bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Implementation of Electrostatic Solver Within OpenFOAM for GT Intake Filtration
Authors: Pinelli Michele , Piovan Mattia , Suman Alessio , Zanini Nicola , Rossin Stefano , Minotti Stefano 
Published: August 2024

Abstract
Gas turbines require filtered air to preserve operability, availability, and efficiency. Fouling, corrosion, and erosion severely affect the performance of the axial compressor and it can be in part prevented by filtering the air intake. For this reason, several stages of filters can be used in series to catch pollutant particles gradually smaller and with a high level of capturing efficiency. Traditionally, the separation is obtained using cartridges of porous material, which provide a high level of filtration but at the same time generate a pressure drop increasing over time. Another common type of filter is the inertial one, whose operating principle is based on the inertial force acting on the solid particles to separate them from the mainstream. The capturing efficiency of the inertial filter is not comparable with the porous one and for this reason, it is used upstream as a pre-filter. In recent years, another technique has been developed to filter air flows thanks to an electrostatic field, that is induced inside the flow. The electrostatic force generated is able to attract and separate metallic particles. In the present work, numerical investigations are carried out to simulate the effect of the electrostatic force for gas turbine filtering systems. The CFD tool used is OpenFOAM, whose official release can simulate inertial and porous filtering media, while for electrostatic one is not possible due to the absence of a library able to simulate the electrostatic force that acts on the discrete phase. A new library was developed in order to calculate: the electric field, the electric potential, and the charge density of the continuous phase. Simulation results show how the calculation of these quantities allows us to predict the electrostatic force acting on particle flows in the presence of electrostatic fields.
Predicting Gas Turbine Power Output in Single Shaft Combined Cycle Power Plants: A Physics-Based and Data Analytics Approach
Authors: Nandagopal Pugalenthi , More Manjunath , Sharma Kirti , Saroj Uttam , Singh Gurdev 
Published: August 2024

Abstract
The measurement of gas turbine power output is essential for original equipment manufacturers (OEMs) and plant operators to evaluate the performance of their gas turbines. Accurate knowledge of the power output allows for better gas turbine control based on customer requirements. By measuring the GT power, OEMs can predict critical internal performance parameters such as turbine inlet temperature, compressor inlet flow, compressor efficiency, and turbine efficiency. Furthermore, accurate prediction of steam turbine efficiency can also be achieved using a mass and energy balance approach. In a multi-shaft combined cycle power plant, gas and steam turbine power are measured separately, enabling analysis of the heat and mass balance approach within individual turbine boundaries. However, in a single-shaft combined cycle power plant, only the total cycle power is measured, making it difficult to predict gas turbine and steam turbine power output separately. Accurate gas turbine power output prediction is critical to prevent improper gas turbine operation, such as over-firing or under-firing. Over-firing the gas turbine can damage the hot gas path life of the turbine while under-firing can result in a loss of gas turbine power.
Additionally, accurate power output prediction enables OEMs to provide precise performance guarantees, reducing the risk of paying liquidity damages. To validate the single-shaft approach for predicting gas turbine power output, data from a multi-shaft combined cycle power plant was used, and accurate gas turbine power output was predicted and compared with the power observed using multiple-shaft gas turbine power.
The first approach of the paper is solely founded on the principles of the first law of thermodynamics. The objective is to validate this first law approach using only a limited data set from a multishift combined cycle power plant, such as compressor inlet temperature, fuel flow, fuel lower heating value, combined cycle power output, and gas turbine power output.
The other methods are Hybrid modeling approach and Data driven approach. In the hybrid method a model has been obtained using mass and energy balance equation and the real gas turbine data is used to obtain the values of unknown parameters in the hybrid model. In the Data driven approach, real gas turbine’s data is used to obtain a black box model. Hybrid models are generally regarded as superior to data-driven models in terms of accuracy because they combine the use of physics-based principles and data. Data-driven approaches, on the other hand, offer a simpler way to model plants or processes as they do not rely on prior knowledge of the system and can be developed solely using process data.
Tuning of an Algebraic Model for Separated Flows by Means of Bayesian Lasso
Authors: Carlucci Andrea , Petronio Daniele , Barsi Dario , Dellacasagrande Matteo , Simoni Daniele 
Published: August 2024

