the interaction between the flow and the electric arc using an axisymmetric configuration, covering the following areas: gas inlet; inside the torch; free jet of plasma in the environment. The model was implemented in a computer code based on the Finite Volume Method (FVM) to enable the numerical solution of the governing equations. For the study, cases were simulated with different operating conditions (gas flow rate; electric current intensity; plasmogenic gases: air and argon; swirl intensity). In order to verify the quality of the model, some results were compared with the literature and showed good agreement: the biggest difference between experimental temperature values and calculated values was 10%, and the average of the differences obtained in the comparisons was approximately ±3.2%. The resulting profiles of temperature and velocity obtained for the region of the arc and the plasma jet allowed the study of the flow behavior in the plasma torch in different conditions. It is concluded that the model developed is able to carry out numerical investigations of the flow in plasma torches and the effects of swirl in the interaction arc/flow.
 
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Publishing Date
2016-01-13
 
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