有限長十字形ノズルから流出する三次元噴流 : 第1報,平均流特性

The mean flow properties of air jets issuing from cruciform nozzles having four aspect ratios into still air have been measured using a pitot static tube. It is suggested that some unusual features of the flow in the present jet are associated with a three-dimensional effect, say the secondary flow. The aspect ratio plays a very important role on the jet development through this three-dimensional effect. In comparison to the other types of nozzle flow, such as rectangular, circular, square and cruciform shapes with a sufficiently large value of aspect ratio, flows out of present nozzles are found to have anomaluos behaviour, including the appearance of a saddle·backed velocity profile, unequal spreading rates both in the symmetric slice and changing rates of centerline velocity decay in the down-stream direction.