The stability of positioning is one of the most important characteristics in ywheel energy storage systems with high-temperature superconducting (HTSC) magnetic bearing . In this paper, we experimentally discuss the drift of the levitation gap in the ywheel system under the revolution. When the revolution speed of the ywheel rotor passes through the mechanical resonant frequencies, the dynamics...

In this work, a large-scale Brushless Doubly Fed Machine (BDFM) built in frame size D400 is tested at different operating conditions in order to examine its noise and vibration levels. A series of measurements were conducted on the machine to establish the main modes of excitation of vibration and noise developed by the machine. The harmonic spectrums of the vibration amplitudes are presented a...

The two main sources contributing to scroll compressor vibration at running frequency are the residual rotational unbalance in the crank-rotor assembly and the reciprocating force due to the Oldham ring. The intent of this paper is to develop a rigid body model of the compressor vibrating on resilient grommets. This model is a design tool capable of identifying the sensitivity, of the steady-st...

This dissertation presents a control law for helicopters to reduce vibration and to increase damping using individual blade control. control synthesis is used to develop a robust controller usable in different operating conditions with different helicopter flight speeds. The control design is applied in simulation to the four-blade BO 105 helicopter rotor, which is equipped with an individual b...

In this paper, two kinds of vibrations are considered for a composite Timoshenko rotor: longitudinal-torsional vibration and two plane transverse one. The kinetic and potential energies and virtual work due to the gyroscopic effects are calculated and the set of six governing equations and boundary conditions are derived using Hamilton principle. Differential quadrature method (DQM) is used as ...

A computational study of helicopter vibration and rotor shaft power reduction is conducted using actively-controlled trailing-edge flaps (ACFs), implemented in both single and dual flap configurations. Simultaneous vibration reduction and performance enhancement is demonstrated under level flight condition at high advance ratios, where dynamic stall effects are significant. Power reduction is a...

Abstract: Unbalanced mass identification is important for rotor systems. Current methods normally use sensors, which only detect vibration in two-dimensional (2D) space. Actually, the rotor systems vibrate in three-dimensional directions. In this paper, a non-contact method is developed to identify unbalanced mass of rotor systems in 3D space. A stereo video system with a pair of synchronized h...

Harmonic vibrations of high-speed rotors in momentum exchange devices are primary disturbances for attitude control of spacecraft. Active magnetic bearings (AMBs), offering the ability to control the AMB-rotor dynamic behaviors, are preferred in high-precision and micro-vibration applications, such as high-solution Earth observation satellites. However, undesirable harmonic displacements, curre...

This paper describes an active control method to prevent unwanted nonlinear vibration response modes of a rotordynamic system. Nonlinear stiffness of components that support or surround a machine rotor can cause a response branch that extends critical vibration (resonance) over a wide interval of rotational speeds. Within this interval, jump transitions between alternative low amplitude and hig...

Vibration derived from the main rotor dynamics and imbalance causes premature wear to the aircraft components, and can cause pilot fatigue. While improvements have been made in rotor track and balance (RTB) techniques; there is room to enhance the quality of the recommended RTB adjustments. One aspect that limits the development of RTB algorithms is the difficulty in quantifying the performance...