bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design of Full-Scale Endwall Film Cooling of a Turbine Vane
Authors: Liu Jian , Du Wei , Zhang Guohua , Hussain Safeer , Wang Lei , Xie Gongnan , Sundén Bengt 
Published: October 2019

Abstract
Endwall film cooling is a significant cooling method to protect the endwall region and the junction region of endwall and a turbine vane, where usually a relatively high temperature load exists. This work aims to find the optimized arrangement of film cooling holes on the endwall and improve the film cooling in some difficult regions on the endwall, such as pressure side-endwall junction region. Several ideas for film cooling hole arrangement design are proposed, based on the pressure coefficient distribution, the streamline distribution, and the heat transfer coefficient (HTC) distribution, respectively. Four specified designs are built and compared. The results are obtained by numerical calculations with a well-validated turbulence model, the k–ω shear stress transport (SST) model. From this work, the designs based on the pressure coefficient distribution (designs 1 and 2) force the flow from the pressure side to the suction side (SS), especially in design 2, which adopts compound angle holes. The designs based on pressure coefficients have benefit in the cooling of the SS but give worse coolant coverage on the pressure side. In addition, designs 1 and 2 have little influence on the original pressure field. The design based on the streamline distributions (design 3) has larger coolant coverage on the endwall and provides good coolant coverage on the endwall and pressure side junction region. The design based on the HTC distribution provides large overall film cooling effectiveness on both the pressure side and the SS. More film cooling holes are placed on the high temperature regions, which is more effective in practice.
Heat Transfer Enhancement for Wake Zone Using Slit Pillar in Microchannel Heat Sinks
Authors: Cheng Xiao , Wu Huiying 
Published: October 2019

Abstract
Pillar microchannel heat sinks have been widely used for chip cooling, while their overall heat transfer performance is restricted by the stagnation flow in pillar wake zone. In this work, a simple but effective method using slit microstructure modified on pillar was proposed to enhance wake zone heat transfer. It enables a special flow path for the incoming fluid that intensively disturbs the wake fluid. To validate the proposed method, a three-dimensional simulation was employed to study the laminar flow and heat transfer characteristics in the slit pillar microchannel. The pillar without slit design was also investigated for comparative analysis. Effects of slit angle (θ), height over diameter ratio (H/D), and blocking ratio (D/W) of a single pillar were systematically studied at the Reynolds numbers of 26–260. Results showed the case with θ = 0 deg always demonstrated lower surface temperature, higher Nusselt number and higher thermal performance index (TPI) compared to other cases with different slit angles at the same conditions. Furthermore, it was interesting to find that the slit configuration was not suitable for long pillar microchannel, but preferred for high blocking ratio pillar microchannel at present ranges (H/D ≤ 1, D/W ≤ 0.5). The slit pillar array microchannel was also explored and observed with improved overall heat transfer performance. The proposed slit microstructure well prevents the heat transfer deterioration in pillar wake zone, which is promisingly to be used for cooling performance improvement of electronic device.
Experimental Validation of ANSYS CFX for Transient Flows With Heat Transfer in a Tubular Heat Exchanger
Authors: Papukchiev Angel 
Published: October 2019

Abstract
Within the European SESAME project, extensive experimental work was performed and complemented by the development, application, and validation activities of thermal-hydraulic simulation tools for different scales. The TALL-3D experimental facility, operated by KTH Royal Institute of Technology in Stockholm, is designed for thermal-hydraulic experiments with lead-bismuth eutectic (LBE) coolant at natural and forced circulation conditions. The heat generated in the primary TALL-3D circuit is transferred via a double-tube counter-flow heat exchanger (HX) to the secondary side, which is cooled by glycerol oil. Validation calculations with the coupled simulation code ATHLET-ANSYS CFX within the European THINS project showed that one of the major challenges for this one-dimensional–three-dimensional (1D–3D) simulation of the experimental facility lies in the calculation of the HX with ATHLET. This is due to the fact that glycerol oil properties are not yet available for ATHLET. In order to better understand the flow and heat transfer phenomena inside the HX, 3D stand-alone calculations with ANSYS CFX were carried out for the SESAME experiment TG03.S301.03. The data generated in this experimental run is challenging for validation of computational fluid dynamics (CFD) codes, because the test combines heat transfer between buoyancy-driven LBE flow in the primary circuit and a turbulent oil flow in the secondary TALL-3D side. Moreover, the validation gets even more difficult for the CFD approach due to the fact that both coolants are nonunity Prandtl fluids, and this requires a careful modeling of the turbulent heat flux. In this paper, the TALL-3D HX behavior during test TG03.S301.03 is analyzed, and the results of the ANSYS CFX calculations are compared with measurements.
Modeling Geared Turbofan and Open Rotor Engine Performance for Year-2050 Long-Range and Short-Range Aircraft
Authors: Mastropierro Francesco S. , Sebastiampillai Joshua , Jacob Florian , Rolt Andrew 
Published: October 2019

