bluuebunny/crossref_metadata_2025_split huggingface dataset:
Loss of the alpha subunit distal furin cleavage site blunts ENaC activation following Na+ restriction
Authors: Nickerson Andrew J. , Sheng Shaohu , Cox Natalie A. , Szekely Kennedy G. , Marciszyn Allison L. , Lam Tracey , Chen Jingxin , Gingras Sebastien , Kashlan Ossama B. , Kirabo Annet , Hughey Rebecca P. , Ray Evan C. , Kleyman Thomas R. 
Published: August 2024

AbstractEpithelial Na+ channels (ENaCs) are activated by proteolysis of the α and γ subunits at specific sites flanking embedded inhibitory tracts. To examine the role of α subunit proteolysis in channel activation in vivo, we generated mice lacking the distal furin cleavage site in the α subunit (αF2M mice). On a normal Na+ control diet, no differences in ENaC protein abundance in kidney or distal colon were noted between wild‐type (WT) and αF2M mice. Patch‐clamp analyses revealed similar levels of ENaC activity in kidney tubules, while no physiologically relevant differences in blood chemistry or aldosterone levels were detected. Male αF2M mice did exhibit diminished ENaC activity in the distal colon, as measured by amiloride‐sensitive short‐circuit current (ISC). Following dietary Na+ restriction, WT and αF2M mice had similar natriuretic and colonic ISC responses to amiloride. However, single‐channel activity was significantly lower in kidney tubules from Na+‐restricted αF2M mice compared with WT littermates. ENaC α and γ subunit expression in kidney and distal colon were also enhanced in Na+‐restricted αF2M vs. WT mice, in association with higher aldosterone levels. These data provide evidence that disrupting α subunit proteolysis impairs ENaC activity in vivo, requiring compensation in response to Na+ restriction.
imageKey points
The epithelial Na+ channel (ENaC) is activated by proteolytic cleavage in vitro, but key questions regarding the role of ENaC proteolysis in terms of whole‐animal physiology remain to be addressed.
We studied the in vivo importance of this mechanism by generating a mouse model with a genetic disruption to a key cleavage site in the ENaC's α subunit (αF2M mice).
We found that αF2M mice did not exhibit a physiologically relevant phenotype under normal dietary conditions, but have impaired ENaC activation (channel open probability) in the kidney during salt restriction.
ENaC function at the organ level was preserved in salt‐restricted αF2M mice, but this was associated with higher aldosterone levels and increased expression of ENaC subunits, suggesting compensation was required to maintain homeostasis.
These results provide the first evidence that ENaC α subunit proteolysis is a key regulator of channel activity in vivo.
Optimum Geometrical Models for Prediction of Phase Transition of Single Crystal Nickel Based Superalloys via the Discrete Cosine Transform and the Maximum Entropy Method
Authors: Hiraguchi Hideo 
Published: August 2024

Abstract
A new prediction method using the combination of the two-dimensional Discrete Cosine Transform and the Maximum Entropy method has recently appeared to estimate the dynamic changes of metallographic structures of the single crystal Nickel-based superalloy for gas turbine blades during the high temperature creep deformation. In the analysis of this method, simple geometrical models are used to estimate the dynamic changes of the phase transition. However, it has not been understood how the difference between the multiple simple geometrical models affect the result of the prediction of dynamic changes of structures yet. Therefore, three different simple geometrical models meshed into 21 × 21 (441 pixels) are prepared as the target model and demonstrated via the above mentioned new method, in the situation that the starting simple geometrical model is the same one. The first model is a symmetrical model whose symmetrical plane is parallel to the i axis and perpendicular to the j axis at the 10th scale line, the second one is a model which the first model is moved in the j axis direction by one pixel and the third one is a model which the first model is moved in the j axis direction by two pixels. As a result, the dynamic changes obtained from the symmetrical model and the one pixel deviation model are the most realistic of the three models.
Effects of Radially Variable Sweep Vanes on Rotor-Stator Interaction Noise
Authors: Shen Zihan , Wang Xiaoyu , Zhang Guangyu , Sun Xiaofeng 
Published: August 2024

