bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Analysis Validation Using Machine Learning
Authors: Nelanti Krishna , Barapu Raviraj , Thiraviyam Suresh , Nidamanuri Naresh 
Published: January 2020

Abstract
Aero-engine components analysis is quite complex in nature and same is the case with thermal analysis. Building an analytical model to simulate actual working conditions of a jet engine is challenging. Many approximations creep into analytical model in the process of simulating real time working environment. Thermal data match is the process to validate analytical model temperatures against experimental data i.e. temperatures measured by the thermocouples instrumented on various components of test engine.
Traditionally, Thermal boundary conditions are varied within permissible limits as mentioned in standard works to account the inability of empirical correlations in capturing physics and assumptions during modeling. Conventional thermal data match requires large number of iterations to match analytical model temperatures against engine data. This demands huge manual efforts and consumes more cycle time.
A methodology is developed using regression based ML algorithm which uses legacy thermal analysis data to identify scale factor to each thermal boundary condition (BC) that influences temperature at a thermocouple location. Initially ML algorithm identifies the weightage that each BC contributes towards data match status at thermocouple location. Once weights are acquired, objective function is formulated using predictor variables (Delta Temperature), response variables (BC Scale factors) along with the weights. Linear programming techniques are employed to solve the objective function subjected to constraints provided in the standard work. Thus, the output of the program is unique optimal scale factors which satisfy prescribed data match criteria.
The proposed methodology in this paper is validated by data matching compressor case analysis results against test engine thermocouple temperature data. With this approach, user intervention is mostly eliminated. 75% of cycle time reduction is achieved.
Modelling of Gas Cooler for S-CO2 Brayton Power Cycle
Authors: Pandey Vivek , Seshadri Lakshminarayanan , Gupta Jayesh , Mariayyah Ravishankar , Santhosh Nagavally Lingappa , Kumar Pramod 
Published: January 2020

Abstract
Supercritical Carbon dioxide (S-CO2) based Brayton power plants are being extensively researched as an alternative to steam-based power cycles due to high degree of recuperation favoured by higher heat capacities in supercritical state. Several studies revealed that PCHEs are suitable candidate for S-CO2 applications. Although, PCHEs have been well researched for various applications, there is very little information pertaining to the design or performance of PCHEs in S-CO2 applications.
This paper presents a novel methodology for design of a PCHE as gas cooler for a S-CO2 power block. In the first part, a thermal resistance network (TRN) model developed using MATLAB is used for full scale modelling of gas cooler. The geometrical information obtained from TRN model is used to optimize the overall footprint. In the second part, the MATLAB code coupled with a 1-D design tool (Flownex SE) and an optimization software; Isight, is used to optimize the inlet-exit manifold based on flow admittance approach. The 1-D design tool discretizes the inlet-exit manifolds to achieve optimum combination of flow admittances which facilitates identical channel mass flow rate and inlet pressure across each channel/stack ensuring minimum overall pressure drop.
In the current paper a case study for a 10 MW PCHE based gas cooler used in a simple recuperated S-CO2 cycle rejecting heat to ambient at 45 °C and 90 bar, is presented. The gas cooler uses water as the primary heat transfer maintained at 4 bar pressure to facilitate single phase heat transfer. Pinch temperature of 5 K is assumed to exist in all heat transfer surfaces. The MATLAB program is coupled with REFPROP property data base to retrieve the thermodynamic properties across all the nodes.
The Effect of Tip Clearance and Hub Rotation on the Performance of an Axial Compressor Stator
Authors: Jiang Chao , Hu Jun , Wang Jiayu , Li Jun , Xu Rong 
Published: January 2020

