Experimental and Numerical Study of Oil Whip in Propeller Shaft

2019 ◽  
Author(s):  
Adarsh Divakaran ◽  
K. Vijayan ◽  
A. Kartheek
Keyword(s):  
Experimental Study ◽  
Numerical Study ◽  
Beam Theory ◽  
Operating Regime ◽  
Propeller Shaft ◽  
Hydrodynamic Bearing ◽  
Time Frequency ◽  
Oil Whip ◽  
Run Up ◽  
Stiffness And Damping

Abstract An experimental study and theoretical study is carried out to understand the vibration signature of a propeller shaft. A test rig consists of a rotor shaft and three-disc supported on hydrodynamic bearing was analyzed. Presence of hydrodynamic bearing makes the systems natural frequency speed dependent. A theoretical model of the rotor disc system was developed using FEM. The rotor was formulated on Euler–Bernoulli beam theory. Proportional damping was assumed for the shaft. The stiffness and damping coefficients of the bearing are calculated by short bearing assumption. A Campbell diagram was plotted to observe the variation in natural frequencies with rotational speed. There was an indication of mode approaching each other with a speed which could result in the self-excited phenomena such as “Oil whip”. The hydrodynamic forces in the fluid film produce Oil whip. The presence of Oil whip was ascertained by carrying out the experimental study. The time-frequency plot during the run-up indicated the presence of a whip. The study indicated the influence of modes on the whip phenomena. This can be used in forming guidelines for the safe operating regime for the propeller shaft.

Influence of Lubricant Film Cavitation On the Vibration Behaviour of a Semi-Floating Ring Supported Turbocharger Rotor with Thrust Bearing

2021 ◽  
Author(s):  
Christian Ziese ◽  
Cornelius Irmscher ◽  
Steffen Nitzschke ◽  
Christian Daniel ◽  
Elmar Woschke ◽  
...  
Keyword(s):  
Squeeze Film ◽  
Two Phase ◽  
Hydrodynamic Bearing ◽  
Lubricating Film ◽  
Oil Whip ◽  
Oil Whirl ◽  
Bearing Stiffness ◽  
Run Up ◽  
Stiffness And Damping ◽  
The Impact

Abstract This contribution investigates the influence of outgassing processes on the vibration behaviour of a hydrodynamic bearing supported turbocharger rotor. The examined rotor is supported radially by floating rings with outer squeeze-film damping and axially by thrust bearings. Due to the highly non-linear bearing properties, the rotor can be excited via the lubricating film, which results in sub-synchronous vibrations known as oil-whirl and oil-whip phenomena. A significant influence on the occurrence of oil-whip phenomena is attributed to the bearing stiffness and damping, which depend both on the kinematic state of the supporting elements and the thermal condition as well as the occurrence of outgassing processes. For modelling the bearing behaviour, the Reynolds equation with mass-conserving cavitation regarding the two-phase model and the 3D energy as well as heat conduction equation is solved. To evaluate the impact of cavitation, run-up simulations are carried out assuming a fully (Half-Sommerfeld) or partially filled lubrication gap. The resulting rotor responses are compared with the shaft motion measurement. Also, the normalized eccentricity, the minimum lubricant fraction and the thermal bearing condition are discussed.

Modal Interactions in Drillstring Borehole Interactions

2019 ◽  
Author(s):  
A. Kartheek ◽  
K. Vijayan ◽  
M. I. Friswell
Keyword(s):  
Theoretical Model ◽  
Numerical Technique ◽  
Operating Regime ◽  
Test Rig ◽  
Modal Interactions ◽  
Time Frequency ◽  
Bearing Stiffness ◽  
Space Formulation ◽  
Run Up ◽  
Gyroscopic Effects

Abstract Understanding the vibration of drillstrings is important for the economical and efficient extraction of oil. Vibrations involve bending, axial, and torsional vibration. Drillstring interaction with the borehole during whirling involves nonlinearities. For the present work the whirling interaction of the drillstring and borehole is studied using an equivalent conceptual experimental test rig and a theoretical model of the drillstring. The drillstring is modeled as an Euler Bernoulli beam with multiple discs considering damping and gyroscopic effects. The finite element method is used as a numerical technique and the eigenvalue problem is solved using a state space formulation. The forward whirling frequency obtained from the experiments was used to update the bearing stiffness of the theoretical model. The contact is modeled experimentally using a tube for the stator with added roughness to aggravate the friction effect. A run up analysis was carried out within the safe operating regime of the test rig and the frequencies were analyzed using a time frequency plot. The effect of typical system parameters was considered such as the location of the contact, the mode excited and the clearance. The results from the study indicated the possibility of interaction between the forward and backward whirling modes which increased the bandwidth of acceleration response.

