Antonino La Rocca

High-Speed Solid Rotor Permanent Magnet Machines: Concept and Design

This paper proposes a novel solid rotor topology for an interior permanent magnet (IPM) machine, adopted in this case for an aircraft starter-generator design. The key challenge in the design is to satisfy two operating conditions that are a high torque at start and a high speed at cruise. Conventional IPM topologies that are highly capable of extended field weakening are found to be limited at high speed due to structural constraints associated with the rotor material. To adopt the IPM concept for high-speed operation, it is proposed to adopt a rotor constructed from semimagnetic stainless steel, which has a higher yield strength than laminated silicon steel. To maintain minimal stress levels and also minimize the resultant eddy current losses due to the lack of laminations, different approaches are considered and studied. Finally, to achieve a better tradeoff between the structural and electromagnetic constraints, a novel slitted approach is implemented on the rotor. The proposed rotor topology is verified using electromagnetic, static structural, and dynamic structural finite-element analyses. An experiment is performed to confirm the feasibility of the proposed rotor. It is shown that the proposed solid rotor concept for an IPM fulfils the design requirements while satisfying the structural, thermal, and magnetic limitations.

Morphological Characterisation of Diesel Soot in Oil and the Associated Extraction Dependence

The size and morphology of soot particles and agglomerates extracted from lubricating oil drawn from the sump of a diesel engine have been investigated and compared using Transmission Electron Microscopy (TEM) and Nanoparticle Tracking Analysis (NTA). Samples were prepared for electron microscopy imaging by both centrifugation and solvent extraction to investigate the impact of these procedures on the morphological characteristics, such as skeleton length and width and circularity, of the obtained soot. It was shown that centrifugation increases the extent of agglomeration within the sample, with 15% of the agglomerates above 200 nm compared to only 11% in the solvent extracted soot. It was also observed that the width of centrifugation extracted soot was typically 10 nm to 20 nm larger than that of solvent extracted soot, suggesting that centrifugation forces the individual agglomerate chains together. Moreover, centrifugation fails to extract a large percentage of particles below 50 nm, with only 4% of the agglomerates smaller than 50 nm in the centrifugation extracted soot, whereas agglomerates in this size range accounted for 19 % using solvent extraction. As TEM represents a comparatively time and cost expensive characterisation tool, unsuitable for high throughput testing required by industry, NTA was explored as a low cost, rapid alternative method for measuring particle size. It was found that results generated by NTA, within the limits of detection, correlated well with those obtained using TEM. This correlative electron microscopy and light scattering approach was further used to appraise the morphological characteristics of two commercial sources of carbon black (CB), enabling the selection of the most suitable soot surrogate, essential for the further development of oils with optimised functional properties.

Development of aircraft electric starter-generator system based-on active rectification technology

More-electric aircraft (MEA) has become a dominant trend for modern aircraft. On-board MEA, many functions, which are conventionally driven by pneumatic and hydraulic power, are replaced with electrical subsystems. Starting aircraft engines with an electric motor instead of using pneumatic power from the auxiliary power unit is one of the major characteristics of future aircraft. This paper presents the development of a novel electric starter–generator system for aircraft applications. This paper describes the main achievements of the AEGART (EU CleanSky Project) project in the key areas, including electric machines, power electronic converters, thermal management, and overall system control design. The developed prototype has been tested successfully, and the test results are presented in this paper.

Evaluating Performance of Uncoated GPF in Real World Driving Using Experimental Results and CFD modelling

Fig. 4. GPF section geometry and mesh  The present work focuses on an experimental durability study on road under real word driving conditions. Two sets of experiments were carried out. The first study analyzed a Gasoline Particulate Filter (GPF) (2.4 liter, diameter 5.2” round) installed in underfloor (UF) position driven for up to 200,000 km. A 1.6 liter Gasoline Direct Injection (GDI) engine was used for the investigation. Ash accumulation versus mileage and soot loading were of interest. A parallel investigation up to 160,000 km with same engine (2 identical vehicles on road on a “specific average” cycle) and GPF installed in closed coupled (CC) position was also carried out. Both UF and CC GPF are NGK 360 cpsi 5 mil wall thickness.  As a route to develop a robust 3-D Computational Fluid Dynamics (CFD) model to gather information on the fluid flow and pressure loss characteristics of GPF, a baseline model is introduced in this work. The computational domain refers to full length individual 3-D channels and focuses on two quarters of an inlet and two quarters of an outlet channels with the aim of reducing complexity of the problem and its computational cost. Although this baseline version does not include yet the soot and ash loading models, it can be used to understand real physical problems and gather insight on velocity and pressure distributions inside filter and its channels