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

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

Chapter 7 - Energy systems

Stabilizing greenhouse gas (GHG) concentrations will require large-scale transformations in human societies, from the way that we produce and consume energy to how we use the land surface. A natural question in this context is what will be the .transformation pathway. towards stabilization; that is, how do we get from here to there? The topic of this chapter is transformation pathways. The chapter is primarily motivated by three questions. First, what are the near-term and future choices that define transformation pathways, including the goal itself, the emissions pathway to the goal, technologies used for and sectors contributing to mitigation, the nature of international coordination, and mitigation policies? Second, what are the key characteristics of different transformation pathways, including the rates of emissions reductions and deployment of low-carbon energy, the magnitude and timing of aggregate economic costs, and the implications for other policy objectives such as those generally associated with sustainable development? Third, how will actions taken today influence the options that might be available in the future? As part of the assessment in this chapter, data from over 1000 new scenarios published since the IPCC Fourth Assessment Report (AR4) were collected from integrated modelling research groups, many from large-scale model intercomparison studies. In comparison to AR4, new scenarios, both in this AR5 dataset and more broadly in the literature assessed in this chapter, consider more ambitious concentration goals, a wider range of assumptions about technology, and more possibilities for delays in additional global mitigation beyond that of today and fragmented international action

Combustion properties of slow pyrolysis bio-oil produced from indigenous Australian species

Bio-oil derived via slow pyrolysis process of two indigenous Australian tree species, red gum (Eucalyptus camaldulensis) from the basin of Murray, Victoria, and blue gum (Eucalyptus globulus) wood from the region of Mount Gambier, South Australia was blended with ethanol and burned in a circular jet spray at atmospheric pressure. Bio-oil flames were shorter, wider and brighter than diesel fuel flames at the same conditions. Adding of flammable polar additives (e.g. ethanol) to bio-oil improved some of the undesired properties of the fuel such as poor atomisation, low calorific value, and high NOx emission from the flame. Nevertheless, adding of ethanol should be carried out with caution since it leads to a reduction of the heat flux from the flame. Changing the concentration of flammable polar additives in bio-oil can be an optimising factor in achieving the proper balance between the best spray formation and the maximal heat flux from the flame

Sliding mode control for longitudinal motion of underground mining electric vehicles

Nowadays, zero-emission electric vehicles (EVs) become more and more attractive personnel transport vehicles for mining industry. However, underground mining electric vehicles (UMEVs) require more stable, reliable and robust vehicle system compared with traditional EVs due to their special working conditions and the complex road conditions. Thus, a proper controller needs to be designed. This paper first presents the modeling of an UMEV for both acceleration and braking. Then, the controller based on the sliding mode control (SMC) is designed to track the longitudinal velocity and keep the longitudinal slip ratio in a desired stable region in the presence of the bounded system uncertainties. The comparison of the simulation results for both the proposed SMC controller and a traditional PID controller shows that the proposed SMC controller has a better performance for the long-distance up/down slopes with varying rolling resistance coefficients

Performance of a DI diesel engine fuelled by blends of diesel and kiln-produced pyroligneous tar

This paper presents results of experiments undertaken to determine the performance of a direct injection (DI) diesel engine fuelled by blends of kiln-produced pyroligneous tar (PT) and diesel. The PT was sourced from Bulgaria where it was produced from a pine feedstock via a traditional kiln method that involves separation of the aqueous pyroligneous acid fraction. The tar is characterized by high carbon concentration, viscosity and high heating value. Although high, at fuel injection temperatures over 120 1C the tar’s viscosity is likelyto be lower than diesel. Analysis by GC revealed a number of compounds typically extracted from wood-based tar products. Blends containing 20% and 40% PT with diesel were tested in a 4-cylinder, 4-stoke DI diesel engine. The blends are stable and readily formed. Little difference in engine performance relative to diesel was found for 20% PT blends. PT blends (40%) exhibit significantly higher in-cylinder gas temperature and pressure. Ignition delay for both blends is longer than diesel, as is the fuel burn rate during the premixed stage of the combustion. During the diffusion stage of combustion, the fuel burn rate is lower relative to diesel. The performance of engines fuelled by blends containing 40% or more PTcould be improved through optimization of engine systems