Papers by Keyword: Rotor

Abstract: Stochastic resonance (SR) in the bistable system can reduce the noise level, reveal the waveform’s outline prominently, and improve the quality of the system output. Under the support of SR techniques, the extraction accuracy of the civil aero-engine rotor vibration information is lifted, especially when treating the signals contaminated by heavy noise. Results indicate that the SR signal preprocessing method via tuning the relative parameters is effective to reflecting the real vibration of the aero-engine rotor. It can also monitor the short-term failure phenomenon in the sampling data.

Abstract: The aim of this paper is the development and validation of an impulse excitation technique to determine static imbalance of a rotor. The experimental measurement of the vibroacustic response is carried out by using a condenser microphone. In determining the center of mass three measurements are needed: one in plane flexure, and other out of the plane flexure, to which is added a measurement for a balanced rotor. By the means of Finite Element Method (FEM), the natural frequencies and shape modes of two rotor specimens are determined. The analysis is carried out in balanced condition as well as unbalanced one, after artificially induced imbalance. The vibration responses of the specimens, in free-free conditions, are carried out using algorithms based on Fast Fourier Transform (FFT). To validate the results of the modal parameters estimated using Finite Element Analysis (FEA) these are compared with experimental ones.

Abstract: Critical speed rotor phenomenon characteristics at gas turbine generator is evaluated using finite element method. In this study, the critical speed is evaluated based on the over speed of 4500 rpm. The critical speed of the rotor is investigated in the Campbell diagram, which shows the relationship between natural frequency and rotational velocity of the system Dynamic characteristic in this paper simulated with ANSYS rotor dynamic software. The Finite Element simulation results will be known forms of vibration at each critical speed. Finally the results od simulation can be a reference for dynamic analysis and optimized the design of rotor generator.

Abstract: The work concerns the research of a propulsion system for an unmanned aerial vehicle MOSUPS in joined wing configuration. Modeling, analysis and experimental research of a statically unbalanced rotor of a ducted fan propulsion system has been conducted.The aim of the analysis was to determine the critical rotational speeds of the rotor due to the probable excitation of oscillations. Due to the complex geometry, Finite Element Method has been used for the calculations. In the study, the critical frequencies (and also rotational speeds) of the rotor as well as precessional instability, flexibly mounted in the bearings have been calculated. Campbell and SAFE diagrams have been presented.Furthermore, the paper presents the idea for a device for automatic dynamic balancing of the mentioned rotor. A mechanism for changing the position of the correction weights has been developed, allowing for a long term operation of rotating parts without the need to stop the unit and correcting the unbalance.The main motivation for work was to fully understand the working conditions of the propulsion system and dynamic properties of the rotor in order to carry out a proper assessment of their impact on the safe operation of the aircraft.

Abstract: On this journal, modeling relation of rotor speed and rotor diameter toward yarn tension on take-off nozzle has been validated by theoretical approach and numeric computation.It shows that value of yarn tension is F=(1,4.10^-13)Tt n_R² d_R² [cN]. Excessively high spinning tension always results in an intolerable increase in yarn breakage. This paper presents a comparative study of theoretical and reference-based experimental result for predicting the actual strength of open-end spinning system.

Abstract: Induction motors with conventional organic insulation are used at technological plants designed for recycling nuclear fuel waste of nuclear power stations. In the nuclear radiation environment, the service life of these asynchronous motors does not typically exceed 3-4 months as the winding insulation is destructed being exposed to nuclear radiation. This results in costs increase. To prolong the motor service life and reduce the costs, a valve-inductor-type motor is being developed for this application field due to a simple construction of the stator windings and the feasibility of using non-organic insulation.

Abstract: The article is devoted to the development of technical solutions centering the axis of rotation of the rotor of the electric motor during movement. Focuses on the problem of optimization of the axis of rotation of an electric machine rotor. The existing types of current unbalances of rotating part of electric machine and their causes are considered. It is specified that the methods used in practice balancing, do not meet the requirements of modern high-precision industries. A new solution to the problem of stabilization of the axial position of the rotating electric machine is suggested.

Abstract: In this paper, a new rotor with two impact in the vertical shaft impact crusher is analyzed, an effect of the angle at the guide device thrown materials on the velocity that material reach the impact plate and rebound to a anvil in the crushing chamber are discussed. three mass ejection Angle are simulated by discrete element software EDEM, and the result shows that effect of two impact of new rotor on acceleration material is best when ejection angle is 25 °.

Abstract: In order to reduce the random noise influence on local wave decomposition (LWD), the original data is adaptively denoised by lifting wavelet transform to strain mode aliasing in LWD, avoid the pseudo mode functions in LWD and improve the quality of LWD. Local wave marginal spectrum is employed to analyze vibration signal for extracting the characteristics information. Intrinsic mode functions obtained by LWD, the instantaneous frequency and amplitude can be calculated by the Hilbert transform. The improved local wave analysis can offer a measure of the energy distribution of vibration signal from its instantaneous frequency. Analysis and experimental result demonstrate the validity of the proposed method.

Abstract: In this article the time change automatically balanced unbalanced rotor automatic ball balancing devices is considered. The calculation of original differential equations is made with numeral calculation using the Runge-Kutt method. The time dependence of the transition process of the balancing process from the parameters of the automatic balancing device is obtained.