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Investigation into the environmental assisted crack initiation mechanism of CMSX-4 in simulated aero engine environments at 450 - 550°C.
Get PDFThe aviation industry has continued to increase the efficiency of gas turbine
engines, which are now designed to operate on a wide variety of flight routes. In
general, the efficiency drive has led to components spending longer times at
temperatures, where accelerated corrosion can occur. This has led to a complex
degradation mechanism being identified in the lower shank region under the
platform of single-crystal turbine blades.
This research aims to understand the mechanism of crack initiation due to the
synergistic effect of stress and high temperature corrosion environments on
CMSX-4 in the lower operating temperature range, 450°C - 550°C, of an aero gas
turbine blade. The first part of the investigation consisted in comparing the effect
of different salt deposits in a 50 ppm SO₂ - air environment at 550°C. A 50 ppm
SO₂ – air concentration was considered because the air going through the lower
shank is fed directly from the compressor, and not from the combustor (which is
the main source of sulphur). Characterisation of the resulting scales were carried
out using scanning electron microscopy, energy dispersive spectroscopy and X-
ray diffraction. Results from thermodynamic modelling are also presented. The
first part of the investigation showed that CMSX-4 sample under an applied stress
and no applied salt did not experience accelerated corrosion attack or crack
formation when exposed to 50 ppm SO₂ - air in a 400-hour period. The same
observation was made for a CMSX-4 sample under an applied stress and salted
with CaSO₄. Sea salt caused accelerated corrosion attack with cracks up to 1.3
mm through the substrate formed after 400 hours of exposure.
Further tests using NaCl salt in 50 ppm SO₂ – air showed that cracks can initiate
after just 10 minutes of exposure at 550°C. Crack growth rates are significantly
reduced after two hours of exposure within a 50-hour salt cycle. Cracks with NaCl
in 50 ppm SO₂ – air have also been observed at temperatures as low as 450°C.
When NaCl salt was applied to CMSX-4 and exposed to air only for 50 hours, the
corrosion attack was reduced considerably, and the initiation of cracks is either
suppressed or significantly delayed beyond a 50-hour period. Although this PhD
has only focused on a 50-hour period, longer exposure times should be carried
out to determine if air exposures delay crack initiation time, or if crack initiation is
completely supressed.
This thesis has therefore shown that the interaction of stress, NaCl and a sulphur-
containing environment are critical to cause early crack initiation in single crystal
nickel-based superalloys in the temperature range 450 - 550°C. The effect of
having small concentrations of moisture in the gaseous environment or as
inclusions retained in the salt are still to be investigated. A working hypothesis is
that that the interaction of alkali chlorides with a sulphur-containing atmosphere
is the trigger to a self-sustaining cycle where metal chloride formation,
vaporisation and oxidation leads to high amounts of H₂ formed at the scale/alloy
interface. Potentially, the H₂ formed at the alloy/scale interface may dissociate
into atomic hydrogen, and lead to hydrogen embrittlement. For further verification
of this hypothesis, a set of tests have been suggested.Engineering and Physical Sciences (EPSRC)PhD in Manufacturin
Crises and the resilience of the aviation industry: a literature review of crises and airline responses
Get PDF12th International Conference on Air Transport – INAIR 2023, The Future of Aviation – is the Sky the Limit? 15-17 November 2023, Tartu, EstoniaThis paper aims to identify major crises that airlines have faced across multiple regions of the world simultaneously, and the responses to them. To comprehend the present status of the literature on this topic, relevant publications are reviewed. Following the COVID-19 pandemic, the coverage of literature analysing airline responses to crises in academia has increased, with new literature emerging at a fast pace. To date, most of the literature that encompasses aviation has formed part of a wider study, usually on tourism, transportation, or hospitality. It normally analyses these fundamental issues generically from the perspectives of many organisations within these vast sectors, with little emphasis on airlines. However, there are only a few exceptions producing academic publications with airline crisis responses and resilience as their focus. This paper breaks down literature into different categories to appraise various types of crises, sourcing literature with a wide variety of methods, geographies, purposes and results. It finds little agreement in academia regarding the best way for an airline to respond to a crisis in a resilient manner. Nonetheless, the study finds that crises events act as a springboard for research into crisis response within the industry.12th International Conference on Air Transport – INAIR 2023, The Future of Aviation – is the Sky the Limit?Transportation Research Procedi
Buying airline partners: parallels between Swissair and Etihad Airways
