Abstract: The airflow ripple was investigated by CFD(computational fluid dynamics) technique.(After) analyzing the flow fields of the device,some parameters,such as distribution of equal pressure surface,the reducing tendency of circumferential velocity,and a curve of airflow ripples were obtained.An(optimizing) design was engaged for the new device to remove the airflow ripples.The simulating compu-(tation) reveals the basic features and their changes of the airflow in the device.The primary principles to(reduce) the airflow ripples were analyzed.