Abstract
Visualization of gas flow is a very important technique for the study of fluidic elements, but it is far more difficult than the visualization of liquid flow. Except some impractical optical methods, most methods for gas flow visualization utilize some tracer in the flow, and in most cases the tracer undesirably changes the flow characteristics. It is desirable, therefore, that the tracer and the operating gas possess the closest resemblance in their flow characteristics.
Ozone absorbs very strongly the ultraviolet radiation of 200 to 300 millimicron wavelength. Therefore, by illuminating a fluorescent plate with parallel ultraviolet radiation through the gas flow, the flow containing ozone can be visualized as a dark silhouette on the plate. The visualization technique based upon this principle was applied to the wall attachment fluidic elements, and it was revealed that the amount of ozone necessary to visualize the air flow is so small that it can hardly affect the flow characteristics. It is also possible to observe the transient state of the flow by adding ozone intermittently into the flow.
