Session: 37-06 Pumps and Hydraulic Systems 1

Paper Number: 78010

78010 - Predictions of Falling Wavy Films Based on the Depth Averaged Thin Film Model and Its Application to Aeroengine Bearing Chamber 

The bearings of an aeroengine are subjected to very high mechanical and thermal loads. The lubricating oil is supplied to the bearings as it serves the dual purpose of lubrication and cooling. In this process, the lubricating oil is atomised in the bearings and dispersed due to the angular momentum of the rotating shaft. The dispersed oil is collected at the inner walls of the bearing chamber and sent back to the lubrication system through the scavenge port. A thin film is formed at the walls of the chamber because of the continuous impingement of oil droplets. Bearing chambers are pressurised by the sealing air to prevent oil leakage. A wavy film on the static components of the bearing chamber is observed because of the interaction of sealing air with the oil film.

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, coarse grids can be used in the wall normal direction. Consequently, this model is computationally efficient as compared to fully resolving the thin film and is hence highly advantageous for industrial simulations. In the case of a falling wavy film, film thickness and film velocity are closely coupled. A coupled solver that solves depth averaged continuity and momentum equation simultaneously has been implemented with the provision to apply smoothing to the curvature of surface tension term to improve the accuracy and robustness of the model. The implemented model provides a stable solution for explicit as well as implicit temporal formulations. The performance of the newly implemented ETFM model is evaluated by comparing numerical results with experimental measurements and high fidelity VOF simulations. The newly implemented model is found to be reliable in predicting free surface film profiles. It is 150 to 415 times computationally cheaper when compared to high fidelity VOF simulations. The sensitivity of newly implemented ETFM model to the film Reynolds number (Re), excitation frequency (f) and test plate inclination angle (α) is assessed by varying these parameters in the range: Re = 10.4 to 21.4, f = 11.3 to 24Hz, α = 35º, 90º. The implemented model is found to be sensitive enough to capture the variation in the film evolution and film profile because of the variation in film Reynolds number, excitation frequency and plate inclination angle. The implemented and validated model is used to predict wavy film inside an aeroengine bearing chamber.

Presenting Author: Kuldeep Singh University of Nottingham

Presenting Author Biography: Dr. Kuldeep Singh is currently working in the Rolls Royce's University Technological Centre in "Gas Turbine and Transmission Research Centre (G2TRC), University of Nottingham, United Kingdom as a senior researcher. He has worked with the diverse team of international researchers. He is a Gold Medallist in B.Tech. He did M.Tech and PhD from IIT Delhi. Before joining his current institution, he was Post-Doctoral Fellow in University of Beira Interior, Portugal. He is recipient of prestigious INSPIRE Faculty Award in 2017 from DST. He has worked on numerous projects sponsored by DRDO, DST, BHEL, Portuguese Foundation of Science and Technology, European Union & RR.

Authors:

Kuldeep Singh University of Nottingham
Andrew Nicoli University of Nottingham
Richard Jefferson-Loveday University of Nottingham
Stephen Ambrose University of Nottingham
Paloma Paleo Cageao University of Nottingham
Kathy Johnson University of Nottingham
Sandeep Mouvanal University of Nottingham
Jing Cao ANSYS Inc.
Adrian Jacobs Rolls Royce plc.