CFD simulation of grease lubrication: Analysis of the power losses and lubricant flows inside a back-to-back test rig gearbox

2021 ◽  
Vol 297 ◽  
pp. 104652
Author(s):  
Marco Nicola Mastrone ◽  
Franco Concli
Keyword(s):  
Cfd Simulation ◽  
Power Losses ◽  
Test Rig ◽  
Grease Lubrication

scholarly journals Bearing Power Losses with Water-Containing Gear Fluids

Lubricants ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 5 ◽  
Author(s):  
Mustafa Yilmaz ◽  
Thomas Lohner ◽  
Klaus Michaelis ◽  
Karsten Stahl
Keyword(s):  
Power Loss ◽  
Stribeck Curve ◽  
Detailed Knowledge ◽  
Power Losses ◽  
Test Rig ◽  
Load Bearing ◽  
Gear Efficiency ◽  
Efficiency Test ◽  
Typical Calculation ◽  
Calculation Procedures

Lubricants have a large influence on gearbox power losses. Recent investigations at a gear efficiency test rig have shown the high potential of water-containing gear fluids in drastically reducing load-dependent gear losses and temperatures. In this study, the bearing power losses with water-containing gear fluids were evaluated at a specific bearing power loss test rig explicitly and compared with mineral and polyalphaolefine oils. For all investigated lubricants, a Stribeck curve behavior of the load-dependent losses is observed. The water-containing gear fluids demonstrate lower no-load bearing losses and higher load-dependent bearing losses at higher rotational speeds. The comparison of measured bearing losses with typical calculation procedures showe partially large differences. The results underline the importance of having detailed knowledge of bearing losses when evaluating gear losses in gearboxes.

Influence of Gas Feeding Position on the Performance of Radial-Inflow Hydrostatic Gas Ultra-Short Journal Bearings

2016 ◽  
Author(s):  
Chao Nie ◽  
Xiaojun Yan ◽  
Xia Chen
Keyword(s):  
Rotational Speed ◽  
Cfd Simulation ◽  
Journal Bearing ◽  
Maximum Speed ◽  
Test Rig ◽  
Thrust Bearings ◽  
Axial Stability ◽  
Speed Measurement ◽  
Gas Leaks ◽  
Better Than

To investigate the influence of gas feeding position on the performance of radial-inflow hydrostatic gas ultra-short (with a L/D value as 0.1) journal bearing two rotor-bearing system test rigs with two different feeding positions (central feeding and bottom feeding) for the journal bearing were designed. A rotor measurement system with an original rotational speed measurement program is built. Rotation experiments to measure the maximum rotational speed of rotors under different inlet pressure of journal bearing were conducted. It was found that, the rotor supported by the central feeding journal bearing worked better, and achieved a maximum rotational speed of 40000 rpm, (83.74m/s for the tip speed). While the test rig with bottom feeding journal bearing could not function well. To verify the reasons behind the failure mentioned above, the flow condition in the journal clearance and the rotor bottom clearance was analyzed by the CFD simulation. It shows that most of the journal bearing gas “leaks” into the rotor bottom clearance in the bottom feeding bearing test rig, disarranging the axial stability of the rotor and the normal functioning of the thrust bearings. In conclusion, the central feeding radial-inflow journal bearing is better than the bottom feeding one, for the better operability and higher maximum speed. And an ideal feeding position is supposed to make the journal bearing does not influence the axial stability of the rotor and the functioning of the thrust bearings.

