抄録
Experiments are conducted on the initial growth of free surface waves on a high-speed (5 to 15m/s) water jet. The free surface fluctuations are measured by using laser beam refraction at the water surface. The variations of boundary layer along the nozzle wall are also measured. The retransition from laminar to turbulent boundary layer causes a quick increase in turbulence at nozzle exit. On the other hand, the free surface waves become continuous, eventually, as the intermittent packets become longer and merge with each other. The agreement between the disappearance of smooth region on free surface and complete retransition at nozzle exit confirmed that the history of the growth of the boundary layer along the nozzle wall has a significant influence on the initial growth of waves.
