bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conjugate Heat Transfer on the Effect of Impinging Distance for Film-Cooled Blade Leading Edge With Staggered-Oblique Impinging Jets
Authors: Li Hongye , Du Qiang , Xu Qingzong , Xu Jiawei , Xu Guangyao , Liu Haoyang , Wang Pengfei 
Published: August 2024

Abstract
As turbine inlet temperature gradually increases, cooling demands on the blade leading edge become notably more pronounced. Staggered-oblique impingement scheme has been proved to be a favorable scheme for achieving great cooling performance while ensuring a uniform temperature distribution on the blade leading edge. Conjugate heat transfer simulations are conducted to investigate the effects of impinging distance on the flow structures and heat transfer characteristics of film-cooled blade leading edge with staggered-oblique impinging jets. Three different impinging distances (L/djet = 3, 4, 5) are discussed at jet Reynolds number of 6000, 12000, and 18000 using a validated SST k-ω turbulence model. Results indicate that Nusselt number and overall cooling effectiveness are enhanced by increasing jet Reynolds number. With an increasing impinging distance, the impingement stagnation point moves far away from the blade stagnation line, enlarging the influenced target area. However, this leads to a reduction in the area-averaged Nusselt number due to diminished wall jet momentum. As the impinging distance increases, there is a slight increase for the area-averaged overall cooling effectiveness on the concerning leading edge wall, while a decrease is observed in the mainstream stagnation region. Moreover, higher impinging distances contribute to improved temperature uniformity on the leading edge external wall. Consequently, the staggered-oblique impingement scheme with impinging distance of L/djet = 4 appears to be the most optimal choice.
Modelling and Optimisation of Energy Systems: Lessons Learned From Six Years of Project Work With Master’s Students, Fostering a Systemic Approach
Authors: De Paepe Ward 
Published: August 2024

Abstract
Engineering students, especially those in the field of mechanical engineering, often tend to focus on specific components or fields, and in doing so, they may overlook the broader system in which these components are used and operate. This issue becomes particularly pronounced when addressing the ongoing energy transition, which demands a systemic approach to achieve sustainable energy production. At the University of Mons (UMONS), our Energy System Modelling and Optimisation course and related project are designed to instil this systemic perspective in our students. In this project, we challenge our first-year master’s students to integrate their specialised knowledge of energy system components, specifically focusing on turbomachinery components, to simulate and optimise a thermal energy system. Through an integrated approach that includes literature reviews, group work, discussions, presentations, and self-evaluation, we aim to enhance their systemic analysis and thinking skills. This paper presents a six-year overview of the project, detailing continuous improvements and evaluations and outlining our future plans for further enhancements. The projects encompassed modelling a micro Gas Turbine (mGT) cycle or a Combined Cycle Gas Turbine (CCGT) (with or without reheat), its optimisation using deterministic optimisation methods and the evaluation of off-design performance employing commercial software. Context, course content, project objectives, and evaluation are shared and discussed. Finally, lessons learned, key messages, and points for improvement are indicated and formulated, as well as the steps required for the implementation of this method in a course in general, allowing for the improvement of educational practices in the future. The key takeaway message is that communication is essential.
Three-Dimensional Fluid Topology Optimization for Intakes and Exhausts Flow Uniformity
Authors: Furino Stefano , Canova Alessandro , Pietropaoli Marco 
Published: August 2024

