Critical speed

About: Critical speed is a research topic. Over the lifetime, 2764 publications have been published within this topic receiving 31365 citations.

In-Plane Stress and Displacement Distributions in a Spinning Annular Disk Under Stationary Edge Loads

Abstract: It is well known that the in-plane stress and displacement distributions in a stationary annular disk under stationary edge tractions can be obtained through the use ofAiry stress function in the classical theory of linear elasticity. By using Lame's potentials, this paper extends these solutions to the case of spinning disk under stationary edge tractions. It is also demonstrated that the problem of stationary disk-spinning load differs from the problem ofspinning disk-stationary load not only by the centrifugal effect, but also by additional terms arising from the Coriolis effect. Numerical simulations show that the amplitudes of the stress and displacement fields grow unboundedly as the rotational speed of the disk approaches the critical speeds. As the rotational speed approaches zero, on the other hand, the in-plane stresses and displacements are shown, both numerically and analytically, to recover the classical solutions derived through the Airy stress function.

Vibration characteristic analysis and numerical confirmation of an axially moving plate with viscous damping

Abstract: In this paper, the vibration characteristics of axially moving plates with viscous damping are analyzed. A partial differential linear equation of motion with four simply supported edges is presented. The effects of two different viscous damping models are highlighted, while both of them have been introduced in previous studies. The investigation into the two different viscous damping models is interesting in itself. It is noteworthy that which model is closer to the fact, for which there are no systematic techniques of investigation to deal with this problem. In order to give a reference for possible verification in experiment, the difference of the two different viscous damping models in theory was proposed. The complex frequencies and its corresponding complex modes are studied by the complex mode approach. As other parameters are fixed, the effect of some parameters, such as viscous damping coefficients, axial speeds, aspect ratios, stiffness ratios, and support stiffness parameters, on the frequencie...

Active vibration control of the flexible high-speed rotor with magnetic bearings via phase compensation to pass critical speed:

Abstract: In modern industries, high-speed motors and generators have received great attention, and they are widely used in micro turbine, centrifugal compressor, blower, etc. However, the resonance vibratio...

Critical rotating speed of rotor cup in an air suction open-end spinning machine

Abstract: Simulation of three-dimensional turbulent flow in a rotor spinning machine is carried out, and the flow structure and behavior in the rotor cup are analyzed. The governing equations are the steady three-dimensional Navier–Stokes equations and the Spalart–Allmaras turbulence model. The results show that the rotating speed has great influence on the flow behavior in the rotor cup. It is found that there is a critical speed of the rotor cup beyond which the pressure and velocity on the slip surface is not changed anymore regardless of the magnitude of the rotating speed. When the rotating speed is larger than this critical speed, the flow structure becomes unstable with the increasing of the rotating speed. The mechanism of this phenomenon is that the airflow in the rotor groove passes about 180 degrees from two sides along the rotor wall and a pressure balance is achieved. When the rotating speed is larger than the critical speed, the balance will break down. When the rotor speed is low, the flow characteri...

Analytical and Experimental Investigation of the Stability of Intershaft Squeeze Film Dampers—Part 1: Demonstration of Instability

Abstract: Modern high-speed multishaft gas tubine engines incorporate viscous damped bearings to decrease overall system vibration and bearing loads. As viscous damper technology is applied to advanced engine design, more sophisticated analytical and experimental techniques are required to prove new concepts. This analysis will present the results of an investigation of the feasibility of damping engine vibration with a viscous damped intershaft bearing on a two-shaft gas turbine engine. Experimental results from a rotor dynamics simulation rig indicate an instability of the rotor system at speeds above a fundamental critical speed. An analytical model of the two-rotor system is presented and the results of both a classical stability analysis and a time transient response analysis verify the experimental data. The analytical model may be used to predict the stability of two-shaft engines which incorporate an intershaft damped bearing.