Specifying and Benchmarking a Thin Film Model for Oil Systems Applications in ANSYS Fluent

A thin film model developed for calculating the oil film flow in aero-engine bearing chamber is described. The performance of the model, which has been implemented in the commercial computational fluid dynamics software product: ANSYS Fluent, is benchmarked by comparing the computational results obtained from a Nottingham UTC in-house code and a development version of Fluent. Both codes are used to solve thin film flow in a test case configuration and based on the same finite area method. With identified constraints, the two implementations agree well.

Download Full-text

Thin Film Modelling for Aero-Engine Bearing Chambers

Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Wind Turbine Technology ◽

10.1115/gt2011-46259 ◽

2011 ◽

Cited By ~ 1

Author(s):

C. Wang ◽

H. P. Morvan ◽

S. Hibberd ◽

K. A. Cliffe

Keyword(s):

Thin Film ◽

Film Flow ◽

Momentum Equation ◽

Thin Film Flow ◽

Simple Formulation ◽

Physical Mechanisms ◽

Thin Film Model ◽

Aero Engine ◽

Flow Features ◽

Engine Bearing

This paper presents a dynamic mathematical model describing the thin film flow in aero-engine bearing chamber. By analyzing the depth averaged continuity equation and momentum equation term by term, the comprehensive physical mechanisms driving thin film flow are revealed. The terms that require extra modeling work are then identified. As a useful first approach, a thin film model based on presumed quadratic velocity profile is adopted. A preliminary study shows that this model can include the main film flow features in aero-engine bearing chamber, whilst maintain simple formulation and work efficiently. Finally, a converging computational strategy is obtained towards the numerical simulation of engine bearing chamber.

Download Full-text

Assessment of an Enhanced Thin Film Model to Capture Wetting and Drying Behavior in an Aero-Engine Bearing Chamber

Volume 2C: Turbomachinery ◽

10.1115/gt2019-91323 ◽

2019 ◽

Author(s):

Kuldeep Singh ◽

Medhat Sharabi ◽

Stephen Ambrose ◽

Carol Eastwick ◽

Richard Jefferson-Loveday ◽

...

Keyword(s):

Thin Film ◽

Contact Angle ◽

Film Thickness ◽

Wetting And Drying ◽

Film Model ◽

Thin Film Model ◽

Aero Engine ◽

Thickness Prediction ◽

Drying Behavior ◽

Engine Bearing

Abstract In the present work, a wetting and drying model is coupled with Eulerian Thin-Film model (ETFM) to analyze the wetting and drying behavior inside the bearing chamber. In the enhanced model, an additional source term is included to account for the contact angle effect. These models were coupled with volume-of-fluid (VOF) such that the core region is resolved by VOF and region close to the chamber walls, where a thin film is expected is resolved by either ETFM or enhanced ETFM model. Numerical studies are conducted for a shaft speed of 5,000 rpm, lubricant and air flow rates of 100 1/hr and 10 g/s respectively, at a scavenging ratio of 4. In the case of enhanced ETFM model lubricant to surface contact angle was varied from 10° to 45°. The performance of enhanced ETFM model is evaluated to capture drying and wetting behavior on a flat plate and found to be satisfactory. Film thickness prediction of enhanced ETFM model is found to be comparable with the VOF predictions reported in the literature. The effect of contact angle on the spreading of oil and film thickness is found to be small for the investigated conditions on an aero-engine bearing chamber.

Download Full-text

Prediction of Film Thickness of an Aero-Engine Bearing Chamber Using Coupled VOF and Thin Film Model

Volume 2C: Turbomachinery ◽

10.1115/gt2019-91314 ◽

2019 ◽

Author(s):

Kuldeep Singh ◽

Medhat Sharabi ◽

Stephen Ambrose ◽

Carol Eastwick ◽

Richard Jefferson-Loveday

Keyword(s):

Thin Film ◽

Film Thickness ◽

Air Flow ◽

Shaft Speed ◽

Oil Film ◽

Film Model ◽

Thin Film Model ◽

Wide Range ◽

Aero Engine ◽

Engine Bearing

Abstract In the present work, a coupled volume-of-fluid (VOF) model with Eulerian thin-film model (ETFM) approach is used to predict the film thickness in an aero-engine bearing chamber. Numerical studies are conducted for a wide range of shaft speeds with lubricant and air flow rates of 100 1/hr and 10 g/s respectively, at a scavenge ratio of 4 on a simplified bearing chamber test rig. Air-flow analysis inside the bearing chamber is also assessed. Primary and secondary airflow predictions are found to be in good agreement with the experimental results. The coupled ETFM+VOF approach is found to be sensitive enough to capture the qualitative trend of oil film formation and distribution over the chamber wall. Oil collection near the sump at a low shaft speed and a rotating oil film at a higher shaft speed are well captured.