Housing Influence on Churning Losses in Geared Transmissions

2007 ◽  
Author(s):  
C. Changenet ◽  
P. Velex
Keyword(s):  
Fluid Flow ◽  
Qualitative Evaluation ◽  
Flow Regimes ◽  
Power Losses ◽  
Test Rig ◽  
Automotive Transmission ◽  
Transmission Geometry ◽  
Analytical Formulas ◽  
Set Up ◽  
Fluid Flow Regimes

In a previous paper, a series of analytical formulas were presented enabling accurate predictions of churning losses for one gear which is typical of automotive transmission geometry. However, this formulation does not take into account the influence of flanges and deflectors. In order to extend the proposed methodology, a test rig has been set up in which several moveable walls can be inserted thus making it possible to modify the radial and axial clearances, i.e., the distances between the tested gear and the walls. Based on a qualitative evaluation of the various fluid flow regimes possible in gearboxes, the influence of the global volume of the oil sump on churning losses is analyzed. By considering a number of flange and deflector arrangements, the following conclusions are drawn: a) radial clearances have a weaker influence than axial clearances and, b) power losses can be minimized by properly chosen axial clearances.

scholarly journals Experimental investigations and analysis on churning losses of splash lubricated spiral bevel gears

2017 ◽  
Vol 18 (4) ◽  
pp. 412 ◽  
Author(s):  
S. Laruelle ◽  
C. Fossier ◽  
C. Changenet ◽  
F. Ville ◽  
S. Koechlin
Keyword(s):  
Experimental Tests ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Spiral Bevel Gear ◽  
Power Losses ◽  
Test Rig ◽  
Specific Test ◽  
Spiral Bevel Gears ◽  
Bevel Gears ◽  
Spiral Bevel

Churning losses are a complex phenomenon which generates significant power losses when considering splash lubrication of gear units. However, only few works deal with bevel gears dipped lubrication losses. The objective of this study is to provide a wide variety of experimental tests on churning losses, especially getting interested in geometry of spiral bevel gears influence. A specific test rig was used in order to study a single spiral bevel gear partially immersed in an oil bath. Experiments have been conducted for several operating conditions in terms of speeds, lubricants, temperatures and gear geometries to study their impact on splash lubrication power losses. These experimental results are compared with the predictions from various literature sources. As the results did not agree well with the predictions for all operating conditions, an extended equation derived from previous works is introduced to estimate churning losses of bevel gears.

Experimental and Numerical Investigation on Windage Power Losses in High Speed Gears

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Daniele Massini ◽  
Tommaso Fondelli ◽  
Antonio Andreini ◽  
Bruno Facchini ◽  
Lorenzo Tarchi ◽  
...  
Keyword(s):  
High Speed ◽  
Spur Gear ◽  
Relative Magnitude ◽  
Navier Stokes ◽  
Power Losses ◽  
Test Rig ◽  
Viscosity Models ◽  
Image Velocimetry ◽  
And Performance ◽  
Aero Engines

Enhancing the efficiency of gearing systems is an important topic for the development of future aero-engines with low specific fuel consumption. An evaluation of its structure and performance is mandatory in order to optimize the design as well as maximize its efficiency. Mechanical power losses are usually distinguished into two main categories: load-dependent and load-independent losses. The former are all those associated with the transmission of torque, while the latter are tied to the fluid dynamics of the environment, which surrounds the gears. The relative magnitude of these phenomena is dependent on the operative conditions of the transmission: load-dependent losses are predominant at slow speeds and high torque conditions, load-independent mechanisms become prevailing in high speed applications, like in turbomachinery. A new test rig was designed for investigating windage power losses resulting by a single spur gear rotating in a free oil environment. The test rig allows the gear to rotate at high speed within a box where pressure and temperature conditions can be set and monitored. An electric spindle, which drives the system, is connected to the gear through a high accuracy torque meter, equipped with a speedometer providing the rotating velocity. The test box is fitted with optical accesses in order to perform particle image velocimetry (PIV) measurements for investigating the flow field surrounding the rotating gear. The experiment has been computationally replicated, performing Reynolds-averaged Navier–Stokes (RANS) simulations in the context of conventional eddy viscosity models, achieving good agreement for all of the speed of rotations.

