Numerical Simulation Of Hydrodynamic Cavitation Effect Of Chitosan Solution On Free Radical Production

With the in-depth study of hydrodynamic cavitation degradation of chitosan,it is found that chemical effect plays a major role in the degradation process.The strength of the chemical effect is related to the yield of hydroxyl radical.Therefore,the hydroxyl radical yield of chitosan degraded by hydrodynamic cavitation was numerically simulated by establishing the downstream bubble dynamics model of cavitation chamber and combining with the minimum free energy method.To explore the influence of different factors on the yield of hydroxyl radical,the main research contents and results are as follows:(1)Considering the solution viscosity,surface tension,compressibility,cavitation and mass transfer,heat transfer and the factors such as turbulence effect,build the more perfect hydrodynamic cavitation bubble dynamics model,because of the cavitation bubble at the instant of the crush keep thermodynamic equilibrium state,so the combination of minimum free energy method,and through the software on bubble dynamics model and formula of minimum free energy method,the preparation of the program.(2)Numerical simulation is carried out for orifice hydradynamic cavitation.The effects of chitosan solution concentration,solution temperature,downstream pipe diameter of cavitation,initial radius of cavitating bubble,downstream recovery pressure and ratio of pipe diameter to pipe diameter on the yield of hydroxyl radical were investigated.The results showed that the concentration of chitosan solution had a significant effect on the yield of hydroxyl radical.With the increase of the initial radius of the cavitation,the amount of hydroxyl radical was increased due to the cavitation collapse.Increasing the temperature of the solution can increase the yield of hydroxyl radical.With the increase of the recovery pressure downstream of the orifice,the amount of hydroxyl radical produced increased.The increase of pipe diameter downstream of orifice has no significant effect on the yield of hydroxyl radical.When the ratio of orifice diameter to pipe diameter increases,the yield of hydroxyl radical also increases.(3)Numerical simulation was carried out for the venturi pipe hydrodynamic cavitation.The effects of concentration of chitosan solution,initial radius of cavitation bubble,downstream recovery pressure and ratio of pipe diameter to pipe diameter on the yield of hydroxyl radical were investigated.The results showed that the concentration of chitosan solution had a significant effect on the yield of hydroxyl radical.With the increase of the initial radius of the cavitation,the amount of hydroxyl radical was increased due to the cavitation collapse.With the increase of the recovery pressure downstream of the orifice,the amount of hydroxyl radical produced increased.When the ratio of orifice diameter to pipe diameter increases,the yield of hydroxyl radical also increases.The results of this paper reflect the trend of the influence of various factors on the yield of hydroxyl radical in chitosan solution,which lays a foundation for the further study on the amount of free radicals produced by the hydrodynamic cavitation bubbles in chitosan solution.