Vibration Of Compressor Research Articles

Coherence technique for noise reduction in rotary compressor

The noise and vibration of a rotary compressor, a type of multi-input, single output system, are generally studied through frequency analysis. Although this method is effective in analyzing frequency components, using this method to identify the specific source of the noise (4 kHz to 6 kHz) is difficult. Hence, noise source should be studied systematically. In this study, a coherence analysis method based on systems analysis is used to identify the compressor noise source. Compressor noise source is identified through the coherence between the vibration signals on the shell of the compressor and the noise signal at one point near the compressor (1 m away from the compressor). A one-third octave band is employed for frequency analysis. The design of experiment is conducted to identify possible noise factors, such as volume, size, and neck area of the resonator in the compressor cylinder. Analysis showed that noise was generated from the cavity of the cylinder and the muffler inside the rotary compressor. A new type of muffler was applied to the rotary compressor to verify this finding. Noise was dramatically reduced.

Vibration Fault Analysis in Screw Compressor and Foundation

With the characteristics of low noise, low vibration, high reliability and long life, Screw Compressor is the indispensable main equipment which widely used in petrochemical field. The abnormal vibration of Compressor will affect normal operation of the host, lead to damage of some main parts such as Compressor and motor and at the same time it’s an unneglectable hidden trouble for equipment’s safe operation. This article takes the data acquisition of vibration and the analyses of shake for two Ammonia Refrigeration Piston Compressors, and study at the reason about shock then take the effective shockproof treatment plan. All these ensure the stable running of the facility.

Analysis of Loads at Crankshaft Bearing for Scroll Compressor

According to the tangential force of crank pin approximately for radial force four times, between the radial gas force Fr and tangential gas force Ft acting on the orbiting scroll, the radial force is invariableness with the spindle rotation angle, but tangential force Ft with the spindle rotation angle changes, and in the discharge angle θ* at maximum. As a result of our comprehensive analyses to loads at crankshaft bearing of the scroll compressor as well as installation angle of the counter weight and mass of the counterweight, it is concluded that the imbalance residual quantity of the crank pin tangential force effects on crankshaft bearing and radial force acting on the crank pin, which results from gas force of orbiting scroll, is balanced, and the vibration of the scroll compressor is decreased. This paper puts forward a set of formulas, which are derived based on analysis of the loads at crankshaft of scroll compressor. The formulas can be used to determine the parameters of installation angle of the counterweight and the force of loads at crankshaft for scroll compressor.

Dynamic Balancing Modal Analysis and Vibration Suppressing Design for Reciprocating Compressor Crankshaft

The purpose of this study is to improve the problem of vibration which occurs in a running reciprocating compressor, by determining an optimal crankshaft counterweight and narrowing the movement trajectory of the crankshaft connecting rod mechanism. An analytical solution method is applied to satisfy the requirements for vibration reduction. Use of finite element software is to simulate the modality and deformation of crankshaft under various conditions of counterweight. Modal testing shows a difference of less than 6 % between the simulation and the experimental results. After the crankshaft counterweight is machined and installed, the new crankshaft is able to reduce compressor vibrations from 32 mm/s down to 15.8 mm/s and noise reduction of 3 dB. This study can provide information pertaining to the design process and assessment to any future new compressor designs.

Experimental Investigation of Vibration and Noise Control of Reciprocating Compressors

The reciprocating compressor contains crank-rod mechanism whose unbalanced inertia force mainly accounts for mechanical noise and vibration during the working process. Through the analysis of fit between the diameter of the compressor piston and the crank eccentricity, influence of imbalance force on the compressor vibration and noise is obtained under no change in other parts. The tests of vibration and noise are followed for the purpose of verification. The results show that the vibration and noise control will be better if a small piston diameter and a big crank eccentricity are utilized.

