bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transient Response Characteristics of a Surface Junction Probe
Authors: Rout Anil Kumar , Sahoo Niranjan , Kalita Pankaj , Kulkarni Vinayak 
Published: January 2020

Abstract
The present work highlights the transient response phenomena captured by a coaxial surface junction thermocouple (CSJT) and subsequent use of the thermal probe for prediction of surface heat flux. To accomplish the objective, an E-type CSJT has been fabricated in-house in a laboratory scale from its thermo-elements with constantan (0.91mm diameter and 15mm length) serving as the inner element and chromel as outer element (3.25mm diameter and 10mm length). Both the thermo-elements are clubbed together coaxially which are separated by a thin layer of insulation in between them along the length. The junction between the thermo-elements is created at the surface through abrasion technique which forms a firm contact through formation of cold weld. The junction feature is then examined through a field emission scanning electron microscope (FESEM). The sensitivity of the probe is found experimentally to be 59 μV/°C.
The transient response characteristics are observed through water plunging and water droplet tests at 55°C for 20ms and 2s time scale. The voltage time data is recorded and with the help of sensitivity value, the temperature history is calculated. The temperature histories from plunging and droplet experiments are used for calculation of heat flux by analytically modeling the sensor as semi-infinite substrate and assuming heat conduction through it is one dimensional. The heat flux is also calculated from the same temperature history by using numerical analysis and compared with the previous one. The measured data provides substantial evidence for usage of these CSJT probes in transient temperature and surface heat flux recoveries within experimental time scale up to 2s with reasonable accuracy.
Vibration Mitigation of Rotors Suspended on Low-Cost Hybrid Gas Foil Bearing
Authors: Basumatary Kamal Kumar , Kalita Karuna , Kakoty Sashindra K. , Garvey Seamus D. 
Published: January 2020

Abstract
The hybrid Gas Foil Bearings combining the Gas Foil Bearing and Active Magnetic Bearing is a possibility for application in high-speed turbomachinery and a few developments have been made in this context. As such, the cost of conventional Gas Foil Bearing increases due to its requirement of precise manufacturing method and the coating material for the top foil and bump foil. In case of Active Magnetic Bearing, the normal electrical arrangement includes a multiplicity of independently controlled current sources usually at least four drives per bearing which increases its cost. Therefore, the hybrid Gas Foil Bearing will have much higher cost. In this work, a new electrical arrangement for the electromagnetic actuators of the hybrid Gas Foil Bearing has been proposed. The new arrangement requires only two drives per bearing and the bias current has been provided (in the same set of windings) through a simple rectifier with small series choke and shunt capacitor. As the number of drives required is less, the proposed bearing will have low cost. Implementing the new approach, the force vectors are achieved using only two current-source drives whereas the usual conventional arrangement requires four such drives. Numerical simulations are performed to explore the capabilities of the low cost bearing.
Entropy Generation Analysis of Mixed Convection Flow in a Nanofluid Filled Porous Cavity Using a Two-Component Lattice Boltzmann Method
Authors: Kashyap Dhrubajyoti , Dass Anoop K. 
Published: January 2020

Abstract
In the present work, a comprehensive analysis is made to understand the effect of velocity boundary conditions on the flow and thermal behaviour during mixed convection flow in a nanofluid-saturated porous square cavity. Two different velocity boundary conditions based on the movement of horizontal walls of the cavity are considered. The vertical fixed walls are differentially heated and the horizontal lids are thermally insulated. We have adopted the two-phase thermal lattice Boltzmann model (TLBM) for nanofluid system and modified this model to simulate nanofluid-filled porous medium by incorporating the Brinkman–Forchheimer-extended Darcy model. The current results provide good concordance with the published results computed through conventional numerical techniques. The detailed study of the heat transfer rate, entropy generation is made for discretely varying Richardson numbers (Ri) from 0.1 to 10 and Darcy numbers (Da) from 10−4 to 10−2 while maintaining Grashof number (Gr) at 104 and volume fractions of Cu nanoparticle (ϕ) less than equal to 5%. It is observed from the results that the optimal flow condition in terms of energy efficiency depends on the values of Ri and Da. From the viewpoint of both 1st and 2nd laws of thermodynamics, the performance of nanofluid is not satisfactory compared to the base fluid for current configurations as the augmentation of entropy generation with ϕ is more prominent compared to heat transfer enhancement.
Unsteady Non-Reacting and Reacting Flow Simulations of a Triangular Bluff-Body Flameholder
Authors: Mannari Manoj , Sriram A. T. , Singh Gursharanjit , Ganesan S. 
Published: January 2020

