scholarly journals CFD study of oil-jet gear interaction flow phenomena in spur gears

2020 ◽  
Vol 124 (1279) ◽  
pp. 1301-1317
Author(s):  
M.C. Keller ◽  
C. Kromer ◽  
L. Cordes ◽  
C. Schwitzke ◽  
H.-J. Bauer
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Spur Gear ◽  
Design Parameters ◽  
Detailed Knowledge ◽  
Phase Flow ◽  
Two Phase ◽  
Gear Teeth ◽  
Flow Phenomena ◽  
Oil Jet

ABSTRACTOil-jet lubrication and cooling of high-speed gears is frequently employed in aeronautical systems, such as novel high-bypass civil aero engines based on the geared turbofan technology. Using such oil-jet system, practitioners aim to achieve high cooling rates on the flanks of the highly thermally loaded gears with minimum oil usage. Thus, for an optimal design, detailed knowledge about the flow processes is desired. These involve the oil exiting the nozzle, the oil impacting on the gear teeth, the oil spreading on the flanks, the subsequent oil fling-off, as well as the effect of the design parameters on the oil flow. Better understanding of these processes will improve the nozzle design phase, e.g. regarding the nozzle positioning and orientation, as well as the nozzle sizing and operation.Most related studies focus on the impingement depth to characterize the two-phase flow. However, the level of information of this scalar value is rather low for a complete description of the highly dynamic three-dimensional flow. Motivated by the advancements in numerical methods and the computational resources available nowadays, the investigation of the oil-jet gear interaction by means of computational fluid dynamics (CFD) has come into focus lately.In this work, a numerical setup based on the volume-of-fluid method is presented and employed to investigate the two-phase flow phenomena occurring in the vicinity of the gear teeth. The setup consists of a single oil-jet impinging on a single rotating spur gear. By introducing new metrics for characterizing the flow phenomena, extensive use of the possibilities of modern CFD is made, allowing a detailed transient and spatially resolved flow analysis. Thus, not only the impingement depth, but also the temporal and spatial evolution of wetted areas on the gear flanks, as well as the evolution of the oil volume in contact with the gear flanks are extracted from the simulation data and compared in a CFD study.The study consists of 21 different simulation cases, whereby the effect of varying the jet velocity, the jet inclination angle, the jet diameter, and the gear speed are examined. Consistent results compared to a simplified analytical approach for the impinging depth are obtained and the results for the newly introduced metrics are presented.

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.

Effect of Tube Diameters on the Flow Phenomena of Gas-Liquid Two-Phase Flow in Microchannels

2013 ◽  
Author(s):  
Hideo Ide ◽  
Masahiro Kawaji
Keyword(s):  
High Speed ◽  
Annular Flow ◽  
Film Flow ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Fused Silica ◽  
Phase Flow ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Flow Phenomena

The studies on microfluidics have advanced with the use of microchannels in micro bioreactors, applications in biomedical engineering, bioengineering and pharmaceuticals, fuel cells and compact heat exchangers for heating and cooling of micro electro mechanical systems. For a wide application of microchannels, it is very important to elucidate the effect of the tube diameters on the flow phenomena of gas liquid two-phase flow in microchannels. The flow phenomena and the frictional pressure drop of gas-liquid two-phase flow were investigated experimentally by using three kinds of circular microchannels made of fused silica tubes, with inner diameters of 0.1 mm, 0.15 mm and 0.25mm. In these channels, bubbly flow, slug-churn flow, and annular flow were observed. In annular flow, two characteristic flows of ring film flow and disturbed ring film flow were observed. For the 0.25 mm diameter microchannel, several conductance probe sensors were flush mounted to the channel wall in order to measure the very thin mean film thickness or liquid holdup in a microchannel. The flow patterns maps were also made by using the high speed video images and the holdup wave signals. The effects of tube diameter on the flow patterns were investigated.

High Speed Imaging and Two-Phase Flow Patterns During Flow Boiling in a Single Microchannel

2008 ◽  
Author(s):  
Jacqueline Barber ◽  
Khellil Sefiane ◽  
David Brutin ◽  
Lounes Tadrist
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Pressure Sensors ◽  
Flow Patterns ◽  
Bubble Nucleation ◽  
Phase Flow ◽  
Vapour Bubble ◽  
Two Phase ◽  
Over Time

Boiling in microchannels remains elusive due to the lack of full understanding of the mechanisms involved. A powerful tool in achieving better comprehension of the mechanisms is detailed imaging and analysis of the two phase flow at a fundamental level. We induced boiling in a single microchannel geometry (hydraulic diameter 727 μm), using a refrigerant FC-72, to investigate several flow patterns. A transparent, metallic, conductive deposit has been developed on the exterior of rectangular microchannels, allowing simultaneous uniform heating and visualisation to be conducted. The data presented in this paper is for a particular case with a uniform heat flux of 4.26 kW/m2 applied to the microchannel and inlet liquid mass flowrate, held constant at 1.33×10−5 kg/s. In conjunction with obtaining high-speed images and videos, sensitive pressure sensors are used to record the pressure drop profiles across the microchannel over time. Bubble nucleation, growth and coalescence, as well as periodic slug flow, are observed in the test section. Phenomena are noted, such as the aspect ratio and Reynolds number of a vapour bubble, which are in turn correlated to the associated pressure drops over time. From analysis of our results, images and video sequences with the corresponding physical data obtained, it is possible to follow visually the nucleation and subsequent both ‘free’ and ‘confined’ growth of a vapour bubble over time.