Abstract
This paper presents a three-dimensional semi-analytic cascade model for the prediction of rotor-stator interaction noise, which includes the effects of radially variable sweep angle and chord length to better account for the latest trends in the fanstage stator design of turbofan aero-engines. The theoretical modelling and solution method are first introduced, with special attention paid to the singularity problem brought by the non-uniformity of the stator vanes in the radial direction. The tonal rotor-stator interaction noise for stators with a radially varying sweep angle or a radially varying chord length are then calculated and analyzed. It is discovered that the phase variation in unsteady pressure loading near the stator leading edge greatly affects the resulting tonal interaction noise, while the sweep of a stator trailing edge shows less influence on the rotor-stator interaction. The duct mode characteristic of the cut-on modes is proved to be an important factor for the design of a swept stator. In addition, the soft vane design can further reduce the tonal interaction noise on a swept stator cascade.
Development of Hydrogen and Micromix Combustor for Small and Medium Size Gas Turbine of Kawasaki
Authors: Aoki Shigeki , Uto Takahiro , Takahashi Nobuaki , Okada Kunio , Kroniger Daniel , Kamiya Hiromu , Yamaguchi Masato , Ishimura Yuki , Wirsum Manfred , Funke Harald H.-W. , Kusterer Karsten 
Published: August 2024

Abstract
Kawasaki (KHI) has made various improvements and commercialized hydrogen gas turbines for existing diffusion combustors (0–100 vol.% H2, wet combustion) and lean pre-mixed DLE combustors (0–30 vol.% H2). However, it is challenging for conventional combustion technology to achieve dry low NOx emissions for 100 vol.% hydrogen. Kawasaki’s unique approach is the development of a new dry combustion technology for high hydrogen content fuel: the micromix (MMX) combustion. Kawasaki established this combustion technology to achieve low NOx for 100 vol.% hydrogen combustion. Micromix is based on a large number of miniaturized non-premixed-type flames, making this concept inherently safe toward flashback. Recently, Kawasaki has commercialized a gas turbine with a micromix combustor as the world’s first dry gas turbine capable for 100 vol.% hydrogen. This paper shows the latest improvements of the micromix combustor before the commercialization with focus on NOx reduction achieved by decreasing the fuel injection hole diameter, and the extension of the operational flexibility by applying a supplemental burner system. During demonstration tests with a 1.8 MWel gas turbine, it could be proven that this novel combustion concept meets Japan’s fundamental NOx regulations (84 ppm referred to 15 vol.% residual O2) for pure hydrogen and furthermore can be operated with natural gas/hydrogen blends in the range up to 50 vol.% H2 over the entire load range.
Nondestructive Creep Damage Evaluation for Ni-Base Superalloys of Controlled Solidification by Laue Method and Effect of Sample Thickness
Authors: Iwasaki Shinya , Kobayashi Daisuke , Tateishi Toshikatsu , Yokoyama Ryoichi , Omote Kazuhiko 
Published: August 2024

