Flow Characteristics Of Rotating Cylinders

Flow field control widely exists in practical engineering fields,such as concrete cooling towers,waterwheels,drilling platforms and bridge piers.The impact of its structural composition will seriously change the strength,stability and safety of structures.In this paper,starting from the actual engineering problems of civil engineering,based on the Fluent and Laminar flow simulation method,the numerical study of the active control flow field of the multi-cylinder structure group under low Reynolds number is carried out,and the analysis is focused on the double attached rotating cylinder and the main cylinder Flow characteristics,mutual interference effects and intrinsic mechanics of the volume structure group,the six-cylinder rotating cylinder and main cylinder structure group,and the tandem rotating double cylinder structure group.The main research work of this article is as follows:(1)Under the conditions of Reynolds number Re=50～200,the flow around the double-subordinate rotating cylinder and the main cylinder structure group is studied,and the hydrodynamic parameters of the main cylinder and the surrounding flow field distribution characteristics of the different rotation speeds are analyzed.Influence,and elaborate its inherent mutual interference effect and mechanical mechanism.The study found that with the increase of the rotation rate,the flow field in the wake area of the main cylinder will change greatly,and the vortex shedding is suppressed.At the same time,the drag coefficient of the main cylinder is significantly reduced.(2)Under the condition of Reynolds number Re=200,the flow around the six auxiliary rotating cylinder and the main cylinder structure group is analyzed,and the two key parameters of the incoming flow angle of attack and the rotation rate are analyzed on the hydrodynamic parameters of the main cylinder and its surrounding The influence of flow field distribution characteristics,and elaborate its inherent mutual interference effect and mechanical mechanism.The study found that changes in the angle of attack and rotation rate of the incoming flow have a greater influence on the flow characteristics around the main cylinder structure group,the flow modes of the flow field and their mutual interference effects.Under different operating angles of 0° to 50°,the critical rotation rate to suppress the vortex shedding of the main cylinder is the minimum angle attack 0° The maximum rotation rate of 30° is the same as the critical rotation rate of the structure group symmetrical to the direction of the incoming flow.With the change of the angle of attack of the flow,the flow mode of the flow field around the main cylinder will change significantly.At rest,the shape of the main cylinder after the wake is diverse.In the high-speed rotation state,the wake of the main cylinder is relatively consistent,and the force coefficient of the main cylinder changes significantly by the angle of attack of the incoming flow.(3)Study the three-dimensional flow problem of the tandem double-rotating cylinder structure group with Reynolds number Re=200 operating conditions,and analyze the two key parameters of the rotation rate and spacing ratio on the hydrodynamic parameters of the tandem double-rotating cylinder and its surrounding flow Influence of distribution characteristics,and elaborate its inherent mutual interference effect and mechanical mechanism.The study found that changes in the angle of attack and spacing ratio of the incoming flow have a greater influence on the flow characteristics,flow modes and mutual interference effects of the five-cylinder structure group.Under the condition of small spacing ratio,the rotation of the cylinder makes the flow field produce a three-dimensional effect.Under the conditions of large spacing ratio,the rotation of the cylinder disappears the three-dimensional effect of the flow field until the rotation rate is large enough to restore the three-dimensional effect.As the pitch ratio increases,the critical rotation rate of the upstream cylinder’s influence on the downstream cylinder gradually decreases.Under the L/D=5.0 working condition,the tandem double cylinders at rest have no mutual influence.At the same time,the pressure coefficient of the lower surface of the cylinder is most affected by the rotation rate.The largest change in vortex shedding is at L/D=4.0.The research in this paper can provide theoretical guidance and reference basis for the optimal design of actual projects and the effective saving of resources and losses.