Abstract
In this work, Fluid Topology Optimization (TO) is used to optimize flow uniformity for intake manifolds and heat exchangers of industrial gas turbines. In manifold intakes, the solver minimizes the inflow distortion to the intake, while preserving mass flow, minimizing losses, and adopting a design that can be manufactured with standard processes. The core of the methodology is an in-house Fluid Topology Optimization solver, ToffeeX, extended in this work to minimize the deviation between the velocity profile at the outlet and a specified target. The TO method relies on emulating the natural sedimentation process inside a design domain. The fluid dynamic system is numerically solved, and a scalar design variable is iteratively updated following a Lagrangian optimization approach which ensures meeting the constraints as well as the minimization of the objective functions. In this regard, the optimization is multi-objective. Pressure losses and flow profile variance are simultaneously minimized. At the end of the process, the design solution is the set of regions with high impermeability (solid structures). The optimizer generates coherent structures that channel the flow to match the velocity target while maintaining low-pressure losses. Different levels of complexity and deviation coefficient are shown accordingly with the relative weights imposed on the multi-objective optimization. Even though related theoretical modelling and similar approaches have been briefly described in the literature, this is the first time that the algorithm has been successfully applied to a realistic geometry with correct Reynolds and in its operating conditions.
Dynamic Performance and Control Analysis of a Supercritical CO2 Recuperated Cycle
Authors: Tucker Swatara , Maccarini Simone , Mantelli Luca , Traverso Alberto 
Published: August 2024

Abstract
Supercritical CO2 (sCO2) power cycles represent a promising technology for driving the energy transition. In fact, various research projects around the world are currently studying the possible applications of this technology, which is characterized by high efficiency, competitive costs, compact machinery and enhanced flexibility with respect to competing systems, such as steam-based power cycles. Within this context, the EU-funded SOLARSCO2OL project aims to build a MW-scale sCO2 pilot facility coupled with a concentrated solar power (CSP) plant. A transient model of the demonstration plant was previously developed in the TRANSEO simulation tool by the Thermochemical Power Group (TPG) of University of Genoa to study the operational envelope of the cycle.
In the present work, the model is upgraded to take into account all the relevant fluid-dynamic and thermodynamic phenomena affecting the transient behaviour of the plant. In particular, a detailed crossflow sCO2-air cooler model is now included, which is crucial for assessing the compressor inlet temperature behaviour and controllability. The system has to comply with several constraints, such as compressor surge margin, turbomachinery inlet temperatures, and compressor inlet pressure. The desired net power output should also be guaranteed. The dynamic responses of the system to step variations in various input variables were recorded and used to design and tune the main operational controls. The input variables considered include: 1) compressor rotational speed, 2) anti-surge valve fractional opening, 3) mass flow rate of air through the cooler, 4) mass flow rate of the molten salts through the heater, and 5) CO2 inventory for injection and extraction of working fluid.
The implemented control structure includes proportionalintegral-derivative controllers (PIDs), feedforward action, and their combinations. The controllers are tuned using a mix of established methods, such as Cohen-Coon response-based PID tuning and adjustments from feedforward controls. The feedforward controls were designed taking into account the steady-state values from off-design simulations, as well as the interactions between each controller and the other controlled variables. The final control setup is tested on various power ramps to assess the capability of the prototype cycle in load following and disturbance rejection, showing very good performance in set-point tracking.
STEP 10 MWe sCO2 Turbine Commissioning
Authors: Moore J. Jeffrey , Klaerner John D. , Wade Jonathan L. , Mortzheim Jason , Jothiprasad Giridhar 
Published: August 2024

Abstract
A 10 MWe sCO2 turbine was developed for the Supercritical Transformational Electric Power (STEP) demo pilot plant, which is a supercritical carbon dioxide (sCO2) test facility located at Southwest Research Institute (SwRI) in San Antonio. The plant was fully assembled for simple cycle operation, and the initial commissioning of the turbine was performed. The project was developed in partnership between Southwest Research Institute, GTI Energy, and GE Vernova Research Center and is sponsored by the U.S. Department of Energy (DOE) as part of the $169 million STEP Demo project. The goal of the program is to demonstrate cycle efficiency in both the simple and recompression recuperated Brayton cycle. Initial testing in the simple cycle configuration will be performed with turbine inlet temperatures up to 500°C. In the RCBC configuration at 700°C, the turbine has a 16 MW output yet weighs under 100 kg, making it one of the highest power densities of any industrial turbine. This paper provides design and assembly information and commissioning results for turbine ancillaries like lube oil and dry gas seal systems. The initial rotation of the turbine is described along with the test results of the over-speed trip system. Other mechanical test data will be presented, including radial vibration and thrust position, along with the operating conditions of the test loop.
Design Options for GHG Reduction of Gas Turbine Driven LNG Plants
Authors: Taher Matt , Meher-Homji Cyrus B. , Gülen S. Can 
Published: August 2024