Abstract
In this paper, 1.5-stage high-speed compressor stator was studied using numerical computation method. Four gap cases were calculated under the condition of the hub being stationary or rotating, and the characteristic curves of the 1.5-stage compressor was obtained. Firstly, the influence of the change of the gap on the total pressure ratio and the efficiency curve was studied when the state of the hub is fixed. Then, the influence of the rotation of the hub on the total pressure ratio and the efficiency curve was discussed when the tip clearance is fixed. Finally, the total pressure loss of the stator channel would be analyzed. The above research would make people understand that the relative motion of the end wall has an important influence on the performance of the axial-flow compressor; when hub is stationary, the optimal gap is greater than 0, while when hub was rotating, the optimal gap was 0; and recognize that the variation of clearance and the motion state of the hub have an important influence on the distribution of total pressure loss along the span.
Numerical Prediction of Cooling Performance Sensitivity of 1st Stage Nozzle Guide Vane Under Aerothermal Conditions
Authors: Prapamonthon Prasert , Yin Bo , Yang Guowei , Zhang Mohan 
Published: January 2020

Abstract
To obtain high power and thermal efficiency, the 1st stage nozzle guide vanes of a high-pressure turbine need to operate under serious circumstances from burned gas coming out of combustors. This leads to vane suffering from effects of high thermal load, high pressure and turbulence, including flow-separated transition. Therefore, it is necessary to improve vane cooling performance under complex flow and heat transfer phenomena caused by the integration of these effects. In fact, these effects on a high-pressure turbine vane are controlled by several factors such as turbine inlet temperature, pressure ratio, turbulence intensity and length scale, vane curvature and surface roughness. Furthermore, if the vane is cooled by film cooling, hole configuration and blowing ratio are important factors too. These factors can change the aerothermal conditions of the vane operation. The present work aims to numerically predict sensitivity of cooling performances of the 1st stage nozzle guide vane under aerodynamic and thermal variations caused by three parameters i.e. pressure ratio, coolant inlet temperature and height of vane surface roughness using Computational Fluid Dynamics (CFD) with Conjugate Heat Transfer (CHT) approach. Numerical results show that the coolant inlet temperature and the vane surface roughness parameters have significant effects on the vane temperature, thereby affecting the vane cooling performances significantly and sensitively.
Numerical Simulation Studies on the Performance of a Diffuser Attached With Last Stage Compressor Outlet Guide Vanes
Authors: Sriram A. T. 
Published: January 2020

Abstract
Combustor pre-diffuser is an important element connecting the compressor and combustor. The design of pre-diffuser should be in such a way that the flow velocity to be within allowable limit to hold the flame in the combustor and also it should recover pressure with less amount of total pressure loss. The general practice is to design the compressor and combustor separately for their performance. However, integrated design of outlet guide vanes and pre-diffuser is given importance, on nowadays, to improve the overall performance. Basically, the outlet guide vane blades are modified to improve the performance. In the present work, numerical simulations studies have been carried out for a well-known high speed compressor, NASA Stage 37, to identify the influence of blade parameters. The computational domain consists of compressor rotor, stator and combustor pre-diffuser. The stator blades serve as outlet guide vanes. In literature, studies were shown that there is improvement in introducing blade sweep. Also, blade lean was shown some advantages for the case of a pre-diffuser with axial inlet and radial outlet with flow turning. However, in the present case of axial inlet and axial outlet, blade lean has not shown improvement in the performance. A diffuser showing slightly unstable condition in the conventional design, Area Ratio (AR) of 1.5 in the present case, has shown improvement with the presence of blade sweep.
Parametric Study for Adoption of Variable Cycle Engine Concept for Low Bypass Ratio Turbofan Engine
Authors: Swaminathan Kaviya , Mistry Chetan S. 
Published: January 2020

