Investigations On Vibration And Instability Suppression Of High-speed Rotating Disk

As a typical structural element of rotating machinery, rotating disks are widely used inengineering. It has important academic significance and engineering application value onthe research of the vibration characteristics and performance improvement of high-speedrotating disk system and its attachments. To solve the problem of mechanical vibration ofhigh-speed rotating flexible disks, some fundamental principles and characteristics ofvibration was studied theoretically and experimentally, a method with thermal stressinduced by temperature increment at disk inner edge was proposed to increase disk criticalspeed and improve vibration stability of flexible rotating disk.Firstly, dynamics of a single rotating flexible disk was investigated. The mathematicalmodel of rotating disk was established and its corresponding boundary conditions wereassigned according to some engineering applications. With the method of Fourier seriesexpansion and radial finite element discretization, partial differential equations andboundary conditions were converted as a set of ordinary differential equations. Naturalfrequency, vibration mode shape at different rotating speeds and critical speed of rotatingflexible disk were solved. Free and impulse responses, steady-state deformation under theaction of gravity and vibration characteristics subjected to air lift force were studiedrespectively.Secondly, a vibration experimental testing of the rotating flexible disk was carried outto study its practical vibration characteristics. The experimental scheme was formulated, anexperimental rig was designed and established, and the main instrument and equipmentwere calibrated. The rotating flexible disk was excited by an electromagnet as a pulse forceat different speeds, acoustic and vibrational response data were collected by using mikecollector and displacement sensor. After the numerical processing of experiment data, the curve of the vibration frequency with respect to disk rotating speed was obtained, thenabove theoretical methods and results were validated to be correct.Finally, including effects of sliders of rotating flexible disk attachment, themathematical models of thermoelastic coupling dynamics and heat conduction equation andcorresponding boundary conditions were build for the rotating flexible disk. Temperaturedistribution, thermal stresses and vibration displacement of rotating flexible disks weresolved, and the natural frequency and dynamic stability parameters of the rotating disksystem were studied. With the thermal stress induced by temperature increment at disk inneredge, the vibration characteristics of the rotating disk system under different conditionswere discussed. Effects of the thermal stress on the improvement of critical speed and thestabilizations of aeroelastic, parametric, thermoelastic, and compound instabilities werediscussed.This work is valuable to understand some fundamental vibration characteristics and toimprove the performance of high-speed rotating flexible disk.