FLOW CHARACTERISTICS OF ROUND JET ISSUING INTO COUNTER-FLOWING UNIFORM STREAM

摘要

Two-color four beam LDV measurements were conducted for the round jet issuing into a counter-flowing uniform stream under well controlled boundary conditions. A comprehensive set of the velocity data was documented for velocity ratios from 0.8 to 7. The linear dependence of jet penetration length on velocity ratio was confirmed for all conditions investigated, including those with velocity ratios less than 1. The proportional coefficient estimated is substantially larger than those reported for similar jets in a water channel. The streamwise variations of mean velocity and turbulence intensity on the jet axis also depend only on velocity ratio. It is very interesting to know that the streamwise turbulence intensity on the jet axis, non-dimensionalized by uniform velocity, is at a maximum near at the stagnation point and that the maximum has a constant value near 1 for velocity-ratios greater than 2. The static pressure was found to become near to zero at the stagnation point and is negative in the core of the recirculation region.