Abstract:

The flow，resistance and heat transfer performance in fluted tube were numerically investigated and compared with smooth tube by application of three-dimensional steady incompressible fluid turbulence model and water as the working medium. Results showed that the heat transfer performance became stronger in fluted tube than that in smooth tube because of the larger local temperature gradient of the bottom layer flow by disturbance and vortex flow. The fluted structure could significantly enhance the disturbance and mixing of fluids，and produce radial vortex，reduce the boundary layer thickness，increase fluid turbulence，and promote the surface boundary layer to update rapidly. As a result，heat transfer was enhanced but the flow resistance increased also. The heat transfer enhancement mechanism in the fluted tube was analyzed using the field synergy principle. Another important way to strengthen the heat exchange was to make the angle of velocity and temperature fields smaller and to improve the coordination level between velocity field and temperature field.