Abstract
In this work, machine learning techniques are exploited to train a new model based on Pope’s tensorial bases, where the common definition of the turbulent viscosity is extended to define the Reynolds stress tensor as an expansion of strain-rate and rotation tensors. Specifically, a Sparse Bayesian approach has been implemented to provide new expressions for the turbulent eddy viscosities appearing in the Pope’s formulation. An experimental dataset acquired with Time-Resolved Particle Image Velocimetry has been used to tune the present model. Data provide the mean flow and the Reynolds stress distributions of different separation bubbles evolving on a flat plate with applied variable adverse pressure gradients, reproducing in some extent the diffusion that characterize the rear suction side of turbine blades. The model has been tuned with different independent conditions of flow Reynolds number and free-stream turbulence intensity. Then, two additional flow conditions have been adopted to cross-validate and test the generated model. The adoption of the Sparse Bayesian approach allows the direct identification of the leading predictors, i.e., flow features, exploiting the main characteristics of the transition scenario (here, the transition process induced by flow separation). Specifically, the correlations here tuned may contribute to improve the capability of RANS solvers in the prediction of transitional flows.
Operation of the Atmospheric Biomass-Fired Topcycle – BTC – “Fuel to Flame” Test Rig
Authors: Hannappel Jan-Peter , Güthe Felix , Alemela Reddy Panduranga , Saldarriaga David , Borg Gustaf , Jofs Martin , Bartlett Michael 
Published: August 2024

Abstract
After the international climate conference (COP28) agreed recently on fossil fuel phase-out, the search for alternative energy sources is further increased worldwide with a focus not only on electricity but also renewable fuels for dispatchable energy production. This decarbonisation challenges existing technology and calls for alternative fuels of synthetic or biogenic origin. Phoenix BioPower is developing a high-efficiency process, called the Biomass-fired TopCycle (BTC), to address this market using forestry and agricultural residues for electricity production. In the BTC, a biomass-fed gasifier produces a hot and pressurized syngas which is subsequently cooled by steam addition prior to clean-up. This highly diluted, steam-rich fuel is combusted in a TopCycle gas turbine resulting in high electric efficiencies. The Phoenix Advanced Combustion System (PACS), which utilizes high steam content and large recirculation zone for stability and flexibility (MILD -Moderate or Intense Low oxygen Dilution), has demonstrated high fuel-flexibility, i.e. hydrogen, syngas or methane, and high load flexibility.
To demonstrate the technology, an atmospheric “fuel to flame” test rig has been constructed and is operated to optimize combustion performance and system integration, regarding operational stability and flexibility. We present the first results using the biomass gasifier product gas as fuel for the PACS combustion system at high steam ratios and co-firing with hydrogen. Challenges lie in the stability of the system and combustor at transient conditions, for weakfuels, as well as with NOx emissions, which arise mostly from the fuel-bound nitrogen of the biomass and, therefore, syngas.
A Through-Flow Approach Associating Velocity and Pressure Gradient Equations for Transonic Axial Flow Compressors Performance Prediction
Authors: Wang Mingyi , Li Tongxi , Wang Zhiheng , Xi Guang 
Published: August 2024

Abstract
The through-flow theory has always been an essential tool for compressor aerodynamic analysis and design because of excellent application value in balancing cost and accuracy. While general methods can give rapid predictions of compressors operation performance, there remains some lack of effective way of how to capture the characteristic at large flow rate for high-loaded transonic compressors. This is because the traditional approach concentrating on solving velocity gradient equation by given flow rate boundary, however, when the compressor runs to the choked condition, the back pressure will drop sharply and the mass flow rate will be almost unchanged, which makes it difficult for the solution to converge to an accurate flow rate and pressure ratio. Therefore, in this paper, the prediction of the aerodynamic performance for transonic compressors by associating the mass flow rate with the pressure boundary is investigated. The operation performance region of map and flow field characteristic can be obtained by solving the velocity gradient equation and pressure gradient equation of the quasi-orthogonal line located on the S2m stream surface based on the streamline curvature approach (SLC). NASA Rotor 37 and the three-stage NASA 74-A axial compressors are analyzed and the results demonstrate this approach has higher accuracy in predicting aerodynamic performance than the previous method especially near the choked condition. At the same time, the approach can achieve rapid solution as well as good stability.
Numerical and Experimental Study of Flow-Induced Vibrations in Micro-Tube Heat Exchangers
Authors: Phan Hien M. , Newman Felix , O’Pray Connor E. , Parikh Dhairya 
Published: August 2024

