Vibration Of Compressor Research Articles

A Review of Linear Compressor Vibration Isolation Methods

Linear compressors exhibit high compression efficiency and low noise characteristics, showcasing broad application prospects in various fields such as aerospace, medicine, household appliances, and more. However, due to the complexity of their structures and operation, the issue of vibration isolation in linear compressors has long been a research challenge within the industry. Addressing this challenge, this paper provides an overview of vibration isolation optimization methods for linear compressors. It delves into the discussion of different vibration sources in linear compressors and their respective measurement techniques. By integrating both single degree of freedom (SDOF) and multiple degree of freedom (MDOF) vibration isolation models, this paper describes both active and passive vibration isolation methods tailored to linear compressors. Furthermore, a feasible optimization approach is proposed. Finally, the paper offers insights into the developmental potential and feasibility of vibration energy recovery strategies.

Fault diagnosis of new type screw compressor of helium liquefier by vibration signal

A diagnostic method for screw compressor faults using vibration signals was introduced and applied to a new type of helium oil-injected screw compressor in the 80L/h helium liquefier. The study revealed that the destruction of the oil film due to impurity particles could lead to rotor rubbing and poor meshing, compromising the reliability of these compressors. Based on frequency-domain analysis, the major vibration occurred at the meshing frequency of screw rotors and a series of its harmonics. The vibration of the characteristic frequency of bearing parts also indicated that the bearing had slight wear in the early stage. The vibration waveform’s time domain diagram exhibited clear clipping, and the axis trajectory shew disorder, which were common characteristic of rotor rubbing. When compressing helium with low molecular weight, the meshing clearance, tooth tip clearance, and end clearance of the rotor were significantly lower than those of traditional refrigerants or air media. Additionally, the thermal gap caused by thermoelastic deformation was smaller due to the large adiabatic index of helium. Therefore, rubbing faults between rotors and between rotors and casing were more likely to occur. The article recommended establishing a vibration signal monitoring system, optimizing the design of helium screw rotor profiles, and setting up reliability standards for screw compressor operation, such as limiting the vibration speed to ≤ 8 mm/s. Additionally, attention should be given to cleaning gas pipelines in cryogenic engineering and monitoring compressor vibration and noise signals during operation to prevent rotor damage due to particle impurities.

Relationship between Casing Pressure and Non-Synchronous Vibration in an Axial Compressor

The relationship between aerodynamic forcing and non-synchronous vibration (NSV) in axial compressors remains difficult to ascertain from experimental measurements. In this work, the relationship between casing pressure and blade vibration was investigated using experimental observations from a 1.5-stage axial compressor under off-design conditions. The wavenumber-dependent auto-spectral density (ASD) of casing pressure was introduced to aid in understanding the characteristics of pressure fluctuations that lead to the aeromechanical response. Specifically, the rotor blade’s natural frequencies and nodal diameters could be directly compared with the pressure spectra. This analysis indicated that the rotating disturbances coincided with the first bending (1B) and second bending (2B) vibration modes at certain frequencies and wavenumbers. The non-intrusive stress measurement system (NSMS) data showed elevated vibration amplitudes for the coincident nodal diameters. The amplitude of the wavenumber-dependent pressure spectra was projected onto the single-degree-of-freedom (SDOF) transfer function and was compared with the measured vibration amplitude. The results showed a near-linear relationship between the pressure and vibration data.

Study on blade vibration of centrifugal compressor - Forced responses caused by casing treatment

A casing treatment of centrifugal compressor for turbochargers is a very important device in aerodynamic performance improvement because it enables to expand an operating range of compressor. However, a rib existing in the circulation flow path of casing treatment is one of the factors causing a resonance problem. In this study, the relationship between a casing treatment and blade vibration was investigated by frequency response analysis that combines computational fluid dynamics and finite element method. As a result, it was clarified that the difference in the amount of vibration response and the excitation mechanism by the existence of rib.

