bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Investigation on Mitigation of Heat Transfer Deterioration of Supercritical CO2 Flow by Introducing Multiple Turbulators Along Helices in a Circular Tube
Authors: Duan Hangfei , Xie Gongnan , Ma Yuan , Li Shulei 
Published: October 2022

Abstract
In order to effectively alleviate the heat transfer deterioration phenomenon of supercritical CO2 (S-CO2) in a vertical circular tube, explores the fluid hydraulic and thermal performance of multiple turbulator distributed along helices through a verified standard k-ω model. The effects of the pitch and the height of turbulators on flow characteristic and heat transfer are observed and analyzed in detail. With the increase of the height of turbulators, the heat transfer coefficient increases significantly. Besides, as the pitch decreases, the fluid re-circulation area behind each turbulator decreases, resulting in stronger mixing of swirling flow, which enhances turbulent kinetic energy of downstream fluid and weakens buoyancy force, thus mitigating heat transfer deterioration. The present results suggest that introducing multiple turbulators distributed along helices into circular tube can be a beneficial way to alleviate heat transfer deterioration and to enhance heat transfer of supercritical CO2 flow.
A Numerical Investigation of Sweeping Air/Mist Jet Film Cooling Through a Passive Fluidic Oscillator, Part II: Sweeping Air/Mist Jets
Authors: Abdelmaksoud Ramy , Wang Ting 
Published: October 2022

Abstract
An ongoing research effort has been conducted for years to investigate the feasibility of mixing the air with mist (micron-level water droplets) to enhance heat transfer. It becomes very interesting to investigate how these tiny droplets behave in conjunction with the periodic sweeping jets. Will they move synchronously with the fluid or asynchronously with a phase lag? How would the interaction between the droplets and the sweeping jets affect the film cooling effectiveness? To answer these questions, Part II of this paper specifically focuses on investigating the droplet dynamics and thermo-flow behavior of droplet evaporation on film cooling effectiveness in a sweeping jet. An unsteady Reynolds Averaged Navier-Stokes (URANS) simulation accompanied by the k-ω SST turbulence model is used in this study. The multiphase CFD model employs an Eulerian-Lagrangian approach. The Eulerian method is used for the continuous phase including air and water vapor and the Lagrangian method in terms of the discrete phase model (DPM) is used to simulate the dispersed phase (e.g., liquid droplets) in a continuous phase (e.g., air). A mist ratio of 10% with a droplet size of 10 microns were used in this study. The results show that, for a blowing ratio of 1, using mist provides better film cooling performance with an average enhancement of 50–90% in comparison to that without mist. Using a mist ratio of 10% could save approximately 50% of the cooling air. It is observed that the liquid droplets mostly follow the main sweeping flow and its vortical structure and horseshoe vortices, but with a phase lag between the droplets and the main sweeping jet. This phase lag further enhances both temporal and spatial film cooling surface protection during the sweeping motion.
Numerical Investigation on HCF Weak Link Locations of a Wide-Chord Laminated Composite Fan Blade With Coupled Modal Vibrations
Authors: Tang Xu , Chen Yong , Zhang Jiguo 
Published: October 2022

Abstract
High cycle fatigue (HCF) of laminated composite fan blade (LCFB) caused by vibration is important content within airworthiness certification. This paper proposed a method suitable for LCFB to evaluate its HCF failure location under complex excitations. First, a high-fidelity finite element model (FEM) of LCFB was built and the classification of modal shapes was carried out. By setting the resonance margin threshold on the campbell diagram, the modal superposition vibration that may be excited at the common rotation speed was found out. Then, a postprocessing strategy was proposed to evaluate HCF weak link locations. Constant life diagrams (CLD) for the unidirectional lamina were employed to determine the HCF weak link location of LCFB in combination with the steady and vibratory stresses along the corresponding material principal directions. For the coupled mode vibration, the HCF weak link locations with different stress components were calculated and the critical failure stress component was identified. For the coupled mode vibrations, the HCF weak link locations with the resultant stresses were calculated with different combination of modal participating coefficients. The results indicated that the HCF weak link locations may change to locations different from that in single mode vibration. Furthermore, the critical failure stress components may be transferred to directions with larger vibratory stress margins. This work presented a useful numerical technique to study the effect of mode coupling on LCFB HCF characteristics under complex operating conditions.
Impact of High Hydrogen Operation on Combustor Performance
Authors: Mohammad Bassam S. , Magina Nicholas , Volk Brian , Mcmanus Keith 
Published: October 2022

