Forming Laminar Flow of Engine Oil Under Conditions of High-Speed Sliding Friction

2019 ◽  
pp. 1137-1153
Author(s):  
V. I. Kubich ◽  
E. A. Zadorozhnaya ◽  
O. G. Cherneta
Keyword(s):  
Laminar Flow ◽  
High Speed ◽  
Sliding Friction ◽  
Engine Oil

Effect of Graphite Content on Cu–Ni–Graphite Composite for Use as Switch Slide Baseplate Materials Sliding Against U75V Steel

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Yiran Wang ◽  
Yimin Gao ◽  
Jun Takahashi ◽  
Yi Wan ◽  
Yunqian Zhang ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Wear Mechanism ◽  
High Speed ◽  
Sliding Friction ◽  
Rapid Development ◽  
Wear Volume ◽  
Fatigue Wear ◽  
Friction Coefficients ◽  
Graphite Composite ◽  
Graphite Content

Abstract The rapid development of high-speed railways necessitates the development of new materials for switch slide baseplates. In this study, a Cu–Ni–graphite composite, containing 1 wt% to 6 wt% graphite and prepared by powder metallurgy, was used as a potential material. Pin-on-disk wear tests were conducted to measure the sliding friction of the Cu–Ni–graphite composite against U75 V steel. The results showed that the friction coefficients gradually decreased when the graphite content in the composite ranged from 1 wt% to 4 wt% in the composite. When the graphite content was 4 wt%, the friction coefficient reached the minimum value (0.153). When the graphite content was low (1 wt% to 4 wt%), the primary wear mechanism was microcutting. An increased graphite content facilitated the generation of lubricating films and decreased the wear damage. As the graphite content increased from 4 wt% to 6 wt%, the friction coefficients also increased. The variation in the wear volume rate had the same tendency as the friction coefficient. When the graphite content exceeded 4 wt%, the primary wear mechanism was delamination and fatigue wear. Due to the tendency to form cracks on the subsurface and the plentiful generation of the spalled pits, the graphite fragments could not completely form lubricating films but separated as wear debris. The lubricating films existing on the U75 V steel were in proportion to the graphite content in the composite. The wear weight loss of the U75 V steel exhibited a reduction with increasing graphite content.

scholarly journals Lubrication Analysis of Micro-Dimple Textured Die Surface by Direct Observation of Contact Interface in Sheet Metal Forming

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 917 ◽  
Author(s):  
Shimizu ◽  
Kobayashi ◽  
Vorholt ◽  
Yang
Keyword(s):  
Metal Forming ◽  
High Speed ◽  
Sliding Friction ◽  
Flow Analysis ◽  
Hydrodynamic Pressure ◽  
Observation System ◽  
In Situ Observation ◽  
Two Phase ◽  
Micro Dimple

: To investigate the underlying mechanism of the effects of surface texturing on lubricated sliding friction in the metal forming operation, an in-situ observation system using transparent silica glass dies and a high speed recording camera was newly developed. To correlate the dimensional parameters of micro-dimple textured structures and tribological properties in the metal forming operation, the in-situ observation was performed during bending with the ironing process of the stainless steel sheet with a thickness of 0.1 mm. The lubrication behavior were compared between the different lubricant viscosities and the micro-dimple textures with different diameters of 10 µm, 50 µm, 100 µm fabricated by using femto-/pico-second laser processing. As a result, the textured die with dimple diameters of 10 µm and 50 µm showed the lubricant flow transferred from one to the other dimples owing to the lubricant reservoir effect, while that of 100 µm indicated the less supply of the lubricant. However, the textured die with a dimple diameter of 10 µm demonstrated higher ironing force than that of 50 µm, due to the severe adhesion of work materials inside the dimple structures. Based on these experimental findings, the dimple size dependencies on lubricant reservoirs effects and the generation of the hydrodynamic pressure were discussed by correlating with the in-situ observation results, a fluid-flow analysis and a laminar two-phase flow analysis using the finite element method.

Dynamic Analysis for the Rotor Drop Process and Its Application to a Vertically Levitated Rotor/Active Magnetic Bearing System

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Yulan Zhao ◽  
Guojun Yang ◽  
Patrick Keogh ◽  
Lei Zhao
Keyword(s):  
High Speed ◽  
Sliding Friction ◽  
Engineering Application ◽  
Magnetic Bearing ◽  
Contact Forces ◽  
Active Magnetic Bearing ◽  
Detailed Model ◽  
Vertical Rotor ◽  
Auxiliary Bearing ◽  
Rotor Dynamic