Influence of Methane-Hydrogen Mixture Characteristics on Compressor Vibrations

Influence of Methane-Hydrogen Mixture Characteristics on Compressor Vibrations

Fault Classification in Reciprocating Compressors: A Comparison of Machine Learning and Deep Learning Approaches

This study compares methodologies for fault classification in reciprocating compressors, focusing on traditional Machine Learning (ML) with classical feature extraction processes and one-dimensional Convolutional Neural Networks (1D-CNN) in Deep Learning (DL). Both techniques demonstrated viability by employing a dataset of compressor vibration signals encompassing ten fault classes. While ML achieved a classification accuracy of 86%, DL reached 90.709%, highlighting its superior learning and generalization abilities, although with longer training times. These findings suggest that, despite ML being effective when relevant prior knowledge is available, DL, particularly with 1D-CNN, offers enhanced fault classification performance for this study case at the expense of additional processing resources.

Identification of Compressor Vibration Aerodynamic Forcing Mechanisms by Spectral Characteristics

Abstract Nonsynchronous vibration (NSV) in axial compressors can be caused either by (1) unsteady aerodynamic forces that are not related to motion of the blades or (2) motion-dependent aerodynamic forcing (e.g., flutter). Aerodynamic forcing mechanisms can be challenging to identify in experimental observations of NSV because the temporal vibration characteristics for both forcing mechanisms can appear similar. This work proposes a method for distinguishing between the two mechanisms using spectral characteristics. The method provides an interpretation of experimental data explicitly consistent with the analytical models used to differentiate between forced response and flutter. Two cases of NSV were observed in a 1.5-stage axial compressor at near-stall conditions. The circumferential wavenumber-dependent unsteady pressure spectra and nonintrusive stress measurement system (NSMS) spectra were observed to have distinct characteristics for the two NSV cases. Based on these distinct spectral characteristics, the first case was identified as blade-row aerodynamic forcing, while the second was identified as motion-dependent (flutter). Numerical simulations confirmed low aerodynamic damping at the conditions where flutter was observed.

Active electric machine control to reduce compressor noise in heat pumps

As heat pumps help to reduce CO2 emission in residential heating, rapidly growing heat pump sales are predicted. In order to install heat pumps in densely populated residential areas, they must comply with strict noise requirements. Due to advances in control technology in recent years, it seemed promising to investigate the noise reduction potential of a heat pump by means of optimized control. An active control strategy called Current Shaping (CS) has been applied to reduce compressor induced heat pump noise by applying suitable currents to the compressors electric machine. For this purpose, by CS we superimposed suitable current harmonics on the almost constant Iq driving current. In this article we focus on how these modified driving currents affect the noise emitted from the compressor and how this reduces heat pump noise. A compressor test bench was built to perform the CS optimization procedure and to determine noise optimal currents by minimizing compressor vibration. An important finding of this investigation is that the compressor vibrations can be efficiently reduced by CS, and hence also the noise emissions. The vibration reduction potential depends on the compressor harmonic and the operating condition. Additionally, pressure pulsations were measured within the refrigerant pipes and found not to be affected by CS. After the test bench optimization, we applied the optimized currents to a heat pump in a sound chamber to proof that these optimized currents efficiently reduce heat pump noise. For the investigated frequency range of up to 400 Hz our investigations show the three following: First, active electric machine control CS is a suitable method to reduce heat pump noise. Second, the test bench, presented in this paper is suitable to determine the CS current harmonics to reduce heat pump noise. Third, it can be confirmed that the main heat pump noise source is compressor vibration. In general, the two main noise sources of a heat pump are the fan and the compressor. For the compressor there are three noise paths, namely structure-borne and air-borne noise, both excited by compressor vibration, and fluid-borne noise, excited by pressure pulsations in the refrigerant in the piping system. Therefore, from the investigations presented here, it can be derived that the compressor noise is dominating heat pump noise. Moreover, compressor vibrations are dominating heat pump noise and not pressure pulsations in the piping system.

