bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Performance and Flow Field Study of Centrifugal Compressor With Supercritical Carbon-Dioxide (SCO2)
Authors: Kumar Hemant , Mistry Chetan S. 
Published: January 2020

Abstract
The Supercritical carbon-dioxide Brayton cycle main attraction is due to the Supercritical characteristic of the working fluid, carbon-dioxide (SCO2). Some of the advantages of using SCO2 are relatively low turbine inlet temperature, the compression work will be low, and the system will be compact due to the variation of thermodynamic properties (like density, and specific heat ratio) of SCO2 near the critical point. SCO2 behave more like liquid when its state is near the critical point (Total Pressure = 7.39 MPa, Total Temperature = 305 K), operating compressor inlet near critical point can minimize compression work.
For present study the centrifugal compressor was designed to operate at 75,000 rpm with pressure ratio (P.R) = 1.8 and mass flow rate = 3.53 kg/s as available from Sandai report. Meanline design for centrifugal compressor with SCO2 properties was done. The blade geometry was developed using commercial CAD Ansys Bladegen. The flow domain was meshed using Ansys TurboGrid. ANSYS CFX was used as a solver for present numerical study. The thermodynamic properties of SCO2 were imported from the ANSYS flow material library using SCO2.RPG [NIST thermal physics properties of fluid system]. In order to ensure the change in flow physics the mesh independence study was also conducted.
The present paper discuss about the performance and flow field study targeting different mass flow rates as exit boundary condition. The comparison of overall performance (Pressure Ratio, the Blade loading, Stage efficiency and Density variation) was done with three different mass flow rates. The designed and simulated centrifugal compressor meets the designed pressure rise requirement. The variation of mass flow rate on performance of centrifugal compressor was tend to be similar to conventional centrifugal compressor. The paper discusses about the effect of variation in density, specific heat ratio and pressure of SCO2 with different mass flow outlet condition. The performance map of numerical study were validated with experiment results and found in good agreement with experimental results. The change in flow properties within the rotor flow passage are found to be interesting and very informative for future such centrifugal compressor design for special application of SCO2 Brayton cycle. 80% mass flow rate has given better results in terms of aerodynamic performance. Abrupt change in thermodynamic properties was observed near impeller inlet region. Strong density variations are observed at compressor inlet.
Multi-Point Optimization of a Centrifugal Compressor Stage
Authors: Ramachandran Dhinagaran , Mayandi Balamurugan , George Libin , A. Vasudevan Chaithanya , Garigipati Ranjith 
Published: January 2020

Abstract
Turbocharger has a paramount influence on the performance of an internal combustion. Improved emission requirements have led to complex after treatment systems, which add pressure drop to the air management system. One of the ways to mitigate negative effects of pressure drop is to improve turbocharger efficiency. The scope of performance improvement for a typical turbocharger majorly lies on the modification of compressor wheel, turbine wheel, volutes etc. The major challenges in compressor wheel modification include setting the right major geometrical dimensions, considering compressor operability at different application requirements, design cycle time and the cost of computation. Present study is about evolving an effective optimization methodology, which comprises of parametrization of compressor stage at preliminary design stage and optimization of the chosen parameters through coupling one dimensional flow analysis tool with a robust optimization tool. The parameters were chosen based on their influence on overall efficiency and pressure ratio at different mass flows and varying engine rotational speeds. Surrogate models have been used to choose the optimal designs from the preliminary design space as per requirement and optimized designs were analyzed further for verification. Final validation has been carried out using a 3D RANS code.
Model Order Identification of Combustion Instability Using Lipschitz Indices
Authors: Harris Salil , Sinha Aniruddha , Kumar Sudarshan 
Published: January 2020

