Flow and heat transfer characteristics of turbulent swirling impinging jets [thesis]

Numerous industrial applications rely on impinging jets to impart convective heat and mass transfer in processes ranging from the cooling of electronic devices and gas turbine blades to drying of paper and food products. Conventionally, non-swirling impinging jets have been employed, but some studies have shown that inducing swirl allows better control of uniformity and improved convective fluxes. A better understanding of the underlying physical mechanisms that lead to such behaviour warrants deeper insights into the flow and heat transfer characteristics of impinging jets, both swirling and non-swirling. Whilst important to achieve, the flow field of an impinging jet is already quite complex even before the addition of swirl which, in free (not impinging) jets, induces vortex breakdown and other instability modes. The addition of swirl to impinging jets thus has the potential to affect the transient and steady-state convective behaviour, both of which are crucial in industrial applications. This study features experimental and numerical investigations of incompressible turbulent impinging air jets that utilize aerodynamically generated swirl. The research focuses on the velocity field, upstream near the nozzle exit plane as well as further downstream, and the way in which it affects heat transfer at the impingement plane, both under transient and steady-state conditions. Boundary conditions at the nozzle exit were measured using Constant Temperature Anemometry. The surface temperature distribution of a thin foil heater, which forms the impingement surface cooled by the ambient temperature jet, was measured using infrared thermography for a range of Reynolds numbers (Re=11,600-35,000), swirl numbers (S=01.05), and impingement distances (H/D=2-6). The effects of different inflow conditions for non-swirling and weakly swirling impinging jets were also simulated (numerically) using ANSYS Fluent (version 16.2). Particle Image Velocity was utilized to resolve the flow field, over low (S=0.30) and higher (S=0.74) swirl over a range of Reynolds numbers (Re=11,60035,000) and nozzle-to-plate distance (H/D=2 and 4). Whilst the use of non-intrusive infrared thermography has been widely reported in studies of the steady-state heat transfer behaviour of impinging jets, an image processing methodology to resolve the time-dependant (transient) convective heat transfer behaviour was lacking. In this context, a MATLAB based method was developed to quantify the role of various impinging jet parameters on the time to reach steady-state. The effect of spatial discretization, image resolution, and the threshold value of time-dependent Nusselt number, on the time to reach steady-state, was also analysed. The role of various operating (Re, S) and geometric conditions (H/D) on the temporal evolution of turbulent impinging jets was also resolved. By applying the innovative image processing methodology developed, results show that for non-swirling jets, transient heat transfer characteristics at some conditions (H/D=4) are distinct if compared to others (H/D=2 and 6) and that the heat transfer distribution over the impingement plate changes significantly over a small interval of time. For swirling jets, the peak Nusselt number shifts to the wall jet region as the intensity of the swirl increases. Two correlations (no-to-low swirl, moderate-to-high swirl) are proposed to predict the time needed to reach a steady-state for Re=35,000. Computational Fluid Dynamics was then used to resolve the role of various (upstream) nozzle exist conditions (velocity profiles) on the emerging heat transfer characteristics at the impingement plane. Results showed that under some conditions (S=0.31, uniform velocity profile) a small recirculation zone, stabilised on the impingement plane, affects the heat transfer compared to other tested velocity profiles. This study also gave valuable insights on the impact of using (simple) geometric inserts to generate for swirl into impinging jets, a method widely used for its simplicity. Results showed that this can fundamentally perturb the results unlike the use of aerodynamic swirl which relies on tangential air ports. For the experimentally measured flow field, vortex breakdown is observed for two of conditions (Re=11,600 and 24,600 at S=0.74) out of the six tested. Impingement affects the position, shape, and strength of the vortex breakdown. For Re=24,600, impingement significantly affects (shape and position) the recirculation bubble when compared to impingement at Re=11,600. Heat transfer characteristics at high swirl are compared with low swirling impinging jets. The vortex breakdown (at high swirl) affects the impingment heat transfer and showed comparatively uniform heat transfer distribution in contrast to low swirling impinging jets. Vortex breakdown significantly deteriorates stagnation zone heat transfer and the Nusselt number peak occurs in the wall jet region. Benefits derived from this study include identifying impingement conditions that allow quicker stabilisation of heat transfer (shorter transients) as well as an improved understanding for the role of impingement on the upstream and downstream velocity field and heat transfer characteristics