Abstract
Ni-base superalloys exhibit high deformation resistance characteristics, even at elevated temperatures. However, it is difficult to determine the state of damage from the appearance and observation of the microstructure. Although it is possible to quantitatively estimate plastic strain and creep strain using electron backscatter diffraction (EBSD), it is a destructive method. On the other hand, X-ray diffraction using the Laue method has the potential to non-destructively evaluate material damage.
In this study, we investigated the effect of sample thickness on the evaluation using the Laue method. We also compared the creep damage evaluation results of solidification-controlled Nibase superalloys using the EBSD and Laue methods and examined the possibility of non-destructive evaluation of creep damage using the Laue method.
The specimens used to investigate the effect of sample thickness were single-crystal blocks of Ni-base superalloys. Samples were prepared with five different thicknesses. Next, we compared the full width at half maximum (FWHM) of Ni-base superalloys in single-crystal blocks of different thicknesses. The measured FWHM were almost constant, independent of the thickness. This may be because the combination of subgrains and X-ray microbeams results in a sparser distribution of detected diffraction spots and a decrease in the number of high-intensity diffraction lines.
The specimens for comparison of the EBSD and transmission Laue methods were Ni-base directionally solidified (DS) superalloys, and damaged pieces were fabricated at several stages of creep testing up to rupture and evaluated using each method. As a result of comparing the EBSD and transmission Laue methods, the technique is capable of detecting microstructural changes associated with the later stages of creep deformation.
These results indicate the transmission Laue method is a promising non-destructive evaluation method because the FWHM does not depend on the sample thickness and can perform evaluations like the EBSD method.
Numerical Simulations of Ice Particle Transport at Representative Turbofan Compressor Conditions
Authors: Parker Liam , McGilvray Matthew , Gillespie David R. H. , Jones Geoffrey 
Published: August 2024

Abstract
Engine icing threatens compressor operation and service life. Ice crystal ingestion at cruise and descent phases of flight result in smaller, partial melted crystals entering the engine core. Here, crystals can stick to stationary surfaces driven by the presence of a water film, and evaporative and melting heat exchange with the mixed phase crystals. Modelling of the ice crystal cloud conditions is needed to understand threat areas within the core and operating envelope and to provide a reliable basis for ice accretion modelling at solid surfaces. A particle transport model in three-dimensions combining tracking, heat transfer, phase change along with a turbophoresis model is presented for non-spherical mixed phase ice crystals. These present a challenge to model effectively considering the complex and anisotropic geometries of ice crystals. Further, crystals can fragment, melt and agglomerate along the gas path. This affects heat transfer, phase change and ice porosity which will implicate the deposition location and composition. The model is validated against previous altitude icing wind tunnel experiments at LP/IP compressor operating conditions. Measured conditions for ice crystal mass flux provide experimental comparison against particle advection and phase change. Particle advection is modelled using an Euler-Lagrangian approach with two-way mass-energy coupling. Particle turbulent dispersion is modelled using a discrete random walk (DRW) model which is appropriate for flows where particles are primarily inertially-moderated. The model is seen to predict particle cloud mass distribution to within 15% of the experimentally measured total water content (TWC). Particle sizes between 2 μm and 131 μm and are modelled as spheroids. The variation in melt response is investigated relative to particle size and aspect ratio. High aspect ratio particles (AR &gt; 10) result in 5% to 20% phase change augmentation depending on the particle angle of attack. Two way coupling is shown to increase the melt ratio by up to 10% and reduce the total water content by up to 25% compared to one-way coupling. The model provides a framework for compressor stage ice particle transport and deposition in ice crystal icing conditions.
On the Combustion of Terpenes Biofuels and Pollutants Characterization Through High-Resolution Mass Spectrometry
Authors: Dagaut Philippe , Dbouk Zahraa , Benoit Roland 
Published: August 2024

Abstract
Terpenes are a class of hydrocarbon compounds naturally found in plants. They already have a variety of uses, such as flavor and fragrance additives. Also, they can be blended with conventional or synthetic liquid fuels. Understanding the kinetics of terpenes combustion is important for the development of cleaner combustion, as well as for evaluating associated air pollution and environmental impacts. Therefore, the oxidation of terpenes has been performed under well-controlled conditions. The cool flame oxidation of limonene, α-pinene, and β-pinene, terpenes commonly emitted by vegetation, was performed in a jet-stirred reactor under fuel-lean conditions, at 1 bar. Samples of the reacting mixtures were collected, dissolved in acetonitrile, and analyzed by high-resolution mass spectrometry. Direct flow injection and chromatographic separation by ultra-high-performance liquid chromatography were used. Heated electrospray ionization and atmospheric pressure chemical ionization were employed to characterize the products of oxidation. H/D exchange using D2O was performed for probing the presence of hydroxyl and hydroperoxyl groups in the products. The Brady reaction was used to assess the presence of carbonyl functional groups in the products. A large set of oxidation products, including highly oxidized organic products with 5 and more oxygen atoms, was observed. Besides, FTIR analyzes of gas products were performed. Aromatic and/or polyunsaturated products were detected. Graphic tools including Van Krevelen plots, aromaticity index, and maximum carbonyl ratio, and Venn plots were used to analyze the results. Reaction pathways are proposed to rationalize the results.
Characterization of Windshield Effectiveness in Improving Air Cooled Condenser Performance Under High Winds and its Impact on Steam Turbine Power Output
Authors: Bianchini Cosimo , Da Soghe Riccardo , Giannini Lorenzo , Gardner Andrew , Wilde Jamie 
Published: August 2024

