Estudo dos efeitos dinâmicos em condutas de PVC durante regimes tansitórios

Alexandre Kepler, Dídia I. Cameira, Luisa F. Ribeiro

Resumen

A teoria clássica do golpe de aríete é usualmente utilizada para a modelaçao de sistemas de condutas em pressão e, tipicamente, considera que a atenuação de uma onda de pressão numa conduta forçada ocorre principalmente devido ao efeito do atrito calculado para condiçoes de escoamento permanente. No entanto, para a descrição do comportamento hidráulico de sistemas existentes, debe ser dada atenção especial aos diferentes efeitos dinâmicos relacionados com a dissipação de energia durante a ocurrência de transitórios hidráulicos. Além disso, a teoria clássica é consideravelmente imprecisa para condutas de plástico (como o polietileno e o policloreto de vinilo), as quais são caracterizadas por comportamento reológico viscoelástico. No presente trabalho, um simulador hidráulico, que incorpora os efeitos de factor de atrito variável e da viscoelasticidade do material da conduta, foi utilizado para análise de transitórios hidráulicos em um sistema experimental composto por condutas de policloreto de vinilo (PVC). Os resultados numéricos demonstraram que, quando apenas o factor de atrito variável é considerado nas simulações, a atenuação e a dispersão das ondas de pressão observadas não são reproduzidas a contento. A incorporação do comportamento viscoelástico do material da conducta resultou em bons ajustamentos dos valores simulados aos dados de pressão medidos numa instalação experimental.

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