Abstract
As the interest in high hydrogen operation is gaining momentum, this paper quantifies the impacts associated with switching from natural gas to 100% hydrogen, leveraging both modelling techniques and experimental data. From the modeling standpoint, a perfectly stirred reactor network model was setup in Cantera. Flame speed increases of up to 50 times that of natural gas were observed with increasing hydrogen content, indicating a significant increase in flashback propensity. This suggests that DLE combustion systems might offer an advantage over RQL systems, operating at low equivalence ratios where the flame speed impact is milder. Additionally, the model shows that the blow off time can be used to classify hydrogen operation into three regimes. With increasing hydrogen content, the BOT begins similar to that of propane and declines at different rates in each regime, establishing the added operational challenges associated with high hydrogen content operation. Equivalence ratio dependencies were investigated along with NOx penalties, where a predicted penalty of ∼40–65% was observed within the flame temperature range of 1750–1950K. Experimentally, a new advanced mixer was used, enabling operation of the full spectrum of natural gas and hydrogen blends up to 100% hydrogen. The impact of hydrogen content on NOx emissions for a representative operating condition was investigated. Comparisons with the model predictions were made, revealing discrepancies, which were investigated and justified thru a mixedness and residence time framework. Finally, the authors show that the proper way to regulate future combustors running with 100% hydrogen should be based on NOx and not NOx15. The findings reported here help clarify and shape the future hydrogen enabling technologies, reaffirming the need for compact and shorter combustors than are used in current technologies.
Optimization Approach for Wind Farm Cable Layout Based on Iterative Self-Organizing Data Analysis Technique Algorithm and Swap Sequence Based Particle Swarm Algorithms
Authors: Yu Deqi , Li Ming 
Published: October 2022

Abstract
In the fast evolving and increasingly competitive wind energy market, to minimize initial capex and maximize production profits are essential when designing a wind farm. The electrical cable accounts for around 10% of the total capex, reasonable layout of cable connections might induce significant reduction of electrical and construction cost. In this paper, the Fuzzy C-means (FCM) clustering algorithm is adopted to determine the location of the substation(s) and the ISODATA (Iterative Self-Organizing Data Analysis Technique Algorithm) is employed to divide the wind farm into finite sub-domains, effectively reducing the complexity of the NP-hard (Non-deterministic polynomial-time hard) problem of cable layout optimization. The optimal cable layout in each sub-domain is obtained through the swap sequence based particle swarm optimization (SSPSO) and practical electrical constraints, while the objective function is to minimize the total cable costs, including material cost and cable laying cost. Current study highlights both applicability of clustering algorithm and particle swarm optimization to the cable layout problem in wind farm.
Validation of Broadband Noise Prediction Methodology Based on Linearised Navier-Stokes Analyses
Authors: Blazquez-Navarro Ricardo , Corral Roque 
Published: October 2022