Active magnetic bearings (AMBs) have been utilized widely to support high-speed rotors. However, in the case of AMB failure, emergencies, or overload conditions, the auxiliary bearing is chosen as the backup protector to provide mechanical supports and displacement constraints for the rotor. With lack of support, the auxiliary bearing will catch the dropping rotor. Accordingly, high contact forces and corresponding thermal generation due to mechanical rub are applied on the dynamic contact area. Rapid deterioration may be brought about by excessive dynamic and thermal shocks. Therefore, the auxiliary bearing must be sufficiently robust to guarantee the safety of the AMB system. Many approaches have been put forward in the literature to estimate the rotor dynamic motion, nonetheless most of them focus on the horizontal rotor drop and few consider the inclination around the horizontal plane for the vertical rotor. The main purpose of this paper is to predict the rotor dynamic behavior accurately for the vertical rotor drop case. A detailed model for the vertical rotor drop process with consideration of the rotating inclination around x- and y-axes is proposed in this paper. Additionally, rolling and sliding friction are distinguished in the simulation scenario. This model has been applied to estimate the rotor drop process in a helium circulator system equipped with AMBs for the 10 MW high-temperature gas-cooled reactor (HTR-10). The HTR-10 has been designed and researched by the Institute of Nuclear and New Energy Technology (INET) of Tsinghua University. The auxiliary bearing is utilized to support the rotor in the helium circulator. The validity of this model is verified by the results obtained in this paper as well. This paper also provides suggestions for the further improvement of auxiliary bearing design and engineering application.

Performance Analysis of High Speed Floating Ring Hybrid Bearing in the Laminar and Turbulent Regimes

2011 ◽  
Vol 197-198 ◽  
pp. 1776-1780 ◽  
Author(s):  
Hong Guo ◽  
Bo Qian Xia ◽  
Shao Qi Cen
Keyword(s):  
Reynolds Number ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Load Capacity ◽  
Flow Equation ◽  
The Finite Element Method ◽  
Static And Dynamic Characteristics ◽  
Hybrid Bearing

This paper presents a theoretical study concerning the static and dynamic characteristics of high speed journal floating ring hybrid bearing compensated by interior restrictor under laminar flow and turbulent flow respectively. The turbulent flow fluid film control equations and the pressure boundary conditions of this floating ring bearing together with the restrictor flow equation are solved by using the Finite Element Method. The variation regularity of static and dynamic characteristics such as load capacity, friction power loss, stiffness, damping etc. is analyzed. By comparing the laminar flow results and turbulent flow results, it is found that the characteristics coefficients are adjacent under small Reynolds number (laminar flow is dominant). But the characteristics coefficients are discrepant under big Reynolds number (turbulent flow is dominant). So turbulence lubrication theory is more accurate to high speed floating ring bearing.

Aerodynamic Drag on Vehicles in Tunnels

1969 ◽  
Vol 91 (4) ◽  
pp. 694-706 ◽  
Author(s):  
S. William Gouse ◽  
B. S. Noyes ◽  
J. K. Nwude ◽  
M. C. Swarden
Keyword(s):  
Laminar Flow ◽  
Drag Coefficient ◽  
Surface Area ◽  
Incompressible Flow ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Diameter Ratio ◽  
Infinite Body ◽  
Tunnel Wall ◽  
Wetted Surface Area

The purpose of this study was to investigate the aerodynamic drag on vehicles moving in guideways of varying degrees of enclosure. The reason for this study was that several potential high speed ground transport system concepts involve high speed motion of vehicles in enclosed guideways for significant portions of their travel time. Analytical and experimental investigations have been carried out. The analytical studies developed the solution for the aerodynamic drag on a vehicle in an enclosed guideway in laminar flow. The analysis is based on an analogy between the governing equations for the unsteady flow resulting when an infinite body is started impulsively from rest and the steady flow that results from steady motion of a semi-infinite body. The results of this analysis for laminar flow provided a base from which to begin in turbulent flow and were used to justify the basing of a drag coefficient on the wetted surface area of a vehicle rather than the frontal area of a vehicle. Preliminary experiments were executed using spheres as vehicle models. Final experimental studies were carried out using cylindrical models in circular tunnels of various lengths and various degrees of wall porosity. A drop testing apparatus was employed and results were obtained for Reynolds number of the order of 5 · 105. Results to date indicate that for vehicle length-diameter ratios of the order of 15 and above, with tunnel to vehicle diameter ratios of 1.5 and greater, a drag coefficient based on the wetted surface area of the vehicle is independent of the vehicle length-diameter ratio for incompressible flow. Results also indicate that, for incompressible flow, employing a tunnel model with a closed end simulates a tunnel length-diameter ratio of infinity. Tunnel wall porosity, assuming relatively unobstructed motion of fluid outside the porous wall, has a marked effect on decreasing the aerodynamic drag on vehicles moving in enclosed guideways and that for the range of variables investigated (clearance ratio as low as 1.4) tunnel wall porosity of 20 per cent is adequate for all the significant drag reduction that is possible. Qualitative predictions of loss coefficient analytical modeling and literature on transonic flow wind tunnel testing with porous walls are in agreement with the data presented.

