scholarly journals Study of Lubricant Jet Flow Phenomena in Spur Gears—Out of Mesh Condition

1978 ◽  
Vol 100 (1) ◽  
pp. 61-68 ◽  
Author(s):  
D. P. Townsend ◽  
L. S. Akin
Keyword(s):  
High Speed ◽  
Gear Tooth ◽  
Velocity Ratio ◽  
Jet Impingement ◽  
Gear Ratio ◽  
Experimental Program ◽  
High Speed Photography ◽  
Gear Mesh ◽  
Mesh Condition ◽  
Oil Jet

An analysis was conducted for oil jet lubrication on the disengaging side of a gear mesh. Results of the analysis were computerized and used to determine the oil jet impingement depth for several gear ratios and oil jet to pitch line velocity ratios. An experimental program was conducted on the NASA gear test rig using high-speed photography to experimentally determine the oil jet impingement depth on the disengaging side of mesh. Impingement depth reaches a maximum at gear ratio near 1.5 where chopping by the leading gear tooth limits the impingement depth. The pinion impingement depth is zero above a gear ratio of 1.172 for a jet velocity to pitch time velocity ratio of 1.0 and is similar for other velocity ratios. The impingement depth for gear and pinion are equal and approximately one-half the maximum at a gear ratio of 1.0. Impingement depth on either the gear or pinion may be improved by relocation of the jet from the pitch line or by changing the jet angle. Results of the analysis were verified by experimental results using a high-speed camera and a well lighted oil jet.

scholarly journals Analytical and Experimental Spur Gear Tooth Temperature as Affected by Operating Variables

1981 ◽  
Vol 103 (1) ◽  
pp. 219-226 ◽  
Author(s):  
D. P. Townsend ◽  
L. S. Akin
Keyword(s):  
High Speed ◽  
Gear Tooth ◽  
Jet Impingement ◽  
Spur Gear ◽  
Constant Load ◽  
Significant Rise ◽  
Transfer Coefficients ◽  
Surface Temperatures ◽  
Jet Penetration ◽  
Oil Jet

A gear tooth temperature analysis was performed using a finite element method combined with a calculated heat input, calculated oil jet impingement depth, and estimated heat transfer coefficients. Experimental measurements of gear tooth average surface temperatures and instantaneous surface temperatures were made with a fast response infrared radiometric microscope. Increased oil jet pressure had a significant effect on both average and peak surface temperatures at both high load and speeds. Increasing the speed at constant load and increasing the load at constant speed causes a significant rise in average and peak surface temperatures of gear teeth. The oil jet pressure required for adequate cooling at high speed and load conditions must be high enough to get full depth penetration of the teeth. Calculated and experimental results were in good agreement with high oil jet penetration but showed poor agreement with low oil jet penetration depth.

Investigation of Oil Jet Impingement on a Rotating Gear Using Lattice Boltzman Method (LBM)

2018 ◽  
Author(s):  
Stephen Ambrose ◽  
Hervé Morvan ◽  
Kathy Simmons
Keyword(s):  
High Speed ◽  
Gear Tooth ◽  
Fuel Efficiency ◽  
Jet Impingement ◽  
Spur Gear ◽  
Qualitative Comparison ◽  
Particle Hydrodynamics ◽  
Order Of Magnitude ◽  
Aero Engines ◽  
Oil Jet

In the drive for greater increases in fuel efficiency and reductions in CO2 emissions from aero engines, an epicyclic reduction gearbox can be used to break the link between the turbine and fan, enabling the engine to run at a higher bypass ratio. However, even small power losses can generate significant amounts of heat, due to the high loads transmitted from the gearbox. A substantial amount of cooling is required to remove this heat and a large part of this is supplied directly to the gear face. Assessing the performance of coolants and minimising the buildup of oil in the system is therefore a critical stage in the design process. Traditionally, finite volume CFD methods have been used to compute flow and heat transfer solutions. More recently, Lagrangian methods such as Smoothed Particle Hydrodynamics (SPH) have also been applied. The Lattice Boltzman Method (LBM) is a mesoscopic particle based method which uses statistical properties of particles based at each point of a lattice to calculate flow properties. This is a fully transient method and allows for a simple and efficient derivation of LES turbulence properties. In this work the Lattice Bolztman Method is used to investigate the impingement of an oil jet on a rotating spur gear. A comparison of LBM simulations is made against published work using other methods such as SPH and CFD — utilising the Volume of Fluid method — as well as a qualitative comparison with published experimental high speed images. These all show an excellent agreement and the simulations take the same order of magnitude of computational power as 3D single phase SPH, but are fully multiphase and have LES turbulence. This method is then used to investigate how changes to the oil feed delivery rate affect the spreading of the oil jet on the gear tooth and the splashing profiles. The potential for applying this method to other scenarios, such as lubricating and cooling meshing gears, is also discussed.

