bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling Tip Flow Structures and Heat Transfer in Contemporary Cooled and Uncooled High-Pressure Turbine Blades
Authors: Christensen Louis , Celestina Richard , Sperling Spencer , Mathison Randall , Aksoy Hakan , Liu Jong , Nickol Jeremy 
Published: September 2023

Abstract
Cooling the squealer blade tips is essential to ensure efficient operation of gas turbine engines. The squealer tip reduces tip leakage flows but it is subject to high levels of thermal loading due to the difficulty in cooling the extended surface. Other studies have identified the dominate flow structures in the squealer blade tips namely the scraping vortex formed due to the relative motion of the turbine shroud and the pressure cavity vortex which forms from flow leaking over the pressure side squealer rim. These vortices influence the tip leakage flowrate across the blade tip, impingement on the squealer cavity floor, and the thermal loading on the squealer rim & cavity floor. Cooling jets can be used to modify these flow structures to reduce the thermal loading on the blade tips.
This work investigates how the tip flow structures are changed when cooling is introduced to the turbine blade. Transient conjugate heat transfer simulations of a turbine passage are run utilizing a solid uncooled turbine blade and a fully cooled high-pressure turbine blade with a contemporary tip cooling scheme. The large leading edge cooling hole disrupts the formation of the scraping vortex and pressure cavity vortex significantly changing the flow structures and thermal loading on the remainder of the cavity. Smaller cooling holes along the blade tip alter the position of the tip vortex structures which can be beneficial or detrimental to the local heat transfer loading. This analysis shows that cooling jets can affect the thermal loading by changing the flow structures within the tip in addition to creating a layer of protective cooling gas.
Turbomachinery for Laboratory-Scale Demonstration of Pumped Thermal Energy Storage System
Authors: Rimpel Aaron , Just Joshua , Smith Natalie 
Published: September 2023

Abstract
Long-duration, grid-scale energy storage technologies provide a potential pathway to enable full penetration of renewables on the electricity grid and still maintain grid reliability and security. One approach is to use a pumped thermal energy storage (PTES) system, which is charged by using a heat pump (consumes electrical energy) to raise the temperature of a warm medium while lowering the temperature of a cool medium, creating hot and cold media stores, respectively. The PTES system is discharged by using a heat engine (produces electrical energy), which is the reverse of the charge cycle. PTES is a promising technology that offers high potential system performance, implementation versatility, no geological or geographical constraints, and leverages many existing component technologies. However, no such air-based system has been built and demonstrated at any scale, which is necessary for validation and eventual commercialization.
This paper describes the development of turbomachinery for a first-of-a-kind demonstration of a PTES system. At the kilowatt scale, no off-the-shelf machinery exists to meet all performance and operability requirements, so custom turbomachines were required — one for the charge (heat pump) cycle and one for the discharge (heat engine) cycle. Each machine comprises a compressor, turbine, and a motor/generator that has an operating speed range up to 55,000 rpm. The scope of this paper focuses on the design of the turbomachines, including description of the machine performance requirements, bearing and damper designs, rotordynamics, mechanical design, manufacturing, assembly, and commissioning activities.
Aeroacoustic Effects on the Forcing of Fan and Compressor Blades Due to Distortion
Authors: Mårtensson Hans , Billson Mattias 
Published: September 2023

