Experimental and RANS Numerical Study on Wall Turbulence Drag Reduction of Viscoelastic Fluid in Straight Pipe
The turbulent drag reduction effect of viscoelastic fluid is of great engineering value and research significance.In this paper,polyacrylamide(PAM)is taken as the research object,and the experiment and Reynolds-averaged Navier-Stokes(RANS)simulation of wall turbulent drag reduction of viscoelastic fluid in straight pipe are carried out.The experimental test device of turbulent drag reduction of viscoelastic fluid is built,and the drag reduction characteristics of PAM solution are tested and analyzed.The RANS control equation of viscoelastic fluid turbulence is constructed by combining the FENE-P constitutive equation and the RSM anisotropic turbulence model.The RANS subroutine of viscoelastic fluid turbulence is compiled by UDF and loaded into FLUENT to establish the viscoelastic fluid turbulence Reynolds average simulation method that meets the needs of engineering calculation,and further explore the drag reduction mechanism.The results show that with the increase of Reynolds number or concentration,the drag reduction rate of PAM solution increases first and then decreases,and finally tends to be stable.In the experimental temperature range(25℃～55℃),the drag reduction rate of PAM solution is negatively correlated with temperature.The drag reduction rate of PAM solution decreases by about 28.90％when it is continuously sheared for 7 hours.And the higher the concentration,the stronger the shear resistance and temperature resistance.Compared with water,the presence of polymer greatly changes the turbulent flow field structure of viscoelastic fluid.The range of buffer layer is widened,the complete turbulent region is narrowed,the Reynolds shear stress is significantly reduced,and the peak value of the root mean square of the instantaneous pulsation velocity gradually moves to the center of the pipe,which indicates that the addition of polymer effectively suppresses the pulsation of the turbulent near-wall region,makes the turbulent dissipation gradually weaken,and thus shows the drag reduction effect.
Viscoelastic fluidWall turbulenceDrag reduction characteristicsFlow field structureRANS
万方数据
维普
