Study On The Internal Flow And Fluid-Structure Coupling Characteristics Of Adjustable Straight Guide Vane Of Bidirectional Submersible Tubular Pump

The submersible tubular pump device adopts a two-way impeller to meet the requirements of its two-way operation,while taking into account the forward and reverse operating efficiency.The guide vane is an important flow component of the pump device,and its matching degree with the impeller determines the hydraulic loss of the guide vane,which affects the efficiency of the pump device.It is difficult to match the impeller and the guide vane when the guide vane of the bidirectional pump device is in forward and reverse operation.Based on this,this paper uses the bidirectional adjustable straight guide vane to study its fluidsolid coupling characteristics by numerical simulation.The vibration characteristics of the guide vane were studied by analyzing the stress distribution of the guide vane under static force,the deformation of the blade,the natural mode,the wet mode of the guide vane under dynamic action,and the frequency and vibration mode after one-way transient fluid-solid coupling.In this paper,the three-dimensional steady numerical simulation of the prototype bidirectional submersible tubular pump device is carried out.The hydraulic characteristics difference between the prototype and the model device,the internal flow characteristics of the guide vane and the internal flow characteristics of the adjustable guide vane under different guide vane placement angles are analyzed.The highest efficiency of the prototype pump device is obtained when the guide vane placement angle is 12°in both forward and reverse operation,and the flow pattern at the inlet of the guide vane is better under different guide vane placement angles.With the increase of the height of the guide vane,the vortex and defluidization extending from the inlet to the outlet of the guide vane are continuously improved.In addition,based on the three-dimensional steady numerical simulation results,the stress and strain distribution of the adjustable guide vane during steady-state operation were simulated and analyzed by one-way fluid-solid coupling method on the Workbench platform.For the rear adjustable guide vane,regardless of the forward and reverse operation,different flow conditions and different blade placement angles,the stress concentration distribution area is relatively consistent,all at the guide vane and shaft connection.In the forward operation,the maximum equivalent stress of the guide vane increases first and then decreases with the increase of the flow rate,and the maximum deformation of the guide vane increases first and then decreases.In the reverse operation,the equivalent stress of the guide vane under different flow conditions is not much different,and the distribution of the maximum deformation position is also consistent.For the front adjustable guide vane,the maximum equivalent stress of the guide vane decreases first and then increases with the increase of the flow rate,and the maximum deformation of the vane increases.In the forward operation,the stress concentration areas are consistent,all at the connection between the blade and the upper and lower shafts.With the increase of flow rate,the maximum equivalent stress is basically the same,and the maximum deformation of the blade is basically unchanged.In order to further study the structural dynamic characteristics of the adjustable guide vane under one-way transient fluid-solid coupling,the unsteady numerical simulation was used to study the pump device with the adjustable guide vane placement angle of 12°.In the forward operation,under the small flow condition,the fluctuation amplitude of the monitoring point near the hub of the adjustable guide vane inlet fluctuates greatly,while the fluctuation amplitude of the monitoring point near the rim shows a certain periodic change.Under the small flow condition and the optimal condition,the outlet of the adjustable guide vane is affected by the internal reflux,vortex and other bad flow patterns and the dynamic and static interference.The monitoring points have large fluctuations,and the low frequency pulsation is obvious.In the reverse operation,the main frequency of pressure pulsation at each monitoring point at the inlet of the adjustable guide vane is at 4 times the rotation frequency,the second main frequency is at 8 times the rotation frequency,and the third main frequency is at 12 times the rotation frequency.Under the optimal conditions and large flow conditions,due to the influence of dynamic and static interference,the water flow at the outlet of the adjustable guide vane is unstable,the pressure fluctuation amplitude fluctuates violently,and the main frequency fluctuation amplitude has no obvious law.In addition,by loading the fluid excitation force obtained by unsteady numerical simulation on the solid domain,and setting monitoring points on the locations where the blade is prone to damage,the stress information of the blade changing with time is obtained,and the natural mode and wet mode of the guide vane are compared and analyzed.Under different flow conditions in the positive and negative directions,the stress at the connection between the inlet and outlet of the blade and the upper shaft is much larger than the stress at the connection between the inlet and outlet of the blade and the lower shaft.At the same time,in the forward and reverse operation,the main frequency of the fluid excitation force of the single guide blade is much smaller than its natural frequency in water,so the blade itself will not resonate.