Air barrier effect in out of mesh jet lubrication of ultra-high speed spur gears

2017 ◽  
Vol 69 (2) ◽  
pp. 81-87 ◽  
Author(s):  
Wentao Niu ◽  
Yanzhong Wang ◽  
Yanyan Chen ◽  
Guanhua Song
Keyword(s):  
High Speed ◽  
Cooling System ◽  
Spur Gears ◽  
Barrier Effect ◽  
Content Type ◽  
Pressure Distributions ◽  
Ultra High Speed ◽  
Oil Jet ◽  
First Time ◽  
Dynamics Method

Purpose This paper aims to reveal the mechanism of air barrier effect in jet lubrication and to figure out the influence of gear parameters and conditions on air barrier, thus providing guidance to the design of jet lubrication in ultra-high speed gear cooling system. Design/methodology/approach The computational fluid dynamics method is used to calculate the flow and pressure of ultra-high speed gears. The flow and pressure distributions are obtained under different gear parameters and working conditions, so their variations are obtained. A multiphase flow model is established to simulate the flow regime of oil jet to ultra-high speed gears. Simple experiments are carried out to observe the air barrier effect of high-speed gears. Findings Air barrier effect exists in the jet lubrication of ultra-high speed spur gears, which could prevent oil jet to reach on the gear surfaces. The results show that the generated pressure has positive relations with gear speed, module and width; however, as the increasing of gear width, their marginal contribution to pressure is decreasing. The computational results coincide well with the experimental results. Originality/value The research presented here proposed the air barrier effect of ultra-high speed gears for the first time. It also leads to a design reference guideline that could be used in jet lubrication of ultra-high speed gears, thus preventing lubrication and cooling failures.

scholarly journals Study of Lubricant Jet Flow Phenomena in Spur Gears

1975 ◽  
Vol 97 (2) ◽  
pp. 283-288 ◽  
Author(s):  
L. S. Akin ◽  
J. J. Mross ◽  
D. P. Townsend
Keyword(s):  
Motion Picture ◽  
High Speed ◽  
Drop Size ◽  
Gear Tooth ◽  
Jet Flow ◽  
Spur Gear ◽  
Spur Gears ◽  
Gear Teeth ◽  
Flow Phenomena ◽  
Oil Jet

Lubricant jet flow impingement and penetration depth into a gear tooth space were measured at 4920 and 2560 using a 8.89-cm- (3.5-in.) pitch dia 8 pitch spur gear at oil pressures from 7 × 104 to 41 × 104 N/m2 (10 psi to 60 psi). A high speed motion picture camera was used with xenon and high speed stroboscopic lights to slow down and stop the motion of the oil jet so that the impingement depth could be determined. An analytical model was developed for the vectorial impingement depth and for the impingement depth with tooth space windage effects included. The windage effects on the oil jet were small for oil drop size greater than 0.0076 cm (0.003 in.). The analytical impingement depth compared favorably with experimental results above an oil jet pressure of 7 × 104 N/m2 (10 psi). Some of this oil jet penetrates further into the tooth space after impingement. Much of this post impingement oil is thrown out of the tooth space without further contacting the gear teeth.

Computational design and analysis of aerostatic journal bearings with application to ultra-high speed spindles

2016 ◽  
Vol 231 (7) ◽  
pp. 1205-1220 ◽  
Author(s):  
Siyu Gao ◽  
Kai Cheng ◽  
Shijin Chen ◽  
Hui Ding ◽  
Hongya Fu
Keyword(s):  
High Speed ◽  
Volume Flow Rate ◽  
Load Capacity ◽  
Computational Design ◽  
Design Guidelines ◽  
Journal Bearings ◽  
Weighted Residual Method ◽  
Precision Engineering ◽  
Pressure Distributions ◽  
Ultra High Speed

Aerostatic bearings are the critical parts of ultra-high speed spindles applied to precision milling, grinding, and other precision engineering applications. In this paper, the computational design and analysis of aerostatic journal bearings at ultra-high speed spindles are investigated particularly in light of the nonlinear compressible Reynolds equation and the associated computational analysis and algorithms using the finite element method-based Galerkin weighted residual method. The steady-state static and dynamic behaviors of aerostatic journal bearings are systematically studied, including pressure distributions, load capacity, stiffness, attitude angle, and volume flow rate under conditions of various operating speeds and eccentricity ratios. The coupling of the aerostatic and aerodynamic effects within ultra-high speed aerostatic journal bearings is further explored. The obtained results are formulated as design guidelines for aerostatic journal bearings applied to air-bearing spindles operating in high precision and ultra-high rotational speeds.