Abstract
Gas turbine combustors employing lean premixed combustion are prone to combustion instability. Combustion instability, if unchecked, will have deleterious effects to the combustor and hence needs to be controlled. Active control methods are preferred to obtain better off-design performance. The effectiveness of active control methods is dependent on the quality of controller which in-turn depends on the quality of model. In the present work, an input-output model structure, where the output of the system at the current instant is modelled as a nonlinear function of delayed inputs and outputs is chosen. As there are infinite possibilities for representation of nonlinear functions, all parameters in the model structure like time delay between input and output, number of delayed input and output terms and the appropriate form of nonlinear function can be obtained only iteratively. However, prior knowledge of delay and number of delayed inputs and outputs reduces the computational intensity. To this end, the present work utilizes the method of Lipschitz indices to obtain the number of delayed inputs and outputs.
The Effect of Temperature on Formability of AA6061-T6 Alloy Material Under Stretching Operation
Authors: Raman Goud R. , Rachala Aryan 
Published: January 2020

Abstract
Forming process is one of the most promising techniques in sheet metal forming process in which flat sheet is converted into desired component. Formability analysis has to be carried out in order to obtain successful forming components. In this paper the effect of temperature on formability of AA6061-T6 alloy material was estimated by conducting stretch forming operations on one mm AA6061-T6 alloy material sheets at different temperatures. The range of specimen sizes wastaken from 110 mm × 20 mm to 110 mm × 110mm of AA6061-T6 alloy material for experimentation. The experiments were conducted on the sheet metal forming setupat temperatures RT (250C), 1000C and 2000C.The obtained results were compared with the finite element analysis. The data extracted by the simulation results was well matched with the experimentation results.
Experimental and Numerical Investigations of Thermal Hydraulic Performance in Ribbed Channel for Combustor Liner
Authors: Bihari Divya , Bokade Sanjay 
Published: January 2020

Abstract
The present study assess the thermal hydraulic performance of V-shaped, W-shaped and 2W-shaped ribs in a rectangular channel with an aspect ratio of 6:1. The rib-roughened copper plates were located at the bottom of the channel to simulate the backside wall cooling of gas turbine combustor liners. The rib height-to-hydraulic diameter ratio (e/Dh) was 0.05834 and the rib pitch-to-height ratio (P/e) was 10 for all the cases. The experiments were carried out at the Reynolds numbers ranging from 32000 to 72000. A steady state heat transfer measurement method is used to investigate the heat transfer enhancement of ribbed wall against a smooth wall. Pressure taps were located at two stream-wise locations in channel walls to measure the pressure loss. To validate the understanding of experimental data, all the rib configurations were investigated numerically using ANSYS FLUENT. A low Reynolds number k-ε turbulence model was used to predict the heat transfer in the channel. The results show that the 2W ribs have the highest heat transfer and pressure loss characteristics in channel. It gives around 1.4–1.6 times increase in average Nusselt number and 2.7–3.3 times increase in friction factor as compare to smooth plate. Among all the cases V ribs obtained lowest heat transfer and pressure loss characteristics. Furthermore, both heat transfer enhancement and pressure loss increases with increasing Reynolds number.
Numerical Study of Vortices and Their Interactions in the Passage of Rotor Blade With Tip Gap
Authors: Rawat Sachin Singh , Prasad B. V. S. S. S. 
Published: January 2020

Abstract
A detailed three-dimensional steady-state numerical investigation using ANSYS CFX-18.2 on a high-pressure turbine blade with linear cascade is done for tip leakage flow of an axial gas turbine. Stationary casing with a fixed blade having tip gap is considered for the present study. There is leakage flow from the pressure side to the suction side of the blade which consecutively rolls up in the passage and forms the tip leakage vortex. The formation of vortices and their interaction with each other inside the passage is complex which makes experimental investigation difficult. The effect of tip gap size, off-design incidence angles, outlet Mach number, pitch size and flow path (stagger angle) are several parameters considered during the present study. The strength of tip leakage vortex and the vortex formed inside the gap is maximum. The losses are compared in terms of total pressure loss coefficient. The deviation of the flow direction is measured in terms of yaw angle distribution. Among various turbulence model available in CFX 18.2 the BSL k-ω turbulence model shows the most reliable results with experimental data. The results are compared with the base model without the tip gap. This investigation incites a better design of the blade tip with a precise reduction in losses.
Experimental Investigation of Solar Still With Varying Pressure
Authors: Sinhmar Harender , Bhati Jitendra , Bhati Ritanshu 
Published: January 2020