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.

Tensile Crack Speed in Brittle Rocks

2021 ◽  
Author(s):  
Mehdi Serati
Keyword(s):  
Size Effect ◽  
Rayleigh Wave ◽  
High Speed ◽  
Brazilian Test ◽  
Frame Rate ◽  
Experimental Program ◽  
High Speed Photography ◽  
Surface Mode ◽  
Crack Speed ◽  
Rock Types

<p>An important issue in rapid brittle fracture is the limiting speed of crack propagation. It is widely believed that brittle mode I crack cannot propagate faster than the Rayleigh wave speed, or the speed of sound on a solid surface. Mode II cracks are also limited by longitudinal speed wave. The origin for this belief stems from the predictions of continuum mechanics. Once the crack speed reaches a theoretical upper limit in a material, which is most often larger than one fifth of the Rayleigh wave velocity, branching of a propagating crack occurs. To verify this hypothesis, this paper presents the results of an experimental program aimed at disclosing the size effect on the crack velocity in the Splitting Tensile Strength indirect test (i.e. the Brazilian Test) using high-speed photography techniques. Over 100 Brazilian tests with more than 10 different rock types at various diameters were prepared and tested according to the ASTM standard recommendations using either a servo hydraulic machine or an electromechanical load frame at a wide ranges of load/displacement rates. By adopting a high frame rate of above 100,000 frames per second (fps), crack initiation, propagation, and coalescence were captured to study the size effect on the crack speed and failure mode on the Brazilian test results.</p>

On the Dynamic Gear Tooth Loading as Affected by Bearing Clearances in High Speed Machinery

1982 ◽  
Vol 104 (4) ◽  
pp. 724-730 ◽  
Author(s):  
B. M. Bahgat ◽  
M. O. M. Osman ◽  
T. S. Sankar
Keyword(s):  
High Speed ◽  
Design Method ◽  
Gear Tooth ◽  
Contact Point ◽  
Velocity Ratio ◽  
Spur Gears ◽  
Governing Equations ◽  
Contact Mode ◽  
Gear Teeth ◽  
Geometrical Constraints

The paper studies the effect of bearing clearances in the dynamic analysis of gear mechanisms in high speed machinery. For this purpose, an analytical model is developed based on the interdependence between kinematics and kinetic relationships that must be satisfied when contact is maintained between the journal and its bearing. The contact modes are formulated such that the bearing eccentricity vector must align itself with bearing normal force at the point of contact. The analysis mainly relies on determining the direction of the bearing eccentricity vector defined as the clearance angles βi at the bearing revolutes for each contact mode of the gear teeth. The governing equations of the clearance angles are developed using the geometrical constraints of the contact point location and the velocity ratio. The clearance angles and their derivatives are subsequently used to systematically evaluate kinematic and dynamic quantities of each gear as well as the dynamic tooth load. A pair of rigid tooth spur gears with two revolute clearances is analyzed to illustrate the procedure. The model presented in the paper provides a design method for investigating the effect of bearing tolerances and wear on the evaluation of dynamic tooth load in high speed gearing systems.

Smoothed Particle Hydrodynamics Simulation of Oil-Jet Gear Interaction

2017 ◽  
Author(s):  
Marc C. Keller ◽  
Samuel Braun ◽  
Lars Wieth ◽  
Geoffroy Chaussonnet ◽  
Thilo F. Dauch ◽  
...  
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
High Speed ◽  
Single Phase ◽  
Jet Impingement ◽  
Spur Gear ◽  
Computational Time ◽  
Qualitative Comparison ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Oil Jet

In this paper the complex two-phase flow during oil-jet impingement on a rotating spur gear is investigated using the meshless Smoothed Particle Hydrodynamics (SPH) method. A comparison of single-phase SPH to multi-phase SPH simulation and the application of the Volume of Fluid method on the basis of a two-dimensional setup is drawn. The results of the different approaches are compared regarding the predicted flow phenomenology and computational effort. It is shown that the application of single-phase SPH is justified and that this approach is superior in computational time, enabling faster simulations. In a next step, a three-dimensional single-phase SPH setup is exploited to predict the flow phenomena during the impingement of an oil-jet on a spur gear for various jet inclination angles. Thereby, a significant effect of the inclination angle on the oil spreading and splashing process is revealed. Finally, a qualitative comparison to an experimental high-speed image shows good accordance.