Abstract
Thermal management presents an increasing challenge in future engineering systems, especially in applications like combined cycle precooling, waste heat recovery, and innovative propulsion systems. These systems face a growing demand for managing higher heat loads while coping with limited heat sink. Central to these thermal management systems is the heat exchanger, with micro-tube heat transfer emerging as a promising solution for future technologies. Micro-tube heat exchangers are becoming popular owing to their ability to significantly enhance the heat transfer surface area while maintaining a compact core volume.
As the demand for high-performance, lightweight heat exchangers escalates, micro-tube heat exchangers are being designed to be increasingly compact yet highly loaded. This trend poses significant challenges to their structural integrity, particularly under harsh operational conditions. Flow-induced vibrations, a critical concern in the design of tubular heat exchangers, can lead to tube failures, compromising the safe operation of engineering systems. While the flow-induced vibrations of conventional-sized heat exchangers have been extensively studied, there is a noticeable gap in the research on similar phenomena in micro-tube heat exchangers.
This paper details ongoing research at Reaction Engines Ltd to aid the design of safe and robust heat exchangers, focusing on the flow-induced vibrations in micro-tube heat exchangers and utilizing a cutting-edge laser vibrometry test facility. A predictive model, employing an unsteady flow simulation approach and eigenvalue analysis, has been formulated. A key observation is the distinctive coupled transverse-streamwise orbital motion in micro-tube heat exchangers, differing from the predominantly transverse direction of failures in conventional-sized heat exchangers.
Film Cooling Efficiency Reconstruction on Turbine Blade Surfaces Based on Point Measurement Data
Authors: Zhang Fengtao , Yu Hongqian , Liu Xing , Yang Li 
Published: August 2024

Abstract
High fidelity and resolution of film cooling data on turbine blades can provide accurate and visually informative insights into physical phenomena, serving as valuable references for designers. However, due to the complexity of heat transfer problems and the limitations of data acquisition devices, obtaining complete and high-resolution data on film cooling efficiency is challenging. Therefore, this study focused on the reconstruction of complete thermo-fluid image data from spatially sparse data. In this study, a multigrid iterative neural operator network (MINO) was proposed as the data completion algorithm. Besides, the prior knowledge of flat plate film cooling was introduced through transfer learning to enhance the predictive accuracy of the model. The results of the study demonstrate that the MINO model can reconstruct the film cooling efficiency distribution of the turbine blade relatively accurately and capture most of the texture details in the flow field. Compared with existing linear interpolation methods, the average predictive error of the MINO model is significantly lower, with an overall reduction of approximately 40% and 50% for the suction side and pressure side, respectively. Furthermore, the MINO transferred model still exhibited robust reconstruction capability even at low sampling densities, with less increase in errors compared to the linear interpolation model as the sampling density decreases.
Experimental Characterization of Very High Turning Single and Tandem Compressor Profiles
Authors: Babin Cedric , Leclercq Kevin , Al Rifai Anis , Princivalle Remy , Fontaneto Fabrizio 
Published: August 2024