Abstract
A distorted air stream entering an aeroengine fan or compressor leads to harmonic forces on the rotating blades. These aerodynamically induced forces are well known causes for blade vibration and associated fatigue problems. Significant levels of distortion can arise from different sources like side wind and high angles of attack that normally occur at specific operating conditions. For aircraft with the engine closely integrated with the fuselage the engine will be exposed to distortion during the entire flight cycle. This increases the risk of operating in conditions where blade resonances are excited. The sensitivity to the forcing is also accentuated in this case as the exposure over time gives a large number of fatigue cycles.
Unsteady response to a specific distortion can be modeled using CFD methods to a high degree of fidelity. With a focus on understanding the aeroacoustic interaction the analyses used here considers generic harmonics of the distortion. Harmonic responses are calculated from low to transonic speeds for a range of cases. Major phenomena and driving parameters affecting the forcing strength and pressure amplitudes in the blade passage are identified from the analyses.
It is demonstrated that the forcing strength is strongly affected by the cut-on/cut-off conditions upstream and downstream of the blades. Also, depending on design parameters of the blade, the aeroacoustics of the blade passage is important for the resulting forcing. The analyses used are made in 2D over a wide range of flow conditions as well as geometric variations.
The results of the study provides an increased understanding of the harmonic forcing of blades. A simple model is proposed that can identify condition where increased pressure amplitudes in the blade passage may be expected. The sensitivities to parameters may also give some guidance in how design and operation can be adapted to reduce the aerodynamic forcing.
Improving the Performance of Turbomachinery Equipment by Selecting Optimized Materials With Good Thermal Stability
Authors: Langille Michael , Tzedaki Maria , Lorenzino Pablo , Davo Belen 
Published: September 2023

Abstract
It is reported that 65% of blade failure in turbo machinery is due to mechanical failures of the blades themselves [1]. The applied stress together with the higher temperatures can have a direct impact on the life of the impeller. It is therefore critical to evaluate the mechanical properties of materials and their durability at the relevant operating temperatures [1, 2]. In this study we will demonstrate the potential of different aluminum alloys to extend the life of a system by evaluating their durability over time at common operating temperatures. With appropriate testing that simulates the mechanisms involved at working conditions, one can benchmark the performance of different products. Comparisons between different alloys used as impellers in turboexpanders, turbo-blowers, turbopumps, turbochargers and superchargers are made. The most common products used in these applications is 2618-T8 and this alloy has been compared with the more recent 2027-T8 that is designed to withstand temperatures above 100°C. The applications demonstrated here for turbopumps and turbochargers will analyze the performance of 2618-T8 and be compared to the new 2027-T8.
The microstructural differences between the two alloys are presented and will be related to the mechanical properties studied. Overall, 2027-T8 demonstrates improved performance at 150°C compared to 2618-T851 in all aspects of material performance: tensile properties, thermal stability, fracture toughness, fatigue and creep performance. These properties are all critical for choosing the appropriate alloy for an impeller or rotor in order to allow either improved performance or increased component lifetime due to over-performance of this newly studied alloy, 2027-T8.
ICME Modeling of Erosion in Coated Metal Alloys and SiC-Based Ceramic Matrix Composites (CMC’s)
Authors: Eftekharian Amirhossein , Park Joshua , Morscher Gregory N. , Huang Dade , Miraj Rashid , Abdi Frank 
Published: September 2023

