Abstract: The spray system is very important to a dishwasher, and the design of the spray arm has impact on the cleaning efficiency of the dishwasher. So it is necessary to study the mode and status of the spray and the rotation impact to the cleaning efficiency. At the same time, the well designed spray could improve the cleaning efficiency and lower the energy consumption and water consumption. We got the values between the tangent of rotation and the vertical water spraying pressure by analysis the working process of the spray, virtual simulation and testing. We got the distribution of the water spraying by virtual images. We got the line chart by analysing different cleaning efficiency from different spray rotation. We got all the information about how the spray is working and gave reference for future dishwasher design.

Key words: Spray arm, Simulation analysis, Washing logic, Experimental study