Abstract
Gas turbines have been traditionally used as drivers of refrigeration compressors in LNG liquefaction plants. The current trend is toward increasing the overall efficiency while reducing greenhouse gas emissions.
The main sources of carbon emissions in LNG liquefaction plants include CO2 in feed gas and CO2 in flue gas from the exhaust of gas turbines and fired heaters.
In LNG liquefaction plants, CO2e/tonne LNG produced is typically in the range of 0.2 to 0.4. In order to further reduce the CO2e/tonne LNG produced a combination of hybrid drives (e.g., gas turbine and steam turbine, or gas turbine and motor) can be used for the refrigeration compressors. Also, bottoming power cycle(s) such as steam Rankine cycle or organic Rankine cycle can be employed to recover the waste heat energy from the gas turbine exhaust.
This paper explains the design options and challenges involved in decarbonization of gas turbine driven LNG liquefaction plants in both brownfield and greenfield applications. Moreover, challenges associated with burning high hydrogen-content fuels in gas turbines and different transcritical CO2 compression pathways are briefly addressed.
Efficiency Gains in a Water-Enhanced Turbofan Compressor – A CFD Study
Authors: Zawadzki Natan , Szymański Artur , Igie Uyioghosa 
Published: August 2024

Abstract
In pursuing energy-efficient, low-emission propulsion concepts, civil aviation takes a renewed interest in compressor water injection (CWI). The unprecedented heat capacity of water can be utilised for effective compressor cooling through evaporation, thus substantially reducing the highly temperature-sensitive nitrogen oxide (NOx) emissions formed in the combustion process. It is also well known that evaporative cooling increases thermodynamic cycle efficiency and thus improves specific fuel consumption. However, relatively little consensus exists on the exact effects of CWI on compressor efficiency and operating limits, raising concerns about the deployment of water injection in aero-engines.
A generic turbofan compressor was studied in detail using Computational Fluid Dynamics (CFD) analysis to shed light on how finely atomised water affects compressor efficiency. The compressor layout comprised an integrated fan stage and a two-stage booster, and water was introduced at the inlet to the core. Take-off operation was simulated under dry (no water) and wet conditions with 1% and 2% injection rates (water to air mass) and varying droplet diameters of 10 and 20 microns. A universal, second thermodynamic law approach was used to quantify the overall entropy generation in the compressor.
The study demonstrated that compressor inter-cooling by evaporating water reduces entropy generation of compression at a rate that can supersede the entropy yield due to phase change. For very small droplet sizes and a moderate injection rate, a staggering 4% efficiency gain was projected when compared to the dry case with no water injection, thus reaffirming the performance benefit of a wet-operated compressor.
Using Simultaneous Differential Scanning Calorimetry and Thermogravimetric Analysis to Develop Braze Processes for Porous FELTMETAL™ Abradable Seal Material
Authors: Volpe Erin , Motyka Elaine , Roeseler Stefan , Plessinger Ryan , Noyes Tyler , Kweder Jonathan 
Published: August 2024

