STEPHEN AMBROSE's Outputs (25)

A machine learning-driven approach to predicting thermo-elasto-hydrodynamic lubrication in journal bearings (2024)
Journal Article
Cartwright, S., Rothwell, B. C., Figueredo, G., Medina, H., Eastwick, C., Layton, J., & Ambrose, S. (2024). A machine learning-driven approach to predicting thermo-elasto-hydrodynamic lubrication in journal bearings. Tribology International, 196, Article 109670. https://doi.org/10.1016/j.triboint.2024.109670

Traditional methods of evaluating the performance of journal bearings, for example thermal-elastic-hydrodynamic- lubrication theory, are limited to simplified conditions that often fail to accurately model real-world components. Numerical models that... Read More about A machine learning-driven approach to predicting thermo-elasto-hydrodynamic lubrication in journal bearings.

Windage Torque Reduction in Low-Pressure Turbine Cavities Part II: Experimental and Numerical Results (2024)
Journal Article
Jackson, R. W., Li, Z., Christodoulou, L., Ambrose, S., Sangan, C. M., Jefferson-Loveday, R., …Scobie, J. A. (2024). Windage Torque Reduction in Low-Pressure Turbine Cavities Part II: Experimental and Numerical Results. Journal of Turbomachinery, 146(6), Article 061005. https://doi.org/10.1115/1.4063876

Minimizing the losses within a low-pressure turbine (LPT) system is critical for the design of next-generation ultra-high bypass ratio aero-engines. The stator-well cavity windage torque can be a significant source of loss within the system, influenc... Read More about Windage Torque Reduction in Low-Pressure Turbine Cavities Part II: Experimental and Numerical Results.

Windage Torque Reduction in Low-Pressure Turbine Cavities Part I: Concept Design and Numerical Investigations (2024)
Journal Article
Li, Z., Christodoulou, L., Jefferson-Loveday, R. J., Ambrose, S., Jackson, R., Lock, G. D., …Scobie, J. (2024). Windage Torque Reduction in Low-Pressure Turbine Cavities Part I: Concept Design and Numerical Investigations. Journal of Turbomachinery, 146(6), 1-16. https://doi.org/10.1115/1.4064224

The windage torque on rotational walls has negative effect on the performance of the low pressure turbine. In this paper, three novel flow control concepts (FCCs) were proposed to reduce the windage torque within a turbine stator well, with upstream... Read More about Windage Torque Reduction in Low-Pressure Turbine Cavities Part I: Concept Design and Numerical Investigations.

Influence of swirl and ingress on windage losses in a low-pressure turbine stator-well cavity (2023)
Journal Article
Jackson, R., Christodoulou, L., Li, Z., Sangan, C. M., Ambrose, S., Jefferson-Loveday, R., …Scobie, J. A. (2023). Influence of swirl and ingress on windage losses in a low-pressure turbine stator-well cavity. Experiments in Fluids, 64(11), Article 173. https://doi.org/10.1007/s00348-023-03715-7

As part of the drive towards achieving net-zero flight by 2050, the development of ultra-high bypass ratio engines will place greater importance on the efficiency of the low-pressure turbine. Stator-well cavities can be a significant source of loss w... Read More about Influence of swirl and ingress on windage losses in a low-pressure turbine stator-well cavity.

High-fidelity CFD-trained machine learning to inform RANS-modelled interfacial turbulence (2023)
Journal Article
Bertolotti, L., Jefferson-Loveday, R., Ambrose, S., & Korsukova, E. (2023). High-fidelity CFD-trained machine learning to inform RANS-modelled interfacial turbulence. Journal of the Global Power and Propulsion Society, 7, 269-281. https://doi.org/10.33737/jgpps/166558

In aero-engine bearing chambers, two-phase shearing flows are difficult to predict as Computational Fluid Dynamics (CFD) RANS models tend to overestimate interfacial turbulence levels, leading to inaccuracies in the modelling of the flow. Turbulence... Read More about High-fidelity CFD-trained machine learning to inform RANS-modelled interfacial turbulence.

A New Thermal Elasto-Hydrodynamic Lubrication Solver Implementation in OpenFOAM (2023)
Journal Article
Layton, J., Rothwell, B. C., Ambrose, S., Eastwick, C., Medina, H., & Rebelo, N. (2023). A New Thermal Elasto-Hydrodynamic Lubrication Solver Implementation in OpenFOAM. Lubricants, 11(7), Article 308. https://doi.org/10.3390/lubricants11070308

Designing effective thermal management systems within transmission systems requires simulations to consider the contributions from phenomena such as hydrodynamic lubrication regions. Computational fluid dynamics (CFD) remains computationally expensiv... Read More about A New Thermal Elasto-Hydrodynamic Lubrication Solver Implementation in OpenFOAM.

