内插自旋直齿扭带换热管压降及流场数值模拟

Numerical Simulation of Pressure Drop and Flow Filed in the Heat Exchanger Tube Inserted Self-rotating Straight-tooth Twisted Tape

为了直观地描述内插自旋直齿扭带管内压降及流场的特性,建立了以水为介质的内插自旋直齿扭带换热管内流场的计算模型,采用RNGk~ε湍流模型对管内压降及流场的特性进行数值模拟研究。计算结果表明,扭带管的压降Δp与流体的流速u成抛物线关系,压降随着流速的增大而增大,并且大于空管的压降;扭带管的流体呈有规律的三维螺旋状流动,且存在二次流,扭带的直齿结构增强了流体的湍流程度;在近管壁区域,扭带管的流体轴向速度比空管平均提高幅度在33.05%~35.17%。

In order to visually describe the characteristics of pressure drop and flow filed self-rotating straight-tooth twisted tape inserted in heat exchanger tube, the computer model for the inner basin of heat exchanger tube was established, in which self-rotating straight-tooth twisted tape is inserted with water as the medium, and numerical simulation was taken to study the characteristics of pressure drop and flow filed in tube by using RNG k^s turbulence model. The resuits of numerical simulation indicated that the pressure drop Ap of the tube with twisted tape into a parabola relationship with the flow velocity u, the faster of the flow velocity, the larger of the pressure drop, and it was greater than that of smooth tube. The fluid was a rule of three-di- mensional spiral flow in the tube with twisted tape, making the fluid form a secondary vortex flow. The twisted tape with straight serration structure enhanced the turbulence of fluid. In the region near tube wall, the flow axial velocity of the tube with twisted tape was averagely increased more in the range of 33. 05% - 35.17% than that of smooth tube.