Energy harvesting induced by the vibration of reciprocating-piston compressor subjected to repetitive impulse

In this study, discrete event time-variant parameter of a lumped SISO dynamical system is obtained for a novel energy harvester. The harvester utilizes the resonance vibration of a coupled fluid-mechanic system, which is comprised of a reciprocating-piston, a tunable oscillator and twin electric turbine generators. The system model is simplified by an underdamped spring-mass-damper with tunable parameters subjected to periodic or arbitrary impulse forces. We developed a method that solves general problems underlining non-homogenous ordinary second order differential equation with discrete event time-variant parameters. The method uses the superposition to compile the general solution by segmenting the problem into ODE equations with constant coefficient. Each segment corresponds to a change in system, and it is solved analytically with recursively updated initial conditions. We utilized this method to tune the system’s natural frequency such that the accumulated energy is maximum within desired time range. We obtained the general solution of the displacement response due to varying parameters and input impulse force. We obtained the displacement peaks and their time of occurrence that could help understand the structural design limitation. We showed system displacement responses (constructive and destructive) corresponding to various impulse repetition patterns. We derived the relationship between energy, volume displacement, and volumetric flow rate (or piston velocity) and provided illustrative case studies. One finding shows that for a given impulse condition the accumulative energy exhibits local maximum and minimum within a narrow band of natural frequency range. The simulations showed the feasibility of generating considerable power from electric turbine when the air flow is driven by a resonating piston.

Research on vibration and noise characteristics of scroll compressor with condenser blockage fault based on signal demodulation

The scroll compressor is the core component of the air conditioning system. It is important to accurately evaluate the operation status of the air conditioning system. In this paper, the condenser failure is simulated to explore the impact on the scroll compressor by building an air conditioning system experimental platform. The characteristic frequencies and generation mechanisms of vibration and noise signals are discussed through Time-frequency analysis. The characteristic frequencies in the x, y, and z directions are shaft frequency, second harmonic frequency of stator slot and magnet frequency. Abnormal vibration of the scroll compressor caused by changes in pressure and unbalanced electromagnetic force. The modulation characteristic frequency of the signal and the trend of modulation characteristic changes under fault conditions are discussed through signal demodulation methods. The amplitude modulation of the characteristic frequency is enhanced by the unbalanced electromagnetic force on the shaft rotor. The amplitude of the modulation characteristic frequency of the vibration signal in the three directions and the noise signal increases by 45.0%, 17.3%, 71.4% and 123.0%. This study reveals the mechanism and modulation characteristics of vibration and noise of the scroll compressor, and provides support for its fault diagnosis and status recognition.

Equilibrium Analysis and Simulation Calculation of Four-Star Type Crank Linkage Mechanism

Unbalanced inertia force is inevitably generated during the operation of crank linkage. It is one of the main excitation sources of air compressor vibration and the focus of managing air compressor vibration noise. In this regard, this paper studies the variation law of inertia force in the four-star type crank linkage mechanism. Certain balancing methods are used to reduce the unbalanced inertia force. Firstly, we present a comparison of perfect and partial balanced problems of crank linkage inertia forces. Then, using the ADAMS software multibody dynamics calculation method, the balancing mass is numerically calculated to optimize the design of the balancing mass for partial balancing of inertia force. Next, the influence law of piston mass asymmetry on the force of crankshaft revolving pair is studied. Lastly, two new types of four-star type crank linkage mechanism are proposed from the viewpoint of completely balanced inertia forces and moments of inertia. The results show that the perfectly balanced inertia force is better than the partially balanced inertia force in terms of a balancing effect. The parametric design of ADAMS software is more efficient and can get the best quality quickly. The design of perfectly balanced inertia force will increase the length and complexity of the crankshaft, while reducing the structural strength. The research results of this paper are important for improving the vibration damping performance of marine air compressors.

A fault diagnosis method on GWO-SPA and MAE for fault diagnosis of reciprocating compressors

Given the non-stationary and nonlinear features of the reciprocating compressor vibration signal, as well as the problems of end-point effect and modal aliasing existing in the current adaptive decomposition method, the fault diagnosis method for reciprocating compressors based on gray wolf optimization-smoothness priors approach (GWO-SPA) and multiscale attention entropy (MAE) is proposed in this paper. The selection of the regularization parameter λ in the SPA algorithm is studied, and the GWO is introduced to improve the decomposition effect of the SPA method. Then, the entropy value of the MAE is calculated for the detrended term components decomposed by GWO-SPA to describe the fault characteristics quantitatively, and perform PCA dimensionality reduction processing. Finally, the optimized feature vector is input into the SVM. Through the experiments show it is proved that the method proposed can effectively extract the fault state features of reciprocating compressors, and realize the accurate distinction of the fault types of reciprocating compressors.

