Thermodynamics - Research
- Combustion noise
- Fuel and emissions optimisation
- Laser imaging of DI engines
- Hydrogen engine design
- Micro-gas turbines
Combustion noise
The problem of combustion instability is of current importance because modern, low emission gas turbines often utilise 'lean, premixed combustion'. Combustion instabilities have been a major problem in several applications for some time, and usually originate from a coupling between the heat released by the flame and the combustor acoustics, when they are referred to as 'thermoacoustic' instabilities. They feature large amplitude pressure oscillations, which in turn may cause excessive mechanical failure, high levels of noise, sub-optimal burning and increased emissions.
Optimisation and control of fuel consumption and emissions from an IC engine
Passenger vehicles feature a so-called '3 way catalyst' in the exhaust that reacts most of the hydrocarbons, carbon monoxide and oxides of nitrogen leaving the engine, prior to entering the atmosphere. These reactions require the engine exhaust to first heat the catalyst to its 'light off' temperature, when these catalytic reactions commence.
A current Ph. D. student, Denis Andrianov, is applying optimisation and control techniques to an integrated engine and catalyst model, in order to minimise fuel consumption and exhaust emissions. This first involves experimental validation of transient engine and catalyst models using the transient dynamometer facility in the laboratory. These models are then integrated into an optimisation code such that the optimal engine control settings, in terms of fuel consumption or emissions, during a known transient trajectory is first determined and then validated on a real engine.
This approach can also be extended to hybrid powertrains. For both conventional and hybrid powertrains, integrated control of the powertrain and catalyst is essential to the emissions problem.
Laser combustion diagnostics of fuel sprays within IC engines
The direct injection (DI) of fuel into spark ignited engines is becoming more popular because of the increased fuel economy and/or power production that it offers. This project involves close collaboration with Holden Limited, which is owned by General Motors, and Orbital Corporation, a manufacturer of direct injection systems.
The animation shows typical images obtained using high powered, ultra violet laser diagnostics, in this case 'laser induced fluourescence (LIF)', of a fuel spray. The strongly turbulent instantaneous structure of the spray, and a coupling with the air motion is clear. Similar images have also been obtained within the engine itself, and numerical simulations have also been performed to complement these experiments.
Efficient and practical hydrogen fuelled vehicle technologies
The generation of carbon dioxide and other gases from human activity is a major cause of climate change. Hydrogen is seen by many as a transport fuel of the future because its reaction with air does not produce carbon dioxide. However, currently proposed hydrogen fuelled vehicles are often criticised as likely to be excessively expensive and impractical.
The overall objective of this research is to develop certain cost effective and practical technologies that may help enable the hydrogen economy.
This involves redesign of a current, production engine that is aimed to achieve the world's highest efficiency for a hydrogen-fuelled internal combustion engine. The University of Melbourne has been developing an advanced combustion technology over more than a decade that should enable very high engine efficiencies. This efficiency will be similar to current fuel cell demonstration vehicles, but will be achieved using production hardware that is a fraction of the cost of a fuel cell, and far more easily prepared for market.
Dynamics and control of a gas turbine air compressor
Compressed air production consumes a significant portion of electricity generated world-wide. The fragility of power infrastructure in many countries has created markets for compressed air plants that run off diesel and natural gas fuels. This project aims to demonstrate a novel air compressor concept that features a natural gas fuelled micro-gas turbine. This device is expected to have comparable thermal efficiency to other air compressors, but with reduced greenhouse and overall emissions, much quieter operation, lower cost and increased device compactness.
The first prototype GTAC compressor has been designed and built, and is currently being tested. Model predictive control schemes are being developed to control this device, and these schemes also have application in generic gas turbine control problems, in particular for military aircraft.