Analysis and verification of a miniature dolphin-like underwater glider

2016 ◽  
Vol 43 (6) ◽  
pp. 628-635 ◽  
Author(s):  
Zhengxing Wu ◽  
Junzhi Yu ◽  
Jun Yuan ◽  
Min Tan
Keyword(s):  
High Speed ◽  
Design Methodology ◽  
Underwater Glider ◽  
Long Distance ◽  
Hydrodynamic Analysis ◽  
Content Type ◽  
Underwater Gliders ◽  
Driven System ◽  
Novel Design ◽  
Dynamics Method

Purpose This paper aims to propose a novel design concept for a biomimetic dolphin-like underwater glider, which can offer the advantages of both robotic dolphins and underwater gliders to achieve high-maneuverability, high-speed and long-distance motions. Design/methodology/approach To testify the gliding capability of dolphin-like robot without traditional internal movable masses, the authors first developed a skilled and simple dolphin-like prototype with only gliding capability. The hydrodynamic coefficients, including lift, drag and pitching moment, are obtained through computational fluid dynamics method, and the hydrodynamic analysis in the steady gliding motion is also executed. Findings Experimental results have shown that the dolphin-like glider could successfully glide depending on the pitching torques only from buoyancy-driven system and controllable fins without traditional internal moveable masses. Originality/value A hybrid underwater glider scheme that combines robotic dolphin and glider is firstly proposed, shedding light on the creation of innovation gliders with maneuverability and durability.

scholarly journals The effect of powder age in high speed sintering of poly(propylene)

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Rhys J. Williams ◽  
Luke Fox ◽  
Candice Majewski
Keyword(s):  
Success Rate ◽  
High Speed ◽  
Dimensional Accuracy ◽  
High Volume ◽  
Content Type ◽  
Polymer Powder ◽  
Powder Properties ◽  
Poly Propylene ◽  
Seven Generations ◽  
First Time

Purpose This study aims to demonstrate for the first time that the cheap, commodity polymer, poly(propylene), can be successfully processed using high speed sintering, and that it can be recycled several times through the process, with little to no detriment to either the polymer itself or the parts obtained. This is significant as a step towards the realisation of high speed sintering as a technology for high-volume manufacturing. Design/methodology/approach A poly(propylene) powder designed for laser sintering was used to build parts on a high speed sintering machine. The unsintered powder was then collected and reused. Repeating this process allowed creation of seven generations of aged powder. A variety of characterisation techniques were then used to measure polymer, powder and part properties for each generation to discern any effects arising from ageing in the machine. Findings It was found that poly(propylene) could be used successfully in high speed sintering, albeit with a low build success rate. Increased powder age was found to correlate to an increase in the build success rate, changes in microscopic and bulk powder properties and improvement to the dimensional accuracy of the parts obtained. By contrast, no discernible correlations were seen between powder age and polymer molecular weight, or between powder age and the tensile properties of parts. Originality/value This is the first report of the use of poly(propylene) in high speed sintering. It is also first study regarding powder recyclability in high speed sintering, both in general and using poly(propylene) specifically.

Design and experimental tests of an active cooling system for a kind of in-vessel inspection manipulator

2020 ◽  
Vol 47 (5) ◽  
pp. 737-745
Author(s):  
Liang Du ◽  
Wei-Jun Zhang ◽  
Jian-Jun Yuan
Keyword(s):  
High Temperature ◽  
System Performance ◽  
Cooling System ◽  
Experimental Tests ◽  
Full Scale ◽  
Content Type ◽  
Temperature Environment ◽  
First Time ◽  
Inspection Task ◽  
High Temperature Environment