Coupling Vibration Analytical Model and Vibration Suppression of Linear Motor Driven Free Piston Stirling Cryocoolers

Linear motors are widely utilized in free-piston Stirling cryocoolers (FPSCs) due to their high efficiency, high reliability, and low noise. The reciprocating motion of the compression piston and the expansion displacer in a FPSC will inevitably lead to the vibration output. Most researches only focused on the vibration of a single moving component, and few studies discussed about the coupling vibration of linear compressor and expander. In this paper, the vibration of a linear motor-driven Stirling cryocooler is studied through theoretical analysis and experiments. A passive absorber is designed to suppress the vibration output from the linear compressor and expander simultaneously. The dynamic model of the Stirling cryocooler system is established, and the network transfer function between the input voltage and the system displacement of the linear motor is derived. The influences of these linear motor parameters of thrust constant, resistance and inductance, and working condition of charged pressure, is investigated in detail, on the system's vibration output. The experimental results are presented to evaluate the validity of the proposed model.

Development of flow-vibroacoustic coupled numerical methods for prediction of noise radiation due to flow-born vibration of compressor discharge piping system

The compressor and fan in air conditioner outdoor unit are the core component which deter-mines noise performance as well as cooling or heating performance. Among these, the com-pressor has larger contribution to the noise of outdoor units. For high efficiency air condition-er, the size and operating speed of compressor are smaller and faster. The high-speed com-pressor causes loud noise which is complaints for the customer. Traditionally, it is well-known that the vibration of compressor and connected duct is main noise source. However, as the compressor speed increases, the refrigerant flow in the compressor discharge duct also emerged as a major noise source. To reduce the compressor noise operating at high speed, it is necessary to analyze vibrational and acoustic characteristics of compressor discharge duct. This duct noise has the two-types source: structure born noise and flow induced noise. The structure born noise is generated by the duct vibration caused by compressor movement. For the flow induced noise, the static pressure field of refrigerant flow in the duct is vibrational source. In this paper, the compressor discharge duct noise considering two mechanisms was investigated. The refrigerant flow is solved using CFD and duct vibration and noise radiation are computed by FE-BE method.

Vibration-Based Measurement of Activated Cylinders in Reciprocating Machines

Vibration signals from rotating and reciprocating machines provide insights into machine health and operating parameters. Reciprocating machines often feature cylinder deactivation systems for increased efficiency. This article presents a vibration-based method for the detection of activated cylinders in reciprocating machines. Simulated compressor vibration signals demonstrate the effect of cylinder conditions on spectral-coherence and mean-envelope-spectrum (MES) estimates. Physical parameters of the mechanical system and the results of the simulations advise the proposed method. With an appropriately chosen region of interest (ROI), the MES-based indicator (MESbI) correctly identified the number of activated cylinders of a four-cylinder reciprocating refrigeration compressor in both field and laboratory test setups. A discussion section addresses measurement uncertainty and calibration, and provides an example application.

Effect of starting position of crankshaft on transient body vibrations of reciprocating compressor

The maximum reciprocating compressor vibrations occur during the startup and shutdown operations and understanding the factors that influence the transient vibrations can help in developing solutions to reduce the excessive displacements. In this study, the effect of crankshaft starting position on the vibration phenomenon is investigated and the optimal starting position to deliver a smooth start is proposed. The structural forces are analytically modeled to estimate the body displacements by considering the system resonance frequencies and modal vectors. An experimental setup is also constructed to validate the prediction model results, with the integration of an encoder to track the crankshaft angular position and transducers to measure the discharge and suction pressures. The transient responses of three different crankshaft start positions are then compared using the experimental setup and the analytical model. The results indicate that if the crankshaft starts to rotate from positions close to the bottom dead center, a higher amount of startup vibrations is observed, revealing the optimal starting position zone.The magnetization effect can potentially be addressed by the sensorless starting strategy developed by Lee et al. (2008) that implements a phase current controller for a smoother startup. While out of scope for this study, shutdown strategies can also be devised to have the piston consistently land at the favorable SAP range. By separately investigating the instances when the ‘stop’ command is provided to the steady-state operating compressor, solutions that attempt to replicate the conditions that lead to the favorable stop position can be developed; a limiting factor in mass production will be implementing the encoder for continuous position tracking and an accompanying undesirable cost increase in manufacturing. Nevertheless, the investigation of passive and active strategies is ripe for research in literature.

