Dynamic Characteristics And Experimental Design Of Blad-Disk Rotor System

As a key component of the gas turbine and turbine rotor system,bladed disk system is subject to complex loads and harsh environment including high temperature,high pressure and high speed.The failure of the disc system of the gas turbine and turbine will lead to the unbalance of the rotor system,the static and dynamic rubbing,even other the extremely serious consequences.Therefore,the study of vibration characteristics of bladed disk rotor system is of great importance to the design,operation and maintenance of rotating machines such as gas turbines and turbines.At present,the gas turbine design and research of the main technical held by four major manufacturers abroad,while domestic also do not possess the ability to produce,maintain,and solve the key technical problems independently.The blade disk system manufacturing and performance analysis are few,it is difficult to ensure the sustained and stable operation under high temperature and high pressure.The research and design of steam turbine is widely used in expert diagnosis and field experience to solve the problem,and there exists theoretical guidance and accurate verification.That' s why it is difficult to accurately diagnose accident causes of the accident,resulting in adverse effects on the operation of the unit and affect the production and economic benefits directly due to processing time delay.All of these have seriously restricted the development of gas turbine and turbine technology,restricted the upgrading of unit efficiency and increased the unit accident rate.In this paper,the rotor system of gas turbine and turbine disk is taken as the object of study,the unbalanced response of rotor rotor system and its application in dynamic balance are carried out.Furthermore,the sensitivity of rotor mass and position to rotor critical speed is analyzed,and the influence of the parameters of the bladed disk system on vibration characteristics is studied.Finally,discuses the influence of the aspect ratio of the blade on the vibration characteristics of the bladed disk system,and the research on Optimization of mistuned bladed disk blade system is studied.The main research contents and achievements are as follows:1.The integrated model of impeller axis is established,and its inherent vibration characteristic and unbalanced response are solved by applying the transfer matrix method,and the correctness of the analytical method is verified.The influence of unbalanced mass on vibration characteristics of bladed disk rotor and its application in dynamic balancing are discussed.The results show that the input of the rotor near the blade rotor is more prone to unbalanced vibration at low frequency,while the output is sensitive to high frequency.The increase of eccentric quality aggravates the unbalance vibration of bladed disk rotor system.Applying the backward unbalance can reduce the amplitude of low frequency vibration and effectively restrain the vibration caused by low frequency.The same direction unbalance can be applied to restrain the vibration caused by high frequency,and the reverse unbalance can be used to realize the dynamic balance of the gas turbine.2.The rotor system model of bladed disk is established to analyze theoretically the rigid thin single disk bias rotor with rigid support at both ends.Through the experimental research,the theoretical analysis outcome coincides with the result from finite element analysis.Based on the sensitivity analysis of,the influence of the wheel mass and position change on the critical speed of the turbine rotor,the results show that the different quality of the wheel mounted on the the center position achieve the minimum critical speed.The more it increase the its mass deviating from the center of the rotor position,the more decelerate the critical speed.Deviation is far greater than the quality,which have influence on the critical speed,about 7?10 times.Deviation of the rotor with the same quantity is more than 40%,causing that the critical speed of the rotor changed obviously.At the same offset position,the mass increment is less than 50%,which makes critical speed of rotor change greatly.3.The analytic model of wheel is established to made a analytical calculation for the circular symmetric structure of the roulette and introduce a the analysis method which based on arranging the sand on the wheel to simulate the wheel vibration type,and verify its reliability.Calculating and analyzing the modality of rotor system based on Group theory algorithm,design 10 group parameter of the leaf discs system under the working condition and discuss the influence factors of blade structure change.The results exhibit that the vibration trend of leaf disc system and the wheel basically tallies.With the quality of leaves increased,the modal frequencies of the blade disk system decrease and the amplitude increased slightly.Increasing its weight on different positions have a small part to the modal frequencies of leaf disc system on various circumstances.When the bladed disk system vibrate with low frequency,disc vibration is a dominant factor,while the leaf vibration is minor.4.By building blade structure model with different aspect ratio,the inherent frequency of the blade is solved and obtain the regulation of the inherent vibration of the blade at various aspect ratio.Twisted blade and Straight blade' s impact on the dynamic frequency of bladed disk system and its change regulation under the different aspect ratio is discussed.The results exhibit that flexural vibration frequency in then high order and low aspect ratio frequency region is more sensitive when blade' s width is the constant value and the natural frequencies of the blade and aspect ratio are inverse proportion.The results exhibit that vibration frequency in then high order and low aspect ratio frequency region is more sensitive when blade's length is the constant value and the natural frequencies of the blade decrease with the aspect ratio increased.5.The natural frequencies of the blade increase with the aspect ratio increased when blade' s length is the constant value,while the torsional vibration frequency increase in a degree.At the same time,the change of the torsional vibration frequency of the blade is more obvious than the bending vibration frequency change.The effect of twisted blade and straight blade on bladed disk system is similar.when blade' s width is the constant value,leaf aspect ratio has little effect of low order frequency of the system,however the influence of higher-order frequency is large.The increase of aspect ratio reduces the frequency of each order system.If the blade's length is the constant value,the effect of aspect ratio on blade twist frequency is more sensitive,increasing with aspect ratio increased.The frequencies of other orders vary little6.Introduce the experiment method of mistuned bladed disk system vibration to test it.Based on iterative response surface and discrete particle swarm optimization algorithm genetic optimization method,obtain the best scheduling scheme of blade vibration.The mistuned bladed disk system were fitted by taking the basic two quadratic polynomial response and rely on quasi Newton algorithm to determine the coefficient of polynomial fitting.Based on discrete genetic particle swarm optimization(PSO)algorithm to solve the extremum of polynomial,optimize the results of leaf sorting.After iterative response surface arrangement optimization,bladed disk system forced vibration amplitude decrease obviously,verse to leaf disc system arranged in sequence according to leaf number.Different frequencies do not change at the same time,causing the big change on the baseband position.