This manuscript presents the application of an improved CFD methodology to simulate the scavenge system film flow phenomena in a real aero engine bearing chamber environment i.e. influence of seals and rotational shaft. Near the scavenge off-take, the usual thin film approach is not valid due to the occurrence of relative thick films (up to 5mm, comp. [1]) where film internal dynamics become very important. Therefore, other multiphase modelling techniques need to be explored. Young and Chew suggest in [2] that the Volume Of Fluid (VOF) method is the most suitable technique for air/oil system applications. Hashmi et al. reported in [3] that this free surface method for shear driven thick wall films in the bearing chamber environment needs additional provisions for turbulence modelling. Accordingly, a simple correction is made to the k–ε RNG turbulence model to improve the simulation results. The improved CFD methodology is applied to an engine representative geometry and proves to be robust and computationally efficient. The test conditions in the simulation was chosen in a way to avoid any droplet stripping from the film surface. It is shown that the applied methodology together with the correction in the turbulence modelling prove to play a vital role for a good comparison with experimental data. After validation the simulation results are used to describe the flow phenomena which occur in the bearing chamber for the investigated condition. The introduced CFD modelling technique shows large potential for the development and trouble shooting purposes in the industrial environment.

This paper presents results of investigations on the interaction between a targeted oil jet and a rotating shaft in an aero-engine typical bearing chamber. Measurements were per formed at atmospheric temperature and pressure in order to study the influence of the operating conditions, nozzle diameters and impingement angles on the efficiency of such an oil supply system. The flow phenomena of the jet-shaft interaction were visualized. A qualitative analysis of the jet-shaft interaction revealed massive droplet generation due to the jet break-up in the air crossflow and its impact on the shaft. The latter could be reduced with shallower impingement angles. Measurements showed that the oil inflow rate, the shaft speed, and the nozzle diameter have a strong influence on the collected oil quantity, which is expressed as catch efficiency, i.e., the ratio of collected and supplied oil. The impingement angle was also identified to have a strong influence on the catch ef ficiency. The ratio of the momentum fluxes of supplied oil and chamber air flow is pro posed as a parameter to correlate the catch efficiency to the operating conditions.

This paper presents results of investigations on the interaction between a targeted oil jet and a rotating shaft in an aero engine typical bearing chamber. Measurements were performed at atmospheric temperature and pressure in order to study the influence of the operating conditions, nozzle diameters and impingement angles on the efficiency of such an oil supply system. The flow phenomena of the jet-shaft interaction were visualised. A qualitative analysis of the jet-shaft interaction revealed massive droplet generation due to the jet break-up in the air crossflow and its impact on the shaft. The latter could be reduced with shallower impingement angles. Measurements showed that the oil inflow rate, the shaft speed and the nozzle diameter have a strong influence on the collected oil quantity, which is expressed as catch efficiency, i.e. the ratio of collected and supplied oil. The impingement angle was also identified to have a strong influence on the catch efficiency. The ratio of the momentum fluxes of supplied oil and chamber air flow is proposed as a parameter to correlate the catch efficiency to the operating conditions.

Hydraulic seals are used in aero engines because of their excellent sealing properties. Sealing of oil inside bearing chambers is extremely important as leakage of oil into internal spaces of the engine increases the oil consumption and can result in undesirable effects, ranging from cosmetic to mechanical. A robust dimensioning of the seal is therefore essential. However, the maximum pressure capacity of the hydraulic seal is not always determined accurately enough with many of the existing design approaches, so a high safety factor must be used. It is desirable to keep improving the accuracy of these methods, in particular to handle ever larger pressure differences. A new dimensionless design method is therefore introduced here to improve the determination of the maximum pressure capacity. This paper reports on a numerical CFD investigation using an axisymmetric Volume-of-Fluid (VOF) method building on the work of Young and Chew [1]. The numerical results are validated with the results of a two-shaft test rig, alongside analytical calculation results. Additionally, a parametric study based on CFD simulations is performed to identify dominant influence quantities. The parameters include the fluid properties of oil, the shaft speeds and the geometry parameters of the seal. Employing a data reduction approach, a new dimensionless number is introduced which allows the presentation of experimental and numerical results of the hydraulic seal in a dimensionless form. Based on this representation, a correlation is proposed, which shows a very promising trend. This validated CFD investigation and subsequent correlation introduced here show significant potential for the dimensionless description of hydraulic seals and their maximum pressure capacity.