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Structural Design,Performance Analysis And Tests Of Finger Seal

Posted on:2007-11-15Degree:DoctorType:Dissertation
Country:ChinaCandidate:H SuFull Text:PDF
GTID:1102360218457113Subject:Mechanical design and theory
Abstract/Summary:PDF Full Text Request
Advanced sealing technology prominent contribution to improve performance of turbine engine has been paid more attention in resent decades. It is investigated that the finger seal has good sealing performance and lower cost compared with brush seal. So the finger seal has been concerned especially nowadays. The hysteresis and wear performance of finger seal are not solved well till now. Most research work aimed at solving hysteresis or wear separately, which bought out limited results in a way. Finger seal has been studied by a lot of test in NASA Research Center, which is costly more. So it is necessary to study the finger seal in a feasible way. This is the background of this research work. And this work has been supported by the national natural science fund and aviation science fund.The finger seal has been studied completely in this paper. Based on the theoretic research work and some test results, an integrated method to analyze the finger seal's performance and structure design are formed basically. The main research work in this dissertation is as follows:1. The hysteresis of finger seal influenced the leakage obviously. The mechanism of finger seal's hysteresis is studied in this paper. The adhesive model has been used to study the finger seal's wear behavior according to the actual conditions. The hysteresis and wear performance have been studied by using the finite element method(FEM). Here the hysteresis rate is presented to describe the hysteresis performance and another parameter integrate stiffness is showed to the wear performance of finger seal. It is found that the hysteresis and stiffness of finger seal are conflict in structural characteristic. So it is confirmed that the structural optimization with the objective of low hysteresis and low stiffness is necessary.2. Finger seal structural optimization contains shape and size optimization. Different methods are used to solve different type of finger seal. The two objectives structural optimization is performed in this paper and the results with multi-objective-optimization character are obtained. Weighting method and constraint method is used here to solve the multi-objective problem. A new integrated objective function is presented in weighting method that can solve the dimension difference between the hysteresis and stiffness of finger seal available. In constraint method the hysteresis is chose as the main objective and the other objective stiffness is changed as an additional constraint. The structure according to the wear life of finger seal can be obtained by this way. In this paper, the multi-objective optimization has been done based on APDL language of the software ANSYS and the results are satisfied therefore.3. The thermal analysis of finger seal is performed by FEM. The friction heat between rotor and finger contact surface is calculated. The heat convection coefficient of the finger seal system has been confirmed also. In this thermal analysis model, the contact heat resistance has been considered, and the reasonable heat resistance is given by the modified formula. Based on software ANSYS, the temperature field distribution of finger seal is known. The thermal-structure coupled field analysis result reveals that the thermal behavior cannot be neglected with the condition of high temperature and fast rotating speed.4. The damped harmonic vibration model and free vibration model are established according to the force to finger seal. The finger's displacement responds in different conditions are obtained by solving the dynamic equations. The movement correspond condition between the rotor and finger has been concluded and the low hysteresis, low wear conditions found on the dynamic results are put forward also. As a result, it is important to study the dynamic performance carefully. It is convenient to study the finger seal systems combined with multi-finger slice sets by using the dynamic model. Maybe it is a good way to meet different conditions with different finger slice sets.5. Finger seal has been test in a test fig at normal temperature with the condition of maximum pressure 0.5MPa and rotate speed 13150rpm. Static leakage test, performance and wear test results are presented. The hysteresis of finger seal influent the leakage obviously. Two different structural finger seal's leakage has been compared, The wear coefficient in adhesive model of finger seal is ascertained by the wear performance result. These test results are consistent with the theory anaiysis of this paper.
Keywords/Search Tags:finger seal, multi-objective optimization, thermal analysis, dynamic performance, finger seal test
PDF Full Text Request
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