scholarly journals Numerical analysis of a radial hybrid lobe bearing with gas lubrication

2021 ◽  
pp. 98-104
Author(s):  
Н.В. Куценко ◽  
М.В. Грибиниченко ◽  
А.В. Нитяговский ◽  
А.В. Куренский ◽  
О.С. Портнова
Keyword(s):  
Numerical Analysis ◽  
Pressure Distribution ◽  
Numerical Study ◽  
Gas Dynamic ◽  
Working Surface ◽  
Lubricating Layer ◽  
Gas Lubrication ◽  
Optimal Values ◽  
Optimization Methodology ◽  
Positive Effect

В работе рассмотрены результаты численного исследования модели радиального гибридного подшипника с газовой смазкой. Установлено наличие оптимальных значений параметров, определяющих форму смазочного зазора, получены их значения и закономерности влияния на них различных характеристик подшипника. Рассмотрено распределение давления в смазочном слое при различном количестве секторов лепестков. Подтверждено предположение о наличии оптимальных значений параметров, определяющих форму смазочного зазора. И опровергнуто предположение о том, что оптимальные значения этих параметров будут зависеть от значений других параметров подшипника. Выявлен положительный эффект от совместного воздействия газодинамического и газостатического эффектов. Относительно газостатических параметров – выявлен параметр, имеющий оптимальное значение (расстояние от выбранного торца подшипника до линии сетки, на которой располагаются питатели ряда с номером р), которое сохраняет постоянное значение. На основе полученных результатов разработаны основы методики расчета и оптимизации радиальных гибридных подшипников с газовой смазкой, имеющих профилированную рабочую поверхность. The paper considers the results of numerical study of gas-lubricated hybrid radial bearing model. The presence of optimal values of parameters determining the shape of the lubrication gap is established, their values and regularities of influence of different bearing characteristics on them are obtained. Pressure distribution in the lubricating layer at different number of lobe sectors has been considered. The assumption of optimum values of parameters determining the form of the lubrication gap is confirmed. And the assumption that the optimal values of these parameters will depend on the values of other bearing parameters is refuted. The positive effect of the combined effect of gas-dynamic and gas-static effects has been revealed. Concerning gas-static parameters - the parameter which has optimum value (distance from the chosen end face of a bearing to a grid line on which feeders of a row with number p are located) which keeps constant value has been revealed. On the basis of the obtained results the bases of calculation and optimization methodology of radial hybrid bearings with gas lubrication, having profiled working surface, are developed.

Numerical Analysis of Pressure Distribution in a Brush Seal based on a 2-D Staggered Tube Banks Model

2019 ◽  
pp. -1--1
Author(s):  
Yuchi Kang ◽  
Meihong Liu ◽  
Sharon Kao-Walter ◽  
Jinbin Liu ◽  
Qihong Ceng
Keyword(s):  
Numerical Analysis ◽  
Pressure Distribution ◽  
Brush Seal ◽  
Tube Banks

scholarly journals Experimental and numerical study of acoustic pressure distribution in a sonochemical reactor

2021 ◽  
Vol 1809 (1) ◽  
pp. 012025
Author(s):  
M O Kuchinskiy ◽  
T P Lyubimova ◽  
K A Rybkin ◽  
O O Fattalov ◽  
L S Klimenko
Keyword(s):  
Pressure Distribution ◽  
Acoustic Pressure ◽  
Numerical Study

The Numerical Analysis of the Velocity and Pressure Distribution of the Oil Film in Heavy Hydrostatic Thrust Bearing

2014 ◽  
Vol 541-542 ◽  
pp. 658-662
Author(s):  
Jian Li ◽  
Yuan Chen ◽  
Yang Chun Yu ◽  
Zhu Xin Tian ◽  
Yu Huang
Keyword(s):  
Mathematical Model ◽  
Numerical Analysis ◽  
Pressure Distribution ◽  
Working Conditions ◽  
Thrust Bearing ◽  
Rotation Speed ◽  
The Other ◽  
Surface Load ◽  
Oil Film ◽  
Volume Method

To study the velocity and pressure distribution of the oil film in a heavy hydrostatic thrust bearing, a mathematical model of the velocity is proposed and the finite volume method (FVM) has been used to simulate the flow field under different working conditions. Some pressure experiments were carried out and the results verified the correctness of the simulation. It is concluded that the pressure distribution varies small under different rotation speed when the surface load on the workbench is constant. But the velocity of the oil film is influenced greatly by the rotation speed. When the rotation speed of the workbench is as quick as enough, the velocity of the oil film on one radial side of the pad will be zero, that is to say the lubrication oil will be drained from the other three sides of the recess.

