非等温湍流射流中脉动量的耗散规律

Dissipation Rates of Kinetic Energy and Temperature in a Circular Non-isothermal Turbulent Jet

本文利用具有高频响应的恒温热线和恒流冷线的组合探头对非等温湍流圆形射流中的湍流脉动动能和脉动温度的耗散率(ε,ε_θ)及其分布规律进行了测量.结果证实了由满足自模条件导出的Taylor微尺度和湍动能耗散率在射流中心线上的变化关系是成立的.推导了中心线上湍流温度耗散率的表达式并得到了较好的结果.

The average rates of dissipation of turbulent kinetic energy and temperature in a non-isothermal circular turbulent jet were investigated using a combined probe with a constant temperature anemometer and a constant current anemometer. The data confirmed the correlations derived from requirements of self-preservation for the streamwise variation of Taylor microscale and the average rate of dissipation of turbulent kinetic energy at the jet axis. An expression for the average rate of temperature dissipation at the jet axis was derived and is supported by experimental results. The correlation may be useful in designing jet experiments and in modelling the turbulent temperature dissipation. The ratio between the time-scale of the thermal turbulent field and that of the turbulent field, the ratio of which is often assumed to be constant in turbulent modelling, is found to decrease with an increase of streamwise distance at the jet axis.