Boundary Layer Flow on a Model Propeller

Flash photographs have been made of a model screw propeller under test in a towing tank, to show the areas of laminar and turbulent flow in the boundary layers over the blades. These areas may be defined from the surface patterns made by ejecting a liquid dye from fine holes in the rotating blade, and the change in extent of each region with change of Reynolds number is coupled with the scale effect evident in model tests.