bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Applications of Data Analytics in Gas Turbine Operation for Distributed Power Generation
Authors: Thirumurthy Deepak , Scudamore Mark 
Published: August 2024

Abstract
Recent advancements in data analytics and digitalization has increased the value which power generating assets, such as gas turbines, bring to power plant customers. Distributed power generation customers are increasingly partnering with gas turbine original equipment manufacturers and third-party digital service providers for cooperation in technology, innovation, and asset management using real-time data. In the past, it has been discussed that data analytics can be a key enabler in addressing challenges such as operational flexibility and efficient asset management.
This paper presents some of the novel applications of data analytics developed by Siemens Energy for gas turbine operation, condition monitoring, and real-time decision making. Specifically, the paper presents the idea, application, and test case of remote diagnostic system, enhanced vibration analytics, and myFleetRisk™.
Remote diagnostic system increases uptime, reduces operating cost by resource optimization, and improves plant output. This paper discusses both the reactive and proactive approach to gas turbine maintenance and how remote diagnostic system can be used with data analytics landscape for deviation monitoring.
In addition to an overview of the underlying concept and its novelty, real-world applications are presented to show the benefits to distributed power generation customers. MyfleetRisk offers optimized and tailored maintenance solutions resulting in significant life cycle cost reduction. Enhanced vibration analytics module enables reliability centered maintenance and thereby addresses key challenges to customers.
An Efficient and Robust Rotor-Stator Interfacing Method Capable of Handling Reverse Flows and Variable Specific Heat Within Multistage Turbomachines
Authors: Wu Hangkong , Tian Xiaopei , Qin Hao , Huang Xiuquan , Wang Dingxi 
Published: August 2024

Abstract
This paper presents the study of an efficient, robust, conservative, and nonreflective rotor-stator interfacing method for aerodynamic analysis of multirow turbomachines. This rotor-stator interfacing method computes flow variable differences by flux differences based on a control volume concept. It is found that this method is robust and can handle flow reversals. So far, the application of this method is restricted to analyzing flow fields with constant specific heat and its application to variable specific heat has not been reported in the open literature. This work will extend this rotor-stator interfacing method from constant to variable specific heat. To showcase its advantage over Holmes’ and flow-based methods, two multirow test cases, i.e. the NASA Stage 35 and the E3 high-pressure turbine, are adopted. The turbine case necessitates the use of variable specific heat due to the big temperature variation in the flow field. The results show that this novel method is more stable than Holmes’ method, especially for reverse-flow cases. Compared with the flow-based method, the novel method, as one type of flux-based mixing plane method, can well guarantee flux conservation. Furthermore, this novel method presents a unified approach for both constant and variable specific heats. It is more efficient and easier to implement in a flow solver than Holmes’ method since there is no need to use the Newton-Raphson method to compute mixed-out flow variables from circumferential area-averaged flux for variable specific heat.
A High-Temperature, High-Speed, Oil-Free Syngas Compressor for Small-Scale Combined Heat and Power
Authors: He Victoria , Van Herle Jan , Schiffmann Jürg 
Published: August 2024

Abstract
For low-emission, small-scale combined heat and power generation, integrating a biomass gasifier with a downstream solid oxide fuel cell system is very promising due to their similar operating conditions in terms of temperatures and pressures. This match avoids intermediate high-temperature heat exchangers and improves system efficiency. However, to couple both systems, a high-temperature and oil-free compressor is required to compress and push the low-density, high-temperature bio-syngas from the gasifier to the solid oxide fuel cell stack. The design and development of this high-temperature, high-speed, and gas-bearing supported compressor is presented in this work. An iterative process involving preliminary design, meanline analysis using commercial tools and in-house models is used for the design, which is then numerically analyzed using computational fluid dynamics. The goal is to achieve a design with a wide operating range and high robustness that withstands extreme working conditions. The 727 W machine is designed to run up to 210 krpm to compress 18.23kgh−1 of syngas at 350°C and 0.81bar. The centrifugal compressor has a tip diameter of 38 mm and consists of 9 backswept main and splitter blades. The impeller is made of Ti6Al4V and coated to prevent hydrogen embrittlement from the hot and highly reactive bio-syngas. The results obtained from the established models suggest a good concordance with the results from numerical analyses, despite the high temperatures and small scale of this design.
The Impact of Pad Elasticity on Frequency-Dependent Linear Dynamic Coefficients of Tilting-Pad Journal Bearings
Authors: Vetter Daniel , Zemella Philipp , Hagemann Thomas , Schwarze Hubert 
Published: August 2024