Abstract
Triangular bluff-body flame-holders, commonly called v-gutters, are used in gas turbine engine afterburners for flame stabilization. Unsteady flow dynamics in the v-gutter wake plays an important role in phenomenon such as combustion instability. The objective of the present work is to simulate the flow features for flow past v-gutter with Unsteady Reynolds-Averaged Navier–Stokes equations (URANS) and Large Eddy Simulation (LES) approach using Eddy Dissipation Model (EDM) for turbulent combustion. Volvo’s bluff body flame-holder rig configuration has been used for the current study. Both non-reacting and reacting simulations have been carried out in commercial Computational Fluid Dynamics (CFD) code FLUENT. In the case of non-reacting flow, the structure of instantaneous velocity field of LES differs from URANS approach. The predicted velocity profiles with LES have shown good agreement with the experiment in most of the regions than URANS for the case of non-reacting flow. In the case of reacting flow, LES simulations have shown unsteady flame with eddy structures. In contrast, URANS simulations have shown more like a steady flame. Overall, the temperature and velocity profiles were better predicted by LES than by URANS approach. In addition, simulations were carried out with circular flame-holder in an annular duct. The oscillation characteristics were found to be more or less similar for both straight and circular flame-holder.
Burning Characteristics of Boron/JP10 Nanofuel Droplets
Authors: Chandra Eshwar , Patel Ujas , Vinu R. , Sahu Srikrishna 
Published: January 2020

Abstract
The demand for higher volumetric calorific value of fuels for modern high performance aircraft has led to development of nanofuels that opens a promising future for enhancing the energy density of liquid fuels. This paper intends to study the effect of addition of boron nano-particles (NPs) on the burning characteristics of JP10 fuel droplets for various particle mass loadings (2%, 5%, 7% and 10%). Stable suspension of the NPs was achieved by adding Span80 and Tween80 as surfactant followed by ultra-sonication of the mixture. The fuel droplet was suspended on a horizontal quartz fiber. All experiments were conducted under atmospheric conditions. The droplet burning process was recorded using a high speed camera. The burning of pure JP10 and JP10 plus surfactant (without NPs) were also studied. In case of burning of pure JP10 fuel, the linear trend in time evolution of normalized droplet surface area suggested that the droplet burning follows the classical d2 – law and formation of bubbles inside the droplet was observed. However, these bubbles did not lead to puffing, which though occurred for JP10 plus surfactant (no NPs). This means that addition of surfactants, which has low burning rate, modifies the droplet burning process. In case of nanofuel droplet, burning occurs in different distinct stages for all mass loadings: initially the burning is smooth similar to pure fuel which is followed by intense periodical swelling and puffing in the later stages accompanied with ejection of secondary droplets from the parent droplet which burn separately. Finally, solo burning of NPs was evident for all cases. With increase in NPs loading from 2% to 10% vigorous surface oscillations and shattering of liquid masses were found which contributed to reduction in droplet lifetime. In such case the normalized droplet surface area showed periodic oscillations indicating departure from d2 – law.
Studies on the Outline of Flow Improvement With Speed Ratio in a Counter Rotating Turbine
Authors: Subbarao Rayapati , Govardhan M. 
Published: January 2020