Flow-Induced Instability on High-Speed Mini Rotors in Laminar Flow

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Emre Dikmen ◽  
Peter J. M. van der Hoogt ◽  
André de Boer ◽  
Ronald G. K. M. Aarts ◽  
Ben Jonker
Keyword(s):  
Laminar Flow ◽  
High Speed ◽  
Research Work ◽  
Beam Theory ◽  
Theoretical Models ◽  
Rotating Machinery ◽  
Inertia Effects ◽  
Modeling Approach ◽  
Friction Models ◽  
Flow Effects

In this study, a modeling approach is developed to examine laminar flow effects on the rotordynamic behavior of high-speed mini rotating machinery with a moderate flow confinement. The existing research work mostly focuses on the flow-induced forces in small gap systems, such as bearings and seals, in which the flow is mostly laminar and inertia effects are ignored. In other studies, medium gap systems are analyzed, taking the inertia effects into consideration, but the surrounding flow is considered as turbulent. However, in high speed mini rotating machinery, the large clearances and the high speeds make the inertia effects significant, even in the laminar flow regime. In the current study, the flow-induced forces resulting from the surrounding fluid are analyzed and these models are combined with the structural finite element (FE) models for determining the rotordynamic behavior. The structure is analyzed with finite elements based on Timoshenko beam theory. Flow-induced forces, which include inertia effects, are implemented into the structure as added mass-stiffness-damping at each node in the fluid confinement. The shear stress is modeled with empirical and analytical friction coefficients, and the stability, critical speeds, and vibration response of the rotor is investigated for different friction models. In order to validate the developed modeling approach, experiments were conducted on a specially designed setup at different support properties. By comparing the experiments with the theoretical models, the applicability of the different friction models are examined. It was found that the dynamic behavior is estimated better with empirical friction models compared to using the analytical friction models.

High-speed laminar flow past a fin–body junction

2013 ◽  
Vol 737 ◽  
pp. 19-55 ◽  
Author(s):  
O. R. Tutty ◽  
G. T. Roberts ◽  
P. H. Schuricht
Keyword(s):  
Laminar Flow ◽  
Flat Plate ◽  
High Speed ◽  
Leading Edge ◽  
Limited Range ◽  
Interaction Region ◽  
Liquid Crystal Thermography ◽  
Heating Effects ◽  
Oil Flow ◽  
Free Stream Mach Number

AbstractInterference heating effects generated by a blunt fin-type protuberance on a flat plate exposed to a hypersonic flow have been investigated experimentally and numerically. Experiments and simulations were carried out at a free-stream Mach number of 6.7 under laminar flow conditions. The surface heating on the plate was measured experimentally using liquid-crystal thermography, which provided quantitative data with high spatial resolution. Complementary surface oil flow and schlieren experiments were also carried out to gain a better understanding of the interference flow field. The effects of fin leading-edge diameter on the heating distribution on the flat plate surface were explored. The results of the experiments and simulations agree well and reveal a highly complex interaction region which extends over seven diameters upstream of the fin. Within the interaction region surrounding the fin, heating enhancements up to ten times the undisturbed flat plate value were estimated from the experimental data. However, the liquid crystals have a limited range, and the numerical simulations indicated localized peak heating many times this value both on the plate and the fin itself.

Numerical Investigation of the Effects of Axial Cylinder Bore Profiles on Piston Ring Radial Dynamics

2003 ◽  
Vol 125 (4) ◽  
pp. 1081-1089 ◽  
Author(s):  
Y. Piao ◽  
S. D. Gulwadi
Keyword(s):  
High Speed ◽  
Piston Ring ◽  
Gasoline Engine ◽  
Engine Performance ◽  
Operating Conditions ◽  
Engine Oil ◽  
Oil Consumption ◽  
Ring Pack ◽  
Cylinder Bore

The role of cylinder bore shapes in engine performance has been the subject of several studies in recent years. In particular, the influence of bore distortion on oil consumption under high speed conditions has generated significant interest. In this paper, the effect of an axial bore profile on radial dynamics of a ring is investigated. Radial ring motions within grooves due to the axial bore profile can generate significant inertial effects and also have an impact on ring end-gap sizes and lubrication conditions at the ring-liner interfaces. The magnitude of such effects is dependent on the ring-pack configuration, engine operating conditions (speed and load) and axial bore profile details. These issues are investigated in this study due to their implication on engine oil consumption, friction and blow-by. The authors have developed an analytical expression to account for the effects of radial ring inertia due to an axial bore profile for implementation in a piston ring-pack simulation tool RINGPAK. Simulation results from a gasoline engine study are presented to illustrate the effects of engine speeds, ring tensions, and characteristics of axial bore profiles on ring radial dynamics and ring-liner lubrication. Relevant qualitative comparisons are made to experimental measurements available in the literature.

Sign in / Sign up

Export Citation Format

Share Document