bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a Low-Pressure Section for Industrial Power Generation Application
Authors: Arcangeli Lorenzo , Aquilino Antonio , Brazzini Filippo , Cosi Lorenzo , Maceli Nicola , Rizzi Sara 
Published: August 2024

Abstract
The Low Pressure (LP) stages are critical components in any steam turbine product line, as their contribution has a significant impact on overall expansion and their specific operability design limits may pose restriction to the turbine operation.
The authors’ company designed a new family of LP stages for power generation applications aimed at improving the efficiency and the overall design of the existing low-pressure sections for 50 Hz and 60 Hz industrial power generation applications of a comparable annulus area.
Industrial power generation comprises a wide range of applications for fixed speed 50 Hz and 60 Hz LP stages, especially in Waste to Energy plants, Concentrated Solar Power plant, Geothermal plants, Combined Cycles plants, Captive Power plants and more recently, energy transition process power plants (e.g. green hydrogen production). This wide application mix establishes an ample set of requirements in terms, among the others, of off design performances, frequent start up, high exhaust pressure capability and capability to sustain operation in low load and erosion promoting conditions which poses a specific challenge in the definition of a single optimal design.
This paper will present a broad review of the typical operational and design requirements dictated by the various industrial power generation applications along with the summary of the all the phases of the design with focus on the technology related aspects of the different components developed, including exhaust system.
Experimental Measurements of Buoyancy Induced Flow in Rotating Cavities Under High Reynolds Number Conditions
Authors: Puttock-Brown Mark R. , Kanjirakkad Vasudevan 
Published: August 2024

Abstract
The buoyancy-induced flow structure and heat transfer in rotating cavities is a well-known conjugate problem. The disc temperatures affect the flow and vice versa. This creates a challenging environment to study as it is: three-dimensional, unstable, and unsteady. Further, the vast timescale range between the flow and thermal transients on the discs prove impractical to simulate within rapid engine design cycles, requiring validated reduced-order physics-based models. Literature has established the relationship between the temperature of the core and heat transfer and how this is affected by compressibility, resulting in a critical Reynolds Number at which disc Nusselt number is maximum.
This work presents new thermal measurements of a rotating cavity at engine representative conditions under elevated test section absolute pressure from the Sussex Multiple Cavity Rig. The axial throughflow temperature rise is recorded by shaft mounted thermocouple rakes, offering the opportunity for first-order energy balance estimates. By increasing the density of the throughflow air, this allows the investigation at Reθ and Gr rarely published from academic facilities, providing further insights into the interplay between the governing non-dimensional parameters. The results have shown, for all comparable cases of constant Ro, increasing Reθ has reduced disc surface temperatures. Despite elevated Gr ≥ 1013 and high temperature gradients, there is no conclusive evidence of thermal stratification and the associated sharp reduction in shroud heat transfer.
Multi-Objective Optimization and Chemical Reactor Network Modelling to Estimate the Minimum NOx and Ammonia Slip in an Aviation Combustor
Authors: Bobi Shahzad , Garai Priyankar , Rahman Ramees K. , Zamora David , Ahmed Marzuqa , Vasu Subith S. 
Published: August 2024

