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.

Experimental study on frictional loss of high-speed bearings based on free-deceleration and energy-balance methods

2019 ◽  
Vol 71 (4) ◽  
pp. 509-514 ◽  
Author(s):  
Shengli Tian ◽  
Xiaoan Chen ◽  
Tianchi Chen ◽  
Ye He
Keyword(s):  
Energy Balance ◽  
Rotational Speed ◽  
High Speed ◽  
Mechanical Systems ◽  
Coupling Factor ◽  
Thermomechanical Coupling ◽  
Frictional Torque ◽  
Frictional Loss ◽  
Content Type ◽  
Relationship Of

Purpose The purpose of this study is to investigate accurate and effective experimental methods for measuring the frictional loss of bearings (FLB) in mechanical systems and to measure the effect of various operating parameters on the frictional loss of high-speed mechanical systems. Design/methodology/approach Two novel methods were studied in this paper to measure the FLB: the free-deceleration method and the energy-balance method. A special high-speed motorised spindle and a friction loss test rig were designed and built to measure the effects of rotational speed, lubrication, preload and operating temperature on the FLB. Findings The experimental results showed that the frictional torque of bearings increases initially but then decreases with an increase in rotational speed. Similarly, the FLB decreases initially and then increases with an increase in temperature because of the influence of the viscosity–temperature relationship of the lubricant and the thermomechanical coupling factor. The optimal lubricant flow was determined, and the effectiveness of a novel preload online adjusting device was verified through experiments. Originality/value The research results of this paper provide the basis and methods for the measurement, reduction and prediction of the FLB in mechanical systems.

A comparative study on simulation and experiment of oil-air lubrication unit for high speed bearing

2016 ◽  
Vol 68 (3) ◽  
pp. 325-335 ◽  
Author(s):  
Qunfeng Zeng ◽  
Jinhua Zhang ◽  
Jun Hong ◽  
Cheng Liu
Keyword(s):  
Low Temperature ◽  
Rotational Speed ◽  
Machine Tools ◽  
High Speed ◽  
Design Method ◽  
Simulation Method ◽  
Lubrication System ◽  
Content Type ◽  
Air Lubrication ◽  
Grinding Machine

Purpose The purpose of this paper is to design an oil-air lubrication system with low temperature rise, vibration and noise simplifies the spindle configuration. The oil-air lubrication unit is a key component for high-speed grinding machine tools. The development of oil-air lubrication unit suitable for high/ultrahigh rotational speed is a daunting task owing to the lubrication challenges. Design/methodology/approach This paper emphasizes three main issues: the analysis of oil-air two-phase flow for tradition oil-air lubrication unit with the simulation method; the design of new oil-air lubrication unit for the high/ultrahigh-speed grinding machine tools and the comparative experiment research of tradition and new oil-air lubrication unit. The optimum structure parameters that create the optimum flow pattern and operating conditions resulting in low temperature increase, vibration and noise of oil-air lubricated spindle can be achieved by the simulation method and experiments. Findings The simulation and experimental results show that new oil-air lubrication unit lubricating a high speed electric spindle has a better performance with a small temperature increase and vibration, which means that our proposed method is an effective design method for oil-air lubrication system. Originality/value A design method suitable for high-speed oil-air lubrication unit is proposed. New oil-air lubrication unit is expected to apply for high/ultrahigh rotational speed grinding machine tools.

Development of Herringbon-Grooved Aerodynamic Journal Bearing Systems for Ultra-High-Speed Rotations

2015 ◽  
Vol 656-657 ◽  
pp. 652-657 ◽  
Author(s):  
Norifumi Miyanaga ◽  
Jun Tomioka
Keyword(s):  
Rotational Speed ◽  
High Speed ◽  
Journal Bearing ◽  
Damping Properties ◽  
Shaft Rotation ◽  
Ultra High Speed ◽  
The Difference ◽  
The Stability ◽  
Stiffness And Damping ◽  
Bearing System

It is absolutely important for ultra-compact rotational machineries to achieve sable shaft rotation at ultra-high-speed. This paper discussed herringbone-grooved aerodynamic journal bearing systems developed for the purpose. In this system, the bearings are supported by rubber-O-rings for accurate and stable operations. To grasp the possibility for stabilization, two types of O-rings with different stiffness and damping properties under bearing supporting were tested in the experiment. As the results, the bearing system demonstrated the maximum rotational speed over 460,000 rpm without unstable phenomenon called whirl. However, the difference in rubber O-rings definitely affected the stability of the bearing system.