Abstract
Aircraft parts and components operate within harsh environments such as high temperatures, sand and debris attacks, and corrosive conditions. Coating is a typical solution to mitigate harsh environment effects and protect multi-layer (substrate, bond coat, and topcoat) components.
However, coated components can experience cracks and bending during process of coating which affects the ultimate functionality and usability of as-built parts due to the manufacturing defects. On the other hand, erosion, which needs to be addressed during the design phase, can limit performance of hot engine components due to EBC/TBC delamination, spallation, and mass loss of CMC as well as fiber breakage and matrix cavity formation.
A physics-based ICME tool that guides designers and analysts for erosion of coated components is highly desired considering the complexity of problem and more importantly cost of extensive testing programs.
The ICME method is based on virtual manufacturing of coating process integrated to virtual testing of erosion. A physics-based multi-scale model is developed to a) track temperature field during coating process, b) support material modeling of substrate, co-bond, and coating including effects of voids and residual stresses, c) simulate cracks and deformation due to coating, and d) determine erosion rate and cavity size and depth caused by the high velocity impact of erodent particles and high temperatures by considering cracks and anomalies introduced during manufacturing. For this purpose, the ICME tool employs a thermo-physics code for thermal properties and a micro-mechanics solution that degrades mechanical properties based on temperature and voids during coating. The degraded mechanical properties including damages and cracks are then applied to an augmented dynamic finite element analysis that calculates progression of erosion due to bombardment of SPH particles and tracks mass loss, delamination, and damages of material constituents.
The ICME tool is test validated for two cases: 1) SiC ceramic panels coated with EBC and 2) Stainless steel substrate with TBC coating. For both examples, simulation results show agreement with test in terms of mass loss and crater size due to erosion. Simulation also demonstrates that coated components suffer from cracks and damages due to coating which can exacerbate erosion rate. Finally, the ICME method is used to predict erosion of a coated SiC/SiC CMC specimens at high temperatures, where multi-scale progressive failure analysis considers fiber/matrix interphase as well as manufacturing defects due to coating process.
Effect of Fuel Injection Method on Flame Characteristics and Exhaust Gas Emission of CO2-Diluted Methane Oxy-Flames
Authors: Jeon Kitae , Lee Jong Guen 
Published: September 2023

Abstract
The effect of fuel injection method on flame characteristics and exhaust gas emission is investigated for a single micro-mixer combustor, running on CO2-diluted oxy-fuel at 4 and 8 atm. The CO2 fraction in CH4/CO2/O2 mixture is fixed at 70% (by volume). The mean flow velocity in the mixing section is fixed at 25 m/sec and the equivalence ratio is varied from stoichiometric condition to LBO (Lean blow-out limit) condition. In addition to completely premixing case, two different injection methods are employed: VI (vertical jet-in-crossflow injection) and TI (tangential jet-in-crossflow injection) where fuel (CH4) is injected at 0.18 m upstream of combustor inlet in the mixing section. Results shows that the degree of premixing between fuel and CO2/O2 mixture is an important parameter in determining combustion efficiency as well as flame structure for CO2-diluted methane oxy-flame and higher combustor pressure results in higher combustion efficiency with a minimal effect on flame length. The tangential jet-in-cross flow injection results in better premixing than the vertical jet-in-crossflow injection. The vertical jet-in-crossflow injection of fuel results in slightly longer flame than perfectly premixed case and the tangential-entry injection of fuel results in the shortest flame. Better premixing between fuel and CO2/O2 mixture leads to higher CO2 and the lower O2 and CO emission over the range of equivalence ratio, suggesting better premixing leads to more complete combustion and hence higher combustion efficiency. Also, more fraction of CO2 can be added into combustor without causing blowout for better premixing cases such as premixed injection and tangential jet-in-crossflow injection.
Influence of a Rib in the Diffuser of a Low-Pressure Steam Turbine on Aerodynamic Excitation at Part Load Operation
Authors: Doll Philipp , Müller Fabian F. , Schippling Stefan , Vogt Damian M. , Aschenbruck Jens 
Published: September 2023

Abstract
In recent years, the requirement profile for steam turbines used for power generation has changed significantly. In addition to highly efficient, eco-friendly and continuously available electricity generation, further demands have become more and more important: flexible operation in an extended operating range, compensation for short term fluctuations caused by renewable energies, and improved efficiency at part load.
Due to the more flexible operation, steam turbines operate frequently at part load. At such operating conditions, excitation phenomena can occur in the flow field, potentially leading to forced vibrations of the last stage rotor blades. A possible phenomenon in this context are rotating instabilities (RI). RI are vortex structures moving circumferentially at a certain frequency in the axial gap between guide vane and rotor blade triggered by flow separations in the blade path.
In the first part of the paper, excitation phenomena at part load operation are experimentally investigated in a model steam turbine. The outer casing of the turbine is equipped with unsteady pressure sensors at various circumferential positions upstream and downstream of the last stage rotor blades to identify operating conditions at part load where RI occur. The radial location and extent of the RI are determined by means of unsteady pressure probe traverses in the axial gap between guide vane and rotor blade.
In the second part of the paper, the influence of a supporting rib in the close vicinity to the last stage blade row on the location and intensity of the RI is investigated both quantitatively and qualitatively.
The occurrence and appearance of RI at various operating conditions is assessed from test data for both the setup without and with supporting rib. Based on the evaluation of this test data, it is shown that the pressure excitation caused by RI is significantly reduced by the rib.
A Compressor Wheel Design for Noise Reduction Due to Pressure Gradient in an Automotive Turbocharger
Authors: Jung Wonbae , Kim Seongsoo , Noh Taeho 
Published: September 2023

