周囲気体と密度の異なる乱流噴流

抄録

Predicting the flow field where gases of different kinds are mixing is important in providing design guidance in a number of engineering systems, e.g. diffusion type chemical lasers, rocket injectors and scramjets.
By using mixtures of air and helium, density and velocity distributions in axially symmetric jet exhausting into the free atmosphere are measured with a high accuracy. It is shown that the far downstream radial distributions of velocity and density are similar and they may all be approximated by the Gaussian distribution. The velocity and density at the centerline are inversely proportional to the streamwise coordinate. The linear increase of the half radius with the axial coordinate is observed, however, the rate of linear spread is found to be strongly dependent upon the difference in density between the jet and the receiving medium. On the basis of the measurements the eddy viscosity and the turbulent Schmit number in fully developed region are calculated by numerical analysis.