Abstract
The frequency-dependent dynamic coefficients of tilting-pad bearings are significantly influenced by the pad pivot elasticity. In addition to the elasticity of the pivot, there is also the flexibility of the structure that predominantly leads to a bending of the pad. For the calculation of the dynamic coefficients, it is common to describe the structural stiffness by a support stiffness in series with the lubricant film. For this purpose, the stiffness according to Hertz’s theory is widely used. This approach only allows the rigid body motion of the pad in the theoretical model. However, the elasticity of the pad leads to a film thickness characteristic, which cannot be represented with a pure rigid-body motion. Additionally, the structural elasticity already includes the stiffness of the contact between the pad and the support and, therefore, the elasticity according to Hertz cannot simply be added. This paper investigates the influence of dynamic pad deformation on dynamic bearing coefficients considering the contact boundary conditions, and examines whether it can be replaced by a suitable support stiffness. A 3D finite element model provides the eigenmodes for calculating the dynamic coefficients by perturbed Reynolds equations within a thermo-elasto-hydrodynamic (TEHD) bearing analysis. The model is validated with measurement data.
A Reduced Order Methodology for Optimizing Turbine Expanders Working With Rotating Detonation Combustors
Authors: Varatharajulu Purgunan Gokkul Raj , Asli Majid , Klopsch Roman , Meister Josh , Stathopoulos Panagiotis 
Published: August 2024

Abstract
Redesigning a gas turbine cycle with creative concepts is one of the most critical possibilities for achieving a significant increase in efficiency. Pressure Gain Combustion (PGC) can be used in place of conventional deflagration combustion since PGC contributes to a considerable gain in thermal efficiency while also emitting low NOx levels. One of the major challenges of PGC is the turbine integration to the outlet of the combustor due to the unsteady turbine inflow conditions. This unsteady exhaust flow causes turbomachinery components to operate under fluctuating off-design conditions which in turn, reduces their performance. In this work, the turbine integration to the Rotating Detonation Combustor (RDC) and an optimization methodology for the turbine are discussed. Due to the highly fluctuating unsteady flow of RDC, three-dimensional CFD simulation of turbine becomes very expensive, specifically if it is considered as the objective function evaluator in an optimization process. Thus, an alternative approach of using one-dimensional unsteady Euler model for the turbine is adopted. A two-stage axial turbine is optimized considering unsteady flow features of a hydrogen-air RDC to minimize the entropy generation. When compared to the baseline design, the optimized turbine shows a nearly 2.6% reduction in entropy generation.
Creep-Fatigue Life Assessment Technique for Steam Turbine Rotors: An Efficient Continuum Damage Mechanics Based Approach
Authors: Sen Suvadeep , Almstedt Henning 
Published: August 2024

Abstract
Incorporation of renewable energy, in the era of energy transition, lead to enhanced creep-fatigue life consumption of conventional power plant components, e.g., steam turbine rotors. The present requirements are difficult to address with the conventional uncoupled life assessment methods due to their inherent conservatism. The use of damage coupled unified constitutive models for the analysis of steam turbine rotors in the past decade has shown promising results. High computational efforts is a major drawback of these models. The methods available for reduction in computation time are based on fixed start-up conditions repeating cyclically, however, flex operation result in arbitrary or non-fixed cycle types. In this paper, novel techniques of mapping the data generated from temperature measurements to derive inelastic strain history for arbitrary cycle types is proposed. Unlike the conventional uncoupled techniques utilizing stress/strain ranges, the derived strain history enables a path dependent progressive creep-fatigue damage prediction employing unified constitutive models. The derived strain history is used together with the concept of Representative Input Cycle using a non-iterative Asymptotic Numerical Method for highly efficient damage computation. Various transient loadings on a steam turbine rotor are studied using a unified constitutive model based on Chaboche’s kinematic hardening including the damage parameter, Chaboche-Rousselier’s isotropic hardening model including the damage parameter, Norton’s viscoplastic flow model, Lemaitre’s damage potential function and Kachanov-Rabotnov’s creep damage law. First, a conventional full finite element method is used and then the proposed method is employed to study the evolution of damage and compared.
Design of a Relational Database for Turbine Center Frames With Application for Geometry Optimization
Authors: Staggl Marian , Sanz Wolfgang , Sterner Thomas 
Published: August 2024

Abstract
The flow path between high- and low-pressure turbines (TCF) is a key component of modern aero engines; the radial offset between the two stages and the small axial length result in a strong curvature and complex flow behavior. A solid database is an important foundation for design and further investigations, especially when applying modern artificial intelligence (AI) methods.
Due to a long research history, the Institute for Thermal Turbomachinery and Machine Dynamics (ITTM) at Graz University of Technology owns an extensive TCF data collection. In order to reuse these data samples, a database application has been developed, providing the functionalities to normalize and store the data uniformly. The TCF data samples are mapped into a common parametric space during import, making them comparable and accessible to AI applications. Furthermore, statistical evaluation tools and an automated CFD export are available.
In the second part of the paper, the database is used for an exemplary geometry optimization task. The approach is to train a surrogate model with data from the database and then use the model for optimization. The results agree with the findings of other authors, and the surrogate model’s predictions coincide well with CFD results.
Numerical Study of Low Engine Order Excitations due to Manufacturing Variability Part 2: An Efficient Approach for Stochastic Studies
Authors: Gallardo Juan Manuel , Pérez Escobar Óscar 
Published: August 2024