Abstract
This paper provides design and performance data for two envisaged year-2050 engines: a geared high bypass turbofan for intercontinental missions and a contra-rotating pusher open rotor targeting short to medium range aircraft. It defines component performance and cycle parameters, general arrangements, sizes, and weights. Reduced thrust requirements reflect expected improvements in engine and airframe technologies. Advanced simulation platforms have been developed to model the engines and details of individual components. The engines are optimized and compared with “baseline” year-2000 turbofans and an anticipated year-2025 open rotor to quantify the relative fuel-burn benefits. A preliminary scaling with year-2050 “reference” engines, highlights tradeoffs between reduced specific fuel consumption (SFC) and increased engine weight and diameter. These parameters are converted into mission fuel burn variations using linear and nonlinear trade factors (NLTF). The final turbofan has an optimized design-point bypass ratio (BPR) of 16.8, and a maximum overall pressure ratio (OPR) of 75.4, for a 31.5% TOC thrust reduction and a 46% mission fuel burn reduction per passenger kilometer compared to the respective “baseline” engine–aircraft combination. The open rotor SFC is 9.5% less than the year-2025 open rotor and 39% less than the year-2000 turbofan, while the TOC thrust increases by 8% versus the 2025 open rotor, due to assumed increase in passenger capacity. Combined with airframe improvements, the final open rotor-powered aircraft has a 59% fuel-burn reduction per passenger kilometer relative to its baseline.
Generalized SAFE Diagram for Mistuned Bladed Disks
Authors: Neri P. , Bertini L. , Santus C. , Guglielmo A. 
Published: October 2019

Abstract
The Singh's advanced frequency evaluation (SAFE) diagram is a design tool commonly used to find and thus prevent bladed disk resonances, allowing those modal combinations with no match in terms of angular harmonic shape to be neglected. In principle, the SAFE diagram is based on the assumption that the disk structure is perfectly cyclic; hence, any degree of mistuning would prevent its validity. However, each natural mode of a mistuned bladed disk can be expressed as a superimposition of angular harmonic components. The numbers of nodal diameters of these harmonics are extracted as the discrete Fourier transform of the eigenvector. In this paper, a new graphical representation is proposed to account for this complete harmonic content, instead of just a single (main or nominal) number of nodal diameters as in the conventional SAFE diagram. In addition, the relative intensities of the modal components are shown in this generalized SAFE diagram, for an indication of the induced vibrational magnitude of each possible resonance. Numerical and experimental cases are presented, obtaining significant examples of the proposed diagram. Analyzing the signals of an aeromechanical test, unexpected resonances were observed, which were not predicted by the conventional SAFE, but were detected with the proposed diagram.
Experimental Investigation for Enhanced Control of Rotating Unsteady Flow Instabilities in an Unshrouded Centrifugal Compressor Impeller
Authors: Mischo B. , Jenny P. , Bidaut Y. , Fonzi N. , Hermann D. , Wirsum M. C. 
Published: October 2019