Abstract
The diffusional solidification of high-temperature brazing compounds interacting with open-pore metallic FELTMETAL™ (FM) materials was investigated using simultaneous differential scanning calorimetry analysis and thermogravimetric analysis (DSC-TGA). As a sintered particle material with an open-pore structure and high total pore volume, FM is an effective abradable seal material primarily used to sustain pressure differentials between stages in propulsion and power generation turbines. FM is commonly vacuum brazed into the turbine stage directly to the outer shroud or backing ring and the braze layer affects the pore structure and properties of this abradable. To facilitate the overhaul and repair of FM abradable seals while in-field and away from a particular service center, investigation into factors affecting non-vacuum brazing processes to bond FM abradables was done using simultaneous DSC-TGA and metallography. Previous work indicated that oxidation of the alloys can begin below the solidus of the brazing compound under a cover gas but that the presence of boron in the brazing alloy can increase the oxidation onset temperature, thus reducing the extent of oxidation. In this work, further investigation was done by including the factors of 1) type of cover gas, 2) heating rate, and 3) type of braze compound. This research demonstrates that simultaneous DSC-TGA can be used to determine which of these factors most facilitate non-vacuum brazing, specifically by minimizing oxidation, achieving sufficient eutectic phase transformation, and forming a diffusional bond. Further, metallography confirmed the diffusional solidification required for bonding the abradable material and extent of oxidation indicated by the DSC-TGA results.
A Framework and Approach for Leveraging Unsteady Response in Turbocompressor Flowfields
Authors: Krivitzky Eric M. , Larosiliere Louis M. 
Published: August 2024

Abstract
Based on the thesis that critical destabilizing flow structures exhibit coherent response to periodic excitation and can be usefully organized via tuned periodic forcing, the work presented herein emphasizes the dynamical behavior of a representative compressor flowfield under periodic transients and the difficulty in extracting useful information on flowfield response in the poststall regime. The paper begins by developing a surrogate model to understand the onset of rotating stall. This model takes the form of a two-dimensional (2D) linear cascade, which serves as a simplified representation of essential turbocompressor flow dynamics. Steady and unsteady Reynolds-averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) modeling is conducted on both single and multi-passage domains. This analysis aims to highlight the advantages and limitations of domainperiodic extent, providing insights into the behavior of the compressor flow under different conditions. The research evaluates both established and developing rotating stall phenomena from a passage control volume perspective. This approach helps identify dynamical traits and underlying flowfield features that contribute to stall inception and development.
Stability analysis and resolvent analysis techniques are applied to the surrogate compressor flowfield to understand the causes of instability onset and potential mechanisms for controlling spike-type stall inception structures. These analyses provide valuable insights into the dynamics of rotating stall and strategies for managing its effects. The paper concludes by demonstrating an example approach for managing rotating stall, showing promising results for improving flowfield robustness to destabilizing perturbations. This approach involves the implementation of tailored periodic forcing to mitigate the effects of stall and enhance compressor usable work transfer.
Investigations on Unsteady Flow Structure Formation in Tandem Bladed Axial Flow Compressor Stage
Authors: Singh Ajey , Mistry Chetankumar S. 
Published: August 2024

Abstract
The axial compressors suffer from the risk of flow separation upon increasing the loading beyond a certain limit due to increased boundary layer thickness on blade surface. The aerodynamic loading of axial compressors can be enhanced by implementing tandem configuration on rotor. The tandem configuration re-energizes the stalling boundary layer over blade suction surface as well as increases the overall loading of the blade. This increase in loading comes at the cost of increased blade row interaction between rotor and stator which impacts stage stability and losses. This study explores the unsteady rotor-stator interaction at design point of an experimental tandem bladed axial flow compressor. The axial compressor stage consists of highly loaded tandem bladed rotor and single bladed stator fine-tuned to match the dual wake rotor exit flow. The stage has a high mean flow coefficient of 1.05 and design pressure rise of 1400 Pa. The tandem configuration results in impingement of dual wakes emanating from the rotor on the downstream stator resulting in unconventional flow structure on the stator entry. The steady state simulations predict the overall flow field but important rotor-stator aerodynamic interaction is undermined due to numerical averaging at the interface plane. The experimentation analysis though real, is limited to finite number of measuring stations for detailed analysis. Important flow interactions within the rotor and stator passage is difficult to access in experimental program due to limitations of probe placement and associated technicalities. Hence a detailed unsteady numerical investigation has been carried out to explore the flow structure at design mass flow rate. The unsteady computations are performed by blade row transformation methods using ANSYS CFX. The effect of radially varying loading is pronounced on the unsteady aerodynamics of stage. The study is carried out at 60% axial distance between rotor and stator. The tandem configuration leads to formation of dual wakes from the rotor. The radial variation in loading and tandem nozzle strength leads to interaction of fore blade wake with nozzle flow for part span and continuation of distinct wakes for rest of the span. This sets out a highly three dimensional flow incidence for the stator leading to high bpf oscillations inside the stator passage. Overall this contributes explores the propagation of unsteadiness from rotor to stator domain.
Experimental Investigation of Rotor Vibration Induced by Rotor-Stator Rubbing With Soft Coating
Authors: Ma Ruixian , Lei Xinliang , Wang Wen , Liao Mingfu 
Published: August 2024

