Study of Underexpanded Supersonic Jets with Optical Techniques

An experimental investigation of underexpanded axissymmetric supersonic jets is presented. Particle Image Velocimetry is used to obtain quantitative measurements of the velocity field, while a high framerate shadowgraph technique is used to assess shock position and stability. The PIV technique demonstrates the ability to consistently resolve the instantaneous velocity field, with major flow characteristics such as shock structures clearly evident. The shadowgraph images show that at lower pressures the shock structures are highly unstable, demonstrating periodic oscillation in angle and position, while in the highly underexpanded condition the location of the Mach disk is stable. A discussion of limitation due to optical resolution and particle fidelity is presented, concluding that the system is more limited by inadequate particle fidelity post-shock than sensor limitations

Absolute kippleization and The Plastosystem: Metaphors to address complex science in the age of the Anthropocene.

This exegesis examines the intersections between the visual arts and science, demonstrating that the methodologies of both disciplines provide a powerful and necessary tool to question and communicate environmental change in the age of Anthropocene. With billions of tonnes of plastic waste entering our waterways and oceans, questions about the future of these environments arise. What are the long-term effects on marine environments? How will marine organisms adapt and evolve to cope with unfamiliar forms supplanting the relationships between living and non-living components within their ecosystems? What will these ecosystems look like in the future, in a post-human world? With an emphasis on the materiality, colour and scale of plastic, to articulate both science and speculation my art practice applies the use of different media; installation, painting, documentary photography, collection and data imaging

When will the hydrogen economy arrive?

The arrival of the hydrogen (H2) economy has been the subject of many studies. Earlier articles were over-optimistic about the timing and extent of global H2 uptake, and predicted private vehicles as leading the way to a H2 economy. The recent strong rise in the global electric vehicle fleet has inevitably led to a reassessment of the prospects for H2, at least for transport. This review paper examines how researchers over recent decades have envisaged how the H2 economy would arrive, and why it was desirable, or even inevitable; it also looks at the future prospects for the H2 economy. The key findings are as follows: ● Among the leading energy forecasting bodies, particularly the International Energy Agency (IEA), even the most optimistic scenarios predict under 10% H2 penetration by 2050. ● IEA forecasts are very optimistic about the prospects for the introduction of carbon dioxide removal technologies and growth of dispatchable sources of low-carbon energy. ● More realistic IEA forecasts would increase the need for the growth of intermittent energy sources such as wind and solar. The subsequent requirement for energy storage would in turn help the case for H2 adoption. ● No new technologies are on the horizon to decisively tip the balance in favor of H2. ● It is concluded that a global H2 economy is still distant, but it could arise in energy-poor countries such as Japan and South Korea, and it could find a niche in freight transport.</p

GREENHOUSE GAS IMPLICATIONS OF ALTERNATIVE TRANSPORT FUELS

Summary This paper evaluates a number of alternatives to oil to see whether their widespread introduction would help reduce greenhouse emissions in transport. It is assumed that at least two decades will be needed for this large penetration, hence total emissions per litre for petroleum fuels--and for alternatives--may be very different from present values, because of any changes in the energy (and thus emissions) needed to produce and deliver each litre of fuel to its point of final use. This paper examines three sets of alternatives: natural gas-based fuels, liquid fuels from biomass, and electric vehicles. The main conclusion is that none of these can reliably reduce emissions significantly, and may even increase them. The potential for vehicle energy efficiency and reduced travel demand is then evaluated. It is concluded that these approaches are already, and will be even more so in the future, the most costeffective means (in terms of CO 2 equivalent avoided per dollar spent) for significant emissions reduction. Vehicle energy efficiency will, however, require a decade or two for significant impact, because of the time for fleet turnover, whereas reduced travel demand measures can be implemented rapidly

Assessing global renewable energy forecasts

In 2013, renewable energy accounted for only 8.9% of global commercial primary energy use, with fossil fuels supplying nearly all the rest. A number of official forecasts project such global energy growing by 50% or more by mid-century, and continuing to rise thereafter, in parallel with continued global economic growth. All energy sources of the future must meet three criteria: reserves or annual technical capacity must be adequate to meet projected demand; their climate change effects must be minimal; finally, they must be able to be widely deployed in the limited time available for climate mitigation. It is argued here that existing future energy scenarios generally fail to meet all three criteria. Most scenarios assume that adequate fossil/nuclear reserves are available, and that technical fixes can overcome greenhouse gas emissions from fossil fuels. The few scenarios projecting that renewables will supply most of the world's energy by mid-century assume unrealistic technical potentials and implementation times. To meet all three criteria, global energy use will need to be reduced, through a combination of energy efficiency improvements and energy conservation efforts

Fast pyrolysis oil fuel blend for marine vessels

The main driver for the investigation of fast pyrolysis oil marine fuel blends is EU directive 2012/33/EU which aims to cut the sulphur content of marine fuel and thereby reduce air pollution caused by marine vessels. The aim of this study was to investigate the miscibility of three- and four- component blends containing pyrolysis oil, 1-butanol, biodiesel (RME) and/or marine gas oil (MGO). The ideal blend would be a stable homogenous product with a minimum amount of butanol, whilst maximising the amount of pyrolysis oil. A successful blend would have properties suitable for use in marine engines. In order to successfully utilise a marine fuel blend in commercial vessels it should meet minimum specification requirements such as a flash point ≥60°C. Blends of pyrolysis oil, RME, MGO and 1-butanol were evaluated and characterised. The mixed blends were inspected after 48 hours for homogeneity and the results plotted on a tri-plot phase diagram. Homogenous samples were tested for water content, pH, acid number, viscosity and flash point as these indicate a blend's suitability for engine testing. The work forms part of the ReShip Project which is funded by Norwegian industry partners and the Research Council of Norway (The ENERGIX programme)

Correlation Analysis of High-Resolution Particle Image Velocimetry Data of Screeching Jets

The authors would like to acknowledge the support of the Australian Research Council, the Research at Cloud Monash National eResearch Collaboration Tools and Resources project funded by the Australia Commonwealth Government, and the School of Engineering and Materials Sciences at Queen Mary University of London