bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three-Dimensional Mode-I Fatigue Propagation of a Tangential Surface Crack in a Sub-Component Test Specimen Featuring the Disk Post of a Turboshaft Engine’s First-Stage High-Pressure Turbine
Authors: Yaren Mehmet Faruk , Bilgiç Ersin , Ayhan Ali Osman , Öztürk Umud Esat , Ertekin Şevket 
Published: September 2023

Abstract
Mode-I fatigue crack growth (FCG) simulations are performed for a tangential surface crack initiated at the highest-stress location of the bottom slot surface of a uniaxially-loaded sub-component test specimen. The specimen represents the disk post of a turboshaft engine’s first-stage high-pressure turbine. All three modes of the stress intensity factors (SIFs) along the growing crack fronts are calculated using three-dimensional (3-D) enriched finite elements. However, as the applied uniaxial loading mimics the centrifugal force of the assembled blades, as an approximation to the truly 3-D problem, the crack is initiated and grown in the corresponding tangential plane using only the mode-I SIF distributions in the employed crack growth law. Having computed the new coordinates of all crack front nodes in the original tangential plane, the parameters of the best-fit ellipse are calculated and the finite element model is updated accordingly to contain the incrementally updated new surface crack. The procedure is then, repeated until SIFs reach the fracture toughness. Using the SIFs from the described procedure, the FCG life is also calculated and compared to those obtained from empirical formula-based predictions using the radial and first-principal stress gradients along the possible directions of crack growth and the differences in the results are highlighted.
DLN Evo Combustion Technology Development for a High-Hydrogen Flexible F-Class Retrofit
Authors: Hughes Michael J. , Berry Jonathan D. , Zhao Wei , Crawley Brad , Onyima Travis , Feiz Homayoon , Paasche Elizabeth , Cretegny Laurent , Hong Seung-Hyuck (John) , Genova Tommy , Bower Hannah 
Published: September 2023

Abstract
GE Gas Power is nearing completion of technology development towards a retrofittable Dry Low NOx (DLN) combustion system for F-Class gas turbines. The “DLN Evo” combustor is envisioned to give existing power plants a path to decarbonize by significantly increasing their Hydrogen capability vs. current GE DLN systems. Hydrogen may be from any source be it electrolysis, reforming, ammonia, or other. Further attributes of the DLN Evo that may benefit operators include reduced min turndown load, reduced NOX emissions, reduced startup emissions, and increased fuel flexibility compared to today’s DLN 2.6+ based systems. This program builds on previous internal technology development programs, previous collaborations with the US Department of Energy, and the successfully fielded DLN 2.6e combustion system currently in operation on the latest GE HA class gas turbines. The DLN Evo combustor is the application of GE Gas Power’s latest experience and most advanced technology to F-Class as turbines.
This paper describes innovative approaches and technologies applied to create the new system. The Three Key Technology elements are the Compact Flames Micro Mixer (CFMM), Next Gen Axial Fuel Staging (NG-AFS) injectors, and unibody cooling that integrates with the Axial Fuel Stage (AFS). These technologies are, for the first time, applied to a can-annular system, and further advanced through extensive analytical simulation and screened via subscale testing at GE Research (GER). The full-scale system was manufactured and has completed a series of shakedown tests at GE Gas Power’s Gas Turbine Technology Lab (GTTL) in Greenville SC. Initial test results are summarized within.
Aerodynamic Design and Performance Optimization of a Centrifugal Fan Impeller
Authors: Avşar Gökhan , Ezertaş Ahmet Alper , Başkan Perçin Özge 
Published: September 2023

Abstract
This study aims to optimize the impeller geometry of a backward-curved blade centrifugal fan in a helicopter oil cooler to improve the aerodynamic performance of the impeller. The study consists of three main parts: aerodynamic design and parametrization of the impeller, numerical analysis of impeller performance, and multi-objective design optimization to maximize fan static pressure and total to static isentropic efficiency. In the first part, a one-dimensional impeller design was performed using quasi-experimental methods and a direct optimization method with the multi-objective genetic algorithm, and the impeller geometry was parameterized through a commercial tool. The three-dimensional flow through the impeller was solved in the second part with a commercial computational fluid dynamics tool. The Reynolds-averaged Navier-Stokes equations were solved on a multi-block grid, and a second-order accurate finite volume method is employed. The most appropriate turbulence model and grid size were selected considering time, cost, and fidelity. In the third part, a sensitivity analysis was performed with the design-of-experiment method, and the parameters that affect the objective function most significantly were determined. A multi-objective design optimization based on a non-dominated sorting genetic algorithm was performed with the Kriging response surface method, and Pareto-optimal solutions were obtained. Results show that, at the design point, there is a 9.6% and 0.96% increase in the fan static pressure and total to static isentropic efficiency, respectively. Trained kriging response surface model predicted the fan static pressure and total to static isentropic efficiency with an error of 0.12% and 0.33%, respectively.
Prediction of Flow Separations in Turbine Center Frames Using Support Vector Machines and Random Forests
Authors: Staggl Marian , Sanz Wolfgang , Leitl Peter , Kurzthaler Maximilian , Pieringer Paul 
Published: September 2023