Digital signal processing-based sensor-less permanent magnet synchronous motor driver with quasi-sine pulse-width modulation for air-conditioner rotary compressor

This study presented a sensor-less permanent magnet synchronous motor (PMSM) driver for controlling air-conditioner rotary compressor speed. In this study, a novel quasi-sine pulse-width modulation (PWM) driving method is proposed. Furthermore, the current feedback control scheme and rotor magnet pole position detection were included. The system structure was implemented using a digital signal processing (DSP) platform. The proposed driving scheme was compared with the square-wave driving without current feedback and six-step square-wave driving method with current feedback. Experimental results demonstrated that the proposed quasi-sine PWM driving method implemented in an air-conditioner compressor driver was capable of reducing the magnitude of rotational speed ripples, compressor vibration and system power consumption.

Isolation Performance Evaluation of Compressor Vibration Isolating Systems Based on LMS Test. Lab Signature

In order to reduce vibration and noise of the compressor used in small and medium-sized refrigeration unit, this paper designs different vibration isolating systems and carries out experiment of isolation performance evaluation based on LMS Test. Lab Signature software. The comparison results of four different vibration isolating systems show that the peak values of vibration velocity response in each system mainly appear at 25Hz, 50Hz, 75Hz and 100Hz, and the maximum velocity does not exceed 22mm/s which is less than the maximum allowed by the national standard[1]. And the Vibration Level Difference (VLD) is taken as evaluation criteria for isolating vibration, that of single-layer vibration isolating system is within 10-20dB, and that of double-layer vibration isolating system is within 20-35dB. Furthermore with the increase of middle-mass, the VLD has a clear upward trend.

Experimental Modal Analysis of Compressor Vibration Isolating System Based on LMS Test.Lab

In order to reduce vibration and noise of the compressor used in small and medium-sized refrigeration unit, this paper designs different vibration isolating systems and carries out experimental modal analysis based on LMS Test. Lab Impact Testing software. The comparison results of modal parameters of four different vibration isolating systems show that the natural frequency of single-layer vibration isolating system is higher than that of non-isolation system and effectively avoids the second order resonance frequency. Furthermore the natural frequency of double-layer vibration isolating system has reduced due to the additional middle-mass. And the system's natural frequency decreases obviously with the increase of middle-mass which is far from resonance frequency and significantly improve the effect of vibration isolating system.

Identify for Scroll Compressor Noise Using Vibration Signal Based on Neural Network

From the theory of structure-bone sound radiation, the properties of vibration and noise of scroll compressor are analyzed, and the relationship of them is researched. On the basis of the analysis, the feasibility for measuring noise level using vibration signal is demonstrated. Then, the noise radiant efficiency curve is plotted using the test data, and disadvantages of this mean are pointed out. At last, a new method of measuring noise level using vibration signal, which is proved in practice effectively, is presented based on neural network.

Vibration analysis of oil-injected twin-screw compressors using simple simulated waveforms

There are few published references on the practical diagnosis of oil-injected twin-screw compressors. In most cases of diagnosis on this type of compressors, usual methods that deal with machine elements, gears, rotational parts, rolling element bearings, couplings, and so on, are employed. These methods are certainly effective but not specified for diagnosis of oil-injected twin-screw compressors. The purpose of this study is to develop an effective tool for diagnosis of vibrations in oil-injected twin-screw compressors. Vibrations in this type of compressors vary with the quality of machining and operating conditions. Therefore, it is difficult to establish a systematic method of analysing vibration data in all practical conditions. This paper reports on a method developed to diagnose lobe meshing vibrations on this type of compressors using synthesized waveform models. Typical vibration waveforms are synthesized from basic waves with measured data and simple assumptions. These synthesized waveforms are then used to diagnose lobe mesh and resonance vibration problems in the compressors, after being modulated into modified waveform models. Waveforms synthesized by this method were fairly in good agreement with measured waveforms, indicating that this method is an effective tool in diagnosing lobe mesh vibration problems. There is no verified method or information on the diagnosis of lobe mesh vibrations in oil-injected screw compressors; this method, therefore, offers a effective analysis.