Machine Learning-based Nutrient Application's Timeline Recommendation for Smart Agriculture: A Large-Scale Data Mining Approach

This study addresses the vital role of data analytics in monitoring fertiliser applications in crop cultivation. Inaccurate fertiliser application decisions can lead to costly consequences, hinder food production, and cause environmental harm. We propose a solution to predict nutrient application by determining required fertiliser quantities for an entire season. The proposed solution recommends adjusting fertiliser amounts based on weather conditions and soil characteristics to promote cost-effective and environmentally friendly agriculture. The collected dataset is high-dimensional and heterogeneous. Our research examines large-scale heterogeneous datasets in the context of the decision-making process, encompassing data collection and analysis. We also study the impact of fertiliser applications combined with weather data on crop yield, using the winter wheat crop as a case study. By understanding local contextual and geographic factors, we aspire to stabilise or even reduce the demand for agricultural nutrients while enhancing crop development. The proposed approach is proven to be efficient and scalable, as it is validated using a real-world and large dataset.Comment: Research articles have: 6 Pages, 6 Figures, and 3 Tables | ACKNOWLEDGMENT: CONSUS is funded under Science Foundation Ireland's Strategic Partnerships Programme (16/SPP/3296) and is co-funded by Origin Enterprises Pl

Data for Thinking Healthy Programme Pakistan trial (THPP-Pakistan)

An anonymised dataset of 570 women (one row per woman) who gave informed consent to participate in a cluster randomised, parallel, superiority, controlled trial in Rawalpindi, Pakistan in 2014-2017. The intervention was an adapted version of the Thinking Healthy Programme, delivered by peers; the control was enhanced usual care. Further details are available in the published protocol and paper. The dataset contains records of variables on stratified randomisation and clusters, socio-demographic information, depression and related outcomes, and therapy adherence. Visits occurred at baseline, and 3 and 6 months post-natal

Digital Repositories in Ecology and Environment: An analytical study

The present study aims to identify the status of Open Access Repositories (OARs) in the field of Ecology and Environment. The data was collected from the Directory of Open Access Repositories (OpenDOAR). Data collected was analysed on different parameters such as geographical distribution, software usage, content type, repository type and language diversity. As of now OpenDOAR holds 176 repositories in the field of Ecology and Environment. The findings further reveal that the maximum number of repositories belong to the USA accounting for 18(10.2%). Also, the maximum number of repositories are institutional accounting for 134(76%)

The content and delivery of psychological interventions for perinatal depression by non-specialist health workers in low and middle income countries: a systematic review.

Psychological interventions delivered by non-specialist health workers are effective for the treatment of perinatal depression in low- and middle-income countries. In this systematic review, we describe the content and delivery of such interventions. Nine studies were identified. The interventions shared a number of key features, such as delivery provided within the context of routine maternal and child health care beginning in the antenatal period and extending postnatally; focus of the intervention beyond the mother to include the child and involving other family members; and attention to social problems and a focus on empowerment of women. All the interventions were adapted for contextual and cultural relevance; for example, in domains of language, metaphors and content. Although the competence and quality of non-specialist health workers delivered interventions was expected to be achieved through structured training and ongoing supervision, empirical evaluations of these were scarce. Scalability of these interventions also remains a challenge and needs further attention

MOOCS: A case study of ALISON platform

Massive Open Online Courses (MOOCs) is a recent trend in distance or e-learning, offering an opportunity to the unlimited number of students from diverse geographical areas, academic backgrounds, and professional pursuits to study high quality courses from prestigious institutions. MOOCs offer a large number of resources that have generated great results across the globe and attracted massive audience due to its free or low-cost innovative courses. It has entirely changed the way of distance-virtual learning. It offers new opportunities for imparting education over the internet and provides learning opportunities to those who aren’t able to attend conventional classes. A large number of MOOCs platforms have been developed independently or in collaboration with various reputed institutions like SWAYAM, Udacity, Coursera, WizIQ, Edx etc. The present study will focus on Alison – Advanced Learning Interactive Systems Online, a major free MOOC platform. The study will explore Alison on parameters such as courses offered, subjects covered and publishers that Alison partners with to offer courses online

