Numerical Research And Aerodynamic Performance Test On Profile And Cascade Of Typical Stage Of A Steam Turbine

The development of high-efficiency and advanced steam turbine has great significance for improving the efficiency of steam power generation and gas-steam combined cycle power generation,and has an important technical means for promoting energy conservation and emission reduction.In this paper,the advanced design concept of the typical medium-pressure 7th stage of the gas-steam combined cycle steam turbine which is the newly generated design by Harbin Turbine Company Limited is studied,through the air blowing experiment and numerical simulation.The aerodynamic performance of the 2D cascades and the aerodynamic performance of the 3D sector cascades of the static blade are studied.The prediction of the loss of the blade profile applied to the static blade is given based on the Reynolds effect.This study is aimed to concept the advanced blade design,and provides technical support for future engineering modifications,design and practical applications.Firstly,in order to study the variation incident angle characteristics of the typical stage profile,six sets of linear cascades were designed which are converted based on the profile on the 10%,50% and 90% blade height.The variation angle blowing experiment shows static pressure coefficient curve of each linear cascade surface,the change of the outlet airflow angle and the change of the total pressure loss on the outlet section.The experimental results show that the profile on each section is the aft-loadeding profile,the loss of profile is very adaptable to the change of negative incident angle,and it is very sensitive to the change of positive incident angle.When the incident angle is too large,the loss increases sharply;The change of the loss with the variation incident angle of the 10% section is more obvious;the profile of the static blade is better for the loss control and the lowest point of pressure,and the best incident angle of the blade is a small negative angle.Secondly,the static blade are studied in detail,and 3D sector cascade of static blade is designed,and is studied by blowing experiments.The 3D sector cascade numerical simulation is carried out with the experimental cascade as a model.The result shows that the airflow at the root of the blade is the most intense,and the degree of blade-loading and the load are the most at the root of the blade.Besides,there is the most sensitive to the variation of the incident angle at the root,especially the positive incident angle.The upper and lower end walls are inclined to optimize the flow of the blade root,but the peak of loss still appears at the root of the blade,and the positive tilting design of the blade makes the radial pressure gradient small,further optimizing the flow at the blade root.The change of negative incident angle has little effect on the flow in the 3D cascade.The area of the high-loss area increases with the positive incident angle increasing,and the root of the blade is more obvious.In addition,the channel vortex changes at the root of the blade more obviously with the change of the incident angle.In the machine design,it should be considered to preferentially flow at a small negative angle of the blade root.Finally,in order to further study the mechanism of profile loss of static blade,and to improve the engineering practicality and provide technical basis for future modification and design,a suitable profile loss prediction model based on Reynolds effect is given.The feasibility of model is studied.The prediction value of the loss model is obtained by calculation and integration.The comparison with prediction value and the experimental results verifies that the profile loss prediction model is applicable to the profile of the 7th stage blade studied in this paper.