Abstract
Rotor-stator rubbing is common in aero-engines, and the resulting vibration characteristic is affected by the coating material and the structure of rotor and stator. Partial rubbing between a soft rubber coated casing and seal labyrinth teeth on a thin-shell rotating drum is investigated. The vibration response of the drum and the rear end of the rotor is analyzed from the perspective of time, frequency and hologram domains. The time waveform of the drum is significantly distorted by rubbing, resulting in strong fluctuations of the vibration amplitude. The rubbing is observed within a very short time, followed by recovery of stable vibration of the rotor. Rotor-stator coupling vibration is excited by this studied rubbing. The natural frequencies corresponding to the pith diameter vibration modes both of the drum and the casing can be observed in the vibration spectrums of the drum. The synchronous forward whirl is suppressed to some extend by rubbing, whereas the synchronous backward whirl is enhanced. The smaller the whirl amplitude ratio between the forward whirl and backward whirl, the more serious the rubbing. The vibration at the rotor rear end is hardly affected.
IncC plasmid genome rearrangements influence the vertical and horizontal transmission tradeoff in
Escherichia coli
Authors: Allain Margaux , Morel-Journel Thibaut , Condamine Bénédicte , Gibeaux Benoist , Gachet Benoit , Gschwind Rémi , Denamur Erick , Landraud Luce 
Published: August 2024

ABSTRACT

It has been shown that an evolutionary tradeoff between vertical (host growth rate) and horizontal (plasmid conjugation) transmissions contributes to global plasmid fitness. As conjugative IncC plasmids are important for the spread of multidrug resistance (MDR), in a broad range of bacterial hosts, we investigated vertical and horizontal transmissions of two multidrug-resistant IncC plasmids according to their backbones and MDR-region rearrangements, upon plasmid entry into a new host. We observed plasmid genome deletions after conjugation in three diverse natural
Escherichia coli
clinical strains, varying from null to high number depending on the plasmid, all occurring in the MDR region. The plasmid burden on bacterial fitness depended more on the strain background than on the structure of the MDR region, with deletions appearing to have no impact. Besides, we observed an increase in plasmid transfer rate, from ancestral host to new clinical recipient strains, when the IncC plasmid was rearranged. Finally, using a second set of conjugation experiments, we investigated the evolutionary tradeoff of the IncC plasmid during the critical period of plasmid establishment in
E. coli
K-12, by correlating the transfer rates of deleted or non-deleted IncC plasmids and their costs on the recipient strain. Plasmid deletions strongly improved conjugation efficiency with no negative growth effect. Our findings indicate that the flexibility of the MDR-region of the IncC plasmids can promote their dissemination, and provide diverse opportunities to capture new resistance genes. In a broader view, they suggest that the vertical-horizontal transmission tradeoff can be manipulated by the plasmid to improve its fitness.