Abstract
The shortage for the pure water exists in many developing countries like India even though three fourth of the earth is sheltered by water. The main reason behind this is the unplanned growth of industry and uncontrolled growth of population. In this context, solar still may serve as an efficient solution for addressing pure water shortage in hot climatic areas facing scarcity of water. Solar still is a very simple device that can be used for converting the available non-potable water into potable water. Various water purifiers based on solar energy have been proposed in literature but most of them are having low water output. This paper presents a novel method of a solar water purifier operating under vacuum to enhance its productivity. An experimental investigation of a scaled model has been carried out and it was observed that productivity of solar still increases with decrease in pressure inside the still.
Comparison of Atomization Characteristics of Jet A-1 and Alternative Aviation Fuels Using High-Speed Imaging Technique
Authors: Kumar Manish , Karmakar Srinibas 
Published: January 2020

Abstract
Environmental pollution from gas turbine engines is becoming a serious concern recently because of the steep growth in the aviation sector globally. Therefore, potential alternative fuels which can partially or fully replace fossil-based jet fuel are getting significant attention. However, the search for suitable candidate fuels which can fulfill the requirement in terms of fuel properties and combustion performance is continuing. The present study deals with an experimental investigation of atomization characteristics of Jet A-1, butanol, and butyl butyrate in quiescent atmospheric air. A high-speed imaging technique has been adopted to make a comparison of ligament breakup characteristics and droplet formation of these alternative biofuels with that of Jet A-1. Various fuel properties, including density, viscosity, and surface tension, are compared. An effort is made to understand how the variation in fuel properties influences the atomization mechanism of each fuel. The surface tension seems to be similar for these three fuels with a slight variation in density. However, there is a significant variation in viscosity. Viscosity appears to play a major role in the difference observed in ligament length and droplet formation. Due to the higher viscosity of butanol, the droplet formation seems to be delayed compared to Jet A-1, whereas the lower viscosity of butyl butyrate promotes faster droplet formation. The effect of blending of these biofuels with Jet A-1 on atomization characteristics will be compared with that of Jet A-1.
Investigation of Performance of Fins Geometry on a Vertical Cylinder
Authors: Yadav Nagendra P. , Srivastava Ayush 
Published: January 2020

Abstract
This paper focuses the prediction of the performance of fins having different geometry on a vertical cylinder in natural convection heat transfer. The extensive experimental investigations are performed for different geometrical profile of fins. The hollow cylindrical base having the same fins on their periphery with variable numbers 6 to 18. The temperature measurement was done at different location on the base of cylindrical surface as well as on the surface of the fins. The temperature behaviors for various fins are discussed with power. The measurement was done after justification of the steady state. The temperature is decreases with measurement location from base to tip of fin. As per the variation of base temperature and thermal resistance, semiconvex profile of fin is better than other geometry of fin. The Nusselt number is higher at low power input and less number of fins. The variation in temperature for different power inputs and geometry of fin and the numbers of fin help us to design fins which can be used up in advanced semiconductors in the newest technology because the cooling of those devices is a major challenge to the industries and researchers.
Investigations on the Effect of Bearing Clearance in Turbocharger Fully Floating Hydro-Dynamic Bearing System
Authors: Chandrasekaran Lokesh , Selvaraj Praveen Kumar , Vengala Prasanth R. , Arthanarisamy Subramani D. 
Published: January 2020

