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A comprehensive CFD investigation of tip vortex trajectory in shrouded wind turbines using compressible RANS solver
Get PDFIt is well known that a shroud placed around a wind turbine can increase its power coefficient, but it brings complex mechanisms by which the shroud alters the flow passing through the rotor. Such mechanisms impose numerical challenges, as the shrouded turbines present nonlinear behavior in the wake. This paper deals with a comprehensive analysis of tip vortex trajectory in shrouded wind turbines using Reynolds Averaged Navier–Stokes numerical solutions. The analysis includes aerodynamic performance and vortex characteristics of the whole wind turbine. The Multiple Reference Frame is used on a high-order unstructured compressible solver to study both, isolated and shrouded rotor. The NREL Phase VI Unsteady Aerodynamic Experiment rotor is used as a test case. The accuracy of results for wind speeds between 7 and 25 ms^-1 is discussed. Overall, good agreement is achieved between the computed pressure distributions and the experimental reference values. At stalled blade, more efforts are needed to improve numerical solutions, especially for integrated load quantities. The vortex structure is examined, showing that shroud impacts tip vortex trajectory by the increase of the axial induced velocity at the rotor plane. This result, demonstrates that the classical Prandtl tip loss is not accurate for shrouded turbine analysis, and modern finite blade functions are needed. The influence of the flow conditions on the tip vortex trajectory, flow separation and shroud interaction are also discussed.Engineering and Physical Sciences Research Council (EPSRC)Energ
Are prestigious directors mere attractive ornaments on the corporate Christmas tree?
Get PDFUsing the UK’s unique institutional setting of Queen’s honours, we examine the influence of director prestige on both short-term and long-term firm performance. We find that the market reacts positively to the appointments of Prestigious Award-Winning Directors (PAWDs). Firms appointing PAWDs also show significantly improved long-term performance, and this performance change is higher when firms appoint PAWDs according to their needs. The evidence suggests that PAWDs make important contributions to the firm by providing effective monitoring, facilitating preferential access to resources, and offering legitimacy. We conclude that director prestige not only signals higher human and social capital but also incentivises effective monitoring of managerial decisions.British Journal of Managemen
Probabilistic modelling of the food matrix effects on curcuminoid’s in vitro oral bioaccessibility
Get PDFThe bioaccessibility of bioactive compounds plays a major role in the nutritional value of foods, but there is a lack of systematic studies assessing the effect of the food matrix on bioaccessibility. Curcuminoids are phytochemicals extracted from Curcuma longa that have captured public attention due to claimed health benefits. The aim of this study is to develop a mathematical model to predict curcuminoid’s bioaccessibility in biscuits and custard based on different fibre type formulations. Bioaccessibilities for curcumin-enriched custards and biscuits were obtained through in vitro digestion, and physicochemical food properties were characterised. A strong correlation between macronutrient concentration and bioaccessibility was observed (p = 0.89) and chosen as a main explanatory variable in a Bayesian hierarchical linear regression model. Additionally, the patterns of food matrix effects on bioaccessibility were not the same in custards as in biscuits; for example, the hemicellulose content had a moderately strong positive correlation to bioaccessibility in biscuits (p = 0.66) which was non-significant in custards (p = 0.12). Using a Bayesian hierarchical approach to model these interactions resulted in an optimisation performance of r2 = 0.97 and a leave-one-out cross-validation score (LOOCV) of r2 = 0.93. This decision-support system could assist the food industry in optimising the formulation of novel food products and enable consumers to make more informed choices.European Union’s Horizon 2020 Research and Innovation Programme through the Nutrishield project (https://nutrishield-project.eu/) Grant Agreement No 818110Food
Monitoring CH4 fluxes in sewage sludge treatment centres: challenging emission underreporting
Get PDFIn this manuscript, CH4 emissions from sludge treatment centres are quantified using an unmanned aerial vehicle (UAV) framework, with particular focus on anaerobic digesters and digestate storage tanks. The outcomes are compared to those obtained using the carbon accounting workbook (CAW), which is the most commonly used industry tool by UK and Irish water companies to estimate the annual greenhouse gas emissions from their process operations. Path integrated concentrations are monitored with the use of an open-path tuneable diode laser absorption spectroscopy sensor embedded on a UAV. Measurements are interpolated using geostatistics (Kriging) and coupled with the mass balance approach to estimate emissions. The findings show that the CAW seems to underestimate emissions from digestate storage tanks by up to an order of magnitude. The results also show that CH4 emissions are linked with the residence time in the tank and temperature of the digestate. This study highlights the limitations of assumptions made using current reporting methods based on the carbon accounting workbook. This study proves that the UAV framework, together with the mass balance approach, provides high spatial resolution data; it captures the dynamic nature of emissions compared to the CAW and can be a cost-effective solution to estimate CH4 fluxes compared to other sensor-based systems.Remote Sensin
