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Discharging green house gases and particulates into the atmosphere has an impact on the global climate. With this current trend of increasing awareness towards the environment alternative fuels are again being examined to reduce the impact of emissions. Hydrogen is perceived as the only long term solution to global warming concerns. It is also the only fuel that will enable large reductions of carbon emissions. When regarding hydrogen combustion there is zero CO 2 emissions produced. Hence, NO x emissions are of main concern. To successfully combust hydrogen with low emissions micro-mix combustion is used to implement miniaturized diffusive combustion. With miniaturized diffusive combustion local flame hot spots that are caused by arising stoichiometric conditions of hydrogen are reduced substantially with an increase in the local mixing intensity. It was recognized that improvements in the mixing quality provided reduced emissions of NO x with a more balanced flame profile. Micro-mix combustion is also examined with different mixtures of fuels including hydrogen, kerosene and methane establishing an adaptive combustor. Comparisons of temperature profiles, NO x emissions and mixing intensities are also reported in this paper. The effect of hydrogen addition to methane is also investigated increasing combustion efficiency with reductions of CO emissions and un-burnt hydrocarbons are acquired. NomenclatureCFD = computational fluid dynamics CH 4 = methane CO = carbon monoxide CO 2 = carbon dioxide GWP = global warming potential H 2 = hydrogen fuel H 2 O = water IPCC = intergovernmental panel on climate change LDI = lean direct injection LH 2 = liquid hydrogen NO x = nitrogen oxides O 2 = oxygen O 3 = ozone SO x = sulfur oxide UHC = unburned hydro-carbons RF = radiative force

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Modern gas turbine combustor design is a complex task which includes both experimental and empirical knowledge. Numerous parameters have to be considered for combustor designs which include combustor size, combustion efficiency, emissions and so on. Several empirical correlations and experienced approaches have been developed and summarised in literature for designing conventional combustors. A large number of advanced technologies have been successfully employed to reduce emissions significantly in the last few decades. There is no literature in the public domain for providing detailed design methodologies of triple annular combustors.The objective of this study is to provide a detailed method designing a triple annular dry low emission industrial combustor and evaluate its performance, based on the operating conditions of an industrial engine. The design methodology employs semi-empirical and empirical models for designing different components of gas turbine combustors. Meanwhile, advanced DLE methods such as lean fuel combustion, premixed methods, staged combustion, triple annular, multi-passage diffusers, machined cooling rings, DACRS and heat shields are employed to cut down emissions. The design process is shown step by step for design and performance evaluation of the combustor.The performance of this combustor is predicted, it shows that NO x emissions could be reduced by 60%-90% as compared with conventional single annular combustors.

Innovations in propulsion system have been the key driver for the progress in air transportation and it is expected to grow at a rapid pace. This incurs challenges in aircraft noise reduction and regulation of hazardous emissions. This paper address the issues associated to reduction in hazardous emissions by investigating the properties and traits of hydrogen. Hydrogen as a fuel is most likely to be the energy carrier for the future of aviation due to its potential zero emissions. A historical review has been carried out on hydrogen usage in aerospace industry till today. The challenges of using hydrogen as a fuel for aero applications have been laid down. The paper also shows various strategies analyzed in order to evaluate hydrogen's feasibility which includes production, storage, engine configurations and aircraft configurations. NomenclatureAAN = army after next CH 4 = methane CO = carbon-monoxide CO 2 = carbon-dioxide GE = general electric GH 2 = gaseous hydrogen GWP = global warming potential HALE = high altitude long endurance H 2 O = water LDI = lean direct injection LH 2 = liquid hydrogen MLI = multi layer insulation NO x = oxides of nitrogen O 3 = ozone UAV = unmanned aerial vehicle UHC = unburned hydrocarbonsI. Introduction ccording to the leading experts the aviation industry is expected to grow continuously, at a rapid pace in the coming few decades. Commercial sectors are projected to increase in the order of 5% and more than that for cargo transportation, despite the downturn in the current world economy