Abstract
In the most industries that manufacture compressors, it is very common to encounter noise issues on the compressor wheel while its operation. This noise is likely due to a pressure gradient along the compressor blades with inlet air flowing through them. This paper presents experimental and numerical investigations of noise reduction for the compressor wheel of an automotive turbocharger by modifying its geometry such as inlet area, inlet and outlet beta angles. The numerical model includes a one-dimensional aerodynamic analysis of the inlet and outlet operating conditions and describes meridional design of the compressor wheel. The design parameters include compressor inlet diameter, trim ratio, throat area, inlet and outlet beta angles, etc. Structural analysis on modal and centrifugal stress verifies the model reliability. CFD analysis of compressor models calculates total and static pressures at inlet and outlet domains, mass flow rate, and aerodynamic efficiency. The experimental data agree well with the numerical predictions while evidences noise reduction from the design method used in this paper. The newly designed compressor wheel meets the desired goals such as maximum efficiency at specific flow rates and rotational speeds and successfully reduces noise due to fluid instability.
Formulation and Validation of a Novel Actuator Line Model for FOWT Applications
Authors: Sanvito Andrea G. , Persico Giacomo , Firpo Agnese , Schito Paolo , Dossena Vincenzo , Zasso Alberto 
Published: September 2023

Abstract
The paper presents a novel in-house CFD solver featuring an original formulation of the Actuator Line Model (ALM), implemented into the OpenFOAM software. The new formulation samples the velocities close to the body-force application point, so to eliminate any effect of the oscillations and disturbance from the sampling. A detailed analysis is conducted using several sampling techniques to achieve proper modelling to be employed in Floating Offshore applications. The proposed formulation is assessed against experiments carried out in the large scale Wind Tunnel of the Politecnico di Milano on a scaled wind turbine laboratory model operated in steady wind and floating conditions. Load cases with both surge and pitching platform motions are considered and simulated with ALM-CFD coupled solver. The new method represents a viable alternative to ALM simulation tools already documented in literature, since it relies on a physical-based spatial velocity sampling of straightforward implementation.
FlameSheet™ Combustion Multi-Platpform Enhancements & Full Interval Validation for Extended Operational Flexibility, Low Emissions & High Hydrogen Capability
Authors: Hernandez Fred , Keshava Bhattu Ramesh , Kalb Bryan , Yaquinto Matt , Vogel Gregory , Rizkalla Hany 
Published: September 2023

