Calculation Of Hydraulic Transient Process Of Three Different Tailrace Surge Chambers

Reasonable layout of tailrace surge chamber can effectively reduce the influence of surge pressure on hydraulic system,which is related to the safety and stability of the whole hydropower station.In this paper,combined with practical engineering examples,several common layout forams of tailrace surge chamber are drawn up,and the mathematical mode.l and boundary conditions of hydropower station are established.By means of professional numerical simulation software,the adjustment guarantee parameters of several different layout forms of tailrace surge chamber under typical working conditions are compared and analyzed,and the following main results are obtained:(1)Compared with straight-line closing rule and slow-then-fast closing rule,the folding point position in fast-first-then-slow closing rule can better control the stability of the unit.(2)In the process of large fluctuation transition,increasing the-size of surge chamber can effectively control the fluctuation amplitude of surge water level in surge chamber,accelerate the attenuation of water level,and better ensure the stability of other adjustment parameters;Increasin g the moment of inertia of the unit is beneficial to the large fluctuation transition process;The minimum value of pipeline roughness before and after surge chamber can ensure the buried depth at the bottom of surge chamber;Comparing the three arrangements,the first arrangement can effectively control the pressure at the end of volute,draft tube and unit speed,while the third arrangement is beneficial to the fluctuation attenuation of surge water level in surge chamber.(3)In the process of small fluctuation transition,increasing surge chamber size,unit inertia and pipeline roughness can effectively reduce surge water level in surge chamber,which is beneficial to adjusting quality parameters.Compared with three layout form s,layout form one can obtain better adjustment quality,and surge water level fluctuation amplitude in surge chamber is more stable and water level attenuation speed is faster.(4)In the process of hydraulic interference transition,increasing the size of surge chamber is beneficial to the hydraulic interference process,while the inertia of the unit has little influence on the hydraulic interference transition process and has poor sensitivity.The increase of pipeline roughness can effectively reduce the output of the unit,but the selection of roughness should be comprehensively determined in combination with other factors.Compared with the three arrangements,the first arrangement is superior to the other two arrangements in all aspects,with smaller output swing value,lower output swing amplitude,lower surge water level in surge chamber and faster water level attenuation.