Koji Hirose

Measurement of a Jet Issuing from a Circular Pipe with a Laser Doppler Velocimeter.

The flow vertically issuing from a circular pipe under gravity is measured by a laser Doppler velocimeter. The flow which is bound on the wall inside the pipe is released at the pipe exit and forms a free surface. First, the jet surface profiles were measured and then, the velocity distributions close to the exit were measured in both pipe and jet. From these experimental data, it is concluded that the profiles of the jet surface and the flow quantities can be expressed appropriately by simple formulas consisting of combinations of three dimensionless numbers: the Reynolds number, the Froude number, and the Weber number.

A flat-plate wing standing on a wall covered with a thick boundary layer.

Pressure distribution on a flat-plate wing surface along the chord is measured in many spanwise positions from the root of the wing, which is immersed in the wall boundary layer, to the wing section far from the wall. The flow near the root of the wing is visualized by the smoke wire method. Two kinds of secondary flow are observed at the junction between the wall and the wing: one is produced by the interaction between the wall boundary layer and the wing; and the other is induced by a static pressure difference between the wall and the suction surface of the wing. With an increasing angle of attack, flow on the suction side of the wing separates from the wing surface. But the two kinds of secondary flow suppress the separation of the flow near the root of the wing. This causes wing characteristics to improve.