Abstract
Turbojet and turbofan engine propulsion system are extensively used in aircraft. Turbojets have simple engine design and extensively used for supersonic flights. Turbofan engine has high mass flow rate and efficient for subsonic application. Variable Cycle Engines, unlike the traditional engines, can vary between high thrust mode for supersonic operations and high efficiency mode for subsonic operations hence are potentially attractive for supersonic transport and advanced tactical fighter aircraft. Variable Cycle Engine can be described as the one that operates with two or more cycles, could serve as a possible solution to reconciling the necessary performance at different operating conditions. The aim of the engine is to combine the best traits of turbojet (high specific thrust) and turbofan (low specific fuel consumption, low noise). Traditional engines have fixed mass flow but VCE can alter the mass flow and function as high bypass engine for the subsonic case and low bypass engine at the supersonic case.
Different variable cycle engine design philosophies were studied and the engine architecture used in F120 was incorporated into the base design of a low bypass ratio Turbofan Engine. Cycle analysis of VCE was primarily done based on theoretical calculation and parametric study performed with the use of Gasturb software. Two Variable Area Bypass Injectors (VABI) were used to vary the mass flow through the core and the bypass stream. We aspire to achieve enhanced performance at subsonic and supersonic mission segments. Subsonic, supersonic and take off conditions were decided and the base engine was modified to have multiple operating points. The VCE combines two cycles (subsonic, supersonic) in same engine body and it is crucial for the engine components to deliver the required performance at both the design points. The engine design procedure consists of the matching of components like turbine, compressor, exhaust nozzle and the exhaust mixing area. Systematic study of turbine matching for such engine configuration with multiple operating points was carried out to understand the utility of variable geometry in a VCE. For turbine matching, the mass flow through turbine was held constant by adjusting the VABIs and this was repeated for different takeoff conditions to analyses the output in detail.
The non dimensional mass flow through the turbine was fixed for both the design points and hence the turbine could be designed to provide high efficiency. The fuel consumption was found to have decreased compared to the baseline condition which in turn leads to low SFC and higher endurance.
Design of High Transonic Axial Compressor Stage for Small Gas Turbine Applications
Authors: Kumar S. Satish , Kumar Lakshya , Kumaran R. Senthil , Kumar Veera Sesha , Shobhavathy M. T. 
Published: January 2020

Abstract
In the quest for achieving high performance, gas turbine engines demand efficient design of various engine components, mainly the compressor stages. The compressor stages consume most of the energy produced by the engine to provide the required pressure ratio. CSIR-NAL is involved in the development of a small gas turbine engine for UAV applications. In this regard, a high transonic single stage axial flow compressor is designed with a mass flow of 4.6 kg/s and pressure ratio of 1.6, for technology demonstration. In this paper, the aerodynamic and structural design of a high transonic axial compressor stage is discussed along with its performance characteristics. Preliminary mean-line design of the compressor stage is carried out, followed by detailed 3D blade design. Aerodynamic performance of the compressor stage is investigated numerically. Grid independency study is carried out, and the flow un-altering grid is used for steady simulations. Steady 3D RANS CFD simulations with SST turbulence model are carried out for estimating the compressor stage performance. At the design speed, the compressor is able to produce the desired pressure ratio and efficiency. Detailed flow investigations across the compressor stage are studied from choke to near stall flow conditions for different speeds. The compressor rotor blisk made of titanium alloy (Ti6AL4V) is subjected to stress analysis. The von-Mises stress and radial deformation are observed to be well within the safe limits of the chosen material. Modal analysis is carried out to study the structural dynamics of the rotor.
An Integral Approach to Designing of an Optimized and Reliable Anti-Icing System Under Off-Design Operating Regimes in a Gas Turbine
Authors: Mehta Nishit , Altukhova Olga , Nassar Abdul , Moroz Leonid 
Published: January 2020