영구자석의 자력을 이용한 동흡진기의 설계

In this work, a dynamic absorber with a plate-type cantilever using magnetic force is proposed to reduce the vibration of a compressor directly. The dynamic absorber using magnetic force has some advantages of easily tuning the control frequency by adjusting the magnet spacing and obtaining wider control frequency band. The dynamic absorber is designed theoretically and tested experimentally to estimate the control frequency band. When the compressor is equipped with the dynamic absorber, the vibration of compressor and the noise level of refrigerator are reduced by 30 % and 3.2 dB respectively.

Study on the Application of Metal Rubber Isolator in Compressor Base

In this paper, the main problem is how to eliminate vibration came from the compressor base in petrochemical industry. The absolute transmissibility was calculated by building the compressor isolation system model. The spectrum information of compressor vibration was got through the vibration test, and the results can be acted as the condition for the isolator’s design. Isolators were designed with damping part connecting metal rubber with helical spring. Nonlinear simulation calculation was completed by finite element software. The results show that the maximum stress of isolator is about 494MPa and its maximum distortion is approximately 6mm. It verifies that the new-style isolator can satisfy vibration elimination of compressor. It is with wide-range rigidity and better capability of energy dissipation than that of general rubber isolator. It has a useful application and perspective on vibration elimination for the mechanical equipment in petrochemical industry.

Study and application of Reliability-centered Maintenance considering Radical Maintenance

Radical Maintenance (RM) takes the root causes of failures as executive objects to make maintenance decisions. A Root Cause Analysis (RCA) is carried out on the function failure of equipment to perform RM and to create a maintenance plan using the combined methods of Failure Mode, Effects and Criticality Analysis (FMECA), and Fault Tree Analysis (FTA). Evaluation criteria and matrixes of criticality are used to evaluate the criticality level of failure modes. Moreover, Minimum Cut Sets (MCS) and importance calculation are applied to analyze the fault tree quantitatively. Based on our research, the concept and the analysis process of Reliability-centered Maintenance (RCM) considering RM are proposed and then applied to an actual engineering project in the petrochemical industry. The results of the application are presented through a maintenance strategy based on the project analysis by establishing the evaluation criteria and matrixes of criticality for petrochemical rotating machines and a fault tree of compressor vibrations. The direct causes of the induction of vibration faults in rotating machinery are classified according to the fault mechanism and frequency domain features in this paper. The research shows that using RM in the traditional RCM can help assign maintenance resources rationally and improve the quality of maintenance strategies.

동조질량 진동흡수기를 이용한 미니 저온쿨러의 진동 절연

적외선 센서를 사용하는 최신 관측용 장비들을 저온으로 유지하기 위해서는 극저온 컴프레서를 센서에 연결한다. 그러나 컴프레서 진동원으로부터 발생한 외란 힘에 의해 취득 영상 품질이 저하된다. 따라서 고품질의 영상을 얻기 위해 극저온 쿨러에 대한 진동 절연 설계가 필요하다. 본 논문은 수동 진동 절연 방법의 장점을 사용하면서 컴프레서 외란 진동에 대한 높은 절연 성능이 있는 시스템을 연구 및 설계하는 것이다. 수동 진동 흡수기는 컴프레서의 구동 주파수를 고려하여 설계했다. 또한, 특정 외란 진동과 고주파수의 진동도 절연되는 쿨러 절연 브래킷을 설계하였고, 성능 분석을 위한 실험을 수행하였다.

Noise and Vibration of Compressor and it's Remedy

Noise and Vibration of Compressor and it's Remedy

선형 압축기의 동적 거동 예측 Simulation Tool 개발

A linear compressor used in a refrigerator has higher energy efficiency than a reciprocating compressor, but its vibration level is still severe than others. The vibration level of linear compressor at the frequency of 60㎐ is dominant since it is the exciting frequency of a motor. In this paper, a simulation tool to predict the shell vibration of the linear compressor was developed. The shell and body parts in a compressor were assumed to be 3-dimensional rigid body having both translational and rotational motion, while the reciprocating piston part has only 1-dimensional translational motion. The flexible loop-pipe was modeled by in-house code of finite element method. To verify the developed tool, five cases of different loop-pipe shapes were examined experimentally. The results by the developed tool showed good agreements with those by experiments.