Abstract
Ammonia has been deemed an attractive option as a carbon-free fuel for power generation gas turbines to address greenhouse gas emissions and to deal with climate change. Recently, ammonia and its blends with hydrogen have been investigated as a prospective aviation fuel. However, high NOx emissions and unburnt ammonia slip during ammonia combustion make it challenging. This study explores chemical reactor networking (CRN) modeling and multi-objective optimization of NO emissions and NH3 slip for similar conditions of an aviation gas turbine. The parametric studies were considered for the equivalence ratio (0.9–1.4), ammonia fuel fraction (0.5–1.0), combustor inlet temperature (644–848 K), and inlet pressure (13–44 bar) at take-off, and high-altitude flight conditions. This simulation model was developed using Ansys Chemkin-Pro software, which consists of a rich burn stage as a network of ideal reactors. The results of CRN simulation indicate that a lean-to-rich equivalence ratio with 100% NH3/air combustion reduces NO emissions and raises NH3 slip trends in the primary stage. Adding hydrogen into the fuel mixture showed a slightly increased NH3 slip and decreased NO emissions at lower and higher inlet pressure and temperature. Moreover, results of optimization studies investigated minimum NOx emissions as low as 13, 38, and 100 ppm at take-off, cruise, and maximum altitude with 30 ms, 10 ms, and 5 ms, respectively, where NH3 slip was observed at less than 1 ppm in all cases of multi-objective optimizations.
CFD Study on the Effect of Rotor Leading Edge Erosion on the Performance of Single Stage Compressor
Authors: Jung Jin-sol , Son Changmin 
Published: August 2024

Abstract
As aircraft engines operate in various environments, they are subjected to adverse external factors, such as ice crystals, sand dust, corrosive gases, etc. which damage engine components. One common damage found in the engines is erosion in a compressor. Due to its rapid rotational speed, even minuscule particles can induce surface abrasions on the compressor airfoil, resulting in performance deterioration.
Considering the impact of compressor erosion, the sensitivity of the location and size of erosion in multistage compressors to its performance map remains an area for continuing research. However, there is very limited experimental data in the public domain, especially for multistage compressors. One and only experimental data available to the authors’ knowledge is a single-stage compressor test results with eroded NASA Rotor 35 airfoils. The rotor assemblies were built to represent three different combinations of nominal and eroded airfoils. The measured pressure fields at the downstream of rotor assemblies are compared. Noticeable difference in rotor performance is only shown near chocking region.
The present study aims to validate CFD against the measured performance of the single-stage compressor with eroded NASA Rotor 35 rotor assemblies. In addition, CFD analysis includes a ‘nominal’, non-eroded airfoil. The computational domain includes a full annular passage of the rotor and a single periodic passage of the stator. A commercial CFD package, Ansys CFX 2021 R2 was used for analysis.
As it was reported from experimental work, the predictions based on CFD showed negligible differences among the three configurations at the design condition. The review on the complete set of analysis matrix including off-design conditions will provide a more comprehensive understanding and useful guides for modelling the effect of erosion on compressor map.
A Modelica Based Integrated Air Vehicle - Novel Propulsor Architecture for Sustainable Aviation
Authors: Tristanto Indi , Thorpe Joseph , Palumbo Nunzio , Cino Andrea 
Published: August 2024

Abstract
To achieve the sustainable aviation target, the design of a novel propulsion architecture requires the ability to assess its performance and efficiency at air vehicle level. This is particularly important for those architectures requiring fuels with either low specific energy or low energy density, or even both.
This paper presents a consistent modelling tool to enable air vehicle level system performance to be considered during the design and operational analysis of a powerplant. A desirable feature is the ability to adjust the fidelity of each sub-system model according to the objective of a particular modelling phase. An equally important feature is the ability to protect intellectual properties owned by sub-system contributors. The paper is ended with an academic exercise comparing a conventional gas turbine, and a hybrid system of battery-boosted fuel cell powered regional aircraft to illustrate how the tool can be used to investigate challenges in designing a novel propulsion system.
A Hybrid Surrogate Modeling Approach for Data Reduction and Design Space Exploration of Turbine Blades
Authors: Ali Sazeed S. , Yadav Vikas S. , Nouri Behnam , Ghani Abdulla 
Published: August 2024