Modified Arrhenius kinetics for double base propellant decomposition: effect of water
Get PDFNumerous studies have been conducted on the decomposition mechanisms of cellulose nitrate (NC), a polymer employed in double base (DB) rocket propellants. It is well known that storage temperature affects the lifetime of these energetic formulations. However, less studies have been published on the influence of water. This research examined the role of water on the stabiliser consumption rate during accelerated ageing of a DB rocket propellant, as well as the impact on the shelf life prediction of the energetic formulation. Different volumes of water (0.8, 1.6, 2 and 4 µl/g) were added to the propellant in sealed vials, which were then isothermally aged (70, 80, 90, 100 °C). Analyses of the stabiliser consumption showed a faster decomposition kinetics in presence of water which is indirectly linked to the shortening of the storage life of the NC based propellant by 35 %. For the conditions, an activation energy of 133 ± 4 kJ/mol was reported for the water catalytic decomposition mechanism. A numerical model that included water as a variable was reported to reduce the uncertainty in the determination of the service life of NC based propellant. International standards such as Allied Ordnance Publication 48 should not overlook the effect of water/moisture on the safety of ammunition containing NC and should implement a modified Arrhenius equation.The authors would like to thank the Mexican Council of Sciences and Technology (CONACYT REFERENCE: 2020–000007–01EXTF-00468) and Cranfield University for supporting this work.Polymer Degradation and Stabilit
Using the learning factory for the integration of sustainability in the engineering curricula in higher education
No full textSustainability, gaining prominence due to perpetual population expansion and rapid depletion of resources, emphasizes economic prosperity, environmental conservation, and social equity. Students in higher education, especially those in engineering disciplines, play a pivotal role in the adoption and implementation of sustainability principles in, both, business and society. Within this context, the systematic integration of sustainability into engineering education is of paramount importance, thus helping to provide the students with awareness of the socio-economic and environmental aspects of sustainable development in addition to improving their technical skills. However, the process of embedding sustainability in the curriculum of higher education faces challenges from various stakeholders, including students, educators, and the higher education institution. The attitudes of students toward the subject, educators’ proficiency in sustainability, and the institutional frameworks’ support (or lack thereof) for this integration are some of the prominent challenges. Learning factories, serving as educational platforms that simulate real production environments and bridge academia with industry, emphasize competency development, facilitating participants in acquiring in-depth knowledge about industrial practices. In this research, the authors delve into the potential of learning factories as a platform to overcome the challenges faced during the sustainability integration process in higher education curricula, and to help foster students’ competency development. A literature review was conducted to thoroughly investigate the challenges of integrating sustainability into higher education. Based on these findings, a comprehensive framework is presented, highlighting how learning factories can address these challenges and enhance students’ competency development.14th Conference on Learning Factories (CFL 2024
Developing the next generation of treatment flowsheets for rural wastewater
Get PDFSeptic tank systems (STS) are one of the most common wastewater treatment
systems in the world however these systems are becoming antiquated,
struggling to meet tighter consent, needing frequent desludging and venting
greenhouse gases to the environment. A flowsheet to tackle these issues was
proposed consisting of an enhanced septic tank (EST) and a constructed
wetland (CW). The proposed flowsheet was assessed by examining the
underlying mechanisms, testing the flowsheet at pilot scale and assessing the
cost and carbon implications of the flowsheet. A key aim of the thesis is to
decrease the maintenance of the flowsheet to once every 5 to 7 years. The
maintenance of septic tank is due to desludging, as the tank needs to be
emptied when the sludge bed reaches a certain height. The desludging of a
septic tank is dependent on the hydrolysis rate within the reactor. Batch studies
into anaerobic digestion found that low operating temperatures in septic tanks
impact the hydrolysis rate. However, temperature is not the dominant factor of
hydrolysis and optimisation of mass transfer between hydrolytic microorganisms
and degradable particulates can increase the hydrolysis rate by 200%. A pilot
scale study investigated using baffles to promote hydraulic mixing within a
septic tank. The presence of hydraulic mixing due to the baffles increased the
hydrolysis rate constant of a septic tank from 0.0089 d⁻¹ to 0.035d⁻¹, extending
the time between desludging from 4.9 to 6.7 years. The proposed flowsheet is