Abstract
The reduction of overall fuel consumption has become one of the main targets in developing new aero engines, where an increasing bypass ratio has proven to be an efficient way to achieve this goal. For widely spread two-spool configurations, this directly impacts the turbine center frame (TCF), located between the high- and low-pressure turbine. For higher bypass ratios, the component has to deal with bigger radial offsets and stronger curvatures, making the channel prone to flow separation and all the undesirable side effects. A large number of parameters and nonlinear interactions between them make it very challenging to define limits within the parametric space beyond which flow separations may occur. In order to investigate this behavior, a large data set of CFD calculations is created, comprising multiple geometrical and boundary-related parameters. The data set is used to train random forest classifiers (RFC) and support vector classifiers (SVC) to predict the appearance of flow separations for given parametric combinations. Both algorithms are tested on a separate data set and are compared in terms of accuracy. Further investigations are dedicated to the identification of the most crucial parameters. Finally, a linear SVC is used to derive an easily interpretable limit in parameter space, in order to avoid flow separations.
Research on Automatic Aerodynamic Performance Optimization for Flue Gas Turbine Blades Under Multiple Conditions
Authors: Yao He , Liu-Xi Cai , Jia-Wei Yao , Yan-Fang Hou , Yun Li 
Published: September 2023

Abstract
Flue gas turbine is one of the important equipment to realize waste heat reduction and energy recovery, which is widely used in electric power, petroleum, chemical industry and other fields. To address the problem of serious local flow loss in the rotor cascade and low aerodynamic performance due to unreasonable aerodynamic design of single-stage flue gas turbine, an automated multi-objective optimization platform is built for turbine blades redesign. The platform is based on the Metamodel of Optimal Prognosis (MOP) which combined with RANS solution techniques and parameter sensitivity analysis. Under the mass flow constraint, thickness distribution of rotor and angles of inlet on camber line are design variables, the optimization objective is maximum isentropic efficiency under multi-conditions. The study results show that the optimized blade efficiency is increased by about 0.38%, 0.35% and 0.45% under different conditions. Severe flow separation on suction side of rotor is alleviated. The aerodynamic performance of the turbine blade is better than that of the reference design. This parameter automatic optimization platform can realize the dimension reduction of design space, and provides a fast and accurate solution to the typical 3D multi-objectives and multi-conditions design problem of turbomachinery in engineering practice.
Techno-Economic Assessment of CO2 Based Power to Heat to Power Systems for Industrial Applications
Authors: Trevisan Silvia , Mehdi Shamsi Syed Safeer , Maccarini Simone , Barberis Stefano , Guedez Rafael 
Published: September 2023

Abstract
The industrial sector is a major source of wealth, producing about one-quarter of the global gross product. However, industry is also a major emitter of CO2 and it represents a key challenge towards achieving the worldwide CO2 emission reduction targets. Nowadays, about 22% of the overall energy demand is heating for the industrial sector, generating about 40% of the global CO2 emissions. Additionally, 30% of the final energy demand of the industrial sector is electricity. Solutions to decarbonize the industrial sector are needed. This work presents the techno-economic assessment of four different molten salts based power-to-heat-to-heat and power solutions aiming at decarbonizing the industrial sector, requiring medium temperature heat. The systems are studied under different electric markets. Dispatch strategies and system sizing are identified to ensure optimal techno-economic performance. The main performance indicators investigated are the levelized cost of heat and electricity (LCoH and LCoE), the operational expenditure, and the attainable savings with respect to alternative business as usual solutions. The results highlight that the proposed system can be cost-competitive, particularly in markets characterized by low electricity prices and high daily price fluctuations, such as Finland. In these locations LCoE as low as 100 €/MWh and LCoH lower than 55 €/MWh can be attained by the base system configuration. The introduction of high temperature heat pumps can provide further LCoH reduction of about 50%. This study sets the ground for further power-to-heat-to-heat and power techno-economic investigations addressing different industrial sectors and identifies main system design strategies.
Thermodynamic Assessment of a Combined Cycle Gas Turbine With Exhaust Gas Recirculation Under Part-Load Operation Toward Carbon Capture Penalty Reduction
Authors: Verhaeghe Antoine , Mendoza Morales Maria Jose , Blondeau Julien , Demeyer Frederiek , Bricteux Laurent , De Paepe Ward 
Published: September 2023

