Abstract-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 electrical motor instead of using pneumatic power from the auxiliary power unit (APU) is one of the major characteristics of future aircraft. This paper presents the development of a novel electric starter-generator system for aircraft applications. The paper describes the main achievements of the project within 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.

No abstract

No abstract

No abstract

No abstract

12The Gasoline Direct Injection engines are an important source of ultra-fine particulate matter. 13Significant research effort is still required as improved understanding of soot formation is critical in 14considering further development or adoption of new technologies. Experimental measurements of 15 engine-out soot emissions have been taken from a modern Euro IV GDI engine at part-load 16operating conditions. The engine speed and torque were varied in the range 1600 to 3700 rev/min, 17and 30 to 120 Nm, respectively. The engine was invariably operated in stoichiometric and 18 homogeneous combustion mode, with fuel injection early in the intake stroke. The results indicate 19 that for engine load in excess of 3 bar Brake Mean Effective Pressure, due to incomplete gas-20 phase mixture preparation, a consistent linear correlation establishes between combustion duration 21 and soot particle number. On average, a six-fold increase in number concentration between 1.0 22 and 6.0x10 6 particle per cc, arises from shortening the rapid duration of 4 crank angle degrees. For 23 engine speed in excess of 3000 rev/min and load in excess of 7 bar BMEP, this correlation 24 appears to be superseded by the effects of spray-to-piston impingement and consequent pool-fire. 25Three main areas of concern have been identified within the part-load running envelope: 1. the 26 higher load-lower speed range and 2. the mid load-mid speed range, where high nucleation rates 27induce copious increases of engine-out soot mass; 3. the upper part-load range where, most likely 28as a result of spray impingement, high levels of soot concentration (up to 10 million particles per 29 cc) are emitted with very small size (23-40 nm). 30 31 321. Introduction 33 34Compared to more conventional Port-Fuel Injection (PFI) engines, Gasoline Direct Injection (GDI) 35 engines show a significant 5 to 15% improvement in fuel economy [1], especially because of higher 36 volumetric efficiency and higher knock resistance, which allow the use of generally higher 37 compression ratios with sizeable benefits in thermal efficiency and specific power output. In spite of 38 this, GDI engines are an important source of environmental pollution because of their fine and 39 ultrafine Particulate Matter (PM) emissions. Sizeable research effort has been devoted in the last 40 two decades to investigate the causes of soot emission from this comparatively young technology. 41 Recent medical research work, showing that aerosol particles in the ultrafine size range (diameters 42 of less than 100 nm) cause adverse health effects [2-6], continue to give relevance and impetus to 43 GDI research. Pulmonary inflammation, asthma and cardiovascular conditions are some of 44 problems associated with the deposition of soot in the respiratory tracts. Health risks generally 45 increase with decreasing particle size and increasing concentration. A recent, large, European 46 study associate an 18% increased risk of lung cancer to a 5x10 -6 μg/cc increase of PM 2.5 in 47 atmospheric air [7]. C...

a b s t r a c tTwo gasoline turbocharged direct injection (GTDI) and two diesel soot-in-oil samples were compared with one flame-generated soot sample. High resolution transmission electron microscopy imaging was employed for the initial qualitative assessment of the soot morphology. Carbon black and diesel soot both exhibit core-shell structures, comprising an amorphous core surrounded by graphene layers; only diesel soot has particles with multiple cores. In addition to such particles, GTDI soot also exhibits entirely amorphous structures, of which some contain crystalline particles only a few nanometers in diameter. Subsequent quantification of the nanostructure by fringe analysis indicates differences between the samples in terms of length, tortuosity, and separation of the graphitic fringes. The shortest fringes are exhibited by the GTDI samples, whilst the diesel soot and carbon black fringes are 9.7% and 15.1% longer, respectively. Fringe tortuosity is similar across the internal combustion engine samples, but lower for the carbon black sample. In contrast, fringe separation varies continuously among the samples. Raman spectroscopy further confirms the observed differences. The GTDI soot samples contain the highest fraction of amorphous carbon and defective graphitic structures, followed by diesel soot and carbon black respectively. The A D1 :A G ratios correlate linearly with both the fringe length and fringe separation.

No abstract