Spray Formation from Spark-Eroded and Laser-Drilled Injectors for DISI Engines with Gasoline and Alcohol Fuels

Copyright © 2014 SAE International.One of the latest advancements in injector technology is laser drilling of the nozzle holes. In this context, the spray formation and atomisation characteristics of gasoline, ethanol and 1-butanol were investigated for a 7-hole spark eroded (SE) injector and its ‘direct replacement’ Laser-drilled (LD) injector using optical techniques. In the first step of the optical investigation, high-speed spray imaging was performed in a quiescent injection chamber with global illumination using diffused Laser light. The images were statistically analyzed to obtain spray penetration, spray tip velocity and spray ‘cone’ angles. Furthermore, droplet sizing was undertaken using Phase Doppler Anemometry (PDA). A single spray plume was isolated for this analysis and measurements were obtained across the plume at a fixed distance from the nozzle exit. The droplet measurements were grouped into bins and maps were created showing droplet sizes and velocities against time and position during and post injection. All tests were performed at 120 bar fuel pressure, two injection chamber ‘back’ pressures (0.5 bar and 1 bar) and two injector temperatures (20 °C and 80 °C), to examine effects relevant to typical engine operating conditions with early intake stroke injection strategies, including fuel flash boiling

Lightweight composite reflector panels

The Hexel Corp. has produced additional composite panels, based on JPL designs, that: (1) have increased the panel size from 0.15 to 0.40 meters, (2) have improved the as-manufactured surface precision 3.0 to approx. 1.0 micron RMS, (3) have utilized different numbers of face sheet plys, (4) have improved face sheet fiber orientation, (5) have variations of aluminum honeycomb core cell size, (6) have combined graphite/epoxy (Gr/Ep) face sheets with E-glass honeycomb cores, and (7) have used standard aluminum core with face sheets composed of combinations of glass, Kevlar, and carbon fibers. Additionally, JPL has identified candidate alternate materials for the facesheets and core, modified the baseline polymer panel matrix material, and developed new concepts for panel composite cores. Dornier designed and fabricated three 0.6 meter Gr/Ep panels, that were evaluated by JPL. Results of both the Hexel and Dornier panel work were used to characterize the state-of-the-art for Gr/Ep mirrors

Developing Low Gasoline Particulate Emission Engines Through Improved Fuel Delivery

Particulate emissions are of growing concern due to health impacts. Many urban areas around the world currently have particulate matter levels exceeding the World Health Organisation safe limits. Gasoline engines, especially when equipped with direct injection systems, contribute to this pollution. In recognition of this fact European limits on particulate mass and number are being introduced. A number of ways to meet these new stringent limits have been under investigation. The focus of this paper is on particulate emissions reduction through improvements in fuel delivery. This investigation is part of the author's ongoing particulate research and development that includes optical engine spray and combustion visualisation, CFD method development, engine and vehicle testing with the aim to move particulate emission development upstream in the development process. As part of this work, a spark eroded and a laser drilled injector were fully characterised in a spray vessel under key engine running conditions. Injector nozzle geometries and mass flow data were also measured in great detail. This paper demonstrates using both steady state and transient engine testing that very significant improvements in particulate emissions can be made. Control strategies enabling multiple injections of smaller volumes of fuel per injection are the most promising technology. The MAHLE Flexible ECU (MFE) combined with injector testing allowed early stage development and demonstrated these effects for a number of key engine operating conditions. Most notably it was found that particulate matter emissions could be reduced by 80-90% during the catalyst light off phase. A new approach was developed (MASTER) to simultaneously assess the effects of calibration changes on all emissions to increase testing efficiency and hence get to more optimised solutions faster. This approach was successfully tested on a production engine comparing two injectors achieving 82% reduction in particulate number emissions during the first 200seconds of the NEDC relative to the EU5b baseline. Finally it was found that both fuel properties and injector deposits can have a significant effect on particulate emissions

Learning Mathematics While Black in Rural Appalachia: Black Students\u27 Counterstories and Freedom Dreams About Mathematics Education

This dissertation aims to illuminate and uncover the experiences of Black students’ learning mathematics in rural Appalachia and specifically West Virginia. The focal theory for this study is Critical Race Theory (CRT) which centers the experience of Black students and their voices. The intersection of race, mathematics education, and the context of rural Appalachia contribute to the analysis of these experiences in specific ways. Participants for this study included six Black high school students from various communities throughout West Virginia. Through interviews and mathematical autobiographies, these students shared their experiences learning mathematics across their schooling experiences and also considering their desires for an ideal mathematics education. The dissertation is presented in the form of three manuscripts. The first manuscript explores these students’ mathematics identities and socialization in this context. I attend to the micro-, meso-, and macro-level influences in their mathematics learning with close attention paid to school and community factors as well as broader sociopolitical and cultural factors in rural Appalachia and the United States at-large. Students’ mathematics identities and socialization experiences are explored through counterstories which elevate their voices. The second manuscript draws on students’ freedom dreams about their ideal mathematics education as Black students in this context. Students consider what they would like mathematics education to be while also considering what they want their teachers to know about teaching Black students in this region. The final manuscript is an autoethnography detailing my own journey as a White male Appalachian and educator toward racial consciousness and to a study framed by CRT. Findings highlight the endemic implicit and explicit racism that exists in Appalachian communities and schools and how this impacts students’ learning of mathematics. It also illuminates how Whiteness functions and morphs in different ways. This research raises issues about how mathematics education functions systemically and instructionally and how deeply ingrained certain de-humanizing features are in the field. It also explores how we can rethink mathematics education to be a more human and just experience for Black students in every context through freedom dreams. In all, this work explores the confluence of race and culture in rural Appalachia through the lens of CRT to center the racialized experiences of Black students in the region

Numerical analysis of a downsized 2-stroke uniflow engine

In order to optimize the 2-stroke uniflow engine performance on vehicle applications, numerical analysis has been introduced, 3D CFD model has been built for the optimization of intake charge organization. The scavenging process was investigated and the intake port design details were improved. Then the output data from 3D CFD calculation were applied to a 1D engine model to process the analysis on engine performance. The boost system optimization of the engine has been carried out also. Furthermore, a vehicle model was also set up to investigate the engine in-vehicle performance

Induced Ge Spin Polarization at the Fe/Ge Interface

We report direct experimental evidence showing induced magnetic moments on Ge at the interface in an Fe/Ge system. Details of the x-ray magnetic circular dichroism and resonant magnetic scattering at the Ge L edge demonstrate the presence of spin-polarized {\it s} states at the Fermi level, as well as {\it d} character moments at higher energy, which are both oriented antiparallel to the moment of the Fe layer. Use of the sum rules enables extraction of the L/S ratio, which is zero for the {\it s} part and $\sim0.5$ for the {\it d} component. These results are consistent with layer-resolved electronic structure calculations, which estimate the {\it s} and {\it d} components of the Ge moment are anti-parallel to the Fe {\it 3d} moment and have a magnitude of $\sim0.01 \mu_B$.Comment: 4 pages, 5 figures, submitted to Phys. Rev. Let