纳米流体在内置弹簧管中的流场特性

Flow field characteristic of nanofluids through the spring inserted heat exchange tube

针对Al2O_3-蒸馏水纳米流体在内置螺旋弹簧管中流场特性问题,运用粒子成像测速仪(PIV)对不同质量分数的Al2O_3-蒸馏水纳米流体与蒸馏水在内置螺旋弹簧管中的流场进行了观测分析。获得了不同质量分数的纳米流体在不同雷诺系数下的速度场和涡量图。结果表明:一定质量分数的纳米流体在内置螺旋弹簧换管中明显增强了流体边界层流体的扰动,纳米流体主流区的流速相比蒸馏水入口处提升了29%。在相同雷诺系数条件下纳米流体的轴向速度梯度更大,同时在纳米流体与弹簧管相互耦合作用下,管壁处的涡量是管中心处的4倍。说明Al2O_3-蒸馏水纳米流体对于内置螺旋弹簧换热管对流换热的强化具有促进作用。

In order to investigate the flow filed characteristic of Al2O3-distilled water nanofluids through the spring inserted heat exchange tube,the particle imaging velocimetry（PIV）was used to observe and analyze the tube flow field of Al2O3-distilled water nanofluids with different mass fraction.The velocity field and vorticity graph was obtained from different mass fraction of Al2O3-distilled water nanofluids under different Renault coefficients.A certain quality score of nanofluids was through the spring inserted heat exchange tube,by analyzing the result of average velocity and vorticity field experiment measurements,it obviously increased the fluid boundary layer disturbance.Moreover,it also increased flow velocity for 29% compered the mainstream area with entrance.Under the same Renault coefficients condition,nanofluids had greater axial velocity gradient.Meanwhile,under the coupling effect of nanofluids and spring tube,vorticity of tube wall was4 times bigger than the pipe of the center.In conclusion,Al2O3-distilled water nanofluids had a promoting effect of spring inserted heat exchange tube convection heat transfer.