通道形状对活塞冷却油腔内工作流体阻力及流动特性的影响

为揭示通道形状对活塞冷却油腔内工作流体的阻力及流动特性的影响，将冷却油腔的直壁通道改为波壁通道，并采用压力差和可视化的方法对通道内工作流体的阻力及流动特性展开了实验研究。压力差实验结果表明，与水在直壁通道内的流动相比，水在波壁通道内层湍转捩点大大提前，将非牛顿流体替换水作为工作流体后，层湍转捩点再次提前；可视化实验结果表明，波壁通道内工作流体在雷诺数较低时就可呈现不稳定流动形态。为在较低雷诺数下继续强化活塞冷却油腔内的热质传递，进一步开展了脉动流场下非牛顿流体在波壁通道内的流动特性实验和数值模拟研究，结果表明：脉动流场的操作参数对波壁通道内非牛顿流体的流动不稳定率有较大影响，且影响了通道内非牛顿流体的质量传递。

Effects of Channel Shape on Resistances and Flow Characteristics of Working Fluids in Piston Cooling Oil Cavities

In order to reveal the effects of channel shape on resistances and flow characteristics of working fluids in piston cooling oil cavities, a straight wall channel was changed into the wave-walled channel, and experimental studies were carried out by pressure difference and visualization methods. The experimental results of pressure difference show that the water in wave-wall channel leads to an earlier transition point of laminar flow to turbulence compared with the flow of water in straight wall channel, and the transition point is brought forward again when non-Newtonian fluid is as the working fluids instead of water. The experimental results of visualization show that the working fluid in the wave-wall channel may observe the unstable flow pattern when the Reynolds number is low. In order to further enhance the process of heat and mass transfer at low Reynolds numbers, the flow characteristics of non-Newtonian fluid in the wave-walled channel were studied under pulsating flow field by experiments and numerical simulation. The results show that the operation parameters of the pulsating flow field have significant influences on instability rate of flow for non-Newtonian in the wave-wall channel, and further impact on the mass transfer.