Browsing by Author "Taylor, Mark"
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Item Open Access Distributed propulsion and future aerospace technologies(Cranfield University, 2007) Ameyugo, Gregorio; Singh, Riti; Bowman, Cliff; Taylor, MarkThis thesis describes an Engineering Doctorate project in Distributed Propulsion carried out from 2004 to 2007 at Cranfield University. Distributed propulsion is a propulsion system arrangement that consists in spreading the engine thrust along the aircraft span. This can be accomplished by distributing a series of driven fans or the engines themselves. The aim of this project is to determine the feasibility of distributed propulsion for civil aviation in the medium term (with small gas turbines) and long term (with driven fans) from a technical and economic perspective. The effect of distributed propulsion was assessed by creating a long-range subsonic airliner baseline with conventional technology for the small gas turbines study, and an equivalent blended wing body baseline for the driven fans study. Different distributed propulsion effects were modelled and integrated together to produce optimised baselines with different technological parameters. The feasibility of small gas turbine distributed propulsion was found to be limited by the excessive fuel consumption associated with small gas turbines. Although advanced heat exchanger technology could improve their performance, the resulting cost advantage might not be large enough to justify the development costs. The feasibility of distributed driven fans depends on the availability of superconductive elements, as electrical power transmission seems to be the only promising transmission method in the long run. If superconductive elements are applied, distributed driven fans could afford fuel burn reductions of more than 50% relative to current technology. As both distributed propulsion concepts rely on small propulsive units, their enabling technologies coincide with those required to develop future unmanned aerial vehicles. UAVs therefore represent the most appropriate technological avenue to develop technologies with the potential to become distributed propulsion enablers. Future work should therefore concentrate on improving engine performance and cost for unmanned aerial vehicles.Item Open Access Investigation of 300M ultra-high-strength steel deposited by wire-based gas metal arc additive manufacturing(Springer, 2023-11-01) Wang, Jun; Diao, Chenglei; Taylor, Mark; Wang, Chong; Pickering, Ed; Ding, Jialuo; Pimentel, Misael; Williams, Stewart300 M ultra-high-strength steel (UHSS) is widely used to produce landing gear components for aircraft. The conventional manufacturing route for these components involves extensive machining and significant material wastage. Here, the application of wire-based gas metal arc additive manufacturing to produce 300 M UHSS parts was investigated. In particular, the influence of torch shielding atmosphere on the process stability and material performance of 300 M UHSS was investigated. The shielding gases used for comparison are pure Ar, Ar with 2.5% CO2, Ar with 8% CO2, Ar with 20% CO2, and Ar with 2% CO2 and 38% He. It was found that the arc length decreased, the transfer mode changed from spray to droplet mode, and spattering became more severe as the CO2 proportion increased. Additionally, replacing Ar with He led to a broader arc core, and a slightly shorter arc length and maintained a spray transfer, which decreased spatter. The wall surface roughness followed the trend in spatter, becoming worse with the increasing CO2 proportion, and better with He addition. Adding CO2 and He in pure Ar significantly increased the bead and wall width. The microstructure and mechanical properties exhibited a strong location dependence in the as-built state, with fresh martensite and higher strength in the top region, and tempered martensite and better ductility in the reheated bulk. Generally, torch shielding gas composition appeared to have no significant effect on the microstructure evolution. This study provides a reference for the subsequent application of gas metal arc additive manufacturing to aircraft landing gear mass production to achieve a high deposition rate and process stability simultaneously.