摘要
对不可压缩脉动流动的流动和换热特性进行了数值模拟研究.当脉动频率较低时,充分发展的振荡速度分布类似于稳态的抛物形分布,而频率很高时,脉动的影响显现出来并且体现在靠近壁面的狭窄区域内.在脉动流动下,入口段的长度值发生类似正弦方式的波动,其相位和振幅受脉动频率的影响,壁面摩擦系数也发生正弦规律的变化,其相位和振幅也与脉动频率有关.另外,脉动对于壁面的换热也有一定影响,随着频率的增大,流体的脉动对于换热的影响逐渐被局限在加热段上游.研究结果表明,脉动流动的摩擦损失和换热特性与稳态流动的截然不同,对于处在非定常流动工况(如振荡流动)下的热系统部件的优化设计,需加以认真考虑.
A numerical study was performed for incompressible laminar pulsating flow in a channel. Comprehensive data on the flow and heat transfer characteristics were obtained in the wide range of two main parameters, i.e. the dimensionless pulsating amplitude, 0<A<0.75, and the dimensionless pulsating frequency 0<M<15.0. The velocity profiles resemble much of the quasi-steady solutions at low pulsating frequency, however, the effects of pulsation are distinct and confined to a narrow zone adjacent to the walls when the frequency is high. The entrance length and the skin friction coefficient of pulsating flow all fluctuate in approximately sinusoidal manner. There are phase lags between these parameters and the inlet velocity, and the phase lags are relevant to the pulsating frequency. The changes in the Nusselt number due to the pulsation are pronounced in the entrance region and minor at far downstream locations, and the effects of pulsation on Nusselt number are almost limited in small entrance region when the frequency is high. The results show that, the physical characteristics of pulsating flow are much dissimilar to the steady throughflow, and should be taken into account when thermal equipment is designed under unsteady flow condition.
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
2004年第9期925-928,共4页
Journal of Xi'an Jiaotong University
基金
国家重点基础研究发展规划资助项目 (G2 0 0 0 0 2 63 0 3 )
国家自然科学基金资助项目 (50 2 760 46)
关键词
脉动流动
脉动频率
脉动振幅
数值模拟
Channel flow
Computer simulation
Heat transfer
Incompressible flow
Laminar flow
Nusselt number
Velocity measurement