Abstract
Large mechanical draft Air-Cooled Condensers (ACC) are prone to a decay of efficiency and to fan blade load fluctuations that largely increase in the case of high-speed winds and strongly depend on wind directions. A common and relatively simple strategy used to mitigate such wind losses is the installation of partially porous screens made of specialized fabric that acts as wind breakers.
A previous numerical study defined a CFD methodology able to quantify the ACC cooling capacity deficit due to wind and identified a ground installed vertical windshield in the shape of a cross as the most effective means to recover such losses under the most critical wind conditions.
In this paper, the same CFD model was used to characterize the windshield performance under different wind conditions covering a large range of wind speeds and directions. Furthermore, the analysis is expanded coupling the ACC heat transfer predicted by CFD with a thermodynamic model of the steam cycle that permitted to compute the thermal equilibrium between the steam and air side.
Feeding the thermodynamic model with appropriate weather forecasts, it was possible to compute the expected extra annual production thanks to the windshield installation. Providing installation costs and energy selling prices, the developed tool permits a reasonable estimate of the payback period for the investment in windshields which proved to vary largely depending on the energy selling price but was always less than a year for the selected locations.
Data-Driven Inverse Design Method for Turbomachinery
Authors: So Kwok Kai , Salamanca Luis , Ozdemir Firat , Perez-Cruz Fernando 
Published: August 2024

Abstract
A data-driven inverse design method based on neural networks is proposed for turbomachinery. In the devised methodology, design parameters are provided as input to the neural network, and performance attributes, e.g. efficiency, as output. Once trained, the network is used for inverse design, i.e. target performance values are prescribed to generate various design parameter sets. Through empirical experiments, it is observed that the true efficiency of the network-generated radial turbine and thrust bearing designs are in good agreement with the prescribed target efficiencies. Furthermore, the proposed model can be used to accurately generate designs beyond the range of the training data set, showing strong generalization properties. The proposed approach offers the additional benefit of easy implementation, being fully data-driven and not requiring any modifications to the data generation process. As long as data is available, the method can readily be extended to account for multi-component and multi-physics aspects. After a model is trained using a set of design parameters, the proposed method can also be used to generate a subset of design parameters for prescribed target attributes with ease. The data-driven inverse design method represents a novel design approach in the age of big data, and is highly relevant and applicable for turbomachinery designs where an abundance of design data, pairing design parameters and target attributes is available. Notably, through generating a large variety of accurate designs with improved performance, the proposed method effectively indicates trust regions in the design space where further design explorations could be carried out, showing a significant impact on optimisation strategies.
Experimental and Numerical Investigation of Hydrogen Combustion in a Dual-Swirl Burner for Aero-Engine Applications
Authors: Gövert Simon , Berger Johannes , Lipkowicz Jonathan Timo , Soworka Thomas , Hassa Christoph , Behrendt Thomas , Janus Bertram 
Published: August 2024

