Abstract
Double coaxial pipe jets which consist of a central round air jet (an inner jet) and an annular air jet (an outer jet) were experimentally investigated. Detailed measurements of the mean-velocity, turbulent intensity and Reynolds stress distributions in the double jets were made. Flow visualization is carried out by mists of a liquid-paraffin for the nozzles with different outer pipe length of L=0, 1Do, 2Do at Reynolds number of 1.35×104. Visualized flows suggest possibilities of the self-excitation of flow in the outside pipe with the length, 1Do.