Computational study of free surface film flow and subsequent disintegration of a sheet and ligaments into droplets from a rotary disk atomizer (2023)
Journal Article
Singh, K., Ambrose, S., Jefferson-Loveday, R., Nicoli, A., & Mouvanal, S. (2023). Computational study of free surface film flow and subsequent disintegration of a sheet and ligaments into droplets from a rotary disk atomizer. Engineering Applications of Computational Fluid Mechanics, 17(1), Article 2162971. https://doi.org/10.1080/19942060.2022.2162971

In the present study, a computational methodology based on computational fluid dynamics (CFD) is developed to investigate free surface film flow and its subsequent disintegration on a rotary disk atomizer. The present study provides an insight into e... Read More about Computational study of free surface film flow and subsequent disintegration of a sheet and ligaments into droplets from a rotary disk atomizer.

Numerical study on the aeroacoustics and interaction of two distributed-propulsion propellers in co- and counter-rotations (2022)
Journal Article
Sharma, S., Huang, G., Ambrose, S., & Jefferson-Loveday, R. (2022). Numerical study on the aeroacoustics and interaction of two distributed-propulsion propellers in co- and counter-rotations. Journal of the Acoustical Society of America, 152(4), A52-A52. https://doi.org/10.1121/10.0015514

Driven by increasing demands for a sustainable and eco-friendly future in aviation, distributed electric propulsion (DEP) systems have received much attention for their high aerodynamic efficiency. DEP systems of lower noise emissions are desired by... Read More about Numerical study on the aeroacoustics and interaction of two distributed-propulsion propellers in co- and counter-rotations.

Modeling of Partially Wetting Liquid Film Using an Enhanced Thin Film Model for Aero-Engine Bearing Chamber Applications (2021)
Journal Article
Singh, K., Sharabi, M., Jefferson-Loveday, R., Ambrose, S., Eastwick, C., Cao, J., & Jacobs, A. (2021). 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, 143(4), Article 041001. https://doi.org/10.1115/1.4049663

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,... Read More about Modeling of Partially Wetting Liquid Film Using an Enhanced Thin Film Model for Aero-Engine Bearing Chamber Applications.

Multiphase Computational Fluid Dynamics Modeling of External Oil Flow From a Journal Bearing (2018)
Journal Article
Berthold, M., Morvan, H., Jefferson-Loveday, R., Young, C., Rothwell, B. C., & Ambrose, S. (2019). Multiphase Computational Fluid Dynamics Modeling of External Oil Flow From a Journal Bearing. Journal of Engineering for Gas Turbines and Power, 141(5), 1-12. https://doi.org/10.1115/1.4041517

High loads and bearing life requirements make journal bearings a potential choice for use in high power, epicyclic gearboxes in jet engines. Particularly, in a planetary configuration , the kinematic conditions are complex. With the planet gears rota... Read More about Multiphase Computational Fluid Dynamics Modeling of External Oil Flow From a Journal Bearing.

Numerical modelling of the rise of Taylor bubbles through a change in pipe diameter (2017)
Journal Article
Ambrose, S., Lowndes, I. S., Hargreaves, D., & Azzopardi, B. (2017). Numerical modelling of the rise of Taylor bubbles through a change in pipe diameter. Computers and Fluids, 148, https://doi.org/10.1016/j.compfluid.2017.01.023

The rise of Taylor bubbles through expansions in vertical pipes is modelled using Computational Fluid Dynamics. The predictions from the models are compared against existing experimental work and show good agreement, both quantitatively and qualitati... Read More about Numerical modelling of the rise of Taylor bubbles through a change in pipe diameter.

Numerical modeling of oscillating Taylor bubbles (2016)
Journal Article
Ambrose, S., Hargreaves, D. M., & Lowndes, I. (2016). Numerical modeling of oscillating Taylor bubbles. Engineering Applications of Computational Fluid Mechanics, 10(1), 578-598. https://doi.org/10.1080/19942060.2016.1224737

© 2016 The Author(s). In this study, computational fluid dynamics (CFD) modeling is used to simulate Taylor bubbles rising in vertical pipes. Experiments indicate that in large diameter (0.29 m) pipes for an air-water system, the bubbles can rise in... Read More about Numerical modeling of oscillating Taylor bubbles.

Windage Torque Reduction in Low-Pressure Turbine Cavities Part 2: Experimental and Numerical Results
Presentation / Conference Contribution
Jackson, R., Lock, G. D., Sangan, C. M., Scobie, J. A., Li, Z., Christodoulou, L., Jefferson-Loveday, R., & Ambrose, S. (2023, June). Windage Torque Reduction in Low-Pressure Turbine Cavities Part 2: Experimental and Numerical Results. Presented at ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition, Boston, Massachusetts, USA

Minimizing the losses within a low-pressure turbine (LPT) system is critical for the design of next-generation ultra-high bypass ratio aero-engines. The stator-well cavity windage torque can be a significant source of loss within the system, influenc... Read More about Windage Torque Reduction in Low-Pressure Turbine Cavities Part 2: Experimental and Numerical Results.