Abstract
Performing Exhaust Gas Recirculation (EGR) is a solution to reduce the negative impact of applying Post-Combustion Carbon Capture (PCCC) on Combined Cycle Gas Turbine (CCGT) power plant. However, knowing that CCGTs will operate most of the time under part-load conditions, to back-up renewable production, the impact of using EGR during part-load CCGT operation is still unclear. Therefore, the objective of this work is to investigate different operating strategies for the application of EGR under full and part-load CCGT operations. To this end, an Aspen Plus model of the CCGT has been built and validated using data from Thermoflow, to which an EGR loop has been added. The PCCC unit is not modelled in this work and will be addressed in future work. The results show that keeping the turbine inlet temperature constant is the operating strategy that maximizes CCGT performance when EGR is applied. In contrast, working with a constant turbine exhaust temperature degrades performance. Therefore, the load control strategy currently used for heavy-duty gas turbines, which follows a fixed turbine exhaust temperature profile, will induce a performance reduction when EGR is applied. A strategy based on a turbine inlet temperature, rather than an exhaust temperature setpoint, would improve performance. Finally, EGR provides flue gas characteristics more favourable to carbon capture in terms of size, performance, and flexibility.
Experimental 3D Analysis of Flame Propagation in a Lean-Premixed Swirl Burner Operated With Hydrogen
Authors: Flebbe Saskia Martina , Tartsch Simon , Sattelmayer Thomas 
Published: September 2023

Abstract
Highly reactive fuels increase the flashback propensity in stationary gas turbines when operated under lean premixed conditions. This leads to undesired events such as flame propagation and flame anchoring. In this study, the flame propagation as well as the propagation to anchoring transition is experimentally investigated for a premixed burner with centerbody and fuel injection in the swirler. The burner is operated with 100% hydrogen as fuel under atmospheric pressure. The preheat temperature corresponds to engine conditions. The flame behavior at different bulk flow velocities is analyzed by means of OH*-chemiluminescence high speed imaging. A 360° optical measurement technique was established to identify the flame propagation to anchoring transition characteristics. The experimental results reveal that the flame propagation through the burners mixing tube exhibits three phases; (1) transition from unconfined to confined state, (2) upstream propagation of the flame up to an intermediate stabilization within the mixing tube and, (3) flame propagation to anchoring transition. Depending on the bulk flow velocity, the three phases take place independently of each other at/along the centerbody or at/along the mixing tube boundary layer. Two modes of flame structure are observed during the flame propagation to anchoring transition for the propagation along the centerbody. Furthermore, the 360° view imaging data reveals that the flame shows a symmetrical propagation behavior for the propagation along the centerbody and an asymmetry of the flame when propagating along the mixing tube wall.
LES Modeling of High-Lift High-Work LPT Blades: Part II—Validation and Application
Authors: Kerestes Jared , Marks Christopher , Clark John , Wolff Mitch , Ni Ron-Ho , Fletcher Nathan 
Published: September 2023

Abstract
Over the years, computational fluids dynamics (CFD) has matured to such a state so as to be indispensable in turbine design. In the past two decades, significant advances in turbine design have been made through the use of CFD — in particular, through the use of Reynolds-Averaged Navier-Stokes (RANS) simulations. Currently, turbine design is RANS-driven; however, significant gains in performance and efficiency are becoming more difficult to achieve using RANS. For this reason, the turbomachinery CFD community is moving toward Large-Eddy Simulations (LES). In the design of low-pressure turbine (LPT) blades, LES is particularly beneficial owing to its ability to capture accurately both transition and separation. In this paper, LES is used to characterize a new family of high-lift high-work LPT blades — designated the LXFHW-LS family — designed at the U.S. Air Force Research Laboratory (AFRL). LES simulations are conducted in accordance with the methodology outlined in Part I of this paper. The purpose of this paper is twofold: 1) to use LES to predict the performance of the LXFHW-LS family and compare to measurements in a low-speed linear cascade and, in doing so, 2) to illustrate how LES may be used in LPT design as it evolves from RANS-driven to LES-driven. For each blade in the family, the loading distribution and loss coefficient are computed for sixteen separate Reynolds numbers. Computational results are validated using detailed experimental measurements from a low-speed linear cascade wind tunnel. Experimental measurements include blade loading distributions, total pressure loss, and particle image velocimetry (PIV) measurements. In comparing computational and experimental results, particular emphasis is placed on the evolution of the suction surface (SS) separation bubble (if one exists). A variety of techniques are used to visualize the extent of the separation bubble, including machine learning.
Increasing the Scattering Coefficient by Modifying the Microstructure of the Thermal Barrier Coatings
Authors: Wang Yao , Hsu Pei-feng 
Published: September 2023