Research on non-parametric prediction method of reciprocating compressor time series based on prediction credibility scale

Aiming at the long-term unpredictability of the reciprocating compressor vibration signal, a non-parametric prediction method of reciprocating compressor time series based on the prediction credibility scale is proposed in this paper. The method is to take the multifractal singular spectrum as the prediction parameter and use the Smoothness Priors Approach (SPA) method to obtain the singular spectrum parameters of different components, and construct the phase space reconstruction dynamic modeling domains. It enables the prediction model to reflect the real-time characteristics of the dynamics evolution of complex systems and highlights the independent influence of each component on the prediction. Meanwhile, the information entropy saturation principle is introduced into the K-Nearest Neighbor (KNN) model to establish the improved K neighborhood dynamic non-parametric prediction model based on the maximum prediction credibility scale, which improves the credibility of the prediction results. Finally, a complete SPA&PSR_KNN prediction algorithm is proposed. Through example validation and error analysis, compared with KNN, BP, and SVM, it can be seen that the prediction results of spectral characteristic parameters obtained by this algorithm have smaller error and higher reliability, and faster operation speed. Thus, the prediction of vibration signal time series of reciprocating compressor is realized.

Performance Analysis of Rotating Shaft of Air Compressor for Hydrogen Battery

The rotating shaft is the key component of the air compressor connecting the bearing seat and turbine disk for hydrogen battery, and its working reliability affects the safety of the air compressor.The rotating shaft is the key component of the air compressor for hydrogen energy battery connecting the bearing seat and turbine disk, and its working reliability affects the safety and life of the air compressor. The performance analysis and comparison of the typical structure of the rotating shaft of an air compressor are carried out, which provides experimental data for the vibration of an air compressor and lays a theoretical foundation for the relevant design of enterprises.

Improved FULMS Algorithm for Multi-Modal Active Control of Compressor Vibration and Noise Reduction

Active control is currently a hot-button issue in the research of reducing vibration and noise created by rolling piston compressors. Active control can effectively suppress the modal vibration of the structure and reduce the modal resonance acoustic radiation. This paper, which focuses on the active control of the compressor shell’s multiple modes with the control of acoustic radiation power being the research objective, studies the relationship between vibration modes and acoustic radiation modes of the compressor shell and the primary sources of noise. An improved Filtered-U least mean square (FULMS) algorithm for compressor vibration and noise control, which is based on the Nesterov accelerated adaptive moment estimation (NADAM) optimization algorithm, is proposed to determine the multi-order modes to be controlled from the perspective of sound energy, and a particle swarm algorithm is used to determine the location and number of secondary sources. The active control model of the compressor shell was established by using the joint simulation platform, and the performance of the improved algorithm was verified and analyzed by the simulation test process. The results show that compared with the traditional FULMS algorithm, the improved FULMS algorithm has better active vibration control effect, higher convergence speed and can effectively suppress structural mode vibration in a short period time.

Experimental and Numerical Study on the Squeal of a Rotary Compressor

This study predicts the squeal instability of a rotary compressor using a full-size finite element model. A complex eigenvalue extraction method was used to study the tendency toward squeal of the rotary compressor during working. The numerical results showed that the unstable vibration frequency of the rotary compressor was 6,908 Hz, which corresponded to the frequency of the rotary compressor squeal. The squealing vibration of the rotary compressor was also measured, with results showing that the measured squeal frequency was in good agreement with that predicted by the finite element model. Transient dynamic analysis results showed that when squeal occurred, the main frequency of the normal acceleration of the upper flange was the same as that of the tangential acceleration. This phenomenon showed that the coupling of the normal vibration and tangential vibration of the upper flange was a main reason for the compressor squeal. Also, the greater the friction coefficient, the higher the likelihood of a squeal occurrence.