Nanoparticles-Laden Gas Film in Aerostatic Thrust Bearing

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Zhiru Yang ◽  
Dongfeng Diao ◽  
Xue Fan ◽  
Hongyan Fan
Keyword(s):  
Effective Viscosity ◽  
Flow Model ◽  
Thrust Bearing ◽  
Volume Fraction ◽  
Load Capacity ◽  
Sio2 Nanoparticles ◽  
Enhancement Effect ◽  
The Novel ◽  
Two Phase ◽  
Air Film

Nanoparticles-laden gas film (NLGF) was formed by adding SiO2 nanoparticles with volume fraction in the range of 0.014–0.330% and size of 30 nm into the air gas film in a thrust bearing. An effective viscosity of the gas-solid two phase lubrication media was introduced. The pressure distribution in NLGF and the load capacity of the thrust bearing were calculated by using the gas-solid two phase flow model with the effective viscosity under the film thicknesses range of 15–60 μm condition. The results showed that the NLGF can increase the load capacity when the film thickness is larger than 30 μm. The mechanism of the enhancement effect of load capacity was attributed to the increase of the effective viscosity of the NLGF from the pure air film, and the novel lubrication media of the NLGF can be expected for the bearing industry application.

Experimental study on load capacity of nanoparticles-laden gas film in thrust bearing

2015 ◽  
Vol 67 (3) ◽  
pp. 233-239 ◽  
Author(s):  
Zhiru Yang ◽  
Dongfeng Diao ◽  
Hongyan Fan ◽  
Xue Fan ◽  
Chao Wang
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Volume Fraction ◽  
Load Capacity ◽  
Displacement Sensor ◽  
Enhancement Effect ◽  
Total Load ◽  
Film Pressure ◽  
Content Type ◽  
Nanoparticles Volume Fraction

Purpose – The purpose of this paper is to study the load capacity of nanoparticles-laden gas film (NLGF) in thrust bearing. Design/methodology/approach – SiO2 nanoparticles were added into gas to form an NLGF. The nanoparticles volume fraction in the film was controlled by a vibrator. The film thickness and the film pressure were measured by a micro cantilever displacement sensor and a membrane pressure sensor, respectively. The total load that makes the film thickness keeping constant was quantified, and then, the film load capacity was obtained. Findings – The investigation shows that nanoparticles can enlarge the film load capacity remarkably; even a little amount of nanoparticles (0.01 per cent) could lead to a sharp rise. With the increase of nanoparticles volume fraction, load capacity increases. However, the increment of load capacity decreases gradually. In addition, the film pressure variation proves the enhancement effect of nanoparticles on the film load capacity. Research limitations/implications – The paper is restricted to the findings based on NLGF, which is formed by dispersing SiO2 nanoparticles in gas film as an additive. The experimental results are applicable within the range of nanoparticles volume fraction of 0.01-0.33 per cent. Originality/value – The fact that nanoparticles could enlarge the gas film load capacity is verified by experiment for the first time. This study reveals the corresponding relation between nanoparticles volume fraction and the film load capacity.

Analysis of flow field in Si3N4 dry granulation chamber with non-standard composite structure

2020 ◽  
pp. 1-12
Author(s):  
Zhuting Jiang ◽  
Xiang Ning ◽  
Tao Duan ◽  
Nanxing Wu ◽  
Dongling Yu
Keyword(s):  
Flow Field ◽  
Composite Structures ◽  
Flow Model ◽  
Volume Fraction ◽  
Volume Distribution ◽  
Phase Flow ◽  
Two Phase ◽  
Dry Granulation ◽  
Combined Structure ◽  
Internal Distribution

In order to improve the whirling phenomenon of Si3N4 particles in the granulation chamber, the influence of the structure of the granulation chamber on the internal distribution is explored. Euler Euler’s two-phase flow model is established. The flow field in the combined structure granulation chamber with different layout is simulated. The volume distribution and velocity field change of Si3N4 particles in the combined structure granulation chamber with different layout are analyzed. The results show that the angle between two adjacent composite structures is 20∘, 60∘, 80∘ and completely standard the Si3N4 particles with volume fraction index greater than 0.8 account for 10.2%, 11.5%, 12.5% and 6.7% of the total volume respectively. When the combined structure is completely standard, several small convolutions are found. The whirling phenomenon in the granulation chamber is improved. When the angle between two adjacent composite structures is 20∘, 60∘, 80∘ and complete standard, the proportion of qualified particles is 59%, 64%, 66% and 68%. The fluidity index is 84, 85, 87 and 88, respectively. To sum up, the combination structure of the granulation chamber is a complete standard, it is beneficial to improve the spin phenomenon of Si3N4 particles in the granulation chamber.