Purpose This paper aims to present the design and experimental tests of an active circulating cooling system for the Experimental Advanced Superconducting Tokamak in-vessel inspection manipulator, which will help the current manipulator prototype to achieve a full-scale in-vessel high temperature environment compatibility. Design/methodology/approach The high-temperature effects and heat transfer conditions of the manipulator under in-vessel environment were analyzed. An active circulating cooling system was designed and implemented on the manipulator prototype. A simulative in-vessel inspection task in a high temperature environment of 100°C was carried out to evaluate the performance of the active circulating cooling system. Findings The proposed active circulating cooling system was proved effective in helping the manipulator prototype to achieve its basic in-vessel inspection capability in a high temperature environment. The active circulating cooling system performance can be further improved considering the cooling structure coefficient differences in different manipulator parts. Originality/value For the first time, the active circulating cooling system was implemented and tested on a full-scale of the in-vessel inspection manipulator. The experimental data of the temperature distribution inside the manipulator and the operating status of the circulating system were helpful to evaluate the current active circulating cooling system design and provided effective guidance for improving the overall system performance.

Convection heat transfer and temperature analysis of oil jet lubricated spur gears

2016 ◽  
Vol 68 (6) ◽  
pp. 624-631 ◽  
Author(s):  
Yanzhong Wang ◽  
Wentao Niu ◽  
Yanyan Chen ◽  
Guanhua Song ◽  
Wen Tang
Keyword(s):  
Heat Transfer ◽  
Convection Heat Transfer ◽  
Distribution Coefficients ◽  
Frictional Heat ◽  
Spur Gears ◽  
Convection Heat ◽  
Transfer Coefficients ◽  
Content Type ◽  
Heat Transfer Coefficients ◽  
Oil Jet

Purpose This paper aims to provide an analytic technique for determining the convection heat transfer and temperature of oil jet lubricated spur gears. Design/methodology/approach A multiphase flow model is developed to calculate the convection heat transfer coefficients on different gear faces during different contact conditions. The frictional heat is calculated and a method to distribute between the two gears is developed. A finite element model is established to calculate the temperatures in both meshing and cooling processes. Findings The convection heat transfer coefficients on different surfaces are obtained successfully. Area-related formulae are developed to calculate the heat distribution coefficients. The gear temperature reaches a maximum at the beginning of meshing, then reduces and gets minimum at pitch point, after that it increases again. The gear temperature descends rapidly to steady temperature during the short time of jet cooling process. The tendency of computational results coincides well with the experimental results. Originality/value The research presented here could be used in the design phase of the jet lubricated spur gears. The precise temperature is obtained to assess the thermal capacity of gears, from which the gear parameters and oil supply conditions could be adjusted and designed.

Ultra-high-speed TEHL characteristics of T-groove face seal under supercritical CO2 condition

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Delei Zhu ◽  
Shaoxian Bai
Keyword(s):  
Rotational Speed ◽  
High Speed ◽  
Maximum Temperature ◽  
Face Seal ◽  
Maximum Temperature Difference ◽  
Content Type ◽  
Flow Effect ◽  
Choked Flow ◽  
Ultra High Speed ◽  
Contact Seal

Purpose The purpose of this paper is to acquire sealing properties of supercritical CO2 (S-CO2) T-groove seal under ultra-high-speed conditions by thermo-elastohydrodynamic lubrication (TEHL) analysis. Design/methodology/approach Considering the choked flow effect, the finite difference method is applied to solve the gas state equation, Reynolds equation and energy equation. The temperature, pressure and viscosity distributions of the lubricating film are analyzed, and sealing characteristics is also obtained. Findings The face distortions induced by increasing rotational speed leads to the convergent face seal gap. When the linear velocity of rotation exceeds 400 m/s, the maximum temperature difference of the sealing film is approximately 140 K, and the viscosity of CO2 is altered by 17.80%. Near the critical temperature point of CO2, while the seal temperature increases by 50 K, the opening force of the T-groove non-contact seal enhances by 20% and the leakage rate declines by 80%. Originality/value The TEHL characteristics of the T-groove non-contact seal are numerically analyzed under ultra-high-speed, considering the real gas effect and choked flow effect. In the supercritical conditions, the influence of rotational speed, seal temperature, seal pressure and film thickness on sealing performance and face distortions is analyzed.

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