Flow Analysis And Optimization Design Of Typical Pipeline Accessories

With the exploration of the sea world by human being, newer and greaterperformance of ships has been acquired. Decreasing vibration of the pipe system causedby the liquid flow has a great positive effect to enhance the performance of ships and tokeep the security of the sailing. Consequently, it is very important to carry out a flowsimulation and turbulent pressure pulsation characteristics analysis of the typicalpipeline fittings.In this paper, by using the Large Eddy Simulation method, the interior unsteadyflow field speed characteristics of tee line, sluice valve and isolating valve and thevibration performance of the pipeline fittings in the drive of turbulent pressure pulsationwere studied under three different circumstances with a free stream velocity of20m/s,30m/s and40m/s. The results show that eddies is produced at the shunt place of the teeline, which leads to the oscillation of pressure and the vibration of the wall of thepipeline. Most of the fluid can flow through the port evenly and placidly when thesluice valve is fully open. Pipeline vibration is mainly caused by the detouring andstriking of a small amount of the fluid in the valve. The secondary flow emerged at thecorner of entrance and exit of the valve, together with eddies caused by fluid flowingthrough the valve, produce a high speed region, and thus give rise to the pipelinevibration. The force and bending moment in the tee line, sluice valve and isolating valveexhibit high-frequency wave characteristics, howerver the wave amplitude is very small.Horizontal stress is bigger than vertical stress. With increasing velocity of the freestream, the force and bending moment and their pulsing becomes bigger and bigger.Based on the study above，an optimization design of the junction and shunt tee linewas made by changing the form of the centre line of the tee line. And the flow speeduniformity coefficient was used to replace the vibration amplitude of the pipelinefittings as the optimization goal. The result of the design shows that the smaller thespeed uniformity coefficient is, the more even will the flow field be. Therefore thepressure oscillation and the pipeline vibration caused by the liquid flow will be smalleras well. In this way, the value of the optimization goal is decreased to0.05395which isreduced by23.1591%compares to the prototype of0.07021. Accordingly, the flowcharacteristics of the pipeline have a great improvement, and the vibration of thepipeline has been significantly reduced.