Abstract
Unshrouded industrial centrifugal compressor impellers operate at high rotational speeds and volume flow rates. Under such conditions, impeller blade excitation is dominated by high frequency interaction with stationary parts, i.e., vaned diffusers or inlet guide vanes. In a previous study conducted on two full compression units of the original equipment manufacturer (OEM), the authors identified, characterized, and quantified resonant blade vibration caused by the interaction of the impeller blades with rotating stall cells during severe off-design conditions. This caused significant dynamic stress in the blades. In a follow-up study, this phenomenon was reproduced successfully experimentally under representative off-design conditions in a downscaled test rig and numerically with unsteady computational fluid dynamics (CFD) and structural mechanical finite element method (FEM) analysis. The gained knowledge was translated into a new diffuser design philosophy, based on sectorwise circumferential variation of the leading edge angle. This paper presents the patented philosophy, which is experimentally verified on the same test rig configuration in terms of flow path geometry and measurement equipment that was used in the mentioned prior study to assess resonant blade interaction. The results confirm the design aims: rotating stall onset was delayed without affecting the aerodynamic performance of the stage. Resonant blade interaction with rotating stall observed in the baseline diffuser could not be avoided with the two new diffuser designs. However, with the two new diffusers, the induced mechanical stresses in the impeller and the excitability were reduced by up to 12%.
Large-Eddy Simulation and RANS Analysis of the End-Wall Flow in a Linear Low-Pressure Turbine Cascade, Part I: Flow and Secondary Vorticity Fields Under Varying Inlet Condition
Authors: Pichler Richard , Zhao Yaomin , Sandberg Richard , Michelassi Vittorio , Pacciani Roberto , Marconcini Michele , Arnone Andrea 
Published: October 2019

Abstract
In low-pressure turbines (LPTs), around 60–70% of losses are generated away from end-walls, while the remaining 30–40% is controlled by the interaction of the blade profile with the end-wall boundary layer. Experimental and numerical studies have shown how the strength and penetration of the secondary flow depends on the characteristics of the incoming end-wall boundary layer. Experimental techniques did shed light on the mechanism that controls the growth of the secondary vortices, and scale-resolving computational fluid dynamics (CFD) allowed to dive deep into the details of the vorticity generation. Along these lines, this paper discusses the end-wall flow characteristics of the T106 LPT profile at Re = 120 K and M = 0.59 by benchmarking with experiments and investigating the impact of the incoming boundary layer state. The simulations are carried out with proven Reynolds-averaged Navier–Stokes (RANS) and large-eddy simulation (LES) solvers to determine if Reynolds-averaged models can capture the relevant flow details with enough accuracy to drive the design of this flow region. Part I of the paper focuses on the critical grid needs to ensure accurate LES and on the analysis of the overall time-averaged flow field and comparison between RANS, LES, and measurements when available. In particular, the growth of secondary flow features, the trace and strength of the secondary vortex system, and its impact on the blade load variation along the span and end-wall flow visualizations are analyzed. The ability of LES and RANS to accurately predict the secondary flows is discussed together with the implications this has on design.
Thermal Modeling and Performance Analysis of a Hybrid Photovoltaic/Thermal System Under Combined Surface Water Cooling in Winter Season: An Experimental Approach
Authors: Sainthiya Himanshu , Beniwal Narendra Singh 
Published: October 2019

Abstract
In this paper, thermal modeling of a hybrid photovoltaic/thermal (PV/T) system has been developed under combined (front and back) water surface cooling. An analytical expression has been derived for solar cell temperature (Tcs), back surface temperature (Tbs), and overall efficiency (ηOE) of the hybrid PV/T system for the winter condition. Statistical analysis has been performed in the cold climate of MNIT, Jaipur (India), for determining performance parameters of the hybrid PV/T system. An experimental validation has been carried out for the developed thermal model, and fair agreement between the numerical and experimental observations has been observed. We have also calculated the electrical (ηele), thermal (ηth), and overall efficiency (ηOE) as 18.83%, 43.8%, and 64.56%, respectively, and output power as 57.39 mW in the winter condition. We have also noticed that better performance is given by 1.5 LPM out of the four (1, 1.5, 2, and 2.5 LPM) flow rates.
Coordination between stochastic and deterministic specification in the
Drosophila
visual system
Authors: Courgeon Maximilien , Desplan Claude 
Published: October 2019

Retinal neurons play musical chairs
As the retina develops in fruit flies, subtypes of certain color photoreceptors, the R7 neurons, are stochastically specified even though the downstream neurons they need to connect to, the Dm8 neurons, are not randomly specified. Courgeon and Desplan find that Dm8 neurons are actually specified in subtypes and are produced in excess. Those Dm8 neurons that connect to an R7 input survive; those that fail to find a match die by apoptosis. The matching is facilitated by a pair of cell adhesion molecules. The stochastic results of R7 differentiation are thus propagated downstream even though those downstream elements are not stochastically determined.

