Optimization Of Inter Stage Guide Vane Of Hydraulic Turbine Type

Hydraulic turbine is a kind of high residual pressure liquid energy recovery device,which is mainly used in seawater desalination,oil hydrocracking,residue hydrotreating,metallurgy and other industries.Some of it is also used for energy recovery in water supply network.At present,most of the hydraulic turbines are pump type.This type of hydraulic turbine directly uses different types of centrifugal pumps?mainly multi-stage pumps?as prime movers.It is simple in structure,low in price and easy to obtain.It plays an important role in the early stage of recovery and utilization of industrial residual pressure.However,the runner and flow passage parts of the pumps as turbines?PATs?are designed according to the working condition of the pump,which is not suitable for the turbine working condition of the prime mover.The efficiency of pumps as turbines?PATs?is low and the operation range is narrow,which results in the secondary waste of energy.With the development of society,in recent years,the country has put forward higher requirements for the sustainable development of energy conservation and environmental protection,and has issued a series of policies,to take the road of high-quality development,and to upgrade the production equipment for the industry,especially for the high energy consumption industry.In response to this call,in recent years,some scholars put forward the research direction of using professional hydraulic turbine for energy recovery.In the research process of multi-stage hydraulic turbine for residual pressure recovery,the design optimization of inter stage guide vane is an important direction.The inter-stage guide vane is one of the most hydraulic loss parts in the flow passage parts of the multistage hydraulic turbine,which seriously affects the efficiency of the hydraulic turbine.There are many structural parameters of inter-stage guide vane,so it is necessary to match and optimize these parameters,so as to reduce the hydraulic loss of inter-stage guide vane as much as possible while providing the flow velocity circulation required by the lower runner,which is reflected in the overall performance of multistage turbine,that is,to ensure the output and head,and to improve the efficiency.This is a multi-parameter and multi-objective problem,which is difficult to optimize.In order to optimize the inter-stage guide vane,based on the CFD numerical simulation,the influence of the parameters of the inter-stage guide vane on the turbine performance is analyzed.By changing the single parameters of the guide vane,the influence on the turbine performance is summarized,and some preliminary conclusions are obtained.On this basis,the orthogonal test with 5 factors and 4 levels was carried out with?-the thickness of the inter-stage guide vane diaphragm,D4-the diameter of the inter-stage guide vane,Z-the number of the inter-stage guide vane guide vane,Rn-the radius of the inner wall fillet at the inlet of the negative guide vane and RW-the radius of the outer wall fillet at the inlet of the negative guide vane as the test factors.The main performance parameters of the turbine model are analyzed,and the influence rules of each factor parameters on each performance index of the hydraulic turbine are obtained.The main rules obtained in this paper are as follows:?1?When the inlet diameter of the guide vane is about equal to the outlet diameter of the upper runner,it will have better effect.If it is too small,it will increase the hydraulic loss of the guide vane,and if it is too large,it will reduce the length of the guide vane,resulting in the reduction of the capacity of the guide vane to change the flow velocity circulation.?2?Increasing the wrap angle and number of guide vanes can enhance the ability of guide vanes to change the circulation of flow velocity,but also increase the hydraulic loss of guide vanes.?3?To a certain extent,increasing the diameter of inter-stage guide vane can reduce the hydraulic loss of inter-stage guide vane.?4?To a certain extent,increasing the inner and outer wall fillets at the inlet of the guide vane can reduce the hydraulic loss of the guide vane,especially if the outer wall is not filleted or the fillets are smaller,the hydraulic loss of the guide vane will be larger.Through a series of analysis and optimization,taking the total output of the model and the total hydraulic efficiency of the model as the comprehensive index,the better combination of the parameters of the inter-stage guide vane is obtained in the level range used in this study,that is,?-the thickness of the inter-stage guide vane diaphragm is taken as 50 mm,D₄-the diameter of the inter-stage guide vane is taken as 750 mm,Z-the number of the inter-stage guide vane is taken as 14,R_n-the fillet radius of the inner wall at the inlet of the guide vane is taken as 336 mm,R_W-the fillet radius of the outer wall at the inlet of guide vane is 180mm.Compared with the two-stage hydraulic turbine model of the original inter-stage guide vane,the total hydraulic efficiency increased from 75.84%to 87.645%,and the total head decreased from 349.769m to 327.625m.The model output was increased from 2081.903kw to2253.529kw.