| With the continuous development of aerospace technology,the needs of performanceof aeroengines are getting higher and higher.As an important factor affecting the performance of aeroengines,seal devices have a significant impact on economic,efficiency,and other aspects.The traditional seals,such as brush seal,mechanical face seal and crucible seal are relatively mature,but they have gradually failed to meet the requirements for aeroengine improvement.Finger seal is a new type of flexible seal that was proposed after brush seal.Due to its flexible dynamic characteristics and low leakage levels,it has great potential for application.The structural characteristics of the finger seal,especially the structural stiffness of the finger stems play a important role in the finger seal performance.Moreover,the hysteresis caused by frictional force between finger slices and back plate and the wear properties between finger feet and rotor runway is another key factor affecting its working stability.Based on the tribological mechanism,wear-resistant coatings are important ways to solve these problems.For this purpose,the current work tested different friction mechanism of coatings through the Pin-disk friction experiments to selected the better coatings,the coatings included tungsten carbide(WC),chromium carbide(Cr3C2)and Teflon coatings(PTFE).On the other hand,the involute finger seal structure was optimized.The finger seal used to do the bench test were performed according to the optimized structure and coated with the better coatings.In the research,first,a finite element simulation model of the finger seal was established in the ANSYS APDL.The loads were applied according to the working principle of finger seal,then thehysteresis and average contact pressure of the finger seal under different friction coefficients in the static simulation were obtained.The contact pressure provide a reference load value for the subsequent friction and wear test.The static simulation provide a method to make the sample data for the optimization of finger seal structure.At the same time,it reveals the relationship between surface friction coefficient and performance of finger seal.Subsequently,the pin-disk friction testof 40 CrNiMo A substrate and the WC,Cr3C2,PTFE coatings was did.The stability and life of the coating were analyzed by the friction coefficient curve recorded by computer.The appearance of wear marks were observed and friction mechanism was analyzed by SEM and confocal laser scanning microscopy.Then,a uniform design tables including 50 sets were made in DPS data processing system.The 50 sets of structural parameters and simulation results of the static analysis are filled into uniform design tables to construct optimized data samples.The good finger seal structure parameters was optimized by neural network genetic algorithm and Nash equilibrium theory.Finally,the finger seal device which was coated with PTFE coating was made according to the optimization results and the bench test was did.The simulation results showed that both the hysteresis rate and the average contact pressure of the involute finger seal would decrease with the decrease of the contact surface friction coefficient.The leakage gap would increases as the rotor speed increases.The pin-disk friction test shows that the friction coefficient of PTFE coating is very low and stable.Because of the self-lubricating of PTFE,it can achieve wear-resisting effects under low load conditions,so used it as anti-friction material in finger seal has a certain application potential to reduce the hysteresis.The friction coefficient of WC coating is low and stable,used it as wear-resistant material to improve the life of finger seal has a certain application potential.Due to constraints of time and economic cost,the final bench test was conducted with a finger seal coated with PTFE coating between the finger feet and the rotor.The results show that the PTFE coating can effectively reduce the wear of finger seal. |
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