Nonlinear Interactions Within a Flexible Rotating Shaft

2019 ◽  
Author(s):  
Amaroju Kartheek ◽  
Kiran Vijayan
Keyword(s):  
Operating Regime ◽  
Turbine Rotor ◽  
Test Rig ◽  
Modal Interactions ◽  
Rotating Shaft ◽  
Time Frequency ◽  
Rotor Stator Interaction ◽  
Bearing Stiffness ◽  
Run Up ◽  
Gyroscopic Effects

Abstract Designing of an industrial gas turbine rotor needs a special attention to ensure safe and reliable operation of the entire machine. Rotor experiences bending, axial, and torsional vibration during the time of operation and Rotor-stator interaction during whirling involves nonlinearities in the form of friction and impact. Rub-impact is the most common fault in rotating machinery, which causes excessive vibration and reduces the efficiency of the machine. Therefore, it is very important to study and understand the contact phenomena in rotor dynamics. The purpose of this study is to understand the modal interactions that occur in a rotating flexible member. A conceptual test rig for the rotor-stator is developed experimentally and a corresponding numerical model for the system is developed. The test rig consists of a flexible rotor with two discs rotating within a localised conduit. The system is modelled as a Euler Bernoulli beam with two discs. Finite element method is used to model the system. The gyroscopic effects of the rotor also included in the model. The forward whirling frequency obtained from the experiments was used to update the bearing stiffness of the theoretical model. The contact is modelled experimentally using localised conduit with added roughness to aggravate the friction effect. A run-up analysis was carried out within the safe operating regime of the test rig and the frequencies were analysed using a time-frequency plot. The results from the study indicated the possibility of interaction between the forward and backward whirling modes which results in steady nonlinear backward whirl behaviour.

Experimental and Numerical Study of Methanol-Water Mixture Single-Phase Heat Transfer in a Micro-Channel Heat Sink

2012 ◽  
Author(s):  
Chun K. Kwok ◽  
Matthew M. Asada ◽  
Jonathan R. Mita ◽  
Weilin Qu
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Sink ◽  
Single Phase ◽  
Numerical Study ◽  
Pure Water ◽  
Molar Fraction ◽  
Water Mixture ◽  
Micro Channel ◽  
Numerical Predictions

This paper presents an experimental study of single-phase heat transfer characteristics of binary methanol-water mixtures in a micro-channel heat sink containing an array of 22 microchannels with 240μm × 630μm cross-section. Pure water, pure methanol, and five methanol-water mixtures with methanol molar fraction of 16%, 36%, 50%, 63% and 82% were tested. Key parametric trends were identified and discussed. The experimental study was complemented by a three-dimensional numerical simulation. Numerical predictions and experimental data are in good agreement with a mean absolute error (MAE) of 0.87%.

Hydrodynamic characteristics of vertical and quadrant face pile supported breakwater under oblique waves

2021 ◽  
pp. 147509022110313
Author(s):  
T J Jemi Jeya ◽  
V Sriram ◽  
V Sundar
Keyword(s):  
Experimental Study ◽  
Hydrodynamic Performance ◽  
Hydrodynamic Characteristics ◽  
Scattering Parameter ◽  
Oblique Waves ◽  
Test Conditions ◽  
Relative Water ◽  
Identical Test ◽  
Run Up ◽  
Water Depths

This paper presents the results from a comprehensive experimental study on the Quadrant Face Pile Supported Breakwater (QPSB) in two different water depths exposed to three different oblique wave attacks. The results are compared with that for a Vertical face Pile Supported Breakwater (VPSB) for identical test conditions. The paper compares the reflection coefficient, transmission coefficient, energy loss coefficient, non-dimensional pressure, and non-dimensional run-up as a function of the relative water depth and scattering parameter. The results obtained for QPSB are validated with existing results. The salient observations show that QPSB experiences better hydrodynamic performance characteristics than the VPSB under oblique waves.

NUMERICAL AND EXPERIMENTAL STUDY ON FREE VIBRATION OF DELAMINATED WOVEN FIBER GLASS/EPOXY COMPOSITE PLATES

2012 ◽  
Vol 12 (02) ◽  
pp. 377-394 ◽  
Author(s):  
J. MOHANTY ◽  
S. K. SAHU ◽  
P. K. PARHI
Keyword(s):  
Experimental Study ◽  
Aspect Ratio ◽  
Free Vibration ◽  
Boundary Conditions ◽  
Natural Frequencies ◽  
Numerical Study ◽  
Shear Deformation Theory ◽  
Composite Plates ◽  
Fiber Glass ◽  
Number Of Layers

This paper presents a combined experimental and numerical study of free vibration of industry-driven woven fiber glass/epoxy (G/E) composite plates with delamination. Using the first-order shear deformation theory, an eight-noded two-dimensional quadratic isoparametric element was developed, which has five degrees of freedom per node. In the experimental study, the influence of various parameters such as the delamination size, boundary conditions, fiber orientations, number of layers, and aspect ratio on the natural frequencies of delaminated composite plates are investigated. Comparison of the numerical results with experimental ones shows good agreement. Fundamental natural frequencies are found to decrease with the increase in the delamination size and fiber orientation and increases with the increase in the number of layers and aspect ratio of delaminated composite plates. The natural frequency of the delaminated composite plate varies significantly for different boundary conditions.