Abstract
Anti-icing systems (AIS) are used in aviation and in ground gas turbines operating in humid climates where relative humidity is above 80% with mist and the temperature of the intake air drops to 5°C and below. Ice formation can disrupt the compressor work by causing vibrations, inlet flow blockage or even a surge in some cases. An anti-icing system is activated in such cases to heat the inlet air before it reaches the compressor. The objective of this work is to design and study an anti-icing system (AIS) for different ambient air parameters and different gas turbine modes of operation. A particular climatic situation (Saint-Petersburg, Russia) is considered as the basis for assessing the suitability of different anti-icing systems and to choose the best configuration out of different possible arrangements. The present work is divided in three major tasks. The first task involves the choice of the anti-icing system arrangement. The second task is to design the heating air supply system by determining the geometric sizes of bypass pipeline with fully open damper to ensure conduction of required air flow at the anti-icing system design condition. In the final task, the entire process is integrated and automated to calculate multiple iterations for different gas turbine operating regimes to assess the reliability of the designed anti-icing system at all operating conditions of the gas turbine. Such assessment is critical as it helps to identify the operating conditions at which the designed anti-icing system would not be able to heat the intake air to a certain temperature above the dew point temperature.
The Study on Effect of the Number of Nozzle Vanes in a Radial Flow Turbine for the Turbocharger
Authors: Kannan Ramesh , Prasad Bhamidi , Koppa Sridhara , George Libin , Karuppanan Kuppusamy 
Published: January 2020

Abstract
The effect of number of nozzle vanes in the turbine stage of a turbocharger is studied using computational fluid dynamics. The nozzle vane unit having 8, 9 and 10 numbers of nozzle vanes configuration is proposed for the radial flow turbine with 30 mm wheel tip diameter. At maximum opening position of the nozzle vanes and for the typical turbine expansion ratio of 2.5, the reduction in mass flow parameter with 10 numbers of nozzle vanes is about 1% lower compared to the 8 numbers of nozzle vanes. The maximum turbine flow range is not affected with higher number of nozzle vanes. The improvement in flow guidance is observed in nozzle vane unit having 10 numbers of nozzle vanes. The improvement in pressure distribution is observed in both the nozzle vane and turbine wheel with increase in number of nozzle vanes. The entropy generation in a turbine stage is found to decrease with increase in the number of nozzle vanes.
Experimental and Numerical Analysis of Turbulent Swirl Flow Structure in Double Swirler Burner
Authors: Sellan Dhanalakshmi , Murugan Raju , Balusamy Saravanan 
Published: January 2020

Abstract
Dynamic and kinematic characteristics of non-reactive turbulent swirl flow studies are significant for optimizing burner design, stability, and validating numerical simulations. The experiments were conducted on unconfined double swirler burner to understand the structure of non-reactive turbulent swirl flow for various inner and outer swirl Reynold’s numbers (Re). The burner is designed with double swirlers, inner and outer; both are medium swirlers with geometric swirl number of 0.8. The instantaneous 3C-2D velocity field in a plane is obtained by using Stereo Particle Image Velocimetry (SPIV) in backward-backward scattering position. In each case, 1000 image pairs are acquired with appropriate calibration and post-processed using cross-correlation and particle tracking technique. Turbulence parameters such as Reynolds stress and turbulence intensity as well as the velocity field of all three components are analyzed for various Re that are useful to understand the effect of turbulent mixing. Numerical study for the same cases are carried out, and experimental results are compared with numerical results. A computational domain contains 1146217 cells are generated for the 3D numerical simulation, and Large Eddy Simulation (LES) approach is used to predict the unsteady behavior of the flow fields. The increase in inner swirl Re increases both axial and azimuthal velocity component, which facilitate mixing in gas turbine application. The inner recirculation zone moves downstream with the rise in inner swirl Re and subsequently increasing the outer swirl Re leads to the operating condition where the blowout may occur.
Does economic growth reduce childhood stunting? A multicountry analysis of 89 Demographic and Health Surveys in sub-Saharan Africa
Authors: Yaya Sanni , Uthman Olalekan A , Kunnuji Michael , Navaneetham Kannan , Akinyemi Joshua O , Kananura Rornald Muhumuza , Adjiwanou Visseho , Adetokunboh Olatunji , Bishwajit Ghose 
Published: January 2020

