Dynamic Property And Optimization Study Of Split Floating Finger Seal

As the performance requirements of gas turbines continue to increase,so do the performance requirements of sealing devices.As an important functional component of gas turbine,the balancing disk and shaft end seal device not only have an important impact on improving the performance of gas turbine,but also play a vital role in improving the life of gas turbine.The gas turbine balancing disc,due to its special structure and working environment,has problems such as inconvenience in disassembly and installation,and large wear and tear.Finger seal has received wide attention because of its advantages of flexibility,low leakage and low cost.For this reason,this study conducts structural design research on split floating finger seal,which is important for developing high performance and long life dynamic sealing technology.The study combines the sealing characteristics of floating finger seal,carries out the analysis of dynamic characteristics of floating finger seal,contact characteristics analysis,structure optimization analysis,and carries out the bench test study of floating finger seal performance to comprehensively evaluate the sealing performance of floating finger seal under different working conditions.The main research contents and conclusions are as follows:(1)In view of the special structure and working conditions of gas turbine balancing disc,according to the actual structure and performance requirements of split and floating seals,the sealing principle and performance characteristics of existing finger seal are used to develop and design a new type of split floating finger seal based on this improvement,which has certain reference significance to reduce seal wear and increase seal life.(2)The geometric model of the floating fingertip seal is established by using the commercial software Soildworks and imported into ANSYS workbench to establish the simulation analysis model,and the dynamic characteristics of the fingertip boot and rotor are studied.The performance of the floating fingertip seal is compared with that of the conventional fingertip seal by calculating the leakage gap and the maximum contact pressure.At the same time,the influence of rotor runout,differential pressure and rotational speed on the performance of floating fingertip seal is studied,and the leakage and wear rate of floating fingertip seal are calculated according to the empirical formula.The results show that:with the increase of rotor runout,the leakage and wear rate of the floating fingertip seal are increasing;with the increase of differential pressure,the leakage of the floating fingertip seal is increasing,and the increase is small,and the wear rate tends to be constant;with the increase of rotor speed,the leakage of the floating fingertip seal increases and then decreases,and the wear rate is increasing.At the same time,compared with the average leakage gap of the conventional fingertip seal in the same working condition,the floating fingertip seal has better followability,and the average leakage gap of the floating fingertip seal is reduced by 49.3%,and the maximum contact pressure is reduced by 36.3%.(3)The DPS data system is used to establish the test samples required for floating fingertip seal optimization,design the optimization range of floating fingertip seal structure parameters and uniform design table,and calculate the average leakage gap and maximum contact pressure of the data samples according to the dynamic characteristic analysis model of floating fingertip seal.Meanwhile,the NASH optimization algorithm is established based on BP neural network,genetic algorithm and NASH equilibrium theory,and the optimization algorithm is modeled according to MATLAB software,initialized parameters are set and solved to obtain the optimal structure of the floating fingertip seal,and the dynamic simulation analysis of the optimization results is carried out.The results show that the average leakage gap of the floating fingertip seal structure obtained by the NASH optimization algorithm is reduced by 13.2%and the maximum contact pressure is reduced by 28.3%,and the sealing performance of the optimized structure is superior.(4)The preparation of the floating fingertip seal test pieces was completed,and a performance bench test program was developed to carry out a bench test study of the floating fingertip seal performance and to compare it with the conventional fingertip seal.The test is divided into static test and dynamic test,the static test results showed that the leakage amounts of the two finger seals were basically the same,and the leakage amount increased with the increase of the differential pressure of the seal.The dynamic test results show that the leakage of both finger seals increases with the increase of differential pressure,and the leakage of both finger seals decreases with the increase of rotor speed,and the leakage of floating finger seal is smaller than that of traditional finger seal,which indicates that floating finger seal can adapt to different working conditions and have better sealing performance.