Impact Vibration Analysis of Screw Compressor Rotor System. 3rd Report. Analysis in consideration of Inertia of both rotors.

In this paper, a rotordynamic experiment on a compressor rotor system is presented and the feasibility of gas foil bearings with inhomogeneous bump foils is verified. A push–pull device is designed to obtain the stiffness curve and the nominal clearance of foil bearings. Operating points and dynamic coefficients of the rotor system at each rotating speed are predicted. In rotordynamic analysis, an alternative model of the impeller is proposed and the critical speed is predicted by employing the finite element method, in which the dynamic coefficients of inhomogeneous foil bearings are taken into account. Compared with the experimental result, the accuracy of the prediction for the critical speed is verified to be about 14% error. Two sets of foil bearings with 22 and 41 μm nominal clearance are manufactured and tested. Test results indicate that the vibration amplitude can be greatly reduced by diminishing the bearing clearance. When foil bearings with 22 μm clearance are used, the high-order harmonic frequencies of rotor vibration are significantly inhibited, and the amplitude of the rotating frequency is obviously restricted. Thus, the foil bearing with inhomogeneous bump foils tested in this paper can meet the speed requirement of the compressor when the nominal clearance is set at 22 μm.

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Nonlinear Vibration Analysis of Rotor considering Cogging and Harmonic Effects

Shock and Vibration ◽

10.1155/2021/6685588 ◽

2021 ◽

Vol 2021 ◽

pp. 1-16

Author(s):

Shanle Li ◽

Feng Liu ◽

Hongyan Wang ◽

Haijun Song ◽

Kuilong Yu

Keyword(s):

Nonlinear Vibration ◽

Vibration Analysis ◽

Magnetic Force ◽

Rotor System ◽

Kutta Method ◽

Rotor Vibration ◽

Motion Equations ◽

Runge Kutta Method ◽

Static Eccentricity ◽

New Formula

This paper aims to investigate nonlinear vibration characteristics of rotor system considering cogging and harmonic effects. Firstly, relative permeance with eccentric was established and then corrected by correction factor caused by the cogging effect. Based on the new formula of relative permeance, the expression of unbalanced magnetic force was obtained, and the coefficient of cogging effect was defined. Motion equations of rotor system were established, and Runge–Kutta method was used to solve the equations. Results showed that errors between finite and analytical results were smaller considering cogging and harmonic effects. When the harmonics were taken into consideration, the vibration of rotor increases sharply. When the cogging and harmonics were taken into consideration simultaneously, the vibration of rotor decreased instead, which means that stator slots have the effect of reducing vibration in rotor system. Rotor vibration was axis symmetry with static eccentricity rather than central symmetry with no eccentricity, and double, four times, and six times supply frequency always existed in the components of main frequency with eccentric.

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Cmm-based Profile Measuring Method for Unknown Screw Compressor Rotor

Proceedings of the 2nd International Conference on Computer Application and System Modeling ◽

10.2991/iccasm.2012.99 ◽

2012 ◽

Author(s):

Xiaogang Ji ◽

Nan Li

Keyword(s):

Measuring Method ◽

Screw Compressor ◽

Compressor Rotor

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Graphic Method Profiling of the End Mill Cutter Generating the Screw Compressor Rotor

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.658.123 ◽

2014 ◽

Vol 658 ◽

pp. 123-128 ◽

Cited By ~ 1

Author(s):

Camelia Lacramioara Popa ◽

Viorel Popa

Keyword(s):

Screw Compressor ◽

Graphic Method ◽

End Mill ◽

Helical Channel ◽

Compressor Rotor ◽

Mill Cutter ◽

Front Section

Helical rotors, components of screw compressors have different structural shapes: rotors circular front section, rotors elliptic front section or asymmetric rotors. Manufacturing rotors involves profiling a tool bordered by a revolution surface, enveloping of each helical channel. This paper proposes a method developed in AutoCAD, in order to determine the profile of end mill cutter which generates the helical channel. Graphic method is based on the principle of complementary theorems' "Substitute Circles Family Method" component of envelope surfaces theory.

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