The Static Characteristics of Bump Foil Thrust Bearing Considering Tilting Condition

2009 ◽  
Author(s):  
Tae-Young Kim ◽  
Dong-Jin Park ◽  
Yong-Bok Lee
Keyword(s):  
High Efficiency ◽  
Thrust Bearing ◽  
Numerical Models ◽  
Load Capacity ◽  
Static Characteristics ◽  
Thrust Bearings ◽  
Foil Bearings ◽  
Foil Thrust Bearing ◽  
Thrust Pad ◽  
Air Film

Air foil thrust bearings are the critical component available on high-efficiency turbomachinery which needs ability to endure the large axial force. Previous investigations about the static characteristics were obtained over the region of the thin air film using finite-difference method and the characteristics of the corrugated bump foil using finite-element method. Moreover, a recent study demonstrated that bearing performance is sensitive to tilting thrust pad condition. In this study, experimentally measured bearing static characteristics are compared with the numerical model of the foil thrust bearing considering tilting pad condition. Three geometrically different type foil bearings were tested to measure their load capacity under tilting conditions that have continuous angles from zero to 0.0002 rad. These data are presented for use i1n the development of more accurate foil thrust bearing numerical models.

An Innovative Two-Phase Flow Pump and Separator Solution

2011 ◽  
Author(s):  
Franc¸ois Gruselle ◽  
Johan Steimes ◽  
Patrick Hendrick
Keyword(s):  
Flow Rate ◽  
Flow Model ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Operating Conditions ◽  
Liquid Volume ◽  
Phase Flow ◽  
Two Phase ◽  
Efficient System ◽  
Measurement Systems

The Aero-Thermo-Mechanics (ATM) department of Universite´ Libre de Bruxelles (ULB) develops a new system to simultaneously pump and separate a two-phase flow, in particular oil/air mixtures. Two-phase flows are encountered in many applications (oil extraction, flow in nuclear power plant pumps, pulp and paper processing) but the study is mainly focused on aeroengine lubrication systems. The main objective is to obtain a compact and efficient system that can both extract the gas of a two-phase flow and increase the pressure of the liquid phase. Particular care is given to the liquid flow rate lost at the gas outlet of the system. A large range of gas/liquid volume ratio has been studied, leading to different two-phase flow regimes at the inlet of the system (slug, churn or annular flow). After successful tests with water-air prototypes, which have allowed to identify the key design and working parameters, the technology has been implemented for a hot oil-air mixture. This paper presents the test results of the first oil/air prototype under real in-flight operating conditions. The tests with oil/air mixtures were performed on the aeroengine lubrication system test bench of the ATM department. The identification and implementation of appropriate two-phase flow rate measurement systems is an essential contribution to the project. Two attractive measurement systems have been considered: a Coriolis density meter for the volume fraction at the liquid outlet and radio-tracing elements for the measurement of the oil consumption at the air outlet. In parallel, the flow field in the pump and separator system has been studied with commercial CFD (Computational Fluid Dynamics) software packages. The choice of the two-phase flow model is highly dependent on the two-phase flow regime. But different regimes can simultaneously exist in the pump and separator system. So, the Eulerian two-phase flow model, the most complex and general model, seems to be the most appropriate. A coupling of this model with a dispersed phase model is under investigation to take all two-phase flow phenomena into account.

Homogenisation of two-phase emulsions

1994 ◽  
Vol 124 (6) ◽  
pp. 1119-1134 ◽  
Author(s):  
Robert Lipton ◽  
Bogdan Vernescu
Keyword(s):  
Surface Tension ◽  
Effective Viscosity ◽  
Volume Fraction ◽  
Normal Component ◽  
Bulk Flow ◽  
Two Phase ◽  
Bulk Stress ◽  
Spherical Bubbles ◽  
Stokes Fluid

We consider an emulsion of two Stokes fluids, one of which is periodically distributed in the form of small spherical bubbles. The effects of surface tension on the bubble boundaries are modelled mathematically, as in the work of G. I. Taylor, by a jump only in the normal component of the traction. For a given volume fraction of bubbles, we consider the two-scale convergence, and in the fine phase limit we find that the bulk flow is described by an anisotropic Stokes fluid. The effective viscosity tensor is consistent with the bulk stress formula obtained by Batchelor [2].