Get PDF12th International Conference on Air Transport – INAIR 2023, The Future of Aviation – is the Sky the Limit? 15-17 November 2023, Tartu, EstoniaDuring the 1990s Swissair adopted an alliance business model through the purchase of minority stakes in a number of carriers. Etihad Airways followed a similar approach from 2011 through until the onset of the Covid-19 pandemic, building equity stakes in a range of carriers in Europe, and the Indo-Pacific region. This paper uses comparative case study analysis, and argues that making substantial equity investments in second-tier (often loss-making or debt-laden) airlines increases risk without offsetting benefits. Viable alternatives to equity stakes exist including code-sharing, strategic partnerships and global alliance membership, that generate equally attractive customer perceived benefits, while avoiding the need for financial capital being applied less efficiently. Furthermore, this paper argues that profitability is not directly linked to alliance membership. Return on investment is arguably even harder to achieve when the alliance is based on a small selection of second tier carriers. The paper concludes with several future scenarios that could play out for airlines contemplating equity-based alliances, and identifies membership of one of the larger global alliances as the probable better option.12th International Conference on Air Transport – INAIR 2023, The Future of Aviation – is the Sky the Limit?Transportation Research Procedi
Transaction processing policies in a flexible shuttle-based storage and re-trieval system by real-time data tracking under agent-based modelling
Get PDFThis study investigates priority assignment rules (PARs) for transaction processing in automated warehouses featuring a shuttle-based storage and retrieval system (SBSRS). By incorporating real-time data tracking through agent-based modeling, the research explores the unique aspect of the SBSRS design, which involves flexible travel of robotic order picker shuttles be-tween tiers. The paper proposes PARs under agent-based modeling to enhance multi-objective performance metrics, including average flow time (AFT), maximum flow time (MFT), outlier transaction AFT, and standard deviations of flow times (SD) within the system. Experimental evaluations are conducted with various warehouse designs, comparing the results against commonly used static scheduling rules. The findings demonstrate that real-time tracking policies significantly improve system performance. Specifically, prioritizing the processing of outliers based on transaction waiting time enhances MFT, SD, and other performance metrics, while minimizing adverse effects on AFT. Certain rules exhibit notable improvements in MFT and SD, while others achieve the lowest AFT values among all experiments. This paper contributes to the existing literature by presenting a multi-objective performance improvement procedure and highlighting the advantages of real-time data track-ing-based scheduling policies in automated warehousing systems
An archaeological foundation to soil sustainability
No full textDiverging from traditional archaeology, our ongoing research focuses on decomposition rather than preserved fragments of what people left behind. We are looking at the bulk of what constitutes archaeological deposits: soil. Comparing the thickness of soil where people have lived to thickness where there has been no human occupation shows greater accumulation, or soil formation, where humans have been active. These same soils are also often characterised by higher fertility than soils formed in the absence of humans. The implication is that the decay of what people throw away, leave behind or bury forms soil. Yet, what we characterise as archaeological sites do not appear to be “wastelands”, because they have been altered by time. Given modern threats to soil security, we are applying what we are learning from wastelands of the past to change attitudes today – we need to embrace waste, trash and rubbish as the soil of the future.Journal of Contemporary Archaeolog
Understanding agile: a case study in educational complexity
Get PDFAs the nature of engineering concepts, products and processes becomes more intricate and detailed, so the task of understanding, managing and implementing them becomes more complex. This paper takes one such development concept, Agile, and examines how the orthogonal, multi-faceted nature of both the concept and its application makes it difficult to understand and employ and considers in this context the andragogical difficulties posed when trying to teach it to level 7 students. The practice of Agile is often considered to be either the application of methods such as Scrum, extreme programming (XP) or Scaled Agile Framework (SAFe), or the implementation of agile values or principles. In practice, however, a greater level of complexity exists and many more facets need to be considered, such as organisational structure, suitability of project and product, skill set of individuals, and even the mind set of those involved, because the adoption of agile requires more than the use of a technique as part of normal business procedures. In order to understand the complexity of a concept such as agile and the implications which it poses for andragogical teaching and learning strategies, the nature of the concept is first considered to identify the challenges that it creates for education, before a mapping of teaching strategies to agile facets is produced, and thought is given to the creation of an andragogical mechanism which will promote and engender student understanding of the concept and how it can be applied across a range of topic areas in context
Design and performance analysis of concentrated photovoltaic cooling.
