Abstract: The uniform distribution of heat medium in drying chamber affects the drying effect of materials. A simplified model of circulating dryer was established， and was used to simulate the flow field in a drying chamber based on Fluent. It consisted of the standard k\|ε approach to model the flow turbulence， and used porous medium model instead of material. The velocity distributions in chamber flow field were obtained and used to analyze the improved designs based on the original structure. The results showed that four vortex zones were formed in original structure because of hitting toward the wall， which led to uneven velocity of material. The ladder\|shaped arrangement of baffle at the entrance could reduce eddy current of flow field， and the uniformity of whole flow field were improved. Uneven coefficient of air velocity through the material decreased from 19.13%， 6.94% and 801% to 7.9%， 3.15% and 5.68%， respectively.

Key words: dryer, flow field, numerical simulation, optimization