Investigations on CFD Simulations for Predicting Windage Power Losses in Spur Gears

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Y. Marchesse ◽  
C. Changenet ◽  
F. Ville ◽  
P. Velex
Keyword(s):  
Three Dimensional ◽  
Volumetric Flow Rate ◽  
Spur Gears ◽  
Power Losses ◽  
Test Rig ◽  
Cfd Simulations ◽  
Specific Test ◽  
Computational Fluid Dynamics Cfd ◽  
Volume Method ◽  
Three Dimensional Simulations

In this paper, a computational fluid dynamics (CFD) code is applied to two- and three-dimensional simulations of windage power loss generated by spur gears rotating in air. Emphasis is placed on the various meshes associated with the finite volume method and on the choice of turbulence model. Comparing CFD predictions with the power losses measured on a specific test rig, it is shown that the fluid ejection in the radial direction must be included in order to reproduce the experimental evidence. The relative importance of the losses generated by the gear front and rear faces along with those due to the teeth is discussed. The volumetric flow rate expelled by the teeth is analyzed and the influence of flanges is highlighted.

A Comprehensive Investigation of Preswirled Flow Through Rotating Radial Holes

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Daniel Riedmüller ◽  
Jan Sousek ◽  
Michael Pfitzner
Keyword(s):  
Experimental Data ◽  
Gas Turbines ◽  
Discharge Coefficient ◽  
Cfd Simulation ◽  
Test Rig ◽  
Outer Annulus ◽  
Flow Phenomena ◽  
Flow Through ◽  
Flow Directions ◽  
Experimental Findings

This paper reports on the flow (centrifugal = radially outward, centripetal = radially inward) through rotating radial orifices with and without preswirl in the flow approaching the orifice in the outer annulus. The aerodynamical behavior of flow through radial rotating holes is different from the one through axial and stationary holes due to the presence of centrifugal and Coriolis forces. To investigate the flow phenomena and the discharge coefficient of these orifices in detail, an existing test rig containing two independently rotating shafts (corotating and counter rotating) was used. To simulate conditions of real gas turbines, where the flow is often influenced by upstream components, various preswirl angles were used in the test rig. Measurements of the flow discharge coefficient in both flow directions through the orifices (centripetal and centrifugal), with and without preswirl generation in the outer annulus, are presented at various flow conditions (pressure ratios across orifices, Mach numbers of approaching flow) and for different geometric parameters (length to diameter ratios, sharp/rounded inlet edges). Flow effects that occur with preswirled flow are clarified. A comparison of the experimental data, for both flow directions, shows a similar behavior of the discharge coefficients with increasing shaft speeds. To supplement the experimental data and to better understand the experimental findings, numerical simulations were performed, which show a good agreement with the experimental results. Furthermore, an optimization model with complete automatic grid generation, computational fluid dynamics (CFD) simulation, and postprocessing, was built to enable large parametric studies, e.g., grid independence of the solutions.

Thermal modelling of a back-to-back gearbox test machine: Application to the FZG test rig

2012 ◽  
Vol 226 (6) ◽  
pp. 501-515 ◽  
Author(s):  
J Durand de Gevigney ◽  
C Changenet ◽  
F Ville ◽  
P Velex
Keyword(s):  
Thermal Model ◽  
Thermal Modelling ◽  
Bulk Temperature ◽  
Test Machine ◽  
Network Approach ◽  
Power Losses ◽  
Test Rig ◽  
Isothermal Method ◽  
Transient Regimes ◽  
Good Agreement

A thermal model of a back-to-back gear test rig relying on a network approach is presented in which the predictions of temperatures and power losses are coupled. The numerical findings are in good agreement with the measurements for transient regimes on a FZG test rig and it is demonstrated that the proposed simulation is reliable. A number of results are presented which illustrate the influence of the pinion and gear immersion depths. It is found that, in certain conditions, the classic isothermal method for estimating integral temperatures is questionable because the actual bulk temperature can substantially deviate from that of the oil sump. The practical consequences in terms of scuffing capacity are emphasised.

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