Calculation and Measurement of the Stiffness and Damping Coefficients for a Low Impedance Hydrodynamic Bearing

1997 ◽  
Vol 119 (1) ◽  
pp. 57-63 ◽  
Author(s):  
M. J. Goodwin ◽  
P. J. Ogrodnik ◽  
M. P. Roach ◽  
Y. Fang
Keyword(s):  
Experimental Data ◽  
Dynamic Stiffness ◽  
Perturbation Technique ◽  
The Novel ◽  
Oil Film ◽  
Hydrodynamic Bearing ◽  
Damping Coefficients ◽  
Stiffness And Damping ◽  
Film Stiffness ◽  
Novel Design

This paper describes a combined theoretical and experimental investigation of the eight oil film stiffness and damping coefficients for a novel low impedance hydrodynamic bearing. The novel design incorporates a recess in the bearing surface which is connected to a standard commercial gas bag accumulator; this arrangement reduces the oil film dynamic stiffness and leads to improved machine response and stability. A finite difference method was used to solve Reynolds equation and yield the pressure distribution in the bearing oil film. Integration of the pressure profile then enabled the fluid film forces to be evaluated. A perturbation technique was used to determine the dynamic pressure components, and hence to determine the eight oil film stiffness and damping coefficients. Experimental data was obtained from a laboratory test rig in which a test bearing, floating on a rotating shaft, was excited by a multi-frequency force signal. Measurements of the resulting relative movement between bearing and journal enabled the oil film coefficients to be measured. The results of the work show good agreement between theoretical and experimental data, and indicate that the oil film impedance of the novel design is considerably lower than that of a conventional bearing.

Identification of Viscously Damped Distributed Structural Dynamic Systems

1991 ◽  
Author(s):  
R. Chander ◽  
M. Meyyappa ◽  
S. Hanagud
Keyword(s):  
Dynamic Systems ◽  
Beam Theory ◽  
Continuous Functions ◽  
Model Parameters ◽  
Unknown Parameters ◽  
Structural Dynamic ◽  
Domain Identification ◽  
Forcing Function ◽  
Cardinal Splines ◽  
Stiffness And Damping

Abstract A frequency domain identification technique applicable to damped distributed structural dynamic systems is presented. The technique is developed for beams whose behavior can be modeled using the Euler-Bernoulli beam theory. External damping of the system is included by means of a linear viscous damping model. Parameters to be identified, mass, stiffness and damping distributions are assumed to be continuous functions over the beam. The response at a discrete number of points along the length of the beam for a given forcing function is used as the data for identification. The identification scheme involves approximating the infinite dimensional response and parameter spaces by using quintic B-splines and cubic cardinal splines, respectively. A Galerkin type weighted residual procedure, in conjunction with the least squares technique, is employed to determine the unknown parameters. Numerically simulated response data for an applied impulse load are utilized to validate the developed technique. Estimated values for the mass, stiffness and damping distributions are discussed.

Efficient Finite Element for Evaluation of Strain Concentrations in Concrete Coated Pipelines

2008 ◽  
Author(s):  
Svein Sævik ◽  
Martin Storheim ◽  
Erik Levold
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Sandwich Beam ◽  
Beam Theory ◽  
Material Model ◽  
Body Motion ◽  
Theoretical Formulation ◽  
Concrete Material ◽  
Non Linear ◽  
Full Scale Tests

MARINTEK has developed software for detailed analysis of pipelines during installation and operation. As part of the software development a new coating finite element was developed in cooperation with StatoilHydro enabling efficient analysis of field joint strain concentrations of long concrete coated pipeline sections. The element was formulated based on sandwich beam theory and application of the Principle of Potential Energy. Large deformations and non-linear geometry effects were handled by a Co-rotated “ghost” reference description where elimination of rigid body motion was taken care of by referring to relative displacements in the strain energy term. The non-linearity related to shear interaction and concrete material behaviour was handled by applying non-linear springs and a purpose made concrete material model. The paper describes the theoretical formulation and numerical studies carried out to verify the model. The numerical study included comparison between model and full-scale tests as well as between model and other commercial software. At last a 3000 m long pipeline was analysed to demonstrate the strain concentration behaviour of a concrete coated pipeline exposed to high temperature snaking on the seabed.

Experimental study on a magnetofluid sealing liquid for propeller shaft

2003 ◽  
Vol 2 (1) ◽  
pp. 66-70
Author(s):  
Chang-fa Zhao ◽  
Rong-hua Sun ◽  
Jin-xing Zheng
Keyword(s):  
Experimental Study ◽  
Propeller Shaft
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