Abstract: Nozzles are one of the key parts of the dry-ice blasting system thanks to its significant influences of the nozzle structure and the air supersonic free jet flow fields on the cleaning results. The modeling and simulation of the nozzles of different dimensions are conducted using Fluent software. Then the pressure and velocity fields of inner air flow and jet air flow of quadrate nozzles are obtained. The simulation results show that the air jet pressure at the nozzle outlet is much higher than the atmospheric pressure; a supersonic under-expanded jet is formed near the nozzle outlet accompanied by shock wave. Increasing the nozzle size can weaken the air jet velocity attenuation and extend the shock wave transmission distance, which may weaken the stability of the jet flow. Therefore larger scale nozzles should be selected properly to improve the cleaning effect and increase the cleaning area.

Key words: dry-ice blasting, nozzle, computational fluid dynamics (CFD), flow field simulation