Download Full-text

Modelling of Partially Wetting Liquid Film Using an Enhanced Thin Film Model for Aero-Engine Bearing Chamber Applications

Volume 2C: Turbomachinery ◽

10.1115/gt2020-15845 ◽

2020 ◽

Author(s):

K. Singh ◽

M. Sharabi ◽

R. Jefferson-Loveday ◽

S. Ambrose ◽

C. Eastwick ◽

...

Keyword(s):

Thin Film ◽

Contact Angle ◽

Film Thickness ◽

Liquid Film ◽

Flow Rate ◽

Operating Conditions ◽

Film Model ◽

Thin Film Model ◽

Wide Range ◽

Aero Engine

Abstract In the case of aero-engine, thin lubricating film servers dual purpose of lubrication and cooling. Prediction of dry patches or lubricant starved region in bearing or bearing chambers are required for safe operation of these components. In the present work thin liquid film flow is numerically investigated using the framework of the Eulerian thin film model (ETFM) for conditions which exhibit partial wetting phenomenon. This model includes a parameter that requires adjustment to account for the dynamic contact angle. Two different experimental data sets have been used for comparisons against simulations, which cover a wide range of operating conditions including varying the flow rate, inclination angle, contact angle, and liquid-gas surface tension coefficient. A new expression for the model parameter has been proposed and calibrated based on the simulated cases. This is employed to predict film thickness on a bearing chamber which is subjected to a complex multiphase flow. From this study, it is observed that the proposed approach shows good quantitative comparisons of the film thickness of flow down an inclined plate and for the representative bearing chamber. A comparison of model predictions with and without wetting and drying capabilities is also presented on the bearing chamber for shaft speed in the range of 2,500 RPM to 10,000 RPM and flow rate in the range of 0.5 liter per minute (LPM) to 2.5 LPM.

Download Full-text

Modeling of Partially Wetting Liquid Film Using an Enhanced Thin Film Model for Aero-Engine Bearing Chamber Applications

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4049663 ◽

2021 ◽

Vol 143 (4) ◽

Author(s):

Kuldeep Singh ◽

Medhat Sharabi ◽

Richard Jefferson-Loveday ◽

Stephen Ambrose ◽

Carol Eastwick ◽

...

Keyword(s):

Thin Film ◽

Contact Angle ◽

Film Thickness ◽

Liquid Film ◽

Thin Liquid Film ◽

Operating Conditions ◽

Film Model ◽

Thin Film Model ◽

Wide Range ◽

Aero Engine

Abstract In the case of aero-engine, thin lubricating film servers dual purpose of lubrication and cooling. Prediction of dry patches or lubricant starved region in bearing or bearing chambers are required for safe operation of these components. In this work, thin liquid film flow is numerically investigated using the framework of the Eulerian thin film model (ETFM) for conditions, which exhibit partial wetting phenomenon. This model includes a parameter that requires adjustment to account for the dynamic contact angle. Two different experimental data sets have been used for comparisons against simulations, which cover a wide range of operating conditions including varying the flowrate, inclination angle, contact angle, and liquid–gas surface tension coefficient. A new expression for the model parameter has been proposed and calibrated based on the simulated cases. This is employed to predict film thickness on a bearing chamber which is subjected to a complex multiphase flow. From this study, it is observed that the proposed approach shows good quantitative comparisons of the film thickness of flow down an inclined plate and for the representative bearing chamber. A comparison of model predictions with and without wetting and drying capabilities is also presented on the bearing chamber for shaft speed in the range of 2500 RPM to 10,000 RPM and flowrate in the range of 0.5 liter per minute (LPM) to 2.5 LPM.

Download Full-text

Influence of circumferential waviness on engine bearing performance

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/0954406001522804 ◽

2000 ◽

Vol 214 (1) ◽

pp. 51-61 ◽

Cited By ~ 4

Author(s):

D. S. Mehenny ◽

C. M. Taylor

Keyword(s):

Thin Film ◽

Film Flow ◽

Film History ◽

Two Dimensional ◽

Thin Film Flow ◽

Main Bearing ◽

Automotive Engine ◽

Form Errors ◽

Minimum Film Thickness ◽

Engine Bearing

The influence of circumferential waviness of the journal on the lubrication of the inter-main bearing of an automotive engine is investigated using a theoretical analysis. The analysis is for two-dimensional thin film flow, with oil-film history. The bearing and shaft surfaces were assumed to be rigid and the lubricant isoviscous. The results show a significant influence of shaft lobing on predicted maximum film pressure and minimum film thickness, particularly as the number and size of lobes increase. It is concluded that, for satisfactory operation of engine bearings, circumferential form errors of the shaft need to be controlled.

Download Full-text