Experimental and Numerical Study of Honeycomb Tip on Suppressing Tip Leakage Flow in Turbine Cascade

2017 ◽  
Author(s):  
Yunfeng Fu ◽  
Fu Chen ◽  
Huaping Liu ◽  
Yanping Song
Keyword(s):  
Numerical Study ◽  
Flow Characteristics ◽  
Leakage Flow ◽  
Exit Section ◽  
Turbine Cascade ◽  
Tip Leakage Flow ◽  
Physical Processes ◽  
Tip Leakage ◽  
Gap Height ◽  
Positive Effect

In this paper, the effect of a novel honeycomb tip on suppressing tip leakage flow in a highly-loaded turbine cascade has been experimentally and numerically studied. The research focuses on the mechanisms of honeycomb tip on suppressing tip leakage flow and affecting the secondary flow in the cascade, as well as the influences of different clearance heights on leakage flow characteristics. In addition, two kinds of local honeycomb tip structures are pro-posed to explore the positive effect on suppressing leakage flow in simpler tip honeycomb structures. Based on the experimental and numerical results, the physical processes of tip leakage flow and its interaction with main flow are analyzed, the following conclusions can be obtained. Honeycomb tip rolls up a number of small vortices and radial jets in regular hexagonal honeycomb cavities, increasing the flow resistance in the clearance and reducing the velocity of leakage flow. As a result, the structure of honeycomb tip not only suppresses the leakage flow effectively, but also has positive effect on reducing the associated losses in cascade by reducing the strength of leakage vortex. Compare to the flat tip cascade at 1%H gap height, the relative leakage flow in honeycomb tip cascade reduces from 3.05% to 2.73%, and the loss at exit section is also decreased by 10.63%. With the increase of the gap height, the tip leakage flow and loss have variations of direct proportion with it, but their growth rates in the honeycomb tip cascade are smaller. Consider the abradable property of the honeycomb seal, a smaller gap height is allowed in the cascade with honeycomb tip, and that means honeycomb tip has better effect on suppressing leakage flow. Two various local honeycomb tip structures has also been discussed. It shows that local raised honeycomb tip has better suppressing leakage flow effect than honeycomb tip, while local concave honeycomb tip has no more effect than honeycomb tip. Compare to flat tip cascade, the leakage flow in honeycomb tip cascade, local concave tip cascade and local raised honeycomb tip cascade decrease by nearly 17.33%, 15.51% and 30.86% respectively, the losses at exit section is reduced by 13.38%, 12% and 28.17% respectively.

The Effect of the Thickness and Angle of the Inlet and Outlet Guide Vane on the Performance of Axial-Flow Pump

2016 ◽  
Author(s):  
Sang-Won Kim ◽  
Youn-Jea Kim
Keyword(s):  
Numerical Analysis ◽  
Numerical Study ◽  
Guide Vane ◽  
Axial Flow ◽  
Inlet Guide Vane ◽  
Guide Vanes ◽  
Pump Performance ◽  
Blade Thickness ◽  
Axial Flow Pump ◽  
Flow Pump

An axial-flow pump has a relatively high discharge flow rate and specific speed at a relatively low head and it consists of an inlet guide vane, impeller, and outlet guide vane. The interaction of the flow through the inlet guide vane, impeller, and outlet guide vane of the axial-flow pump has a significant effect on its performance. Of those components, the guide vanes especially can improve the head and efficiency of the pump by transforming the kinetic energy of the rotating flow, which has a tangential velocity component, into pressure energy. Accordingly, the geometric configurations of the guide vanes such as blade thickness and angle are crucial design factors for determining the performance of the axial-flow pump. As the reliability of Computational Fluid Dynamics (CFD) has been elevated together with the advance in computer technology, numerical analysis using CFD has recently become an alternative to empirical experiment due to its high reliability to measure the flow field. Thus, in this study, 1,200mm axial-flow pump having an inlet guide vane and impeller with 4 blades and an outlet guide vane with 6 blades was numerically investigated. Numerical study was conducted using the commercial CFD code, ANSYS CFX ver. 16.1, in order to elucidate the effect of the thickness and angle of the guide vanes on the performance of 1,200mm axial-flow pump. The stage condition, which averages the fluxes between interfaces and is accordingly appropriate for the evaluation of pump performance, was adopted as the interface condition between the guide vanes and the impeller. The rotational periodicity condition was used in order to enable a simplified geometry to be used since the guide vanes feature multiple identical regions. The shear stress transport (SST) k-ω model, predicting the turbulence within the flow in good agreement, was also employed in the CFD calculation. With regard to the numerical simulation results, the characteristics of the pressure distribution were discussed in detail. The pump performance, which will determine how well an axial-flow pump will work in terms of its efficiency and head, was also discussed in detail, leading to the conclusion on the optimal blade thickness and angle for the improvement of the performance. In addition, the total pressure loss coefficient was considered in order to investigate the loss within the flow paths depending on the thickness and angle variations. The results presented in this study may give guidelines to the numerical analysis of the axial-flow pump and the investigation of the performance for further optimal design of the axial-flow pump.

