PhD, EngD and MSc by research theses (SATM)

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Browsing PhD, EngD and MSc by research theses (SATM) by Course name "MSc by Research in Aerospace"

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    ItemOpen Access
    Development of tail rotor power analysis model with feasibility study of electrical tail rotor.
    (2016-09) Subramanian, Nithya; Lawson, Craig
    In recent years, there has been significant work undertaken by the aviation industry to increase the overall rotorcraft performance, and eventually, eliminate leak prone hydraulic fluids and to reduce CO₂ emissions. Even though a mechanical-gearbox-driven tail rotor has been extensively used in several applications, it comes at the expense of high life cost of the gearbox and shaft gear mechanism. This thesis concentrates on the developing a model to analyse the power requirement for the tail rotor drive and feasibility investigation of an electrical tail rotor to substitute the shaft geared system and the conventional tail rotor power transmission gearbox. A case study is conducted on the Sikosky UH-60A rotorcraft to assess the conventional tail rotor power requirement and Electrical systems. A mathematical model based on Rankine Froude’s momentum theory is created to analyse the power required to drive the anti-torque system, which could be adapted to any conventional drive train (with the main rotor and a tail rotor) rotorcraft. A mission profile and trajectory are created and implemented into Excel based mathematical model. The challenges in implementing electrical drivetrain (electrical generation, energy conversion and electric transmission) are briefly discussed in this thesis. Electrical load analysis database is generated to find the electrical load of the generator for the entire flight phases and utilised to up-scaled the generator to compensate the new load from Electrical tail rotor. The electrical powertrain system is designed with a Brushless DC motor attached to the tail rotor and the generator and the battery for redundancy purposes. The research thesis develops an understanding of current electric motor and battery technology to create a novel design of electric tail drive that increases the reliability of the helicopter system.
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    ItemOpen Access
    Evaluating gas turbine fouling degradation and impact of washing on engine performance.
    (2017-11) Lewis, Andy; Igie, Uyioghosa
    Fouling of the compressor of a gas turbine is one of the major contributors to its performance degradation, not only in terms of a reduction in the potential power output revenue and increased fuel costs but also raising the operating temperatures to levels that will have an impact on the servicing intervals and costs. In view of the current economic climate and with the ever-increasing pressure on governments to reduce emissions that contribute to global warming, the need to operate power generating gas turbines in the most efficient way possible is becoming more important. The aim of this study is to demonstrate that using a single compressor dual high-pressure washing system, on multiple gas turbines and a combination of a strict on-line compressor washing regime it is possible not only reduce the rate of compressor degradation, that will enable the period between off-line washes to be extended but also maintain a higher rate of power output throughout this period. Additional benefits will include better fuel efficiency which will lead to a lowering of emissions and the added flexibility of the overall plant operation by reducing the service interventions and shutdowns for off-line washes to the minimum. This study utilises the readily available data from the gas turbine control system to understand how the performance is affected by compressor fouling over time. Once corrected to remove the variations caused by changes in the ambient conditions, the performance trend of the data can be examined in 2 ways. The comparison of the recorded degradation against the gas turbine’s own historic figures and secondly against the relative performances of adjacent machines over similar time periods. The data gathered, from 4 gas turbines, over the 3 years 8 months recording period, provided the opportunity to select 'like for like' starting points in the various life cycles. This enabled direct comparisons of the results, between the various gas turbines that had operated with different compressor washing regimes. These comparisons demonstrated that maintaining an effective on-line compressor washing regime allows for greater potential revenue from exported power; whilst at the same time being more fuel efficient and lowering operating temperatures.