Abstract
Flow through the Counter Rotating Turbine (CRT) stage is more complex due to the presence of two rotors that rotate in the opposite direction, the spacing between them and the tip clearance provided on rotors. This flow aspect may change, if we change the parameters like speed, spacing and blade angles. Current effort contains simulation studies on the flow topology of CRT through dissimilar speed ratios in the range of 0.85–1.17. CRT components stator and the rotors are modelled. At nozzle inlet, stagnation pressure boundary condition is used. At the turbine stage or rotor 2 outlet, mass flow rate is specified. Skin friction lines are drawn on rotor 1 as well as rotor 2 on all over the blade. Not much variation of skin friction lines is witnessed in rotor 1 on the pressure side with exception to the position of the separation line close to leading edge. On suction side, skin friction lines are more uniform when the speed ratio is greater than 1. Skin friction lines on rotor 2 pressure surface show the presence of re-attachment lines. The position of the nodal point of separation near the hub remained same, but the strength is decreasing with speed ratio. On rotor 2 suction side, near the tip, all along the stream wise direction, line of re-attachment is observed that spreads from leading edge to trailing edge, whose strength is varying with speed ratio. Near the hub as well, line of re-attachment is observed, which is of more intensity in lower speed ratios. For the same region in rotor 1, there is proper reattachment as nodes are observed instead of lines, suggesting that more improved flow is occurring in rotor 1 than rotor 2. Thus, the present paper identifies the flow modification with speed ratio in a counter rotating turbine. Also, effort is made to see the consequence of flow change on the output of CRT.
Numerical Simulation of the Effects of Manufacturing Deviations in Compressor Wheel Geometry on Performance
Authors: Ramachandran Dhinagaran , Mayandi Balamurugan , Dasappagoundenpudur Arthanarisamy Subramani , Murugan Vanamurthy , Boolingam Saravanan , Reddy Shanmugam Ranganathan 
Published: January 2020

Abstract
Increasingly stringent emission norms place tougher challenges on the efficiencies of a turbocharger. Higher efficiency requirement on turbocharger translates into tighter tolerances on the various geometrical dimensions. While this is applicable for all the components, in this study, the focus is on the compressor wheel. Compressor wheels are either cast or milled and variations are possible in either of the processes. Even small changes in the dimensions of compressor wheel (like diameter, angle distribution, thickness distribution, axial length and blade width etc.), cause the performance losses in Turbo charger. Loss in Performance of turbocharger affects Low-end torque, power rating, fuel economy as well as increasing compressor exit temperature. It is therefore important to understand and quantify the impact of the variation in blade geometry on pressure ratio, choke flow and efficiency. In this paper, a few case studies of manufacturing variations in blade thickness, blade height and axial length are shown based on gas stand tests as well as 3D CFD simulations. A process for extracting real geometry from white light scan data obtained from the manufactured wheel is shown which helps to compare the differences with the design intent geometry. Flow simulations with the real geometry show the impact on performance. Subsequently a systematic analysis of the variations is carried out to quantify the performance impact.
Design and Development of Diesel Turbocharger Compressor With Low-Pressure Ratio for Low BMEP Engines
Authors: Simonradha Franklin Praveen , Ramachandran Dhinagaran , Mayandi Balamurugan , Kashirajan Tamilarasan , Vengidasamy Alagarsamy , Boolingam Saravanan 
Published: January 2020