Windage Torque Reduction in Low-Pressure Turbine Cavities - Part 1: Concept Design and Numerical Investigations
Presentation / Conference Contribution
Li, Z., Christodoulou, L., Jefferson-Loveday, R., Ambrose, S., Jackson, R., Lock, G. D., Sangan, C. M., & Scobie, J. A. (2023, June). Windage Torque Reduction in Low-Pressure Turbine Cavities - Part 1: Concept Design and Numerical Investigations. Presented at ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition, Boston, Massachusetts, USA

The windage torque on rotational walls has negative effect on the performance of the low pressure turbine. In this paper, three novel flow control concepts (FCCs) were proposed to reduce the windage torque within a turbine stator well, with upstream... Read More about Windage Torque Reduction in Low-Pressure Turbine Cavities - Part 1: Concept Design and Numerical Investigations.

Numerical Simulation of Multi-Scale Oil Films on a Rotating Cup Using VOF and Coupled Eulerian Thin-Film-DPM Approaches
Presentation / Conference Contribution
Nicoli, A., Singh, K., Jefferson-Loveday, R., Ambrose, S., & Mouvanal, S. (2022, June). Numerical Simulation of Multi-Scale Oil Films on a Rotating Cup Using VOF and Coupled Eulerian Thin-Film-DPM Approaches. Presented at ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition, Rotterdam, Netherlands

In this study, the newly developed Nottingham Gas Turbine and Transmission Research Centre (G2TRC) Bearing Chamber Test Module is presented and investigated computationally. The module houses a rotating cup and shaft configuration in order to simulat... Read More about Numerical Simulation of Multi-Scale Oil Films on a Rotating Cup Using VOF and Coupled Eulerian Thin-Film-DPM Approaches.

High Fidelity Cfd-Trained Machine Learning To Inform Rans-Modelled Interfacial Turbulence
Presentation / Conference Contribution
Bertolotti, L., Jefferson-Loveday, R., Ambrose, S., & Korsukova, E. (2022, September). High Fidelity Cfd-Trained Machine Learning To Inform Rans-Modelled Interfacial Turbulence. Presented at GPPS Chania22, Chania, Greece

In aero-engine bearing chambers, two-phase shearing flows are difficult to predict as Computational Fluid Dynamics (CFD) RANS models tend to overestimate interfacial turbulence levels, leading to inaccuracies in the modelling of the flow. Turbulence... Read More about High Fidelity Cfd-Trained Machine Learning To Inform Rans-Modelled Interfacial Turbulence.

COUPLED EULERIAN THIN FILM MODEL AND LAGRANGIAN DISCRETE PHASE MODEL TO PREDICT FILM THICKNESS INSIDE AN AERO-ENGINE BEARING CHAMBER
Presentation / Conference Contribution
Mouvanal, S., Singh, K., Jefferson-Loveday, R., Ambrose, S., Eastwick, C., Johnson, K., & Jacobs, A. (2022, September). COUPLED EULERIAN THIN FILM MODEL AND LAGRANGIAN DISCRETE PHASE MODEL TO PREDICT FILM THICKNESS INSIDE AN AERO-ENGINE BEARING CHAMBER. Presented at GPPS Chania22, Chania, Greece

In aero-engine bearing chambers, two-phase shearing flows are difficult to predict as Computational Fluid Dynamics (CFD) RANS models tend to overestimate interfacial turbulence levels, leading to inaccuracies in the modelling of the flow. Turbulence... Read More about COUPLED EULERIAN THIN FILM MODEL AND LAGRANGIAN DISCRETE PHASE MODEL TO PREDICT FILM THICKNESS INSIDE AN AERO-ENGINE BEARING CHAMBER.

Numerical characterisation of noise generated by a distributed-propulsion propeller
Presentation / Conference Contribution
Sharma, S., Huang, G., Ambrose, S., & Jefferson-Loveday, R. (2022, June). Numerical characterisation of noise generated by a distributed-propulsion propeller. Presented at 28th AIAA/CEAS Aeroacoustics 2022 Conference, Southampton, UK

The shift towards sustainable and eco-friendly future of aviation is further catalysed by the aggressive targets set by administrative and industrial stakeholders. It has emerged as one of the solutions with the potential to increase overall efficien... Read More about Numerical characterisation of noise generated by a distributed-propulsion propeller.