Abstract
In turbomachinery rows, the geometric variability between the airfoils induces non-uniformity in the flow, which directly translates into Low Engine Order (LEO) excitation and vibration in the adjacent rows. Direct simulations of this phenomenon involve full-row CFD analyses, where the exact geometry of each individual blade needs to be properly reproduced. The related computational cost of such simulations is very significant. Since the geometric variability due to the manufacturing scatter is stochastic, valuable information could be derived from Monte Carlo analyses involving randomly generated geometries; nevertheless, this approach would be very resource-intensive. In this paper, we propose a simplified method to determine the flow perturbation generated by this geometric variability. The method is based on studying the underlying properties of the geometric scatter using PCA techniques, obtaining a compact description of the variability of the airfoils. The flow perturbation due to a reduced number of reference cases is obtained through direct, large scale simulations. By assuming linearity in the flow perturbations, the solution for a general case of geometric distortion may be obtained very efficiently from these reference cases, which makes Monte Carlo studies to analyze stochastic geometric distortion easily affordable. The capabilities of the method are demonstrated in a test case considering the real geometry scatter from an aircraft turbine. According to the results, the average LEO response due to the random geometry scatter involves significant vibration levels, comparable (in terms of alternating stress) to the response due to the blade-passing excitation.
Equivalence Ratio Driven Flame Response of an Industrial Premixed Burner: Experiments and Modeling
Authors: John Tony , Magina Nicholas , Han Fei , Kaufmann Jan , Vogel Manuel , Sattelmayer Thomas 
Published: August 2024

Abstract
This paper presents an analysis of the unsteady heat release rate response of premixed flames to equivalence ratio perturbations for an industrial premixed swirl-based burner. During this investigation, perfectly and technically premixed flames were acoustically forced via fuel/air mixture flow and air flow modulations respectively, at the same operating conditions. From the resulting flame transfer functions (FTFs), measured using the multi-microphone method, the equivalence ratio driven FTF was isolated and extracted by removing the velocity driven component, i.e. the measured FTF from the perfectly premixed flame, from the technically premixed FTF with two novel extraction techniques. The results are compared with FTFs obtained directly in a previous experimental campaign [1] where the fuel flow was acoustically forced, the resulting equivalence ratio fluctuations measured via an IR absorption technique, and the heat release rate response to the forcing was quantified using chemiluminescence measurements. The results from both measurement approaches agreed well highlighting the validity of the techniques. Further, to understand the governing features of the equivalence ratio driven FTF, a physics-based analytical model following the G-equation approach was developed. The contributions from flame surface area, flame speed, and heat of reaction oscillations were modeled to describe the heat release rate dynamics. A limited number of physical parameters in the analytical model were anchored on one test condition, optimized and restricted to values which were all physically reasonable, and were subsequently used for model predictions at other operating conditions. The FTF model predictions compared well with experimental data across a range of different operating conditions. Finally, the relative contributions from flame surface area, flame speed, and heat of reaction oscillations on the features of the FTFs were identified and explored.
Fusion Energy and Future Fusion Power Plants
Authors: Acres Jack , Clements Chris 
Published: August 2024

Abstract
Fusion energy offers clean, reliable power for future generations and is undeniably part of a fully sustainable energy mix. Fusion combines two light atomic nuclei to form a single heavier one while releasing massive amounts of energy. To fuse atoms requires extremely high temperatures and pressures, in a plasma, to overcome the nuclei’s mutual electrical repulsion — achieving these conditions on earth, which is typically achieved in stars, has a host of challenges.
Within a magnetic confinement device (tokamak), plasma is heated using ohmic and a mixture of neutral beam and/or radio-frequency heating to exceed 80 million Kelvin (K) where fusion happens. Strong magnets are needed to shape and control the plasma. Generating and sustaining the extreme temperatures and magnetic conditions, requires significant amounts of energy — which is difficult to manage at scale.
The technical challenge of efficiently and effectively extracting power from a fusion machine and integrating these multiple energy sources into a thermodynamic cycle is significant. This requirement is further compounded by the operational timeframes of typical tokamaks.
These challenges and the scales of the next generation of fusion tokamaks will require significant thermal electrical power transfer and conversion technologies, as well as electrical infrastructure equipment. This paper illustrates these challenges by evaluating possible fusion power plant efficiencies and how this is significantly influenced by the thermodynamic efficiency of the power conversion technology.
Experimental research has been in progress for nearly 70 years, but we are now at a tipping point with active private and public funded fusion power plants programs seeking to exploit fusion energy. UKAEA’s Spherical Tokamak for Energy Production (STEP) project and Tokamak Energy’s Spherical Tokamak Fusion Pilot Plant (ST-X FPP) are examples of such programs.
The Role of Materials in Enabling Gas Turbine Technologies
Authors: Shifler David A. 
Published: August 2024