Abstract
The conventional iterative geometry optimization process for turbine blades using computer aided engineering (CAE) simulations is both cost and time consuming and has limitations in terms of computational requirements and data management. A particularly problematic aspect is that the generated 3D simulation data of computational fluid dynamics (CFD) and finite element analysis (FEA) cannot be fully reused for future optimizations. The data for multiple geometry variations of the turbine blade can range from several hundred gigabytes to multiple terabytes. This leads to difficulties in storing and accessing them for a longer period. To address this challenge, we introduce a methodology based on machine learning models for data reduction and forecast of 3D surface field data.
Specifically, we develop a convolutional variational autoencoder (VAE) that combines two models: the encoder and the decoder. The encoder transforms the input data into a representation of reduced dimensionality in a latent space, and the decoder reconstructs the input data from the given latent representation in its original space. The latent representation of the input data and the trained VAE together result in much smaller data amounts, solving the issue of data storage for future use. Furthermore, we train a fully connected feed-forward mutilayer perceptron (MLP) that learns the mapping of the geometry parameters, responsible for generating the variations, to the latent space. Thereby, we combine the MLP with the trained decoder of the VAE to our proposed multilayer perceptron variational autoencoder (MLP-VAE) hybrid neural network model. The MLP-VAE predicts the surface field data results for new and unseen blade geometry variations and generates their latent representations without any additional cost.
Combustor Operational Flexibility in the Ansaldo Energia GT36 Fleet
Authors: Sierra Sánchez Patricia , Pennell Douglas , Smith Richard L. R. , Wickström Anders , Gant Francesco , Boudy Frédéric 
Published: August 2024

Abstract
Ansaldo Energia has successfully introduced the GT36 H-class gas turbine to the market. The GT36 is equipped with a two stage Constant Pressure Sequential Combustion (CPSC) system, which consists of a premix burner system (Multi-Burner First Stage, MBFS) and a sequential burner (SB) in series within a can combustor architecture. The development and validation of the combustor system was accompanied by publications at recent ASME conferences, with a focus on fuel flexibility, turndown and future hydrogen applications.
In this paper, the optimized version of the CPSC system that is running commercially on various GT36 units will be described. Supported by field data, the paper will elaborate on important aspects of combustor operation, such as: Ignition and startup reliability, stable operation during engine load transients (including fast loading/de-loading, load rejection, and ancillary services such as primary frequency response), robustness against variable fuel properties, and operability under changing ambient conditions. Additionally, dedicated data is shown to demonstrate the extended turndown capability to below 20% relative load and the low emission levels from ignition to full load. The emission data covers fuel composition variation from virtually pure methane (&lt; 0.5% C2+) to higher order hydrocarbon compound concentrations of up to 14% C2+.
Integrating Location-Specific Non-Destructive Inspection Simulation With Probabilistic Damage Tolerance Assessment
Authors: Enright Michael P. , Zaman Yasin , Foucher Fabrice , Lonné Sebastien , Dubois Philippe , Leberre Stephane , Calmon Pierre 
Published: August 2024

Abstract
Conventional probability of detection (POD) curve development is an expensive process that may not adequately capture local parameters that can influence POD outcomes. Non-destructive evaluation (NDE) simulation has the capability to consider these parameters but requires information regarding the anomaly sizes that must be found. Probabilistic damage tolerance (PDT) can be used to quantify anomaly sizes that are associated with failure at specific locations throughout a component. In this paper, a methodology is presented for integrating NDE simulation (via the CIVA software) with PDT analysis of turbine engine components (via the DARWIN® software). High risk locations are identified using PDT analysis. Anomaly sizes and orientations that lead to failure are identified for the NDE simulation. The resulting POD curves are applied to PDT assessments to quantify the influence of NDE on fracture risk enabling the analyst to identify the locations in a component that may benefit most from NDE inspection. The methodology is illustrated for a representative gas turbine engine component.
Laminar Burning Speed Measurements of Hydrogen/Natural Gas Mixtures at 10 atm
Authors: Safdari Ahmed F. , Yovino Louis , Kim Gihun , Rahman Ramees K. , Vasu Subith S. 
Published: August 2024