Abstract
Turbocharger technology helps in achieving reduced emissions, increased performance and downsizing of automobile engines. The rotor system of the TC is supported with the help of hydrodynamic fully/ rotating floating ring (RFRB) bearing systems. Hydro-dynamic bearing systems are more sensitive to inner and outer clearances. The possibility of maintaining nominal clearance in the mass produced turbocharger is limited to manufacturing capabilities and constrains. The inner and outer bearing clearances are always in the controlled range. This range creates four different combination of clearances which need to be validated to ensure safe shaft motion, which incurs huge development & testing cost and time. In hot gas stand, using NVH Data Acquisition System (DAQ) with frequency analyzers and eddy current displacement sensors, rotor shaft motion behavior was studied for the nominal bearing clearances. Numerical simulation model was created for the nominal clearances case. In numerical simulations, multi-body dynamics (MBD) of flexible rotor and housing structures are coupled with Elasto-hydrodynamics (EHD) of the inner and outer oil films. The energy equation is considered for calculation of oil film temperature in EHD using thermal boundary conditions obtained from 3D FE simulation. Simulation and tested results are compared and correlated. With this validated simulation methodology, investigation is conducted for the four different combination of clearances and results are discussed in this paper.
Time Dependent Low Velocity Impact Response of Turbomachinery Blade Made of Porous Exponential FGM
Authors: Das Apurba , Agarwal Gopal , Inaba Kazuaki , Karmakar Amit 
Published: January 2020

Abstract
This study presents transient dynamic response of porous and non-porous exponential functionally graded (E-FGM) conical shells subjected to low velocity single and multiple impact. Hertzian contact law in modified form considering permanent indentation is used to calculate the impact response parameters. For finite element formulation eight-noded isoparametric shell element having five degrees of freedom per node is used. The dynamic equations for the low velocity impact problems are solved by Newmark’s time integration scheme. Parametric studies in terms of contact force, initial velocity of impactor, impactor displacement and shell displacement for Stainless Steel-Silicon Nitrite porous and non-porous conical shells (idealized as rotating turbo-machinery blade) under low velocity single and multiple impact are analyzed. Twist angle has significant effect on contact force but has marginal effect on contact duration. Contact force for perfect (porosity free) case is higher than that of porous one and the contact forces are found to decrease with higher porosity factor. Even porous FG conical shell is predicting lower contact force and higher shell displacement than that of uneven porous FG conical shell for a given porosity factor.
Literature review: technological interventions and their impact on quality of life for people living with dementia
Authors: Sanders David , Scott Philip 
Published: January 2020

ObjectivesRapid technology-driven innovation in the healthcare sector has led to an increasing ability to effectively respond to health challenges. However, the cognitive challenges faced by a person with dementia exacerbate the difficulty of designing enduring technological dementia care solutions. Despite this, and in the absence of a cure, facilitating well-being and improved quality of life becomes pivotal for those living with dementia and their caregivers. This review aimed to identify and consolidate the provision of technological solutions for dementia care, and how these are perceived to impact the quality of life of a person with dementia.MethodsArticles and journals were identified using keywords including those relating to quality of life, assistive technologies and technology adoption and acceptance. Greater priority was given to resources published after 2010 due to the speed of technological advancement, and peer-reviewed articles were preferred.Results91 resources were identified, with 38 contributing to the final review. In addition to multiple quality of life measurement tools, the literature identified a large variety of solutions that fell into three categories: those used ‘by’, ‘with’ or ‘on’ a person with dementia.ConclusionsThis review concludes that the ‘one size fits all’ approach to many solutions reflects the lack of supporting evidence, negatively impacting trust in their usefulness among caregivers and their subsequent adoption rates. This could be attributed to limited involvement of people with dementia in studies of effectiveness and adoption. Additional research is recommended to further consolidate research on quality of life and to understand the individuality and progression of dementia and its influence on dementia care solutions.
Physical activity and exercise in youth mental health promotion: a scoping review
Authors: Pascoe Michaela , Bailey Alan P , Craike Melinda , Carter Tim , Patten Rhiannon , Stepto Nigel , Parker Alexandra 
Published: January 2020