Abstract
The quest for greenhouse gas (GHG) reduction is driving the need for higher hydrogen combustion capability for power production, while renewable energies demand more operational flexibility from industrial gas turbines (IGT). The first FlameSheet™ gas turbine combustion system entered commercial operation in 2015 demonstrating high operational flexibility; and in 2022 the fleet leader achieved full interval status of 32k hours of operation demonstrating great durability. Since 2015, there has been significant technology advances on the FlameSheet™ leading to a widening of operational envelope and increased hydrogen capability with lower emissions. This paper provides a detailed inspection of key lifing areas in the combustor after a full 32k hours interval and the validation of the analytical structural analysis predictions. The paper also provides details of FlameSheet™ enhancements of the pilot injector using advanced micro-mixer technology. The latter, combined with the original FlameSheet™ trapped vortex main injector enables improved flammability margin and lower emissions resulting in increased operational flexibility and hydrogen capability to support a renewable penetrated energy market and future provisions of GHG reduction mandates. In addition to the fuel and operational flexibility, provisions to enable multi engine platform compatibility has been implemented, and the paper provides a comparison of the operational characteristics of the FlameSheet™ combustor from a mechanical and aerothermal perspective when operating in an F-Class Siemens Westinghouse 501F, GE 7F.03 or E-Class GE 7E.03 industrial heavy duty gas turbine engine. This paper is a complement to the existing FlameSheet™ paper referenced in [4] which already provided information of the low pressure drop FlameSheet™ combustor variant implementation alongside Power Systems Manufacturing (PSM) Gas Turbine Optimization Package commercial install in an F-Class heavy duty gas turbine.
Applicability of Simplified Data-Driven Models in Gas Turbine Diagnostics
Authors: Loboda Igor , Pérez-Ruiz Juan Luis , González Castillo Iván , Yepifanov Sergiy 
Published: September 2023

Abstract
Gas turbine engine diagnostic algorithms based on gas path measurements constitute the principal subsystem of an engine monitoring system. These algorithms follow two main approaches. The first of them called a Gas Path Analysis (GPA) relies on a physics-based model (thermodynamic model) to transform gas path measurements into engine components’ health parameters. Within the second approach, diagnosis is made in the space of the deviations of measurements from an engine baseline using the pattern recognition theory. This approach mainly employs data-driven models and does not directly use the thermodynamic model. But the thermodynamic model helps to generate the necessary input data.
The thermodynamic model presents a complex software exigent to computer resources. Moreover, the model computation cyclic procedure does not converge sometimes. To simplify diagnostic algorithms and make them reliable, a linear model was introduced in the first GPA studies. Since the linear model is not accurate enough, surrogate nonlinear data-driven models were proposed later.
The present paper deals with the thermodynamic model and three simplified data-driven models for the steady-state operation of an industrial aero-derivative gas turbine. The paper focuses on the influence of the model choice on the final diagnostic reliability. Not only the reliability level is studied with these models, but also the influence of diagnostic conditions is investigated. In this way, the applicability of simplified data-driven models is validated. We hope that the paper results will stimulate the design of simple, but reliable diagnostic solutions and general progress in the development of real monitoring systems.
A Numerical Heat Transfer Investigation of Lattice Structures As an Alternative AM-Enabled Design for Cooled sCO2 Airfoils
Authors: Otto Marcel , Wardell Ryan , O’Neal Parker , Veselý Ladislav , Kapat Jayanta 
Published: September 2023

Abstract
Supercritical Carbon dioxide (sCO2) power cycles are rapidly developing and gaining popularity in waste heat recovery systems, as primary power cycles for a variety of heat sources such as nuclear, or as a stand-alone power cycle where fossil fuels are combusted. Akin to conventional gas turbines, sCO2-powered systems are pushing the boundaries for firing temperatures for higher efficiencies. Direct oxy-fired sCO2 systems will demand internal cooling of the airfoils for safe and reliable operations. Gas turbine cooling technology can be leveraged for that purpose. However, two key differences exist. First, the coolant medium is sCO2 instead of air, and second, sCO2 airfoils are much smaller compared to power-generation gas turbines. Novel AM manufacturing techniques promise advanced internal cooling geometries. This paper investigates a novel trailing edge cooling design to replace conventional pin fin arrays. Here, a lattice structure with microchannels is introduced. The study presents the changes in heat transfer due to the substitution of the heat transfer medium and the new geometry. The component is assumed to be printed Inconel 718. Based on an oxy-fired combustion sCO2 power cycle, coolant temperature and pressure and hot gas path temperature and pressure are chosen. The converging trailing edge duct is simulated in StarCCM+ using COOLPROP for sCO2 properties as a conjugate heat transfer model.