Investigation of resonant modes and frequencies of plate vibrations as applied to turbomachine blades

The results of experimental and numerical investigations of resonant vibration frequencies and modes for rectangular cantilever plates of constant thickness are presented. The investigations are carried out using the methods of interference holography and finite elements, and the results may serve as basic references in determining resonant frequencies and modes of compressor and turbine blade vibrations.

Journal Bearing “Morton Effect” Cause of Cyclic Vibration in Compressors

A tilting pad bearing supporting an integrally geared compressor in an air separation service had gradually developed symptoms of very consistent cycling of high synchronous vibration levels. The vibration envelope increased and decreased over a roughly six-minute period. There was a difference in the phasing of vibration increase at one end of the rotor versus the other such that the two ends were not in phase but not 180 degrees out of phase either. Intensive site testing determined that no rotor critical speeds were close to the running speed of the pinion or of the bull gear shaft. However, it was observed with infrared thermography that the temperatures of the bearing pedestals were also cyclic with the same period as the vibration, as were the bearing pad and exit oil temperatures. The temperature cycle peaks were not in phase with each other or with the vibration. Various process parameters were changed on an experimental basis, indicating that the main parametric influence was bearing oil inlet temperature. If the oil temperature was optimized in a certain range, the cycling stopped. The conclusion was that the cyclic vibration behavior was a form of “Morton effect,” as discussed in recent research papers. The worn bearing clearances and shaft straightness were being changed by the bearing oil film temperature, which in turn was being affected by the vibration level, which was in turn affected by the instantaneous clearances and the degree of the instantaneous shaft bow. This chain of events, together with the significant time lag associated with transient thermal conduction, led to the cyclic but stable oscillation of the envelope of the amplitude of synchronous vibration. In a double overhung rotor such as the one involved here, this effect was found to happen with a peak cycle amplitude at each end occurring at different times, and with the apparent phase angle shift of the “hot spot” being limited in a deceiving, but ultimately explainable, manner. Field testing showed that maintaining an oil inlet temperature above a practical threshold temperature minimized viscous shearing forces in the bearing film enough to prevent the thermal cycling from occurring. Another option for eliminating the problem would be a bearing re-design to reduce the hot spot temperature severity and sensitivity. Review led by Gordon Kirk

New seals solve compressor vibration problem

Sour gas compression trains are at the heart of the sulfur removal process in a sour crude refining plant. The requirements of higher emission standards and cleaner fuel are placing increased emphasis on the stability and reliability of these machines. This feature describes the introduction of a new labyrinth seal design to solve the stability problems experienced on sour gas compressors of a central Asian oil producer.

Investigation of the scroll compressor porting process. Part II: local characteristics of the porting process and properties of the ports

As the flow field experiences drastic changes at the discharge and dummy ports of a scroll compressor, the local geometry and movement, including the sizes, shapes, and movement of the ports and scrolls, have significant impact on the porting process. To assess quantitatively the performance of a given design during porting, the local characteristics of the porting process are studied. The study is conducted both on the field quantity distributions and area-averaged parameters. These field quantities define both temporal and spatial changes of the flow field at the discharge and dummy ports. The investigation on these field quantities, provides a basic understanding of the porting process. The fundamental phenomena controlling the porting process are identified. The area-averaged parameters describe the dynamic features of the porting process. The components involved in the porting process, especially the scrolls, dummy and discharge ports, are studied. The area schedule, mass flowrate, pressure, temperature changes at the dummy and discharge ports are quantified. The impact of the porting process on the compressor efficiency, vibration, and noise generation is analysed.