Numerical Simulation Of Turbulence Drag Reduction Characteristics Of Bionic Rib In Gas Pipeline

The provision of tiny grooves on the smooth surface flow can effectively reduced the wall friction and reduced the energy loss during transportation.For the gas pipelines with different shape ribs on the inner surface,numerical simulation was used to simulate different flow states.This paper used CFD software to simulate different types of pipelines.The turbulence model of RNG enhanced wall function and large eddy simulation are mainly used for calculation.Flow field velocity,turbulent kinetic energy,vorticity and Reynolds shear stress were analyzed.The simulation results show that the ribs of different shapes have the effect of drag reduction;the vortex formed by the turbulence forms a small reverse small vortex in the rib when passing through the rib,transforming the sliding friction between the fluid and the wall into rolling friction,reduced the frictional resistance.The smooth section wall,the rib peak of the rib and the velocity profile of the bottom surface only differ greatly in the vicinity of the wall surface,and tend to be consistent away from the wall surface,and the influence of the rib on the flow field mainly occurs in the near wall area.First,designed different rib shapes on the slab.Numerical calculations were carried out on different rib models.The resistance of different types of ribbed plates and smooth plates was compared.It was found that the triangular ribs on the plate had the best drag reduction effect.Then,the triangular ribs and the spaced triangular ribs are constructed in the round tube,and the wall resistance is compared with the smooth gas pipeline.It is found that the triangular ribs have the best drag reduction effect.By analyzing the different velocity,turbulent kinetic energy,vorticity and Reynolds shear stress cloud diagram in the turbulent boundary layer of the smooth tube and rib surface,the influence of the rib shape on the drag reduction effect in the circular tube is obtained.Secondly,the triangular ribs with better drag reduction effect were selected to simulate the inner wall of the round tube with different Reynolds numbers.The different Reynolds numbers Re are selected as 4000,6000,8000,10000 and 12000 respectively.The numerical simulation of the triangular ribs embedded in the circular tube is carried out to compare the surface resistance of the ribs in five different cases.The reductive effect is relatively good when Re=8000 is obtained.it is good.Again,numerical simulations of different sized triangular ribs on the inner wall of the tube are performed.By comparing the drag reduction ratios of the two-size triangular ribs,it is found that the ribs have a drag reducing effect at s~+=22.1 and 41.7.Finally,according to the theory of bionics.A new rib shape was constructed in the circular tube,and a large eddy simulation is used to calculate the Reynolds number 8000 with better drag reduction effect.Comparing the wall resistance with smooth ribs and traditional triangular ribs,it is found that the new ribs have the best drag reduction effect.The speed,turbulent kinetic energy,vorticity and Reynolds shear force of different ribs were analyzed to obtain the effect of rib shape on the drag reduction effect in the round tube.