Abstract
Materials used in high-temperature structures have design constraints in additional to those materials used at or near room temperature. Three important constraints are time-dependent inelastic strain (creep), thermal stability of microstructure, and high-temperature oxidation and/or corrosion. The U.S. Navy employs gas turbine engines for aero-propulsion and for propulsion and auxiliary power for select surface ships. For modern aircraft gas turbines, combustion gas temperatures up to 2100°C and alloy temperatures as high as 1150°C is possible. This is well above the melting point of most alloys, so film cooling of the combustion chamber is necessary. Materials (nickel-base superalloys, ceramic matrix composites (CMCs), refractory alloys, overlay, diffusion, and thermal barrier- and environmental barrier coatings) in commercial, marine and aero gas turbine engines must be able to withstand a variety of aggressive, harsh operating conditions. Current gas turbine engines employ the Brayton cycle where overall turbine efficiencies increase as the engine temperatures increase.
Predicting corrosion of metals, alloys, or coated alloys is often difficult because of the variable operational demands placed on Predicting corrosion of metals, alloys, or coated alloys is often difficult because of the variable operational demands placed on a given power system, and the variable composition of the corrosive environment. Prediction is further complicated because materials often degrade in a high-temperature environment by more than a single corrosion mechanism.
Research is underway to use other cycles such as the Atkinson or Humphrey Cycles that hold the promise of improved efficiency when applied to gas turbine type machinery. A rotating detonation engine (RDE) is an engine is an engine using a form of pressure gain combustion, where one or more detonations continuously travel around an annular channel. In detonative combustion, the flame front expands at supersonic speed. It is theoretically more efficient than conventional deflagrative combustion by as much as 25%. That would translate to major fuel savings. During the combustion very high temperatures (3000–4000K) and pressure (1–100 bar) levels are attained through the combustor. Although RDE research is continuing to establish combustion stability and reduce noise, materials will need to be developed or applied to promote long term performance. These materials will need to endure temperature spacial inhomogenieties and fluctuations, pressure cycling, and harsh environmental operational conditions.
Experimental Investigation of the Film Cooling Effectiveness Deviation Using Pressure Sensitive Paint Measurement for Different Hole Structures
Authors: Lou Yuzhu , Tao Zhi , Li Haiwang , Zhou Zhiyu , Zhang Jinghan , Xie Gang 
Published: August 2024

Abstract
Film cooling is a crucial cooling method to ensure the operation of turbine blades under high-temperature conditions. Turbine blades operate under high-speed and complex flow conditions. In the classic method of measuring adiabatic film cooling effectiveness using Pressure Sensitive Paint, the substitution of the pressure field of the air-case with that of the foreign gas-case has introduced measurement deviation, when the density of two jets is different. The use of a specific ternary oxygen mixture during the test processes enables the correction of the deviation. The shaped holes widely used in turbine blade alter the mainstream-jet mixing process. To obtain the deviation distribution generated during the PSP measurement of shaped holes, measurements were conducted on a flat plate operating at a mainstream Mach number of 0.5 using both the traditional method based on Test3-Air and the corrected method based on Test3-OM for five types of film holes, including a circular hole, a hole with a 45-degree compound angle, double jet ejection, a fan-shaped hole, and a laid-back fan-shaped hole The results reveal that various hole structures broadly exhibit measurement deviation, which generally increases with an increase in the blowing ratio. The deviation originates from the difference in momentum between jets of different densities under the same blowing ratio, leading to distinct flow patterns. Significant negative deviation is observed near the holes under high blowing ratios, while pronounced positive deviation occurs downstream. The distributions of deviation are varied for different structures. The compound angle leads to increased and asymmetrical deviation. For the same pressure deviation, the effectiveness deviation is larger where the film cooling effectiveness is lower. Due to the higher effectiveness downstream of the double jet ejection deviation, the range of the deviation is limited near the hole. The fan-shaped hole and the laid-back fan-shaped hole prevent coolant jet lift-off from the wall, reducing measurement deviation. However, under high blowing ratio conditions, the measurement deviation remains significant and should not be neglected.