Abstract
This paper presents an integral validation of a synthetic turbulence broadband noise prediction methodology for Fan/Outlet-Guide-Vane (OGV) interaction. The test vehicle is the ACAT1 fan, a modern scaled-down fan, experimentally analysed in 2018 within the TurboNoiseBB project. Three operating points, namely Approach, Cutback, and Sideline, and two different rig configurations in terms of the axial gap between the fan and OGV are examined within this work. The methodology consists of using a RANS solver to model the fan wake and the use of two-dimensional frequency-domain linearised Navier-Stokes simulations to resolve the acoustics, including quasi-3D corrections to obtain representative results. The RANS results with no ad-hoc tuning are compared in detail against hotwire data to determine the degree of uncertainty incurred by this kind of approach. The predicted broadband noise spectra and noise azimuthal decompositions are compared against the experimental data. The spectral levels are well predicted, despite an average under-prediction of around 3dB. The noise azimuthal decompositions feature a remarkable agreement with the experiment, denoting accurate modelling of the main physics governing the problem. The impact of increasing the fan/OGV axial gap is quantified numerically for the first time. It is concluded that increasing the gap is detrimental for the broadband noise footprint, unlike intuitively could be expected. Overall, the presented broadband noise methodology yields robust broadband noise predictions at an industrially-feasible cost and enables a deeper understanding of the problem.
On the Pneumatic Hammer of Hybrid Gas Bearings: Measurements and Predictions
Authors: Jung Hyunsung , Sin Seki , Kim Kyuman , Heo Junwon , Wee Minsoo , Ryu Keun 
Published: October 2022

Abstract
Hybrid bearings integrating an external pressurizing source are widely used in high-speed turbomachinery due to their notable advantages, including low friction and wear, enhanced reliability and durability, and accurate rotor positioning, as well as large static stiffness and load carry capacity even lubricated with low viscosity liquids. This paper reports experimental data and predictions to identify the characteristics of pneumatic hammer of hybrid gas bearings, 60 mm in diameter, with increasing feed gas pressures. Pneumatic hammer characteristics with static load stiffnesses and flow rates of the test bearing are recorded for increasing static loads with various shaft center positions. A computational program for modeling of hybrid gas bearings predicts static load characteristics of the test bearings. Predictions show a remarkable agreement with measurements. Comparisons of measurements and predictions reveal that calculated reduced damping factors and damping coefficients of hybrid bearings, relying on volume ratio between recess and fluid film, are reliable indicators to estimate the onset condition of pneumatic hammer instability.
Numerical Study of Roughness Effect on Performances in Representative Heat Exchanger Channels
Authors: Jabbour Joseph , Serret Damien , Yassin Hussein 
Published: October 2022

Abstract
Heat exchangers (HX) are vital elements specially to improve the performance of thermal and energetic cycles. It can be obtained by reducing induced pressure drop or by increasing compactness and heat transfer efficiency. The HX designers always tend to develop a new architecture with thermal enhancement tools. In this context, Additive manufacturing (AM) offers the opportunity to reach new performances and integrations through the development of innovation geometries of HX.
For the last 10 years, AM was explored producing compact and efficient thermal components. This has led to the improving the process and the ability to manufacture complex and very thin structures. In parallel, new design software and new design methodologies have been developed such as generative design or implicit CAD modeler. This imposes the development of new innovative heat transfer intensification structures based on local heat transfer and CFD analysis.
A dedicated analysis was focused on the surface roughness impact. The generated roughness with AM can be substantially larger than with conventional manufacturing process. Moreover, wall roughness varies according to their orientation based on the main direction of printing. This parameter was taken into consideration during fins optimization in both experimental or numerical work.
This paper investigates both approaches and presents comparative studies in term of numerical and experimental characterizations.
Multidisciplinary Optimization of Radial Outflow Turbines With Highly Deformable Blades
Authors: Governo André , Saracoglu Bayindir H. 
Published: October 2022

