In safety-critical applications such as aerospace and marine, electrical machines are limited to meet several stringent requirements such as physical, electrical, magnetic and thermal isolation between two three-phase channels, in order to be considered for fault-tolerant operation throughout its service life. This paper presents novel sectored fault-tolerant PM synchronous machines which include single, double and four sectored designs where one pole pair section of the machine’s stator is cut out to meet the fault-tolerant constraints. A detailed electromagnetic analysis is carried out in terms of their electromagnetic performance which is then compared with the benchmark 30s/10p combination for a given output power of 50kW. Due to the heightened power density in the innovative design, a highly effective thermal management system became necessary. This led to the identification of a novel and efficient cooling configuration. Leveraging the four gaps between the four sectors, an efficient cooling system was successfully implemented. As a result, the current density increased by 18.2%, representing an increase of 2A/mm² compared to the benchmark machine design.

The recent advancement of cooling methodologies for critical components such as turbine blades, combustor liners, and afterburner liners has led to the development of a combination of impingement and film cooling. The present study proposes an efficient cooling technique for a modern aero-engine afterburner liner based on the combination of jet impingement and film cooling. To achieve this, a numerical model is devised to model the film flow over a corrugated liner with several jets impinging over it. The numerical model is validated in a set of in-house experiments as well as against experimental data available in the literature. The experiment is performed for a limited temperature range (i.e., with a low-density ratio). However, the numerical simulations are carried out by varying the blowing ratio from 0.3 to 0.6. The density ratio during the simulations is kept at 3.5. The minimum distance between the impinging plate and the liner is kept at h/D = 1. A detailed analysis of the numerical results indicates a significant drop in the temperature distribution over the liner surface because of the employed cooling technique. The present study also reveals that, under similar operating conditions, the combined jet impingement and film cooling system has the ability to achieve the targeted cooling effect at a lower bleed air flow rate due to its higher effectiveness than that of the standard film cooling arrangement.

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.

The trapped-vortex combustor (TVC) is an alternative combustor design to conventional aeroengine combustors. The separate fuel and air injection of this combustor and its compact design make it a perfect candidate for conventional fuel usage. Moreover, the performance of a trapped-vortex combustor with alternative fuels such as ammonia and hydrogen in the actual operating conditions of an aeroengine is not well understood. The present paper focused on the performance evaluation of TVCs with the futuristic fuels ammonia and hydrogen including under the realistic operating conditions of a combustor. The investigated fuels were injected into a cavity with 0-,15-, 30- and 45-degree transverse-angled air injectors to evaluate the mixing enhancement of the air and fuel under idle and low-power conditions. The mixing behavior of hydrogen showed a significant difference from the conventional fuel, i.e., propane. It was also noticed that the transverse injection of the air helped to improve the mixing efficiency as compared to the normal injection configuration. Mixing efficiency was higher for the 30- and 45-degree transverse-angled air injectors compared to the 0- and 15-degree transverse-angled air injectors.