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As a fuel commonly used by air heaters for ground tests of high-speed aircraft, the combustion mechanism of ethanol in air heaters is still unclear, especially the atomic-level chemical mechanism of important intermediate products represented by hydrogen in maintaining stable flame combustion needs to be further studied. In this paper, the combustion process of ethanol/oxygen mixtures under different hydrogen additions was simulated using the reactive force field (ReaxFF) molecular dynamics (MD) method. The results show that increasing the proportion of hydrogen in the mixed gas can not only reduce the ignition delay time of ethanol combustion but also promote the consumption of ethanol and accelerate the progress of the combustion reaction. It was also found that hydrogen and ethanol produced a competitive relationship for oxygen, which changed the ideal stoichiometric ratio (1:3) of complete combustion of ethanol and oxygen and significantly affected the intermediate products and reaction paths of ethanol and oxygen. In addition, increasing the combustion reaction temperature will affect the reaction path of ethanol/oxygen, and the number of intermediate products produced will reach the peak faster and then decompose. Theoretical support for a deeper understanding of the intermediate product hydrogen in the combustion of the three-component air heater of ethanol/liquid oxygen/air and also for improving the combustion efficiency of liquid rocket engine fuel are provided in this study.

Y₂O₃:Eu nanopowders were synthesized by urea combustion method containing different concentration of Eu. The synthesized Y₂O₃:Eu nanopowders were characterized by X-ray diffractometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), energy dispersive X-ray analysis (EDX) and photoluminescence spectroscopy (PL). The particle size was calculated to be in the range of 15–30 nm using Scherrer's formula. The Ia-3 structure of synthesized Y₂O₃:Eu nanopowders were confirmed with X-ray diffractometry. The crystallinity of Y₂O₃:Eu nanopowders were confirmed by SAED and TEM images. The ⁵D₀–∑⁷F_J (J = 0, 1, 2, 3) and ⁵D₁–⁷F₁ transitions bands were observed at 575–650 and 530–550 ranges in the photoluminescence spectrum. The concentration quenching was estimated to be about 5 mol% of Eu. The best chromaticity to the standard red color was observed with the sample containing 3 mol% of Eu.

This paper presents a numerical method to calculate combustion coupled ejection flow in nozzle processes in Liquid Rocket Motor (LRM). A two-dimensional axi-symmetric numerical simulation for the injector element-combustor-and-nozzle model is carried out using the Finite Different (FD) method. In the simulation, the available Computational Fluid Dynamics (CFD) software FLUENT is employed with three key enhancements for material modelling. Firstly, the influence of the two-phase reacting flow is considered, in which the coupled implicit two-step finite difference method to solve the Re-averaged conjugated N-S equation with component conservative equation is used. Secondly, the 17-component, 12-step finite-rate chemical reaction model is employed. Thirdly, the Baldwin-Lomax model is used as turbulence model. These three enhancements are incorporated into the FLUENT code through its user subroutine capability. For both ignition and exhausted stages, the unsteady flow method is used while the steady flow method is adopted for the normally working stage. The distributions of the flow parameter in the combustor-nozzle system are achieved. In addition, the variations of flow parameter along with the time in different stages are also obtained. The results obtained from the numerical simulation are compared with independently available field tests data. Good agreement is observed.

Nitrous oxide, or N₂O, is a greenhouse gas that is largely considered to be the cause for depletion of the ozone layer. As nearly 70% of the global emissions seem to arise from bacterial and fungal denitrifications and nitrification processes in soils, there is a growing concern to identify mitigation techniques to improve the atmosphere in which we live. Fertilizers in agricultural soils are the primary source. This chapter will explain the causes of nitrous oxide emissions in the atmosphere as well as explore these mitigation methods that have been researched, tested and successfully implemented.

A new kind of Opposite Axial Piston Engine (OAPE) in small scale specially designed for the portable generating system was presented. The working theory of OAPE was studied, based on which the combustion process was simulated in FLUENT. Then the internal flow field and the variation of temperature and pressure in cylinder were recorded. Results show the flame front is a sphere centered at the spark point. The maximal pressure in power cylinder is 2.13Mpa and maximal pressure in charge cylinder is 0.235Mpa. The work done by power cylinder per cycle is 1.24J, while the charge cylinder consumes 0.22J per cycle.

The combustion and NOx (Nitrogen Oxide) emission characteristics experiment fueled with conventional diesel fuel and four different fuel blends of acidic oil biodiesel (B5, B10, B15 and B20) were conducted in a four-cylinder, electronic controlled high-pressure common-rail, turbocharged diesel engine without any structure modifications. The results showed that operations with acidic oil biodiesel blends had increase in ignition delay, maximum in-cylinder pressure, heat release rate peak in diffusion combustion duration, cumulative heat release and maximum in-cylinder temperature compared with baseline diesel. In addition, the heat release rate peak and in-cylinder pressure rise rate peak in premixed combustion duration of biodiesel blends were decreased and their crank angular positions were lagged obviously. The NOx emission of biodiesel blends increased, especially at high loads.