Abstract
Fossil fuels, when burned in the air, release large amounts of carbon dioxide (CO2) and greenhouse gases (GHG) into the air, causing a significant increase in pollution. To reduce exhaust emission of fossil fuels on the environment, we can use natural gas (NG). Extending the lean burn area similarly reduces emissions of greenhouse gases (CO and CO2) and NOx pollutants. Temperature, pressure, and reactive mixture composition all influence measuring laminar burning speed (LBS). LBS is helpful because it (i) provides a measure of combustion efficiency and heat release rate; (ii) makes it possible to validate chemical kinetic mechanisms; (iii) provides turbine design engineers with a metric for the anticipated amount of time needed to burn the fuel charge. While studies on natural gas and hydrogen combustion near atmospheric conditions exist, very few investigations exist on high pressures in the literature. Here, we report data on natural gas/hydrogen LBS measurements up to an initial pressure of 10 atm and initial temperature of 296 K. To investigate its impact on LBS, a wide range of equivalence ratios were used. As part of the validation procedure for the results, they are also contrasted with the performance of comprehensive kinetic models.
Experiments on Structurally Mistuned UHBR Open-Test-Case Fan ECL5/CATANA
Authors: Brandstetter Christoph , Schneider Alexandra P. , Fiquet Anne-Lise , Paoletti Benoit , Ottavy Xavier 
Published: August 2024

Abstract
The operational capabilities of turbofan engines encounter limitations due to instabilities arising from tightly coupled interactions among aerodynamics, acoustics, and structural mechanics. Modern fans and compressors exhibit Non-Synchronous Vibration (NSV), leading to safety-critical blade oscillations. In contrast to self-excited phenomena such as flutter, NSV stems from the convection of aerodynamic disturbances that synchronize with blade eigenmodes. Understanding this phenomenon is challenging, as its intricate interaction patterns and the occurrence of flow separations constrain the predictive capabilities of current state-of-the-art methods.
To establish a comprehensive benchmark dataset on the aeroelastic behavior of modern Ultra-High Bypass Ratio (UHBR) architectures, the European CleanSky-2 project CATANA aimed to examine a carbon composite fan stage, ECL5, utilizing multiphysical instrumentation. Recently, experiments on a structurally tuned reference configuration were conducted, revealing highamplitude Non-Synchronous Vibration (NSV) at multiple subsonic speedlines. The observed interaction modes and instability onset differed significantly from numerical predictions using both LRANS and URANS with prescribed harmonic blade motion.
In an effort to enhance the dataset, two additional fan configurations with identical blade profile geometries were investigated: one featured a structurally mistuned rotor with approximately doubled frequency variation of all eigenmodes compared to the reference, and the other involved a case with locally increased tip clearance on individual blades.
This paper presents the experimental results of a sensitivity study and explores the influence of structural mistuning and tip clearance variation associated with manufacturing tolerances.
Contrary to the intended outcome, it will be demonstrated that the mistuned case exhibited higher blade vibration amplitudes than the reference case during NSV. Detailed instrumentation reveals that the mistuning pattern was effectively transferred to the rotating system, but aerodynamic mistuning, particularly concerning tip clearance, emerged as a dominant factor. The non-synchronous forced-response nature of NSV during highly throttled operation ultimately dictates the observed response levels under different conditions, necessitating a thorough analysis to evaluate the robustness of a specific configuration.
These results contribute valuable insights to the open dataset for the ECL5 configuration, benefiting the research community. Particularly noteworthy is the detailed capture of blade-to-blade variations in this research, which will prove instrumental in validating numerical methods.
Techno-Economic Analysis of Emerging Energy Storage Technologies for a Microgrid
Authors: Schmitt Joshua , Hofer Douglas , Pryor Owen , Khawly George , Karg Bulnes Fernando , McClung Aaron 
Published: August 2024