Background/AimThis scoping review examined the breadth and outcomes of controlled trials testing the effect of physical activity and exercise interventions across all mental health outcomes for mental health promotion and indicated prevention studies in young people.MethodsThe literature search was conducted using ‘Evidence Finder’.ResultsThirty publications were included. Available evidence suggested that interventions of varying intensity may lead to a reduction in depression symptoms and that moderate-to-vigorous-intensity and light-intensity interventions may reduce anxiety symptoms. Effects of physical activity/exercise interventions on additional mental health outcomes were also shown; however, the number of studies was small, indicating a limited evidence base. Robust research regarding the effects of physical activity/exercise on mental health promotion and as an indicated prevention strategy in young people is lacking.ConclusionThe available evidence suggests that physical activity/exercise is a promising mental health promotion and early intervention strategy and warrants further investigation.
Campylobacter prevalence and risk factors associated with exceeding allowable limits in poultry slaughterhouses in Spain
Authors: Sevilla‐Navarro Sandra , Marin Clara , Cortés Verónica , García Cristina , Catalá‐Gregori Pablo 
Published: January 2020

BackgroundCampylobacter is the main pathogen involved in zoonotic gastrointestinal diseases. In 2018, European Regulation 2017/1495 on Campylobacter in broiler carcases came into force. In this context, the aim of the study was to assess the potential risk factors associated with exceeding the 1000 cfu/g (colony‐forming units per gram) limit set by the EC in several slaughterhouses in Spain.MethodsData relating to 12 factors were collected using questionnaires. Samples were collected from 12 Spanish abattoirs in June, July and August 2017 (n=1725) and were analysed following the ISO 10272‐2:2006 method.ResultsThe proportion of Campylobacter‐positive samples was 23.7 per cent (n=409). Analysis of flock age (41–50 days) revealed a significantly increased odds ratio (OR) in Campylobacter enumeration (OR=7.41). Moreover, scalding temperature (51.9°C–54°C) was positively associated with an increase in OR (OR=2.75). Time in transit to slaughter for 1–1.5 hours showed a significant decrease in OR (OR=0.25), while time in transit for more than two hours showed an increase in OR (OR=4.44). With regard to carcase weight, a weight of 3.21–3.58 kg showed a decrease in OR (OR=0.01).ConclusionThe outcomes of this study suggest that although most chickens are contaminated by the bacterium, the prevalence of those exceeding the 1000 cfu/g limit is not so high as thought.
A review of possible pathways of marine microplastics transport in the ocean
Authors: Li Yanfang , Zhang Hua , Tang Cheng 
Published: January 2020

Abstract
Marine microplastics pollution has been a new challenge to marine environmental protection. The research results have shown that microplastics exist everywhere in the ocean. However, understanding of the transport of microplastics in the ocean, including coastal zones, is not clear. This paper provides a holistic overview of the modelling of microplastic transportation. The transport processes are complex, including surface drifting, vertical mixing, beaching, and settling. Besides the dynamic conditions of oceans, the transportation of microplastics is influenced by their physical characteristics, such as size, shape, and density. For buoyant particles, a Lagrange track model is used to simulate the surface drift process, considering current, windage effect, and Stokes drift. It is difficult to observe the vertical mixing process of microplastics because of their small size (<5 mm), therefore the parameters of the vertical mixing process in the model are still less known. Large accumulation of microplastics in sediments may be a result of settlement and entrainment. Also, biofilm formation can increase their density and thus, deposition. Considering sedimentation of microplastics is somewhat different from sediment deposition, some primary parameters (e.g., diffusivity, Stokes-drift, settling rate, biofouling rate) are required in future studies to better understand the transport of marine microplastics.