Analysis of time dependent thermal properties for high rates in selective laser sintering

2018 ◽  
Vol 24 (5) ◽  
pp. 894-900 ◽  
Author(s):  
Katrin Wudy ◽  
Maximilian Drexler ◽  
Lydia Lanzl ◽  
Dietmar Drummer
Keyword(s):  
Thermal History ◽  
Laser Power ◽  
High Speed ◽  
Selective Laser Sintering ◽  
Laser Sintering ◽  
Maximum Temperature ◽  
Laser Exposure ◽  
Heating Rates ◽  
Content Type ◽  
Impact Time

Purpose The thermal history during laser exposure determines part properties in selective laser sintering (SLS). The purpose of this study is to introduce a new measurement technique based on a CO2 laser unit combined with a high-speed DCS. A first comparison of the thermal history during laser exposure measured with Laser-high-speed-(HS)-differential scanning calorimetry-(DSC) and in SLS process is shown. Design/methodology/approach This Laser-HS-DSC allows an imitation of the SLS-process in a very small scale, as the sample is directly heated by a CO2 laser. For this study, the laser power and the impact time is varied for determining temperature and achieved heating rates. Consequently, the temperature levels measured by the Laser-HS-DSC are compared with measurements in SLS-process. Findings The influence of laser power and impact time on resulting maximum temperatures und heating rates during laser exposure are investigated. With increasing laser power and impact time the maximum temperature rises up to approximately 450°C without material degradation. The heating rate increases up to an impact time of 3 ms and stays almost equal for higher durations. Research limitations/implications The Laser-HS-DSC experiments are based on few particles limiting a complete comparison with SLS process. In SLS, one volume element is exposed several times. In this study the PA12 material was exposed only once. Originality/value For the first time, laser sintering experiments can be transferred to a laboratory scale to analyze the influence of laser exposure on resulting temperature field during laser exposure without superimposing effects.

Simulation of Drilling on the Copper of PCB with Ultra-High-Speed

2011 ◽  
Vol 188 ◽  
pp. 739-742 ◽  
Author(s):  
Hong Qun Tang ◽  
Jun Wen ◽  
Cheng Yong Wang ◽  
Lu Shu Wu ◽  
Yue Xian Song
Keyword(s):  
Cutting Force ◽  
High Speed ◽  
Printed Circuit Board ◽  
Cutting Temperature ◽  
Circuit Board ◽  
Maximum Temperature ◽  
Drilling Process ◽  
Ultra High Speed ◽  
High Speed Drilling ◽  
Center Area

This paper gives an introduction of the simulation of ultra-high-speed drilling on the copper of printed circuit board (PCB) by using finite element method (FEM). The cutting force, cutting torque and the distribution of cutting temperature are predicted. The value of cutting force is also be compared with the experimental value. The simulation results show that the experimental value of cutting force agrees well with the FEM value and the value of cutting torque is very small in the drilling process , in addition，the maximum temperature of copper comes up to 209 °C in center area and the temperature of copper chip evacuation from the spiral groove ranges from 135°C to 155 °C.

Thermal-fluid-solid coupling deformation of hydrostatic thrust bearing friction pairs

2019 ◽  
Vol 71 (3) ◽  
pp. 467-473 ◽  
Author(s):  
Mubing Yu ◽  
Xiaodong Yu ◽  
Xuhang Zheng ◽  
Hui Jiang
Keyword(s):  
Failure Mechanism ◽  
Rotational Speed ◽  
High Speed ◽  
Thrust Bearing ◽  
Lubricating Oil ◽  
Oil Viscosity ◽  
Heavy Load ◽  
Content Type ◽  
Coupling Deformation ◽  
Bearing Friction

Purpose The purpose of this paper is to study thermal-fluid-solid coupling deformation and friction failure mechanism of bearing friction pairs under the working conditions of high speed and heavy load. Design/methodology/approach The deformation is simulated based on thermal-fluid-solid coupling method, its deformation distribution law is revealed and the relationships of deformation of friction pairs, rotational speed and bearing weight are obtained. Findings The results prove that the oil film temperature rises sharply, the lubricating oil viscosity decreases rapidly, the film thickness becomes thinner, the deformation increases, the whole deformation is uneven and the boundary lubrication or dry friction are caused with the increase in rotational speed and bearing load. Originality/value The conclusions provide theoretical method for deformation solution and friction failure mechanism of hydrostatic thrust bearing.

Development of bearings for a small high speed cryogenic turboexpander

2012 ◽  
Vol 64 (1) ◽  
pp. 3-10 ◽  
Author(s):  
Subrata Ghosh ◽  
Parboti Mukherjee ◽  
Sunil Sarangi
Keyword(s):  
Rotational Speed ◽  
High Speed ◽  
Design Methodology ◽  
Input Parameter ◽  
Journal Bearings ◽  
Content Type ◽  
Thrust Bearings ◽  
Academic Literature ◽  
Practical Implications ◽  
Taking Care

PurposeThe purpose of this paper is to examine the development of aerodynamic thrust bearings and aerodynamic journal bearings applied to a small high speed cryogenic turboexpander in Indian conditions.Design/methodology/approachAs a part of indigenous programme in the process of development, some input parameter was taken from the available literature and then dimensions were optimized and computed while taking care to minimize fabrication constraints.FindingsA series of tests were conducted to confirm the findings. Detailed study of the effect of stability and vibration of bearings was taken up. The maximum rotational speed obtained was 200,000 rpm.Practical implicationsThe outcome may help the designers, researchers and manufacturers of these components.Originality/valueAlthough manufacturers design and develop the bearings of turboexpanders for their production, no academic literature has been available for this purpose until now.