Abstract
Miniature radial outflow turbines are used to generate onboard power for various aerial devices using the ram effect. The incoming air flow axially entering the inlet conduit of the turbine housing spins the turbine rotor, which may have excessive tip gap and a sizable hub cavity, and radially discharges from the turbine flow passages. The current class of turbine rotors under investigation are typically made of polymeric materials for serial production at reduced cost. The turbine airfoils are designed with significant overhanging sections over the large hub cavity. Such configuration allows regulating the rotational speed of the rotor, at high inlet velocity conditions, by enabling the rear part of the blades to bend under the effect of centrifugal and fluidic forces. However, such deflections may lead to material non-linearities and strongly affect the flow development through the blade passages, which are not yet documented in the open literature. This paper investigates the complex flow field inside such turbines for a wide range of operating conditions. A multidisciplinary design optimization routine was utilized to assess the conflicting influence of the aerodynamical and structural performance for this class of turbines. The strategy utilizes an in-house metamodel-assisted optimizer (CADO) based on artificial neural networks and genetic algorithms to maximize the power output while evaluating the impact of the rotational speed on blade displacement and flow behaviour. A decoupled fluid-structure interaction approach was established in the computational fluid dynamics solver integrated with the optimizer. The methodology validation was achieved through the experimental results on high-speed blade deformation of the initial turbine mockup. The results show striking changes to turbine geometry mainly dictated by the centrifugal force as compared to the fluidic loads play when a hub cavity exists. A change in the blade loading is identified due to the three-dimensional geometric modifications of the rotor under load solicitations and connected with a modification of the incidence angle and profile curvatures. Such a process decreases the turbine’s efficiency, especially at very high rotational speeds. The results of this work provide a comprehensive design space and guidelines on the development of radial outflow turbines through the extensive optimization study for preliminary design choices for turbines with similar geometries.
Evaluation of Various Numerical Methods for Blade Row Interaction in Turbomachinery
Authors: Liu Yangwei , Yong Xiaosong , Tang Yumeng 
Published: October 2022

Abstract
The flow within turbomachinery is inherently unsteady, thereby the unsteady rotor-stator interaction usually has a large effect on the performance of multistage turbomachines. However, fully unsteady simulations are still too time-consuming for in the routine design of turbomachinery, thus, the steady simulation with mixing-plane method that neglects the interaction is still widely used. Some reduced-order unsteady methods, such as harmonic balance (HB) method and space-time gradient (STG) method, have been proposed to simulate the unsteady periodic flow for the purpose of reducing CPU time consumption with sufficient accuracy. In this work, four mixing-plane methods, the HB method, and the STG method are implemented into the open source CFL3D solver. Effect of these methods on predicting unsteady rotor-stator interaction are evaluated in two flow cases, including a quasi-three-dimensional radial slice of a turbine stage and a 1.5-stage high-speed axial compressor. Results show that both the high-order HB and STG methods own the similar ability as the conventional unsteady simulation in predicting the wake transmitting from upstream to downstream, while the steady mixing-plane methods fail. Numerical results of the 1.5 stage compressor show that the wake of the first row can reach the third blade row. And this phenomenon can be also clearly captured by HB and STG methods. Fourier analysis method is used to analyze the interaction in different blade rows to evaluate various numerical methods.
Breaking-Up Sedentary Behavior and Detraining Effects on Glycemic Control: A Randomized Crossover Trial in Trained Older Adults
Authors: Correia Inês R. , Magalhães João P. , Júdice Pedro B. , Hetherington-Rauth Megan , Freitas Sofia P. , Lopes Júlia M. , Gama Francisco F. , Sardinha Luís B. 
Published: October 2022

In a randomized crossover trial, we examined the effects of interrupting sedentary behavior on glycemic control in trained older adults, before and after 2 weeks of detraining. Fourteen participants (65–90 years old) completed two 7-hr conditions before and after 2 weeks of detraining: (a) uninterrupted sitting (SIT) and (b) sitting plus 2 min of moderate-intensity activity every 30 min (INT). Both before and after detraining, no differences were observed for 7-hr glucose area under the curve (7 hr AUC) and mean glucose between sitting plus 2 min of moderate-intensity activity and uninterrupted sitting conditions. After detraining and for the SIT condition, higher values of 7-hr AUC (p = .014) and mean glucose (p = .015) were observed, indicating worsened glycemic control. No changes were observed in INT condition between both time points. Frequent interruptions in sedentary behavior had no effect on glycemic control, prior to or after detraining. Even so, older adults experiencing a short-term detraining period should avoid prolonged bouts of sedentary behavior that may jeopardize their glycemic control.
Fashion Versus Comfort: Exploring the Gendered Marketing Messages of Sport Team Licensed Merchandise
Authors: Sveinson Katherine , Hoeber Larena 
Published: October 2022