BackgroundThere is mixed evidence and lack of consensus on the impact of economic development on stunting, and likewise there is a dearth of empirical studies on this relationship in the case of sub-Saharan Africa. Thus, this paper examines whether economic growth is associated with childhood stunting in low-income and middle-income sub-Saharan African countries.MethodsWe analysed data from 89 Demographic and Health Surveys conducted between 1987 and 2016 available as of October 2018 using multivariable multilevel logistic regression models to show the association between gross domestic product (GDP) per capita and stunting. We adjusted the models for child’s age, survey year, child’s sex, birth order and country random effect, and presented adjusted and unadjusted ORs.ResultsWe included data from 490 526 children. We found that the prevalence of stunting decreased with increasing GDP per capita (correlation coefficient=−0.606, p<0.0001). In the unadjusted model for full sample, for every US$1000 increase in GDP per capita, the odds of stunting decreased by 23% (OR=0.77, 95% CI 0.76 to 0.78). The magnitude of the association between GDP per capita and stunting was stronger among children in the richest quintile. After adjustment was made, the association was not significant among children from the poorest quintile. However, the magnitude of the association was more pronounced among children from low-income countries, such that, in the model adjusted for child’s age, survey year, child’s sex, birth order and country random effect, the association between GDP per capita and stunting remained statistically significant; for every US$1000 increase in GDP per capita, the odds of stunting decreased by 12% (OR=0.88, 95% CI 0.87 to 0.90).ConclusionThere was no significant association between economic growth and child nutritional status. The prevalence of stunting decreased with increasing GDP per capita. This was more pronounced among children from the richest quintile. The magnitude of the association was higher among children from low-income countries, suggesting that households in the poorest quintile were typically the least likely to benefit from economic gains. The findings could serve as a building block needed to modify current policy as per child nutrition-related programmes in Africa.
A study of the nature and level of trust between patients and healthcare providers, its dimensions and determinants: a scoping review protocol
Authors: Rasiah Supathiratheavy , Jaafar Safurah , Yusof Safiah , Ponnudurai Gnanajothy , Chung Katrina Pooi Yin , Amirthalingam Sasikala Devi 
Published: January 2020

IntroductionThe aim of this scoping review is to systematically search the literature to identify the nature and or level of trust between the patient, the users of health services (eg, clients seeking health promotion and preventive healthcare services) and the individual healthcare providers (doctors, nurses and physiotherapists/ occupational therapists), across public and private healthcare sectors, at all levels of care from primary through secondary to tertiary care. It also aims to identify the factors that influence trust between patients, users of health services (clients) and providers of healthcare at all levels of care from primary care to tertiary care, and across all health sectors (public and private). The study will also identify the tools used to measure trust in the healthcare provider.Methods and analysisThe scoping review will be conducted based on the methodology developed by Arksey and O’Malley’s scoping review methodology, and Levacet al’s methodological enhancement. An experienced information specialist (HM) searched the following databases MEDLINE, EMBASE, the Cochrane Library, Cumulative Index to Nursing and Allied Health Literature. The search terms were both keywords in the title and/or abstract and subject headings (eg, MeSH, EMTREE) as appropriate. Search results were downloaded, imported and stored into a ‘Refworks’ folder specifically created for reference management. The preliminary search was conducted between 7 December 2017 and 14 December 2017. Quantitative methods using content analysis will be used to categorise study findings on factors associated with trust between patients, clients and healthcare providers. The collection of studies will be also examined for heterogeneity. Qualitative analysis on peer reviewed articles of qualitative interviews and focus group discussion will be conducted; it allows clear identification of themes arising from the data, facilitating prioritisation, higher order abstraction and theory development. A consultation exercise with stakeholders may be incorporated as a knowledge translation component of the scoping study methodology.Ethics and disseminationEthical approval will be obtained for the research project from the Institutional Review Board. The International Medical University will use the findings of this scoping review research to improve the understanding of trust in healthcare, in its endeavour to improve health services delivery in its healthcare clinics and hospitals, and in its teaching and learning curriculum. The findings will also help faculty make evidence based decisions to focus resources and research as well as help to advance the science in this area. Dissemination of the results of the scoping review will be made through peer-reviewed publications, research reports and presentations at conferences and seminars.