An experimental rig was constructed which made it possible to research the influence of air mass flow, pressure, preheating temperature, and fuel/air ratio on the behavior of a full-scale burner. Because the investigations were carried out in the high pressure test facility at the DLR in Cologne, and not in a real gas turbine, the parameters could be varied independently of one another. Based on these systematic measurements, it is possible to predict flame stability limits and emissions for any gas turbine under any operating condition. For example, it can be shown that NOx emissions from the GT8 with ABB’s new second-generation premixing burners will not exceed 25 ppm (for 15% O2) and COwet will be less than 8 ppm at full load (16 bar, 420°C). In addition, the data measured were compared to results obtained from correlations frequently used, such as that NOx is proportional to p0.5. It was shown that this equation is too optimistic even if the flame type remains unchanged.
In this comparative study, a solid composite, AN/HTPB‐based propellant was prepared by conventional processing in a mechanical mixer and by applying an advanced processing technique relying on resonant acoustic mixing (RAM). After curing of the propellants, cross‐sections were prepared and characterized by scanning electron microscopy. Also the density of the propellants was measured and finally the ballistic properties were measured using chimney burner tests. The experimental results clearly showed that the oxidizer particles, the homogeneity of the propellants, the density and the burn rate properties are hardly affected by the processing method. For the propellant studied in this research, resonant acoustic mixing is a very promising, advanced processing technique that can be applied as an alternative to the conventional mechanical mixing of this high solid load propellant composition.
This paper describes the recent theoretical and experimental research by the Netherlands Organisation for Applied Scientific Research (TNO) into green replacements for hydrazine, hydrazine derivatives and nitrogen tetroxide, as propellants for in-space propulsion. The goal of the study was to identify propellants that are capable of outperforming the current propellants for space propulsion and are significantly less hazardous for humans and the environment. Two types of propellants were investigated, being monopropellants and bipropellants. The first section of the paper discusses the propellant selection. Nitromethane was found to be the most promising monopropellant. As bipropellant, a combination of hydrogen peroxide (HP) and ethanol was selected, where the ethanol is rendered hypergolic with hydrogen peroxide. The second part of the paper describes the experimental verification of these propellants by means of engine testing. Initiation of the decomposition of nitromethane was found to be problematic, hypergolic ignition of the hydrogen peroxide and ethanol bipropellant however was successfully demonstrated.
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