Numerical simulation research on effect of oil groove forms on thermal behavior of friction pair in hydro-viscous clutch

2016 ◽  
Vol 68 (2) ◽  
pp. 287-298 ◽  
Author(s):  
Fangwei Xie ◽  
Yaowen Tong ◽  
Diancheng Wu ◽  
Bing Zhang ◽  
Kaiyu Dai
Keyword(s):  
Temperature Field ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Friction Pair ◽  
Maximum Temperature ◽  
Theoretical Expression ◽  
Optimized Design ◽  
Maximum Temperature Difference ◽  
Cross Sectional ◽  
Content Type

Purpose – The purpose of this paper is to study the influence of different cross-sectional shapes (rectangular, trapezoidal, oval and triangular) and layout forms of oil grooves (radial, circumferential, inclined, compound, helical and double-helical), and determine the optimal section shape and layout form of oil grooves on the temperature field. Design/methodology/approach – Heat conduction theory model was established based on startup characteristics and friction heat principle of hydro-viscous clutch (HVC), and then the theoretical expression of angular velocity of the friction pair and control pressure were deduced, and the heat flux and its distribution on friction disk and separator disk were calculated. Finally, the finite element method was used to solve the temperature field of the friction pair. Findings – The studies show that the circumferential oil groove got the highest temperature, and on the surface of all other structures, hot spots appear with different sizes and temperatures, and the maximum temperature difference in the friction zone is about 3°C, and in the oil groove zone is about 16°C, wherein the compound oil groove has the lowest average temperature. This research shows that the compound oil groove with rectangular cross-section is the best choice for the friction pair. Originality/value – In this paper, it was found that the compound oil groove with rectangular cross-section is the best choice for the friction pair, and it provided a favorable theory reference and technical support for the structural design of the friction pair and optimized design of the high-power HVC.

Experimental study on the water lubrication of non-contacting face seals for turbopumps

2014 ◽  
Vol 66 (2) ◽  
pp. 314-321 ◽  
Author(s):  
Zhang Guo-yuan ◽  
Wei-gang Zhao ◽  
Yan Xiu Tian
Keyword(s):  
Experimental Study ◽  
High Speed ◽  
Rocket Engine ◽  
Groove Depth ◽  
Liquid Oxygen ◽  
Liquid Rocket Engine ◽  
Face Seal ◽  
Content Type ◽  
Face Seals ◽  
Liquid Rocket

Purpose – A new type of hydrostatic and hydrodynamic non-contacting face seals has been designed to meet the requirements of lower leakage, longer life and more repeatedly start and stop on shaft seals raised by liquid rocket engine turbopumps. And an experimental study on the performance of the face seal in the actual liquid oxygen turbopump was completed where low-viscosity water was selected as the seal fluid for the sake of safety. The paper aims to discuss these issues. Design/methodology/approach – Different performances of face seals under preset conditions were obtained by repeatedly running tests, and the main performance parameters encompass leakage, fluid film pressure between the faces, operating power, face temperature, and so on. Findings – The results indicate that the designed face seal has a smaller amount of leakage, with a minimum value of 3 ml/s. Furthermore, the designed face seal has been proved to demand lower operating power. Since its operating power changes slightly with different sealed fluid pressures, the new seal can be deployed in the harsh working condition with high pressure or with high speed (greater than 20,000 rpm). However, one proviso is that when liquid is employed as the seal fluid, the groove depth should be relatively deeper (greater than 10 μm). Research limitations/implications – In response to future engineering requirements, study on the controllable spiral-groove face seals to improve the current design is being conducted. Originality/value – The advancement of such non-contacting face seals proffers important insights to the design of turbo-pump shaft seal in a new generation of liquid rocket engine with regard to the requirement of frequent start and stop as well as long life on it.

Temperature Field Analysis of CRTS-II Ballastless Track Slab Structure on Soil Subgrade

2014 ◽  
Vol 587-589 ◽  
pp. 1255-1261 ◽  
Author(s):  
Lei Zhao ◽  
Lu Sun ◽  
Tong Jiang Fan
Keyword(s):  
Temperature Difference ◽  
High Speed ◽  
Field Analysis ◽  
Temperature Fields ◽  
Maximum Temperature ◽  
Maximum Temperature Difference ◽  
Temperature Changes ◽  
Ballastless Track ◽  
Heat Transfer Theory ◽  
Track Slab

Temperature changes have a significant impact on the CRTS-II track structure in Beijing-Shanghai high-speed railway which has longitudinally connected type. In this paper temperature fields of ballastless track superstructure are simulated based on heat transfer theory and subroutine of ABAQUS that solar radiation DFLUX and ambient temperature FILM. The results showed that: the maximum temperature difference on the top of track slab is 20°C in summer and 10°C in winter; the maximum temperature difference in CA mortar layer is 4°C in summer and 2°C in winter; the maximum temperature difference in concrete substrate is 2°C in summer and 1°C in winter.

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