Science
, this issue p.
eaay6727
MOG-Ab prevalence in optic neuritis and clinical predictive factors for diagnosis
Authors: Ducloyer Jean-Baptiste , Caignard Angelique , Aidaoui Ramzi , Ollivier Yolaine , Plubeau Guillaume , Santos-Moskalyk Sonia , Porphyre Lindsay , Le Jeune Caroline , Bihl Lionel , Alamine Samy , Marignier Romain , Bourcier Romain , Ducloyer Mathilde , Weber Michel , Le Meur Guylène , Wiertlewski Sandrine , Lebranchu Pierre 
Published: October 2019

ObjectiveWhat is the proportion of antibodies to myelin oligodendrocyte glycoprotein (MOG-Ab) in optic neuritis (ON) in adults and what would be the ON presentation for which MOG-Ab should be tested?MethodsMulticentric prospective study conducted during 1 year on all patients diagnosed with acute ON in all ophthalmological units in hospitals in a region in western France.ResultsSixty-five patients were included. MOG-Ab prevalence was 14% (9/65) during an acute ON and 13% (7/55) after exclusion of patients already diagnosed with multiple sclerosis (MS) (8) or MOG+ON (2). Compared with MS and clinically isolated syndrome, MOG+ON had no female preponderance (67% of men in case of MOG+ON and 22% of men in case of MS and clinically isolated syndrome, p<0.05) were more often bilateral (44% vs 3%, p<0.005) and associated with optic disc swelling (ODS) (78% vs 14%, p<0.001). To predict MOG+ON, the positive predictive values (PPVs) of male sex, ODS and bilateral involvement were 29% (95% CI 9% to 48%), 41% (95% CI 18% to 65%) and 40% (95% CI 10% to 70%), respectively, while the negative predictive values (NPV) were 93% (95% CI 86% to 100%), 96% (95% CI 90% to 100%) and 91% (95% CI 83% to 99%), respectively. The combined factor ‘ODS or bilateral or recurrent ON’ was the best compromise between PPV (31% (95% CI 14% to 48%)) and NPV (100% (95% CI 100% to 100%)).ConclusionAmong ON episodes, MOG-Ab were found in 14% of cases. MOG+ON occurred without female preponderance and was significantly associated with ODS and/or bilateral ON. Testing MOG-Ab only in patients presenting with ODS or bilateral or recurrent ON would limit MOG-Ab tests to fewer than half of all patients without the risk of missing any MOG+ON cases.
Colorectal cancer screening with faecal testing, sigmoidoscopy or colonoscopy: a systematic review and network meta-analysis
Authors: Jodal Henriette C , Helsingen Lise M , Anderson Joseph C , Lytvyn Lyubov , Vandvik Per Olav , Emilsson Louise 
Published: October 2019

ObjectiveEvaluate effectiveness, harms and burdens of faecal blood testing, sigmoidoscopy and colonoscopy screening for colorectal cancer over 15 years.DesignWe performed an update of a Cochrane systematic review, and performed network meta-analysis comparing randomised trials evaluating colorectal cancer screening with guaiac faecal occult blood test (gFOBT) (annual, biennial), faecal immunochemical test (FIT) (annual, biennial), sigmoidoscopy (once-only) or colonoscopy (once-only) in a healthy population, aged 50–79 years. We conducted subgroup analysis on sex. Follow-up >5 years was required for analysis of colorectal cancer incidence and mortality.Results12 randomised trials proved eligible. Compared with no-screening, we found high certainty evidence for sigmoidoscopy screening slightly reducing colorectal cancer incidence (relative risk (RR) 0.76; 95% confidence interval (CI 0.70 to 0.83) and mortality (RR 0.74; 95% CI 0.69 to 0.80), while gFOBT screening had little or no difference on colorectal cancer incidence, but slightly reduced colorectal cancer mortality (annual: RR 0.69; 95% CI 0.56 to 0.86, biennial: RR 0.88; 95% CI 0.82 to 0.93). No screening test reduced mortality nor incidence by more than six per 1000 screened over 15 years. Sigmoidoscopy had a greater effect in men, for both colorectal cancer incidence (women: RR 0.86; 95% CI 0.81 to 0.92, men: RR 0.75, 95% CI 0.71 to 0.79), and mortality (women: RR 0.85; 95% CI 0.71 to 0.96, men: RR 0.67; 95% CI 0.61 to 0.75) (moderate certainty).ConclusionsIn a 15-year perspective, sigmoidoscopy reduces colorectal cancer incidence, while sigmoidoscopy, annual and biennial gFOBT all reduce colorectal cancer mortality. Sigmoidoscopy may reduce colorectal cancer incidence and mortality more in men than in women.PROSPERO registration numberCRD42018093401.
Lymphoedema management by independent hospices: a cohort study
Authors: Brown Andrea , Nicholson Carol , Fearing Adam , Newton Julia , Gordon Simon , Hughes Andrew , Egdell Andrea , Ellam James 
Published: October 2019

