Experimental and Analytical Investigation of Near-Field Coaxial Mixing.

摘要

In the near field of coaxial jets,the structure of the flow field undergoes rapid changes as it evolves from the boundary layers at the nozzle exit,through a quasi-two-dimensional shear-layer region,to an axisymmetric jet flow. These rapid changes in flow structure have raised questions concerning the applicability of turbulent flow models in the near field,but few experimental results are available to test predictive techniques. In this report,the results of a series of experiments concerned with the near field of coaxial,nearly constant density,air-air jets are described. The experiments were carried out at an external stream velocity of 30.5 m/sec,and at nominal inner jet-to-outer jet velocity ratios of 3:1, 2:1,and 1:1.