Open Access Computer Science Journals in the DOAJ: An analytical study

Open Access movement has shown tremendous growth over the years throughout the world in various regions, countries and disciplines. This paper aims to evaluate the publishing trends of the open access journals in the computer science discipline registered in the Directory of Open Access Journals (DOAJ). The data collected after the in-depth examination of the directory was analysed and tabulated using simple techniques to fulfil the set objectives. The study evaluates the highest number of contributions country wise, language wise and other factors associated with journals found in DOA

Librarians and their distinctive personality traits in the 21st century digital era

While there is a fair extension of literature in terms of core skills required by librarians but there is rareness of research on competencies that librarians should possess in terms of their personality traits that distinguish them from the rest of the professions. The role of librarians in the 21st century has migrated from information disseminators to the talent searchers, technological experts, innovators, strategy makers, and entrepreneur. Accordingly, they cannot rely on so-called soft skills of primitive nature; their skills must have a touch of dynamism. The study being theoretical type describes the personality based traits of the librarians on source of 16 Personality Factor (16PF), a widely researched normal personality inventory i.e., Reasoning, Dominance, Emotionally Stable, Liveliness, Social Boldness, Self-reliance, Vigilance, Privateness, Warmth, Tension Free, Rule-Consciousness, Perfectionism, Sensitiveness, Abstractedness, Apprehensive and Openness to Change

A Game-Based Method for Teaching Entrepreneurship

Entrepreneurship is often thought of as the act of commercializing an innovation. In modern open economies, entrepreneurship is one of the key aspects for economic growth. Teaching and learning entrepreneurship is therefore of importance and schools, colleges and universities can play an important role by including entrepreneurship and innovation in their curricula. The Berkeley Method of Entrepreneurship is a holistic and student-centered teaching and learning approach that is hypothesized to enable engineers to be more entrepreneurial. It encompasses three main elements; networks, mindset and frameworks. Networks and Framewoks are covered in most entrepreneurial curricula, whereas only few curricula explicitly include the mindset perspective. The Berkeley Method of Entrepreneurship is based on the hypothesis that the mindset of an entrepreneur can be characterized by a distinct set of behavioral patterns, and that an inductive game-based teaching approach is a successful vehicle for introducing and re-enforcing these. The game-based teaching approach lets the students explore his/her current mindset and compare it with that of entrepreneurs. The paper presents two of the hypothesis behind the Berkeley Method of Entrepreneurship; the set of behavioral patterns, and the game based teaching approach. The paper outlines the concepts behind this novel teaching approach as well as future research

A Student-Centered Approach and Mindset-Focused Pedagogical Approach for Entrepreneurship and Leadership

The ease and abundance of knowledge acquisition that is unparalleled in history, renders knowledge transition and practicing of skills in education insufficient. The importance of personal reflection and identity, i.e. the individual’s mindset, is increasingly important. Re-thinking educational approaches, to entrepreneurship and leadership in particular, is important since they are activities for which perfect information cannot be gathered.This paper introduces a new pedagogical approach that we will refer to as the MIND methodology, which incorporates aspects of the individual’s mindset. The novel pedagogical approach includes four building blocks; theory practice, mindset and engagement-and-networking. The MIND-methodology is based on accepted pedagogical theories and known psychological aspects: social learning, communities of practice, and fixed and growth mindset.The novelty of the methodology lies in its clear student-centered approach and its focus on the student’s mindset. The methodology has been used in ongoing education in entrepreneurship and leadership over the course of about 10 years, and is gradually evolving. The results from applying the methodology show promising results for the main stakeholders; students and future employees. Students’ ranking years after graduation is unusually high and reveal that the curricula has provided life-long learning, the mindset activities are valued the most, and salaries and salary-increases provided by their eventual employers indicate that the students possess qualities sought after in today’s labor market