Abstract
With the growing need for decarbonization, microgrids that independently produce carbon-neutral power will become an important part of the solution. An analytical model has been developed based on the historical demand at Southwest Research Institute (SwRI). This model incorporates general energy production and storage technologies into a flexible framework for assessment of scenarios for a microgrid. For solar photovoltaics (PV), the model incorporates time-series renewable data on solar PV performance from the NREL System Advisor Model (SAM). The capital cost and operating cost information for storage and generation were sourced from public studies and were escalated to 2023 costs using inflation. Using these inputs, the analytical model projects the 30-year performance of the power generating system and applies economic parameters to establish a blended cost of electricity that is a levelized cost of electricity (LCOE) for the capital and operating cost of behind the meter assets along with any purchased electricity or natural gas from utilities. A variety of electricity producing technologies were examined, including PV, gas generator with carbon capture and storage (CCS), lithiumion battery, hydrogen production and utilization, and pumped thermal energy storage. For shifting PV generation in daily cycles, the storage systems were implemented as long-duration energy storage (LDES) with a minimum duration of 6 hours.
The trends in blended electric cost showed how electric energy consumed on the SwRI campus can be decarbonized by 40%, while reducing costs by about 12% through the addition of behind the meter PV generation alone. Adding storage to utilize curtailed PV increased system cost, but it improved decarbonization to 55% before reaching parity with present electric costs. Reaching 90% decarbonization with PV and LDES came at the cost of an additional 37% increase of blended costs. The trends showed that costs beyond 90% decarbonization increase dramatically because LDES became very large to balance longer trends in PV power production and reach 100% decarbonization. A combined system that installed a gas generator with CCS showed how the last 10% of decarbonization can be achieved without the dramatically escalating costs of a PV with LDES system alone beyond 90%.
Numerical Analysis of Oscillating Blade in Linear Cascade at Transonic Flow
Authors: S. Ragupathy , Kushari Abhijit , Keerthi M. C. 
Published: August 2024

Abstract
This paper explores the numerical simulation of stall flutter in transonic compressor blades. The primary objective is to characterize the flutter patterns observed in oscillating blades impacting stationary blades in a linear cascade arrangement. The study focuses on the STC-5 airfoil configuration, utilizing a cascade assembly with five blades arranged in a linear manner. The oscillation amplitude is set at 2 degrees for the blades adjacent to the center blade (0 degrees) Both steady-state simulations and time-dependent analyses, considering three incidence angles and varying reduced frequencies and IBPA’s. The study underscores the significant role of surface pressure fluctuations induced by shock oscillation in determining unsteady aerodynamic forces affecting blade stability. These fluctuations primarily resulted from the movement of the shock impingement point on the blade surface. It reveals that the oscillation of the separated region, resulting from shock-boundary layer interaction, contributes to additional pressure fluctuations along the blade surface. Both shock oscillation and the movement of the separated region are identified as critical factors influencing unsteady aerodynamic behavior and vibration characteristics in the transonic compressor cascade.
Analysis and Optimization of the Fatigue Damage Accumulation Under Transient Vibrations of Mistuned Bladed Disks
Authors: Jing Tong , Zang Chaoping , Petrov Evgeny 
Published: August 2024

Abstract
This paper develops an efficient method for calculations of stress levels, accumulation of HCF and mistuning optimization aimed at the reduction of the fatigue damages for mistuned bladed disks under transient vibrations caused by variation of the rotation speed in the vicinity of resonance frequencies. The expressions for the sensitivities of the stress intensity at critical locations, and fatigue damage at loading cycles concerning the mistuning are derived analytically, providing high accuracy and speed of their evaluations. A gradient-based optimization method based on the sensitivities is applied to find the blade mistuning patterns providing the minimum and maximum fatigue damage accumulated during gas-turbine acceleration or deceleration of a mistuned bladed disk for extending the service life. The method uses realistic large-scale finite element modelling for bladed disks, accounting for the varying damping and excitation loads with amplitude and frequency spectrum changing with rotation speed. The method has been implemented in a computer code. The fatigue accumulation caused by the transient vibration has been studied using a realistic bladed disk model. The gradient-based optimization search for mistuning patterns providing the minimum and maximum fatigue damage accumulation during rotor acceleration is performed.