Abstract
Green hydrogen produced by electrolysis offers a high potential for reducing CO2 emissions and thus represents a promising approach for the decarbonization of aviation. However, propulsion systems based on direct hydrogen combustion require modified fuel injectors and combustion chambers to account for the particular combustion characteristics of hydrogen. Engineering those modifications requires the acquisition of experimental and numerical tools especially suited for this task and in the end validating them in a suitable environment. In this context, hydrogen combustion and its numerical simulation is presented with a dual-swirl burner in an optically accessible atmospheric combustor as an intermediate step. The fuel injector was originally designed to simulate kerosene combustion with natural gas at atmospheric conditions by producing a gas film with mixing properties similar to a kerosene film. In this study, this natural gas fuel injector is adopted for combustion of pure hydrogen. To ensure safe operation and to reduce the risk of flashback, fuel and air are injected non-premixed. Good flame stability and mixing, which leads to potentially low NOx values, is achieved by introducing a swirling motion into the flows. Therefore, the air is fed through a co-rotating dual-swirler configuration. In the circumferential shear layer in-between, hydrogen is injected axially with a co-rotating velocity component. In this study, the combustor is operated under atmospheric pressure at a globally lean equivalence ratio. While hydrogen and cooling air are injected at ambient temperature, the burner air is preheated to 376.2 K. Cooling air is lead along the inner walls of the heat shield for convective cooling and enters the combustion chamber at the outer walls where it forms a cooling film for the side walls. Further cooling air is introduced via downstream located dilution ports to reduce the temperature at the combustor exit. Measurements of OH* radical chemiluminescence as well as infrared radiation as a marker of the hot water vapor distribution have been carried out to identify the flame location and shape. The configuration is further analyzed by means of reacting Large-Eddy-Simulations using the Flamelet-Generated-Manifolds combustion model in combination with the Dynamic Thickened Flame model. The comparison of the simulation results with the experimental reference data shows that the flame lift of height and global flame spread are correctly predicted by the simulation for both operating conditions. However, the combustion model does not precisely capture the flame stabilization mechanism, leading to a radial offset of the flame front.
Experimental Investigation on the Dynamic Response of a Turbocharger Centrifugal Compressor in Surge Transitions
Authors: Silvestri Paolo , Marelli Silvia , Usai Vittorio 
Published: August 2024

Abstract
Centrifugal compressors play a critical role in various industrial applications, and understanding their operational behavior, especially during surge conditions, is essential for enhancing efficiency and reliability. Surge is a phenomenon that leads to significant pressure and mass flow rate fluctuations. Compressors can be damaged from surge instability, which results in vibrations and thermal stress. This study investigates surge transitions in centrifugal compressors by employing a comprehensive approach that integrates dynamic mass flow rate and pressure measurements using anemometric fiber film probes and high frequency piezoresistive pressure transducers together with dynamic structural response data.
To gain insight into the transition from the stable to the unstable region of the compressor, an extensive experimental analysis on a centrifugal compressor was conducted at the University of Genoa test bench for components of propulsion system. The activity involves measurements used to characterize and identify the behavior of the compressor in correspondence of surge inception conditions.
Measurements were conducted for different corrected rotational speed level stable and unstable operating points on the compressor characteristic curves including incipient and deep surge conditions were acquired, considering also different outlet circuit lines.
Pressure transducers and anemometric film probes were employed to gather data on the compressor’s fluid dynamics. Frequency and time-frequency data analysis techniques have been employed to examine the inflow pressure and the anemometric signal. The purpose is to identify their characteristics and define the compressor operation as stable or unstable. Synchronous averages, applied in the time domain, have proven to be effective for detecting incipient surge conditions jointly with variance computation. Additionally, statistical techniques, such as variance and spectral kurtosis, have been utilized for the detection in signals with strong additive noise of transient and non-deterministic contents may rise approaching instable conditions.
A method for system identifying in deep surge is introduced, particularly a correlation between the compressor circuit geometries and the operating condition of the turbocharger is proposed. This approach enhances the diagnostic capability of the monitoring system by providing a better knowledge of surge occurrence. The paper is aimed to provide information for the development of advanced control strategies and predictive maintenance protocols to mitigate surge-related issues and improve the overall performance and reliability of centrifugal compressors.