Abstract
As Indian OEMs are marching towards to meet the latest emission norms set by Government, the automotive industry is improving the performance of turbocharged internal combustion engines in terms of improved low-end torque, peak torque, peak power, fuel economy and reduced emissions. This, in turn, raises the demand for highly efficient turbocharging technology. The key strategy to improve turbocharger performance is to tailor the performance characteristics of the compressor. The type of turbocharger application governs the performance requirements of the compressor. Certain Indian commercial vehicle manufacturers in LCV segment especially tractor manufacturers apply low BMEP engines to have good durability and such applications require low-pressure ratio and wide flow compressors with peak efficiency island below the pressure ratio 1.3 to 1.4. A careful investigation is required to study the influence of compressor design features to design a low-pressure ratio compressor. However, the number of geometrical parameters influencing the compressor performance is high and investigating all the parameters may take a lot of time and computational effort. Furthermore, the trade-off between efficiency at low-end torque, peak torque, peak power and part-load efficiencies dictates the need for a multi-disciplinary optimization tool to design the compressor stage. The computational effort required to perform optimization through 3D CFD is also quite high. Hence, in this paper, we are introducing an approach to optimize the compressor design at multiple operating points through streamline calculations with the help of AxStream and validating the selected designs numerically through CFD and FEA calculations. This approach helps to design tailor-made compressors based on customer requirements and deliver the proto samples in a shorter period.
Design and Development of a Radial Turbine for Low Flow Turbocharging
Authors: Ramachandran Dhinagaran , Billa Srinivasa Rao , Mayandi Balamurugan , Balappan Perumal , Kanthila Shyamaprasad , Srivastava Neeraj 
Published: January 2020

Abstract
The scope of this study is to develop a turbocharger turbine wheel with improved aerodynamic performance at low mass flow rates and with reduced inertia for better transient response. The contrasting effect of geometrical shape and size parameters on the objectives of aerodynamic performance and transient response gives rise to the need to explore the design space for the best design having good trade-off between the multi-objective requirements. The search for an optimum aerodynamic design is a challenge due to structural requirements as well. A turbine wheel that is best suited for the current application is selected from the library as a baseline and this wheel is further optimized to meet the targets. Preliminary screening allowed the identification of parameters having major impact on the objectives and these results have been used to train a Response Surface (RS). Further, in the interest of reducing computational cost, a virtual optimization algorithm based on the RS has been employed to predict optimum design within the design constraints. The optimum designs thus obtained are validated with Computational Fluid Dynamics simulations for flow performance and Finite Element solver for satisfying structural requirements. This approach has allowed for application-based design of turbine wheel for instance, by changing key parameters like blade angle distribution, number of blades, axial length, blade height and width. An inertia reduction up to 10% has been obtained while retaining the performance at low mass flow rates.
Parametric Behaviour of Closed Loop Pulsating Heat Pipe in the Presence of Water As a Working Fluid
Authors: Yadav Nagendra P. , Madhuri  , Kumar Anil 
Published: January 2020

Abstract
This paper focuses on the parametric behavior of a closed loop pulsating heat pipe in the presence of water as a working fluid. The experimental study was done in the presence of different vacuum pressures inside the heat pipe with 50 percent filling ratio. The temperature was measured through the DAQ system with help of Lab VIEW 15.1 software at 12 locations of heat pipe at variable power inputs (10W–70W). Thermal resistance and variation of temperature are used to predict the performance of the heat pipe. Thermal resistance of heat pipe decreases with decrease in vacuum pressure inside the heat pipe. This work is useful for the transfer of heat of electronic devices and integrated circuit technology due to the high coefficient of convective heat transfer in the presence of phase change of working fluid inside the heat pipe.
Hypophosphatasia mimicking hypoxic–ischaemic encephalopathy: early recognition and management
Authors: Picton Aled , Nadar Ruchi , Pelivan Alexandra , Garikapati Vidya , Saraff Vrinda 
Published: January 2020

BackgroundHypophosphatasia (HPP) is a rare inherited disorder affecting bone and teeth development. Perinatal HPP is the most severe form and associated with a high mortality. Features include respiratory distress, skeletal abnormalities and low alkaline phosphatase (ALP) activity.CaseA baby boy developed respiratory distress, hypotonia and seizures within an hour of birth. Blood gas showed mixed acidosis and abnormal base deficit. Hypoxic–ischaemic encephalopathy (HIE) was suspected and managed with therapeutic hypothermia. Subsequent investigations identified low ALP activity and abnormal bone mineralisation, leading to a diagnosis of HPP. On day 5 of life, enzyme replacement therapy (ERT) was commenced, its first use via direct NHS England funding since UK licensing in 2017.ConclusionsEarly hypotonia is an atypical presentation for perinatal HPP. Combined with acidosis and encephalopathy, it can clinically mimic HIE. Early recognition of biochemical and radiological features of HPP is essential for rapid diagnosis and timely initiation of life-saving ERT.
Bubble versus other continuous positive airway pressure forms: a systematic review and meta-analysis
Authors: Bharadwaj Shruti K , Alonazi Abdullah , Banfield Laura , Dutta Sourabh , Mukerji Amit 
Published: January 2020