Predictions of falling wavy films based on the depth averaged thin film model and its application to aeroengine bearing chamber
Presentation / Conference Contribution
Singh, K., Nicoli, A., Jefferson-Loveday, R., Ambrose, S., Paleo Cageao, P., Johnson, K., Mouvanal, S., Cao, J., & Jacobs, A. (2022, June). Predictions of falling wavy films based on the depth averaged thin film model and its application to aeroengine bearing chamber. Presented at ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition, Rotterdam, Netherlands

In the present study, the evolution of a falling wavy film with upstream forced excitation is investigated using the depth averaged thin film model, known as Eulerian Thin Film Model (ETFM). Because of the depth averaging of the governing equations,... Read More about Predictions of falling wavy films based on the depth averaged thin film model and its application to aeroengine bearing chamber.

Numerical simulation of multi-scale oil films on a rotating cup using VOF and coupled Eulerian thin-film-dpm approaches
Presentation / Conference Contribution
Nicoli, A., Singh, K., Jefferson-Loveday, R., Ambrose, S., & Mouvanal, S. (2022, June). Numerical simulation of multi-scale oil films on a rotating cup using VOF and coupled Eulerian thin-film-dpm approaches. Presented at ASME Turbo Expo, Rotterdam, Netherlands

In this study, the newly developed Nottingham Gas Turbine and Transmission Research Centre (G2TRC) Bearing Chamber Test Module is presented and investigated computationally. The module houses a rotating cup and shaft configuration in order to simulat... Read More about Numerical simulation of multi-scale oil films on a rotating cup using VOF and coupled Eulerian thin-film-dpm approaches.

Investigation of Droplet Shedding in an Aeroengine Bearing Chamber Using Convolutional Neural Networks
Presentation / Conference Contribution
Farbrother, K., Cageao, P. P., Johnson, K., & Ambrose, S. (2022, June). Investigation of Droplet Shedding in an Aeroengine Bearing Chamber Using Convolutional Neural Networks. Presented at ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition, Rotterdam, Netherlands

More efficient aeroengines are needed to reduce the environmental impact of civil aviation. Design changes for increased efficiency mean that higher loads are transmitted through the bearings supporting the rotating shafts. Better bearing chamber des... Read More about Investigation of Droplet Shedding in an Aeroengine Bearing Chamber Using Convolutional Neural Networks.

Numerical Investigation Into Maximum Pressure Capability of Intershaft Hydraulic Seals
Presentation / Conference Contribution
Warusevitane, A., Johnson, K., & Ambrose, S. (2022, June). Numerical Investigation Into Maximum Pressure Capability of Intershaft Hydraulic Seals. Presented at ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition, Rotterdam, Netherlands

Hydraulic seals are used as intershaft seals in aero-engines and consist of an oil filled trough on the higher speed shaft and a fin on the lower speed shaft that dips into the oil forming the seal. Rotation is imparted to the sealing fluid within th... Read More about Numerical Investigation Into Maximum Pressure Capability of Intershaft Hydraulic Seals.

Experimental Investigation Into Oil Shedding From a Rotating Cup Geometry
Presentation / Conference Contribution
Cageao, P. P., Johnson, K., Ambrose, S., & Omar, R. (2022, June). Experimental Investigation Into Oil Shedding From a Rotating Cup Geometry. Presented at ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition, Rotterdam, Netherlands

Oil shedding from rotating components and static elements within rotating systems has a number of applications within the design and understanding of transmission systems as well as wider industrial applications. There is a reasonable body of prior r... Read More about Experimental Investigation Into Oil Shedding From a Rotating Cup Geometry.

Assessment of an Enhanced Thin Film Model to Capture Wetting and Drying Behavior in an Aero-Engine Bearing Chamber
Presentation / Conference Contribution
Singh, K., Sharabi, M., Ambrose, S., Eastwick, C., Jefferson-Loveday, R., Cao, J., & Jacobs, A. (2019, June). Assessment of an Enhanced Thin Film Model to Capture Wetting and Drying Behavior in an Aero-Engine Bearing Chamber. Presented at ASME Turbo Expo 2019 Turbomachinery Technical Conference & Exposition, Phoenix, Arizona, United States

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 con... Read More about Assessment of an Enhanced Thin Film Model to Capture Wetting and Drying Behavior in an Aero-Engine Bearing Chamber.

Prediction of Film Thickness of an Aero-Engine Bearing Chamber using Coupled VOF and Thin Film Model
Presentation / Conference Contribution
Singh, K., Sharabi, M., Ambrose, S., Eastwick, C., & Jefferson-Loveday, R. J. (2019, June). Prediction of Film Thickness of an Aero-Engine Bearing Chamber using Coupled VOF and Thin Film Model. Presented at ASME Turbo Expo 2019 Turbomachinery Technical Conference & Exposition, Phoenix, Arizona, United States

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 lu... Read More about Prediction of Film Thickness of an Aero-Engine Bearing Chamber using Coupled VOF and Thin Film Model.