Transient Coupled Borehole/Formation Fluid-Flow Model for Interpretation of Oil/Water Production Logs

SPE Journal ◽  
2016 ◽  
Vol 22 (01) ◽  
pp. 389-406 ◽  
Author(s):  
Amir Frooqnia ◽  
Carlos Torres-Verdín ◽  
Kamy Sepehrnoori ◽  
Rohollah Abdhollah-Pour
Keyword(s):  
Fluid Flow ◽  
Flow Model ◽  
Volume Fraction ◽  
Fluid Phase ◽  
Coupling Method ◽  
Average Pressure ◽  
Petrophysical Properties ◽  
Two Phase ◽  
Flow Models ◽  
Oil Water

Summary Interpretation of two-phase production logs (PLs) traditionally constructs borehole fluid-flow models decoupled from the physics of reservoir rocks. However, quantifying formation dynamic petrophysical properties from PLs requires simultaneous modeling of both borehole and formation fluid-flow phenomena. This paper develops a novel transient borehole/formation fluid-flow model that allows quantification of the effect of formation petrophysical properties on measurements acquired with production-logging tools (PLTs). We invoke a 1D, isothermal, two-fluid formulation to simulate borehole fluid-phase velocity, pressure, volume fraction, and density in oil/water-flow systems. The developed borehole fluid-flow model implements oil-dominant and water-dominant bubbly flow regimes with the inversion point taking place approximately when the oil volume fraction is equal to 0.5. Droplet diameter is dynamically modified to simulate interfacial drag effects, and to effectively account for variations of slip velocity in the borehole. Subsequently, a new successive iterative method interfaces the borehole and formation fluid-flow models by introducing appropriate source terms into the borehole fluid-phase mass-conservation equations. The novel iterative coupling method integrated with the developed borehole fluid-flow model allows dynamic modification of reservoir boundary conditions to accurately simulate transient behavior of borehole crossflow taking place across differentially depleted rock formations. In the case of rapid variations of near-borehole properties, frequent borehole/formation communication inevitably increases the computational time required for fluid-flow simulation. Despite this limitation, in a two-layer reservoir model penetrated by a vertical borehole, the coupling method accurately quantifies a 14% increase of volume-averaged oil-phase relative permeability of the low-pressure layer caused by through-the-borehole cross-communication of differentially depleted layers. Sensitivity analyses indicate that the alteration of near-borehole petrophysical properties primarily depends on formation average pressure, fluid-phase density contrast, and borehole-deviation angle. A practical application of the new coupled fluid-flow model is numerical simulation of borehole production measurements to estimate formation average pressure from two-phase selective-inflow-performance (SIP) analysis. This study suggests that incorporating static (shut-in) PL passes into the SIP analysis could result in misleading estimation of formation average pressure.

scholarly journals Low Pressure Experimental Validation of Low-Dimensional Analytical Model for Air–Water Two-Phase Transient Flow in Horizontal Pipelines

Fluids ◽  
2021 ◽  
Vol 6 (6) ◽  
pp. 220
Author(s):  
Hamdi Mnasri ◽  
Amine Meziou ◽  
Matthew A. Franchek ◽  
Wai Lam Loh ◽  
Thiam Teik Wan ◽  
...  
Keyword(s):  
Multiphase Flow ◽  
Experimental Validation ◽  
Flow Model ◽  
Transient Flow ◽  
Volume Fraction ◽  
Laboratory Data ◽  
Low Pressure ◽  
Two Phase ◽  
Fluid Properties ◽  
Low Dimensional

This paper presents a low-pressure experimental validation of a two-phase transient pipeline flow model. Measured pressure and flow rate data are collected for slug and froth flow patterns at the low pressure of 6 bar at the National University of Singapore Multiphase Flow Loop facility. The analyzed low-dimensional model proposed in comprises a steady-state multiphase flow model in series with a linear dynamic model capturing the flow transients. The model is based on a dissipative distributed parameter model for transient flow in transmission lines employing equivalent fluid properties. These parameters are based solely on the flowing conditions, fluid properties and pipeline geometry. OLGA simulations are employed as an independent method to validate the low-dimension model. Both low-dimensional and OLGA models are evaluated based on the estimated two-phase pressure transients for varying gas volume fraction (GVF). Both models estimated the two-phase flow transient pressure within 5% mean absolute percent error of the laboratory data. Additionally, an unavoidable presence of entrained air within a pipeline is confirmed for the case of 0% GVF as evidenced by the pressure transient estimation. Thus, dampened oscillations in the simulated 0% GVF case exists owing to an increase in the fluid compressibility.

