圆管湍流脉动流动与换热的数值模拟

Numerical Simulation of Turbulent Pulsating Flow and Heat Transfer in Tubes

利用标准k-ε模型结合脉动燃烧器尾管的实验参数进行湍流脉动流动与换热的数值模拟,通过修正模型内的冯·卡门常数建立适用于实验条件下的脉动流动的湍流计算模型,并研究脉动湍流中压力振幅和频率对湍流流动和换热特性的影响。研究发现:符合实验条件下的冯·卡门常数范围为0.48～0.52;脉动瞬时截面上的速度在靠近壁面附近出现峰值且速度变化较大;速度与温度分布呈周期性变化;压力振幅越大,速度和温度波动范围就越大,频率越大,速度和温度的波动范围则越小;壁面摩擦系数随着压力振幅的增加而减小,随着频率的增加而增大;壁面平均对流换热系数随压力振幅的增加而增大,随频率的增加而减小。

Numerical simulation of turbulent pulsating flow and heat transfer was done with standard k-ε turbulent model and experimental parameters which came from the tail tube of a pulse combustor. The Von Karman constant was modified in order to suit for the experiment condition, and turbulent pulsating model was established and the influence of amplitude and frequency on turbulent flow and heat transfer was investigated. The results show that the Von Karman constant value is 0.48-0.52 under the experimental condition; the velocity at the instant pulsating flow section varies significantly near the inner surface where it gets the peak value; the distribution of velocity and temperature present the periodical variation; the larger the pressure amplitude gets, the wider variation range of the velocity and temperature fluctuation becomes and it inverse for the frequency; the wall surface friction coefficient declines as the pressure amplitude rises, and it increases as the frequency; the surface average heat transfer coefficient increases along with the growing of the pressure amplitude and declines with the growing of frequency.