Supersonic Jet Impingement on a Cylinder and Characterization of the Resulting Deflected Jets

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Ameya Pophali ◽  
Markus Bussmann ◽  
Honghi Tran
Keyword(s):  
High Speed ◽  
Supersonic Jet ◽  
Jet Impingement ◽  
High Speed Photography ◽  
Pitot Pressure ◽  
Kraft Recovery Boilers ◽  
Recovery Boilers ◽  
Transverse Distance ◽  
Oval Cross Section ◽  
Jet Characteristics

The interaction between a mildly underexpanded supersonic jet and a single cylinder was studied experimentally at laboratory scale by using the schlieren technique coupled with high-speed photography and pitot pressure measurements. This study was motivated by the need to optimize sootblowing operation in kraft recovery boilers. The effects of the transverse distance between the jet and cylinder centerlines (eccentricity), nozzle–cylinder distance, and cylinder size on jet–cylinder interaction were determined. Results show that upon impingement on a cylinder, a supersonic jet deflects at an angle and creates a weaker supersonic jet that we refer to as a “secondary” jet. The angle and strength of the deflected or secondary jet depend on the eccentricity between the primary jet and cylinder centerlines. When a jet impinges on a cylinder of diameter comparable to that of the jet or smaller, secondary jets form not only when the cylinder is placed close to the nozzle (in the stronger portion of the jet) but also when the cylinder is placed far away (in the jet's weaker portion; up to 20–24 nozzle exit diameters in the present study). Changing the eccentricity slightly results in a significant change in the secondary jet characteristics. For a cylinder much larger than the jet, secondary jets do not form at zero eccentricity (head-on impingement); the eccentricity at which they begin to form increases with the cylinder size. A study of the secondary jets shows that they spread out much more than the primary jet and are sheet- or fan-like with an oblong, oval cross section. The centerline pitot pressure of the secondary jets remains as high as the primary jet for a considerable distance from the tube only during weak interaction between the primary jet and the cylinder (i.e., during strongly eccentric/off-centerd impingement). As the interaction between the primary jet and the cylinder intensifies at lower eccentricities, the maximum centerline pitot pressure of the secondary jet decreases, and the pitot pressure decreases more quickly with distance from the tube.

Experimental Studies of Reactive and Non-Reactive Flows in Dump Combustors

1990 ◽  
Author(s):  
A. S. Nejad ◽  
S. A. Ahmed ◽  
L. A. Roe ◽  
R. S. Gabruk
Keyword(s):  
Heat Release ◽  
High Speed ◽  
Equivalence Ratio ◽  
Experimental Studies ◽  
Recirculation Region ◽  
Experimental Program ◽  
High Speed Photography ◽  
Velocity Measurements ◽  
Dump Combustor ◽  
Dump Combustors

The objectives of this experimental program are two fold; first, to investigate, understand, and document the effects of heat release on the characteristics of a dump combustor flowfield; secondly, to provide a benchmark set of experimental data to aid the development of time averaged CFD codes. A limited number of velocity profiles are reported in this manuscript to illustrate the effects of combustion and heat release, at an equivalence ratio of 0.65, on dump combustor flows. High-speed photography and spectral analysis complemented velocity measurements and served to examine and characterize combustion instability limits. Results indicate that combustion altered the dump combustor flowfield and significantly reduced the length of the corner recirculation region.

On Dynamic Gear Tooth Loading Due to Coupled Torsional-Lateral Vibrations in a Geared Rotor-Hydrodynamic Bearing System

1989 ◽  
Vol 111 (3) ◽  
pp. 418-425 ◽  
Author(s):  
B. Kishor ◽  
S. K. Gupta
Keyword(s):  
Gear Tooth ◽  
Velocity Ratio ◽  
Operating Conditions ◽  
Hydrodynamic Bearing ◽  
Gear Teeth ◽  
Gear Mesh ◽  
Lateral Vibrations ◽  
Mass Unbalance ◽  
Stable Operating ◽  
Bearing System

This paper is an attempt to provide an estimation of dynamic gear tooth loading due to coupled torsional-lateral vibrations in a geared rotor-hydrodynamic bearing system. The effects of mass unbalance and geometrical eccentricity of the pinion and the combined effects of manufacturing errors and profile modifications of gear teeth have been considered. Gear mesh compliance and damping at gear teeth are also included in the analysis. Journal lateral motions in the oil film spaces of hydrodynamic bearings are shown to be associated with variations in the angular velocity ratio of meshing gears and with dynamic loading of gear teeth. The journal center is observed to trace trajectories of limited amplitudes under stable operating conditions.

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