Hydraulic resistance of tubes with internal helical finning designed by deforming cutting

Abstract

An object of investigation is a tube having helical fins on the internal surface and different geometric sizes. Investigation methods: experiments to obtain quantitative results for hydraulic resistance of tubes with internal helical finning and to verify computational algorithm; numerical simulation to visualize the flow structure in the tube. The hydraulic resistance of tubes with internal helical finning was studied over a wide range of operating and geometric parameters: ReD=2…103·2.5…105, under the variation of the angle of swirling α=14°-87°, the relative height of a protrusion h/d=(25-87,5)…10-3, and the relative axial pitch p/d=0.16-12.73. It has been revealed that the hydraulic resistance of tubes with helical finning increases by a factor of 1.1 to 11.7. The numerical simulation results show that with an increase in the angle of helical swirling, in the near-wall layers the share of the circumferential velocity component increases and the share of the longitudinal component decreases. And since the finning height exceeds the boundary layer thickness, the hydraulic resistance grows.