Abstract: By using CFD method and multiphase flow model , based on the Euler-Euler method,the internal flow field of an internal mixed catalytic cracking feed atomizing nozzle is si-mulated. The distribution of gas-liquid flow field in the nozzle and their mixing characteristics ar-e studied.In order to enhance the entire perforamce of the nozzle,a helical structure is built into it, and the comparative simulation is conducted.The results show that the original structure of the two-phase distribution is relatively concentrated,the tangential velocity of the fluid is almo-st zero,this makes the atomization effect of the nozzle drops,and limited spray range ;the h-elical structure can rotate the fluid inthe mixed chamber and thus fluid obtains a tangential velocit-y with the maximum value of 18.49 m/s. In additon,the turb-ulence intensity of two-phase flow is increased and the average velocity is effectively raised.So the atomization performance of the spr-ay nozzle is finally enhanced.

Key words: FCC feed, atomizing nozzle, helical structure, two phase flow, numerical simulation