scholarly journals Vibration Analysis of a Single-Cylinder Reciprocating Compressor considering the Coupling Effects of Torsional Vibration

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Siyuan Liu ◽  
Wanyou Li ◽  
Zhijun Shuai ◽  
Meilong Chen
Keyword(s):  
Torsional Vibration ◽  
Vibration Analysis ◽  
Transfer Functions ◽  
Cylinder Liner ◽  
Angular Speed ◽  
Reciprocating Compressor ◽  
Connecting Rod ◽  
Single Cylinder ◽  
Rotating Speed ◽  
Instantaneous Angular Speed

A piston slap is one of the main vibration sources of the reciprocating machinery. Much work has been done in this field, most of which was based on a constant rotating speed. However, in practice, the speed of a crankshaft may always fluctuate due to the uneven load or excitation. The inertia forces of moving components are much different at the fluctuating rotating speed comparing with that at a constant speed. In this paper, the piston slap and the induced vibration are analyzed based on the instantaneous angular speed measured on a single-cylinder reciprocating compressor. Firstly, the dynamics of a crank-connecting rod mechanism is analyzed based on the measured instantaneous angular speed which contains the torsional vibration of the air compressor. The time histories of piston slap impact forces considering and without considering torsional vibration are compared. Then, in order to correlate the piston slap impact with the slap-induced vibration, the corresponding transfer functions between the middle stroke of the outer surface of the cylinder liner and the excitation points are measured. And the excitation force on the main bearing is also taken into account to bring the simulation closer to the experimental results. The effects of a torsional vibration on the vibration of the cylinder liner are analyzed, and the simulation results show that the torsional vibration is a factor that must be taken into account in the vibration analysis of the single-cylinder reciprocating compressor.

Dynamic Analysis of the Crank Train in a Single Cylinder Diesel Engine Using a Lumped Parameter Method

2016 ◽  
Author(s):  
X. Y. Zhang ◽  
J. Guo ◽  
Zhang Wenping
Keyword(s):  
Diesel Engine ◽  
Dynamic Analysis ◽  
Internal Force ◽  
Parameter Method ◽  
Cylinder Pressure ◽  
Connecting Rod ◽  
Single Cylinder ◽  
Rotating Speed ◽  
Lumped Parameter ◽  
Lumped Parameter Method

The kinematic and dynamic behaviors of the crank train in a single cylinder diesel engine are analyzed in the paper. The crank train mechanism consists of four parts: a crank without counterweight, a connecting rod, a piston associated with a cylinder and two stops at both ends of a stroke. The dynamic model is developed using a lumped parameter method. The inertia of mass or moment are considered by an equivalent treatment in the centers of the piston pin, the crank pin, the main journal, respectively. The longitudinal deformations of the connecting rod are simulated by spring-damping elements, as well as the angular and bending deformations of the crank. As a result, it was possible to predict the effects of the component inertia of mass or moment and stiffness on the internal force and rotating speed of the crank under the cylinder pressure.

scholarly journals Study of the Piston Secondary Movement on the Tribological Performance of a Single Cylinder Low-Displacement Diesel Engine

Lubricants ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 97
Author(s):  
Jorge Duarte Forero ◽  
Guillermo Valencia Ochoa ◽  
Wlamyr Palacios Alvarado
Keyword(s):  
Mathematical Model ◽  
Diesel Engine ◽  
Hydrodynamic Lubrication ◽  
Lateral Displacement ◽  
Cylinder Liner ◽  
Deformation Model ◽  
Analysis Tool ◽  
Connecting Rod ◽  
Single Cylinder ◽  
Piston Skirt

The present study aims to analyze the secondary movement of the piston considering the deformations present in the piston skirt, the hydrodynamic lubrication, and the effects of the clearances in the connecting rod bearings. The analysis of the piston movement is performed by developing a mathematical model, which was used to evaluate the dynamic characteristics of the piston movement, the slap force on the piston skirt, the effect of the secondary piston movement on the connecting rod, and the influence of clearances in the connecting rod bearings and in the piston. For the study, the geometric of the crankshaft-connecting rod–piston system of a single-cylinder diesel engine is taken as a reference. The deformation model of the piston was carried out by means of a symmetric finite element model (FEM), which was integrated into the mathematical model of the piston. MATLAB® software (The MathWorks Inc., Natick, MA, USA) is used for the development of model simulations. The obtained results show that during the combustion cycle, there are six changes of direction in the secondary movement of the piston with lateral and angular velocities that can reach a magnitude of 0.13 m/s and 4 rad/s. The lateral and angular movement of the piston during its travel causes the appearance of impacts on the piston skirt with the cylinder liner, which produces an increase of approximately 500 N in the hydrodynamic forces in the connecting rod bearings. The force analysis shows that the range of the maximum magnitudes of these forces is between 1900 N and 3480 N. The increase in clearance between the cylinder liner and the piston skirt (Cpc) causes a greater lateral displacement and an increase in the angle of inclination of the piston. Analysis of the change in connecting rod bearing clearance shows that there are critical values in relation to clearance Cpc. The model presented allows us to analyze the different characteristics of the secondary movement of the piston, which involve the interaction between the piston skirt and the cylinder liner. Additionally, the influence of this movement on the connecting rod bearings is considered. The foregoing can be used as an analysis tool for the study of designs and/or modifications in the engine in such a way that greater durability of the components, reductions in acoustic emissions, and reduction in friction losses are achieved.

Torsional vibration analysis of a rotating tapered sandwich beam with magnetorheological elastomer core

2018 ◽  
Vol 29 (11) ◽  
pp. 2406-2423 ◽  
Author(s):  
Saeed Bornassi ◽  
Hossein M Navazi
Keyword(s):  
Magnetic Field ◽  
Layer Thickness ◽  
Torsional Vibration ◽  
Vibration Analysis ◽  
Sandwich Beam ◽  
Vibration Characteristics ◽  
Magnetorheological Elastomer ◽  
Lagrange Equations ◽  
Rotating Speed ◽  
Setting Angle

In this study, the torsional vibration analysis of a rotating tapered sandwich beam with a magnetorheological elastomer core has been investigated. The magnetorheological elastomer material is used as a constrained damping layer embedded between two elastic constraining skins in order to improve the vibrational behavior of the sandwich beam. The three layers of the sandwich beam have rectangular cross-sections with symmetric arrangement. The problem formulation is set up based on the torsional theory of rectangular laminated plates. The assumed modes method and the Lagrange equations are used to derive the governing equations of motion of the system. The validity of the presented formulation is confirmed through comparison of the obtained results with those available in the literature. A detailed parametric study is carried out to investigate the effects of applied magnetic field, tapering ratios, magnetorheological elastomer layer thickness, rotating speed, hub radius, and setting angle on the free vibration characteristics of the sandwich beam. The results show that magnetic field intensity, magnetorheological elastomer layer thickness, and tapering ratio have significant influences on the torsional vibrating characteristics of the sandwich beam, and the effects of rotating speed and hub radius are considerable. The setting angle has no substantial effect on the torsional vibration characteristics.

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