Abstract: A three-dimensional fluid flow model for a self-rotating twisted-tape-inserted tube was presented.The RNG k-ε turbulent model was used to simulate the fluid flow and heat transfer in the self-rotating twisted-tape-inserted tube.The characteristics of fluid flow and heat transfer in the self-rotating twisted-tape-inserted tube were determined.Numerical simulation results showed that the fluid flow was a complex three-dimensional helix flow in the self-rotating twisted-tape-inserted tube.Axial velocity was higher in the annular area near the tube wall than that in the smooth tube; the tangential velocity in the diameter area corresponding to the width of twisted tape increased with the radius.The tangential motion in the annular area between the twisted tape and tube wall was obvious, but the tangential velocity decreased with the radius. However, the tangential motion of the fluid in the smooth tube was only stochastic, and the tangential velocity was smaller by two orders of magnitude.The radial velocity and turbulence intensity were also larger than those in the smooth tube.Due to increase of the axial velocity,tangential velocity,radial velocity and turbulence intensity, the convection heat transfer of the fluid was strengthened and the surface heat transfer coefficient for the self-rotating twisted-tape-inserted tube was larger than that of the smooth tube.In addition, numerical simulation results of the velocity field were compared with the experimental data measured by Laser Doppler Velocimeter （LDV） system.The numerical simulation results showed reasonably good agreement with the experimental data.

Key words: 自转螺旋扭带管, RNG k-ε模型, 数值模拟, 强化传热

摘要： 建立了内置自转螺旋扭带管的三维流动模型，采用RNG k-ε湍流模型对管内流场进行了数值模拟，得到了流体的流动和传热特性.研究表明：自转扭带管内的流动是复杂的三维螺旋流动.流体在扭带与管内壁环缝区域的轴向速度比光管的大;流体在与扭带宽度等直径范围内的切向速度随半径的增大而增大，流体在扭带与管内壁环缝区域内也存在明显的切向速度，但随半径的增大而减小;而光管内流体的流动只有随机的切向运动，且其切向速度要比扭带管内的切向速度小2个数量级;扭带管流体的径向速度和湍流度也比光管的大.扭带管内流体近管壁区域轴向、切向、径向速度和湍流度的加大，强化了管内的对流传热，其表面传热系数大于光管.另外，速度场的模拟值与激光测试值进行了比较，二者吻合较好.

关键词: 自转螺旋扭带管, RNG k-ε模型, 数值模拟, 强化传热