a lower cost treatment system than a conventional package treatment system
(e.g. submerged aerated filter) over a 30 year life time and leads to a significant
reduction in lifetime carbon emissions compared to a STS. The cost and carbon
reduction of the flowsheet make the flowsheet a viable abatement technique.PhD in Water, including Desig
Work, private, self – towards an integrative framework of accountability: the case of low-status expatriates in precarious employment
Get PDFFelt accountability, the perceived expectation that one’s decisions and actions will be evaluated and rewarded or sanctioned, is a key driver of human behaviour and impacts work-related outcomes such as unethical behaviour and job satisfaction. The COVID-19 pandemic has shown the importance of low-status expatriates (LSEs), a vulnerable and neglected group, which is often employed under challenging working conditions in low-status occupations. In this paper, we explore how LSEs experience and manage accountabilities in their often-precarious working lives. We draw on 36 qualitative interviews with LSEs employed in Germany. The data were analysed using a directed content analysis method. Our findings highlight that while LSEs feel less accountable towards stakeholders within their organisation, they experience accountabilities from multiple stakeholders outside their organisation. We demonstrate that while LSEs consider work-related accountabilities, their key accountabilities are rooted in individuals’ private lives and can lead to higher degrees of accountability intensity. This study provides unique insights into the importance of private life accountabilities and how these intersect with accountabilities at work. We offer a revised framework of accountability that includes private life as an important dimension to enhance its applicability to LSEs
An innovative tactile sensor roller for composites inspection
Get PDFA vision-based tactile sensor roller prototype has been designed and developed to detect defects on composite prepreg and dry fabric surfaces. The tactile sensor features an innovative design comprising a transparent acrylic tube encased in a gel elastomer. The outer tube serves as a protective and flexible layer, while the inner structure includes a connecting shaft equipped with a camera, force, and speed sensors. This configuration allows for detailed capture of tactile information, integrating visual and pressure data for comprehensive sensory feedback. The connecting shafts are fitted with wheels and handles at both ends, enabling human manipulation and control. Typical defects such as wrinkles, gaps, overlaps and foreign objects and debris (FOD) can be detected by this prototype. In this study, we assessed the performance of the tactile sensor roller by rolling it across areas affected by human-made composite prepreg and dry fabric defects that include wrinkles and foreign objects. With the comparison of the tactile image results, we have demonstrated that the tactile sensor roller can identify flaws with a precision of 0.125mm. It can efficiently examine a 35cm by 18cm section of woven fabric without compromising the integrity of the 3D data gathered. This innovative tactile sensor is set to enhance the automation of the hand layup process. It enables real-time quality control, substantially reducing the need for extensive manual inspections. This leads to a significant cut in inspection costs, making the manufacturing process both more efficient and cost-effective.2024 IEEE International Conference on Industrial Technology (ICIT
Towards time-resolved multi-property measurements by single-frequency FRS
Get PDFThe filtered Rayleigh scattering technique (FRS), extended by the method of frequency scanning, has historically been limited to time-averaged multi-property flow measurements. In our recently published work, we present a concept that potentially enables the combined measurement of time-resolved pressure, temperature and three-component (3C) velocity fields. It is based on the observation of the region of interest from six perspectives and a single excitation frequency. This work summarizes and expands on a follow-up publication that experimentally verifies this concept on an aspirated circular duct flow. For this purpose, the results obtained from single-frequency data processing are compared with reference pressures, temperatures and corresponding LDA velocity measurements. Overall, a very good agreement is found for all operating points with accuracies of 3.4% in pressure, 1.3% in temperature and ±2 m/s in axial velocity. Concerning precision, a newly developed multistage evaluation procedure enables values for pressure, temperature and velocity as low as 3 hPa, 2.2 K and 1.7 m/s. In a second flow configuration, an axial swirler is introduced into the duct. The resulting secondary flow structure and deformation of the axial velocity field caused by swirler geometry and support are very well captured with the single-frequency analysis. A closing discussion on the implementation challenges of a single-frequency multi-property FRS instrument with pulsed laser radiation reveals significant obstacles to overcome. Due the considerable optimization potential identified, chances are high that true time-resolved multi-property measurements by FRS will become a reality.The SINATRA project leading to this publication has received funding from the Clean Sky 2 Joint Undertaking (JU) under grant agreement No 886521 (EU Horizon 2020)21st International Symposium on Applications of Laser and Imaging Techniques to Fluid Mechanic