Abstract
Thermal barrier coatings (TBCs) are widely used to protect hot components in gas turbine engines. With higher turbine inlet temperature, the thermal radiative transfer becomes important in the overall heat transfer in the coating layer. The microstructure, including pore size distribution and pore morphology, has the primary impact to radiative properties in TBCs. Modifying the microstructure is an effective method to change the radiative heat transfer and the overall heat transfer in the TBC. In this study, a new approach is developed to modify the microstructure of air plasma spayed topcoat by mixing the fugitive polyester powder into the base 8 wt.% yttria-stabilized zirconia (8YSZ) powder. By changing the polyester powder size and the volumetric mixing ratio of polyester vs. 8YSZ, 8YSZ coating films of various microstructure are fabricated. The directional-hemispherical transmittance and reflectance are measured at the wavelength range of 1.4 to 2.6 μm under the room temperature. The scattering coefficient and the absorption coefficient are reduced by using a hybrid method combing the Kubelka-Munk four-flux method and the discrete ordinates method over the wavelength range. Using image processing tools on the SEM images of the 8YSZ films’ cross sections, the morphology-based pore size distribution (MPSD) is obtained. The results show that mixing polyester into 8YSZ powder is a very effective way to modify the microstructure of the topcoat, which, in turn, can increase the scattering coefficient.
Performance, Emissions, and Decarbonization of an Industrial Gas Turbine Operated With Hydrotreated Vegetable Oil
Authors: Runyon Jon , James Stuart , Kadam Tanmay , Ofir Barak , Graham David 
Published: September 2023

Abstract
As part of Uniper’s plans for its 22.5 GW of installed power-generating capacity in Europe to be carbon neutral by 2035, a Kraftwerk Union/Siemens V93.0 gas turbine (GT) in Malmö, Sweden was operated with hydrotreated vegetable oil (HVO) as a low-carbon replacement for gas oil in July 2021. An extensive feasibility study was first undertaken to understand the potential impacts of replacing gas oil with HVO in this GT. This included a fuel analysis, flame temperature modelling to predict the impact on NOx emissions, and a detailed hazard identification study for the short-duration trial. During the two-day demonstration, baseline GT performance and accredited emissions were first measured using the existing gas oil. HVO was subsequently used in all operating conditions including start-up, full load, part load, and shut-down. Accredited emissions of NOx, CO, SO2, and dust were measured to allow direct comparison between fuels. When operating with HVO, all required performance targets were achieved, including an onload fuel switch from HVO to gas oil. Direct flame imaging through a silo combustor sight-glass was used to observe the HVO start-up ignition process and to allow for a flame intensity comparison between fuels. NOx emissions were measured for each fuel, and no significant difference was identified across all operating conditions. As a result, no changes to the water injection rate for NOx control were required when switching fuels, which confirmed the predictions of the preliminary flame temperature modelling. Measurable reductions in dust, CO, and SO2 emissions were observed during HVO operation. These emissions reductions are respectively attributed to the low ash and aromatic contents of HVO, the increased hydrogen content of HVO relative to gas oil, and that HVO is essentially sulfur-free. HVO also enables significant lifecycle CO2 emissions reductions of over 90% compared with fossil diesel. In this trial, ∼163 tCO2 emissions were avoided by using HVO. The success of this demonstration provides evidence for future site conversion and has led to successful HVO demonstrations on other liquid fuel and dual-fuel GTs in the Uniper fleet. Long-duration testing and monitoring is required to build the evidence base regarding the impact of HVO operation on fuel storage, fuel delivery, and hot gas path components. To the authors’ knowledge, this field trial is the first successful demonstration of HVO use in an industrial gas turbine in the world.
Multi-Disciplinary Optimization of Thermodynamic Cycles for Large-Scale Heat Pumps With Simultaneous Component Design
Authors: Gollasch Jens , Lockan Michael , Stathopoulos Panagiotis , Nicke Eberhard 
Published: September 2023

Abstract
The performance of high temperature heat pumps is highly dependent on the efficiency of its main components, which need to be optimally matched especially in closed cycles. The design process is therefore a challenging task as many disciplines and varying modeling depths need to be considered. Consequently, this is usually a sequential procedure beginning with cycle definition and raising the fidelity for component design. Fundamental design decisions are made based on assumptions for component performance. Mistakes in the phase of cycle definition are hard to be reversed in later design stages. Therefore, the present work introduces holistic approaches for multi-disciplinary design of closed Brayton cycles. Aerodynamic compressor design with 2D throughflow analysis and geometry based heat exchanger sizing are simultaneously optimized with thermodynamic cycle parameters. The presented methodologies are making use of highly sophisticated design tools drawing on many years of experience in gas turbine design. The results demonstrate that holistic heat pump optimization can be successfully performed with reasonable computational effort. The advantages compared to conventional sequential design are elaborated. Comparison of two optimization concepts indicates that splitting up the design vectors of cycle and components shows the tendency to improve robustness. Finally, the trade-off between system compactness and performance is demonstrated with a multi-objective optimization study.