ObjectivesTo consider the type and cost of clinical services delivered for patients with lymphoedema.DesignClinical cohort.SettingIndependent hospices in the North East of England.ParticipantsAll those attending lymphoedema services delivered by the independent hospice sector 2017/2018.Results13 914 lymphoedema appointments were recorded across four independent hospices. Twelve thousand nine hundred and sixty-five were attended, which equates to an approximate cost of £1.56 million. Those with lymphoedema were predominately aged over 65 (54.5%) years with females across all age groups being more predominant (3.3:1). Where the cause was recorded, 66% of activity related to lymphoedema was not secondary to cancer.ConclusionIndependent hospices are providing a specialist lymphoedema service, which is high in volume and largely invisible. This service is delivered at not insignificant cost. In contrast to previous work, in the North East of England, lymphoedema sufferers are more likely to be female and not have the condition in association with cancer. The availability of rigorous data collection will allow the independent hospices to understand better the delivery and associated costs of lymphoedema services.
Contemporary epidemiology and outcomes in recurrent infective endocarditis
Authors: Freitas-Ferraz Afonso B , Tirado-Conte Gabriela , Vilacosta Isidre , Olmos Carmen , Sáez Carmen , López Javier , Sarriá Cristina , Pérez-García Carlos Nicolás , García-Arribas Daniel , Ciudad Marianela , García-Granja Pablo Elpidio , Ladrón Raquel , Ferrera Carlos , Di Stefano Salvatore , Maroto Luis , Carnero Manuel , San Román J Alberto 
Published: October 2019

ObjectiveRecurrent infective endocarditis (IE) is a major complication of patients surviving a first episode of IE. This study sought to analyse the current state of recurrent IE in a large contemporary cohort.Methods1335 consecutive episodes of IE were recruited prospectively in three tertiary care centres in Spain between 1996 and 2015. Episodes were categorised into group I (n=1227), first-IE episode and group II (n=108), recurrent IE (8.1%). After excluding six patients, due to lack of relevant data, group II was subdivided into IIa (n=87), reinfection (different microorganism), and IIb (n=15), relapse (same microorganism within 6 months of the initial episode).ResultsThe cumulative burden and incidence of recurrence was slightly lower in the second decade of the study (2006–2015) (7.17 vs 4.10 events/100 survivors and 7.51% vs 3.82, respectively). Patients with reinfections, compared with group I, were significantly younger, had a higher frequency of HIV infection, were more commonly intravenous drug users (IVDU) and prosthetic valve carriers, had less embolic complications and cardiac surgery, with similar in-hospital mortality. IVDU was found to be an independent predictor of reinfection (HR 3.92, 95% CI 1.86 to 8.28).In the relapse IE group, prosthetic valve endocarditis (PVE) and periannular complications were more common. Among patients treated medically, those with PVE had a higher relapse incidence (4.82% vs 0.43% in native valve IE, p=0.018). Staphylococcus aureus and PVE were independent predictors of relapse (HR 3.14, 95% CI 1.11 to 8.86 and 3.19, 95% CI 1.13 to 9.00, respectively) and in-hospital-mortality was similar to group I. Three-year all-cause mortality was similar in recurrent episodes compared with single episodes.ConclusionRecurrent IE remains a frequent late complication. IVDU was associated with a fourfold increase in the risk of reinfection. PVE treated medically and infections caused by S. aureus increased the risk of relapse. In-hospital and long-term mortality was comparable among groups.