scholarly journals Lubrication Analyses of Cam and Flat-Faced Follower

Lubricants ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 31 ◽  
Author(s):  
Hazim U. Jamali ◽  
Amjad Al-Hamood ◽  
Oday I. Abdullah ◽  
Adolfo Senatore ◽  
Josef Schlattmann
Keyword(s):  
Film Thickness ◽  
Pressure Distribution ◽  
Surface Deformation ◽  
Numerical Study ◽  
Point Contact ◽  
Radius Of Curvature ◽  
Operating Cycle ◽  
Essential Step ◽  
Parabolic Shape ◽  
Principal Factors

The principal factors that affect the characteristics of contact problem between cam and follower vary enormously during the operating cycle of this mechanism. This includes radius of curvature, surface velocities and applied load. It has been found over the last decades that the mechanism operates under an extremely thin film of lubricant. Any practical improvement in the level of film thickness that separates the contacted surfaces represents an essential step towards a satisfactory design of the system. In this paper a detailed numerical study is presented for the cam and follower (flat-faced) lubrication including the effect of introducing an axial modification (parabolic shape) of the cam depth on the levels of film thickness and pressure distribution. This is achieved based on a point contact model for a cam and flat-faced follower system. The results reveal that the cam form of modification has considerable consequences on the level of predicted film thickness and pressure distribution as well as surface deformation.

scholarly journals Numerical Study of a Single-Point Mooring Gravity Fish Cage With Different Deformation-Suppression Methods

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Hui Cheng ◽  
Karl Gunnar Aarsæther ◽  
Lin Li ◽  
Muk Chen Ong
Keyword(s):  
Current Velocity ◽  
Numerical Study ◽  
Single Point ◽  
Local Environment ◽  
Full Scale ◽  
Tension Force ◽  
Wave Loads ◽  
Practical Advice ◽  
Rigid Frame ◽  
Positive Effect

Abstract Compared with the multipoint mooring fish cage, the single-point mooring (SPM) fish cage can spread out the fish wastes and uneaten feeds in a larger area, and it can also prevent the local environment from being overwhelmed. Thus, it has attracted much attention recently. In this research, different deformation-suppression methods are applied to the SPM system with a typical Norwegian fish cage aiming to increase the cultivation volume under the action of current and/or wave loads. A well-validated software, fhsim, is used to conduct the full-scale numerical study. The effects of the three deformation-suppression methods, i.e., (i) adding the lower bridles, (ii) adding the frontal rigid frame and (iii) adding the trawl doors, are analyzed under pure current and combined wave–current conditions. The results indicate that all the three deformation-suppression methods can improve the cultivation volume at least by 32% compared to the original SPM fish cage when the current velocity is larger than 0.5 m/s. In addition, moving the conjunction point close to the bottom ring can bring a positive effect on the cultivation volume maintaining with an only small increment in the tension force. This study can provide practical advice and useful guides for the SPM fish cage design.

scholarly journals Experimental and Numerical Study of Pre-Swirl Stators PSS

2020 ◽  
Vol 8 (1) ◽  
pp. 47 ◽  
Author(s):  
Kourosh Koushan ◽  
Vladimir Krasilnikov ◽  
Marco Nataletti ◽  
Lucia Sileo ◽  
Silas Spence
Keyword(s):  
Numerical Analysis ◽  
Energy Saving ◽  
Scale Effect ◽  
Financial Incentives ◽  
Numerical Study ◽  
Considerable Improvement ◽  
Scale Model ◽  
Propulsion Efficiency ◽  
Wake Field ◽  
Additional Resistance

Energy saving within shipping is gaining more attention due to environmental awareness, financial incentives, and, most importantly, new regional and international rules, which limit the acceptable emission from the ships considerably. One of the measures is installation of energy saving devices (ESD). One type of such a device, known as pre-swirl stator (PSS), consists of a number (usually 3 to 5) of fins, which are mounted right in front of the propeller. By modifying the inflow and swirl into the propeller, the fins of a PSS have the possibility to increase the total propulsion efficiency. However, at the same time, they may introduce additional resistance either due to changes in pressure distribution over the aft ship or due to its own resistance of fins. In this paper, the authors present experimental and numerical investigation of a PSS for a chemical tanker. Numerical analysis of the vessel with and without PSS is performed in the model and full scale. Model testing is performed with and without PSS to verify the power savings predicted numerically. Among other quantities, 3D wake field behind the hull is densely measured at different planes, starting from the PSS plane to the rudder stock plane. 3D wake measurements are also conducted with a running propeller. The measurements show considerable improvement in the performance of the vessel fitted with PSS. On the numerical side, analyses show that scale effect plays an important role in the ESD performance. Investigation of the scale effect on the vessel equipped with an ESD provides new insight for the community, which is investing more into the development of energy saving devices, and it offers valuable information for the elaboration of scaling procedures for such vessels.

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