The Hydraulic Performance Study Of The Elbow And The Prismatic Draft Tube Based On Flow Calculation

Draft tube is an important component of counter turbine parts,It’s function is to export the kinetic energy of the turbine runner into pressure energy, and recovering some of the energy flow.Generate vibration during the operation of turbine units will affect the stability of the unit,the flow in draft tube has important influence on the stability of the turbine units,Select the appropriate draft tubes has important significance of unit operation stability and unit energy characteristics.This thesis taking a hydropower station model for HL365-LJ- 233 turbine as the research object,using the SolidWorks as 3d modeling,Flow field analysis using FLUENT software.The main research is compare with prismatic draft tube and elbow draft tube under different working conditions,The results of the study are based on the FLUENT software flow field analysis of the speed, pressure and flow diagram.Graphics can be compared with two kinds of draft tube under different conditions of internal water flow, to determine what kind draft tube is better in internal flow and stability.Comparison of performance through simulation calculation of prismatic draft tube and elbow draft tube:Under the small flow rate, both the draft tube internal flow is disorder, the two backflow and stagnation phenomenon is serious;under the optimal operating conditions and the large flow,the velocity and pressure distribution are reasonable, the flow pattern is relatively stable, and the flow line is relatively smooth.In general, the elbow draft tube’s speed, pressure and flow distribution compared with the prismatic draft tube is more uniform.The elbow draft tube internal flow is reasonable, small hydraulic loss, restore good performance,close to the actual situation.