Analysis of Transient Two-Phase Flow in Pressure Safety Valve Outlet Headers

2018 ◽  
Author(s):  
Maral Taghva ◽  
Lars Damkilde
Keyword(s):  
Steady State ◽  
Shock Waves ◽  
High Speed ◽  
Two Phase Flow ◽  
Safety Valve ◽  
Strong Shock ◽  
Flow Property ◽  
Phase Flow ◽  
Transient Pressure ◽  
Two Phase

To protect a pressurized system from overpressure, one of the most established strategies is to install a Pressure Safety Valve (PSV). Therefore, the excess pressure of the system is relieved through a vent pipe when PSV opens. The vent pipe is also called “PSV Outlet Header”. After the process starts, a transient two-phase flow is formed inside the outlet header consisting of high speed pressurized gas interacting with existing static air. The high-speed jet compresses the static air towards the end tail of the pipe until it is discharged to the ambiance and eventually, the steady state is achieved. Here, this transient process is investigated both analytically and numerically using the method of characteristics. Riemann’s solvers and Godunov’s method are utilized to establish the solution. Propagation of shock waves and flow property alterations are clearly demonstrated throughout the simulations. The results show strong shock waves as well as high transient pressure take place inside the outlet header. This is particularly important since it indicates the significance of accounting for shock waves and transient pressure, in contrast to commonly accepted steady state calculations. More precisely, shock waves and transient pressure could lead to failure, if the pipe thickness is chosen only based on conventional steady state calculations.

scholarly journals Experimental Investigation of the Performance and Spray Characteristics of a Supersonic Two-Phase Flow Ejector with Different Structures

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1166 ◽  
Author(s):  
Shizhen Li ◽  
Wei Li ◽  
Yanjun Liu ◽  
Chen Ji ◽  
Jingzhi Zhang
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Fire Suppression ◽  
Cone Angle ◽  
Water Mist ◽  
Pulsation Period ◽  
Phase Flow ◽  
Two Phase ◽  
Half Cone ◽  
Half Cone Angle

A two-phase flow ejector is an important part of a water mist fire suppression system, and these devices have become a popular research topic in recent years. This paper proposes a supersonic ejector that aims to improve the efficiency of water mist fire suppression systems. The effects of ejector geometric parameters on the entrainment ratio (ER) were explored. The effects of primary flow pressure (PP) on the mixing process and flow phenomena were studied by a high-speed camera. The experimental results show that the ER first increases and then decreases with increasing PP. ER increases with increasing ejector area ratio (AR). The PP corresponding to the maximum ER of ejectors with a different nozzle exit position (NXP) is 3.6 bar. The ejector with an NXP of +1 and AR of 6 demonstrate the best performance, and the ER of this ejector reaches 36.29. The spray half-cone angle of the ejector increases with increasing ER, reaching a maximum value of 7.07°. The unstable atomization half-cone angle is mainly due to a two-phase flow pulsating phenomenon. The pulsation period is 10 ms. In the present study, a general rule that provides a reference for ejector design and selection was obtained through experiments.

6. Inviscid instability of high speed two-phase flow

1998 ◽  
Vol 1 (1) ◽  
pp. 7-7 ◽  
Author(s):  
G. H. Schnerr ◽  
S. Adam
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Inviscid Instability

Estimation of Average Void Fraction for Gas-Liquid, Two-Phase Flow in an Industrial Nozzle Assembly Using a Quick-Closing-Valve

2008 ◽  
Author(s):  
Mohammad A. Rahman ◽  
Johana Gomez ◽  
Ted Heidrick ◽  
Brian A. Fleck ◽  
Jennifer McMillan
Keyword(s):  
Void Fraction ◽  
High Speed ◽  
Two Phase Flow ◽  
Video Camera ◽  
Synchronization Error ◽  
Phase Flow ◽  
Closing Time ◽  
Two Phase ◽  
Void Fractions ◽  
Atomization Performance

Experimentally accurate void fraction measurements are a challenge in an air/water, two-phase flows through an industrial nozzle assembly, as a highly non-uniform void fraction exists in the feeding conduit prior to the nozzle. In this study, average void fractions were measured by isolating a section in the feeding conduit of a horizontal nozzle assembly, termed as the quick-closing-valve (QCV) technique. A high-speed video camera was utilized to capture the asynchronization closing time, tac. The average closing time and asynchronization for the pneumatically controlled valves were 200 ms and 2 ms, respectively. Based on the equation of 100umtac (1−α)/αlc, the synchronization error between the two valves was 1.12%, 1.26%, and 1.79% for the 1%, 2% and 4% ALR cases, respectively; here um is the mixture velocity, α is the void faction, and lc is the closing length. Higher synchronization error at 4% ALR occurs due to enhanced momentum in the flow regime. Experimental results indicate that the average α over the 33.4 cm feeding conduit (6.25 mm ID) was 76% (αtheoretical = 75%) for the 2% ALR, and 85% (αtheoretical = 83%) for the 3.3% ALR. In the two-phase, two-component flow the α affects the drop size and stability of the spray produced from an industrial nozzle assembly. Learning from this study will yield insights and conceptual understanding of two-phase flow phenomena in conduit, which would affect stability, pulsation tendency, and possibly atomization performance of the nozzle downstream. Two-phase flow nozzles have wide applications in the industries, e.g. petrochemical, pharmaceutical, and others.

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