BackgroundUse of bubble continuous positive airway pressure (CPAP) has generated considerable interest in neonatal care, but its comparative effectiveness compared with other forms of CPAP, especially in developed countries, remains unclear.ObjectiveTo systematically review and meta-analyse short-term clinical outcomes among preterm infants treated with bubble CPAP vs all other forms of CPAP.MethodsProspective experimental studies published from 1995 onward until October 2018 comparing bubble versus other CPAP forms in preterm neonates <37 weeks’ gestational age were included after a systematic review of multiple databases using pre-specified search criteria.ResultsA total of 978 articles were identified, of which 19 articles were included in meta-analyses. Of these, 5 had a high risk of bias, 8 had unclear risk and 6 had low risk. The risk of the primary outcome (CPAP failure within 7 days) was lower with bubble CPAP (0.75; 95% CI 0.57 to 0.98; 12 studies, 1194 subjects, I2=21%). Among secondary outcomes, only nasal injury was higher with use of bubble CPAP (risk ratio (RR) 2.04, 95% CI 1.33 to 3.14; 9 studies, 983 subjects; I2=42%) whereas no differences in mortality (RR 0.82, 95% CI 0.47 to 1.92; 9 studies, 1212 subjects, I2=20%) or bronchopulmonary dysplasia (BPD) (RR 0.8, 95% CI 0.53 to 1.21; 8 studies, 816 subjects, I2=0%) were noted.ConclusionBubble CPAP may lead to lower incidence of CPAP failure compared with other CPAP forms. However, it does not appear to translate to improvement in mortality or BPD and potential for nasal injury warrants close monitoring during clinical application.Trial registration numberCRD42019120411.
Gestational diabetes and long-term risk for dyslipidemia: a population-based historical cohort study
Authors: Chodick Gabriel , Tenne Yaara , Barer Yael , Shalev Varda , Elchalal Uriel 
Published: January 2020

ObjectivesTo assess the course of lipid levels over time in postpartum women according to gestational diabetes status, taking into account potential confounders, such as comorbid conditions and body weight.MethodsThe data for the present analysis were collected from a 2.3 million member integrated care provider in Israel. Included were all female members aged 15–50 years who performed a 50 g glucose challenge test (GCT) between March 1995 and May 2009. We collected all follow-up lipid consecration tests performed from date of delivery following the GCT (index date) until April 2017. Data analysis was performed for each lipid component individually (triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C)) and the effects of the several risk factors (history of gestational diabetes mellitus (GDM), age at delivery, obesity status and smoking status) were investigated using general linear model taking into account potential confounders.ResultsA total of 160 527 women (6.1 million person-years of actual follow-up) were eligible for the analysis, including 10 234 women with GDM (6.4% of the entire cohort). During the study follow-up period, a total of 2.1 million lipid tests were performed. When adjusting for follow-up time, age at index date, body mass index status, and smoking status, GDM was associated with a 1.8-fold risk (95% CI 1.73 to 1.88) for dyslipidemia defined by TG, 1.45-fold risk (95% CI 1.38 to 1.52) for dyslipidemia defined by LDL-C, and 1.44-fold risk (95% CI 1.39 to 1.50) for dyslipidemia defined by HDL-C.DiscussionThe results of this retrospective cohort analysis indicate that gestational diabetes confers added risk for developing hyperlipidemia post partum, particularly dyslipidemia defined by TG, as compared with women with normal glucose tolerance.