The Numerical Simulation Study Of Wet Steam Probe Based On Bidirectional Fluid Solid Coupling

Wet steam plays a key role in the economy and safety of steam turbines.The research on wet steam at home and abroad is mainly focused on two aspects:optical probe experiment and wet steam two phase flow simulation.The wet steam probe on wet steam flow field interrelate at the last stage of steam turbine.The numerical analysis of the complex three element flow problem is carried out by the two-way flow solid coupling technique.The fluid solid coupling model is built by using ANSYS Workbench platform,the two-way coupling calculation of flow field and solid field is achieved.A detailed partition of the fluid grid around the probe ensures the fineness of the near wall mesh and the quality of the whole grid.The k-? model based on turbulent shear stress transport(SST)and dynamic mesh technology are used to improve calculation accuracy and accelerate the convergence.The results of steady state calculation are in good agreement with the results of boundary layer separation theory and vortex shedding theory.The steady state calculation results are used as the initial field to calculate the bidirectional fluid solid interaction.The vibration of the probe and flow field are analyzed.The conclusion shows that The vibration period of the X,Y and Z three directions of probe fluctuate slightly.It is about 0.018s.The oscillation amplitudes in X,Y,Z direction are 0.28mm,4.75?m,5.50?m respectively.The amplitude of the X direction is much larger than the other two directions due to the impact of the fluid.The X and Z direction vibration baseline shift 0 points,Y direction as the probe on both sides of the periodic vortex appear and vibration baseline close to 0 points.Due to the special structure of the optical probe,the pressure differential force acting on the tip of the probe is very small,leading to a decrease in the growth rate of the shape variable at the front end,and the vibration shape is rather special.In the probe vibration period,the stress concentration position of the probe remained unchanged,namely 2/3 point back flow direction of the probe,here is the risk of stress probe.The vibration frequency of the probe deviates from the natural frequency,and the maximum stress is lower than the allowable stress.The turbulent flow near the wall of the solid vibration in high Reynolds number turbulence causes turbulence and variation.The numerical results show that the flow field has a sudden change between two cross section with very small space.The vibration of the probe and the change of the flow field near the probe will have a certain effect on the safety and accuracy of the measurement.