Axisymmetric Turbulent Counter Jet in Uniform Flow

Abstract

LDV measurements were conducted in the turbulent round jet issuing into a counterflowing uniform stream for various velocity-ratios from 0.8 to 6. The penetrating length of the jet into the counterflowing stream depends only on the velocity-ratio and increases exactly linearly with it. The mean velocity and the turbulent intensity variations on the jet axis depend also only on the velocity-ratio. It is very interesting to know that the turbulent intensity on the jet axis, non-dimensionarized by the uniform counterflowing velocity, takes a maximum nearly at the stagnation point and the maximum has a constant value of 1 for velocity-ratios greater than 2. Surprisingly enough, measurements with a static tube show that the pressure difference from the ambient flow becomes zero at the stagnation point and is negative almost everywhere in the jet.