Sport team licensed merchandise plays an important role in sport fan experiences. Existing work has explored how consumers perceive these items, motivation and consumption habits, and intent to purchase. Extending upon the performative sport fandom framework, this study explores the marketing messages of sport fan merchandise, and the resulting implied gendered and fan performances. Employing a multimodal critical discourse analysis, we analyzed the top 20 T-shirts for men and women for five National College Athletic Association institutions on their official ecommerce sites. By examining the text descriptions, visual images, and messages perceived when combining text and visuals, we found that the marketing messages of clothing items rely heavily on traditional discourses of femininity and masculinity, placing gender performances as more relevant to fan performances for women. Atypical designs suggest alternative gender and fan performances but continue to indicate that gender identity is central to clothing appearance and messaging to consumers.
Apoptotic Processes Precede Infection with Symbionts in a Pogonophoran Lavrae (Siboglinidae, Annelida)
Authors: Rimskaya-Korsakova N. N. , Temereva E. N. , Malakhov V. V. 
Published: October 2022

Abstract
The fine structure of the body wall and gut was for the first time studied in the competent larvae of the frenulate pogonophoran Siboglinum fiordicum. Mass apoptosis of cell nuclei was observed in the dermo-muscular body wall and coelomic epithelium. Apoptotic nuclei were found in both cell cytoplasm and outside of the larval body. In the latter case, each nucleus was surrounded by the plasmalemma, and the entire cluster was covered with the cuticle. Cells of the larval gut retained the usual structure with the cytoplasm filled with numerous yolky granules and the nucleus displaying usual morphology. Similar apoptotic processes have been described in vestimentiferans and found to be initiated by penetration of symbiotic bacteria through the integument into the dorsal mesentery. The process of apoptotic rearrangement of body wall cells and the formation of unique symbiosis with bacteria were assumed to be time-spaced in S. fiordicum, occurring sequentially rather than simultaneously, unlike in vestimentiferans.
Global diabetes burden: analysis of regional differences to improve diabetes care
Authors: Bour Charline , Ahne Adrian , Aguayo Gloria , Fischer Aurélie , Marcic David , Kayser Philippe , Fagherazzi Guy 
Published: October 2022

IntroductionThe current evaluation processes of the burden of diabetes are incomplete and subject to bias. This study aimed to identify regional differences in the diabetes burden on a universal level from the perspective of people with diabetes.Research design and methodsWe developed a worldwide online diabetes observatory based on 34 million diabetes-related tweets from 172 countries covering 41 languages, spanning from 2017 to 2021. After translating all tweets to English, we used machine learning algorithms to remove institutional tweets and jokes, geolocate users, identify topics of interest and quantify associated sentiments and emotions across the seven World Bank regions.ResultsWe identified four topics of interest for people with diabetes (PWD) in the Middle East and North Africa and another 18 topics in North America. Topics related to glycemic control and food are shared among six regions of the world. These topics were mainly associated with sadness (35% and 39% on average compared with levels of sadness in other topics). We also revealed several region-specific concerns (eg, insulin pricing in North America or the burden of daily diabetes management in Europe and Central Asia).ConclusionsThe needs and concerns of PWD vary significantly worldwide, and the burden of diabetes is perceived differently. Our results will support better integration of these regional differences into diabetes programs to improve patient-centric diabetes research and care, focused on the most relevant concerns to enhance personalized medicine and self-management of PWD.