Get PDFKahagala Gamage, Upul - Associate SupervisorThe use of solar energy as a global energy source has increased over the past
two decades. Photovoltaic cells, which utilise the sun to generate electricity, are
a promising alternative to fossil fuels that contribute to climate change. However,
the high intensity of concentrated solar radiation can cause overheating in
photovoltaic cells, reducing their efficiency and power output. Researchers
worldwide are improving cooling in concentrated photovoltaic cells (CPV) to
enhance temperature uniformity and improve power output. Previous studies
have demonstrated that pulsating flow can effectively enhance heat transfer in
various fields, including electronics, mechanical engineering, and medicine.
In this research, three flow patterns (continuous flow, uniform pulsating flow, and
bio-inspired pulsating flow) were studied in both simulation and experimental
designs. Two cooling designs were considered: the conventional design (C-
Design) and the parallel design with baffles (W-B) and without baffles (Wout-B).
With the implementation of 30 pulses per minute bio-inspired pulsating flow a
reduction of 1.96% in solar cell temperature was observed when compared to
continuous flow. This reduction in temperature was consistently observed across
a range of flow rates from 0.5 to 2.5 L/m, employing the parallel Wout-B design.
Notably, the bio-inspired pulsating flow shows better performance in comparison
to uniform pulsating flow, as well as the conventional designs with continuous
flow and uniform pulsating flow, resulting in notable improvements in cooling
efficiency of 1.22%, 2.14%, and 4.00%, respectively.
In terms of a direct comparison, the implementation of uniform pulsating flow in
the parallel Wout-B design exhibited a maximum cooling improvement of 0.74%
when contrasted with continuous flow. Furthermore, when assessing uniform
pulsating flow against the C-design with uniform pulsating flow in the parallel
Wout-B design, a noteworthy enhancement of 0.93% was observed. Remarkably,
the C-design with uniform pulsating flow demonstrated a superior effectiveness
of 1.90% when compared to the C-design with continuous flow.MSc by Research in Energy and Powe
Interior Illuminations
No full textThis image was gained from placing the head of a common LED torch into a 610 Xradia Versa System with an overall scan time of ~90 hours. By using a single high-resolution scan, a full 3D digital volume of the torch has been made which allows for us to view its inner components without damaging the object. Through analysing the data, it becomes clear which features represent the battery, circuitry, springs, buttons and aluminium within the torch. My PhD is centred around using X-Ray data to identify the defects and elements within metallic alloys for benefit to the quality control and manufacture processes. The use of these systems is both extremely time consuming and resourcefully expensive; being able to gain robust data from a single scan is invaluable for future research and efficiency.Atomics Weapons Establishment, University of Mancheste
Malvern Tests - ERICE
No full textThis item contains the data from the tests done for characterization of flow using Malvern Particle Analyzer for the ERICE project. Data includes: 1) Labview files (x2) - '.lvm' format (to be read with MS Excel), 2) Excel sheet with data post-processing (x2) - '.xlsx' format (to be read with MS Excel), 3) Test run video files (x2) - '.mkv' files, 4) README txt file (x1) - explaining the headers for the labview data and the instrumentation involved. Test 1 refers to the test run at 60k RPM & Test 2 refers to the test run at 50k RPMClean Sky 2 Joint Undertaking (CSJU) grant number 82130
AI-enabled interference mitigation for autonomous aerial vehicles in urban 5G networks
Get PDFIntegrating autonomous unmanned aerial vehicles (UAVs) with fifth-generation (5G) networks presents a significant challenge due to network interference. UAVs’ high altitude and propagation conditions increase vulnerability to interference from neighbouring 5G base stations (gNBs) in the downlink direction. This paper proposes a novel deep reinforcement learning algorithm, powered by AI, to address interference through power control. By formulating and solving a signal-to-interference-and-noise ratio (SINR) optimization problem using the deep Q-learning (DQL) algorithm, interference is effectively mitigated, and link performance is improved. Performance comparison with existing interference mitigation schemes, such as fixed power allocation (FPA), tabular Q-learning, particle swarm optimization, and game theory demonstrates the superiority of the DQL algorithm, where it outperforms the next best method by 41.66% and converges to an optimal solution faster. It is also observed that, at higher speeds, the UAV sees only a 10.52% decrease in performance, which means the algorithm is able to perform effectively at high speeds. The proposed solution effectively integrates UAVs with 5G networks, mitigates interference, and enhances link performance, offering a significant advancement in this field.Engineering and Physical Sciences Research Council (EPSRC).
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