Performance of novel air foil thrust bearings with taper-groove on surface of top foil

2020 ◽  
Vol 235 (1) ◽  
pp. 79-92
Author(s):  
Hongyang Hu ◽  
Ming Feng
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Groove Depth ◽  
Friction Torque ◽  
Width Ratio ◽  
Local Dynamic ◽  
The Novel ◽  
Rarefaction Effect ◽  
Foil Thrust Bearing

To improve the load capacity of air foil thrust bearing, the micro taper-grooves on the surface of top foil was introduced and studied. A modified Reynolds equation considering the gas rarefaction effect was established, in which the Knudsen number was affected by the film thickness and pressure. A new bump stiffness model was built with the consideration of bump rounding, friction, and bending stiffness of foil. By considering the variation of gas film thickness, the load capacity, friction torque, and power loss of novel bearing with grooves were calculated by the finite difference method. Moreover, the effect law of groove parameters, groove shape and grooves number on the novel bearing performance was studied systematically. The results show that the predicted axial load capacity considering gas rarefaction effect is decreased slightly in smaller clearance and more consistent with the actual test data. The novel air foil thrust bearing with taper-groove can weaken the air end leakage and enhance the local dynamic pressure efficiently in the parallel portion of top foil, thus improving the static characteristics of bearing. For the novel air foil thrust bearing with taper-groove depth of 10 µm, the load capacity can be increased by about 13.33%, compared with traditional bearing. With the increments of taper-groove depth and length on top foil, the load capacity can be increased. However, the friction torque is decreased when there is a longer taper-groove in the circumferential direction. Meanwhile, the optimal groove width ratio is about 0.5, and the structure of multi-grooves is beneficial to the decreased friction torque. The validity of presented theoretical model has been verified by the literature data, and the results are expected to be helpful to bearing designers, researchers, and academicians concerned.

An Analytical Two-Phase Flow Model for Prediction of Leakage in Wet Gas Labyrinth Seals and Pocket Damper Seals. Is Simplicity Still Desired?

2021 ◽  
Author(s):  
Jing Yang ◽  
Luis San Andres
Keyword(s):  
Analytical Model ◽  
Flow Model ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Gas Mixture ◽  
Phase Flow ◽  
Rotor Speed ◽  
Labyrinth Seals ◽  
Two Phase ◽  
Wet Gas

Abstract Current and upcoming two-phase pump and compression systems in subsea production facilities must demonstrate long-term operation and continuous availability. Annular pressure seals, limiting secondary flow, also influence the dynamic stability of turbomachinery. Hence, it becomes paramount to quantify the leakage and dynamic performance of annular seals operating with a liquid in gas mixture (wet gas). The paper develops a simple analytical model predicting the leakage and cavity pressures for Labyrinth seals and pocket damper seals (PDSs) operating with two-phase flow. The model adapts Neumann's equation with a homogeneous flow model. Predicted leakage for a four-blade PDS operating under a low supply pressure (2.3 and 3.2 bar) and a low rotor speed (5,250 rpm) agree well with experimental results for both a pure gas and a wet gas conditions. For an eight-blade PDS supplied with air at 62.1 bar, discharge pressure 31.1 bar and rotor speed of 15 krpm, the analytical model predicts leakage that is just 2% larger than a CFD prediction. For the PDS supplied with an oil in gas mixture having gas volume fraction = 0.92 ~ 0.98, the simple model delivers leakage that is up to ~ 6% lower than published CFD results. Throughout the life of an oil well that sees radical changes in gas and liquid composition as well as pressure conditions, the expedient model, quick and accurate to estimate leakage in wet gases seals, can be readily integrated into an engineering routine or practice.

Two-phase modelling of a fluid mixing layer

1999 ◽  
Vol 378 ◽  
pp. 119-143 ◽  
Author(s):  
J. GLIMM ◽  
D. SALTZ ◽  
D. H. SHARP
Keyword(s):  
Boundary Conditions ◽  
Flow Model ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Mixing Layer ◽  
Constitutive Law ◽  
Fluid Mixing ◽  
Phase Flow ◽  
Two Phase ◽  
Self Similar Solution

We analyse and improve a recently-proposed two-phase flow model for the statistical evolution of two-fluid mixing. A hyperbolic equation for the volume fraction, whose characteristic speed is the average interface velocity v*, plays a central role. We propose a new model for v* in terms of the volume fraction and fluid velocities, which can be interpreted as a constitutive law for two-fluid mixing. In the incompressible limit, the two-phase equations admit a self-similar solution for an arbitrary scaling of lengths. We show that the constitutive law for v* can be expressed directly in terms of the volume fraction, and thus it is an experimentally measurable quantity. For incompressible Rayleigh–Taylor mixing, we examine the self-similar solution based on a simple zero-parameter model for v*. It is shown that the present approach gives improved agreement with experimental data for the growth rate of a Rayleigh–Taylor mixing layer.Closure of the two-phase flow model requires boundary conditions for the surfaces that separate the two-phase and single-phase regions, i.e. the edges of the mixing layer. We propose boundary conditions for Rayleigh–Taylor mixing based on the inertial, drag, and buoyant forces on the furthest penetrating structures which define these edges. Our analysis indicates that the compatibility of the boundary conditions with the two-phase flow model is an important consideration. The closure assumptions introduced here and their consequences in relation to experimental data are compared to the work of others.

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