Abstract
The axial compressor front stages of the forthcoming aircraft engines architectures will operate at high subsonic inlet Mach number over a large range of incidence angles, while providing unprecedented turning levels. In this study, a single vane profile and a tandem vane configuration, designed for identical inlet flow conditions and for a design turning in the excess of 45 degrees, have been experimentally assessed in a linear cascade arrangement. The present paper outlines first the aerodynamic design philosophy for the tested profiles. Then, the design of the facility and of the test section are presented in view of the challenges imposed for the performance evaluation of very high turning compressor cascades at engine-like conditions. The instrumentation is also presented, and finally, the performance comparison of each blade configuration is given and put into perspective with the measurement uncertainty. The analysis of the blade sets performance aims to highlight the advantages and drawback of each configuration. The use of both the experimental data and CFD computations help to provide an insight into the loss driving mechanisms. This paper demonstrates that single profile blades and tandem configurations can be designed to provide identical performance close to the design incidence region of the loss bucket, with the latter outperforming at high positive and negative incidences despite a smaller solidity.
Combustion System Development and Test for Stoichiometric H2/O2 Combustion in Steam Atmosphere
Authors: Hase Matthias , Meisl Jürgen , Prade Bernd 
Published: August 2024

Abstract
An Oxy-H2 in steam atmosphere combustion system for the use in a novel application is presented. The combustion system is intended to be used in a steam boosting system (“Clean Steam-Booster”) for steam cycle applications. The steam boosting system can provide additional heat and mass flow for peak power demands as well as for grid stabilization by increasing the steam temperature and the mass flow for short operation periods. The approach is free of the classical combustion emissions, NOx and CO, as well as from the greenhouse gas, CO2. The combustion system is intended to be operated at close to stoichiometric conditions.
The combustion system has been developed with the primary targets stable combustion, low H2 and O2 contents in the exhaust steam, and a good thermal design concept which allows meeting life for a production design. A couple of different burner and combustor variants were designed. All burners are diffusion style burners to avoid flashback issues which is a major risk for the Oxy-H2 combustion in case of premixing due to the very high flame speeds. The general design concept for the combustion system is a two-stage steam supply with one steam stage in the burner and a second through the combustor. To support design decisions, kinetic analyses were performed which are also discussed in the present paper.
A core development step of the combustion system design is the design validation in a high-pressure combustion test. To enable such tests, a labscale rig was designed, manufactured, and erected, including pressure vessel and back pressure valve for tests up to 15 bar operation pressure. Also, the supply infrastructure for steam, O2 and H2 was well as the measurement and control system had to be setup at the combustion test facility of Siemens Energy in Mülheim/Germany.
In the validation test, stable combustion operation up to 15 bar could be demonstrated. Moreover, low H2 and O2 contents in the exhaust gas were achieved. The thermal design worked as expected.
The precise mass flow measurement and control were identified as major challenge for the operation of the combustion system close to stoichiometric conditions. Small deviations from a stoichiometric mixture have a direct and significant impact on the H2 and O2 fractions in the exhaust.
As next steps another design iteration for the combustion system design, an up-scaling of the combustion system and closed loop steam cycle tests are planned.
Coupled Design of Multi-Component Distortion-Generating Devices for Aircraft Engine Ground Tests – Part I: Design Methodology and Numerical Validation
Authors: Grondin Julissa , Leborgne Michaël , Baert Lieven , Lepot Ingrid , Gouttière Alexandre , Dieu Donavan , Wunsch Dirk , Boufidi Elissavet , Madasseri Payyappalli Manas , Fontaneto Fabrizio , Spriet Tony , Talbotec Jérôme 
Published: August 2024

Abstract
Engine performance, operability and vibration can be drastically affected by inlet flow non-uniformity. Devices that can accurately and flexibly recreate total pressure and swirl distortion cartographies in test environments are required to assess engine-airframe incompatibilities as soon as possible during the design process. This paper presents a numerical design methodology for a two-component distortion device that a) is manufacturable with additive manufacturing for maximum flexibility, and b) is able to reproduce complex and realistic patterns featuring high levels of total pressure distortion and flow angles magnitudes.
The device consists in the combination of a honeycomb total pressure screen with airfoil-shaped edges, and a turning vanes assembly. This first part paper describes the design methodology, from the preliminary design of each isolated component to their joint optimization by means of a global surrogate-assisted optimization strategy making use of a multi-fidelity model for the coupled device. The preliminary design tools are applied and validated on two canonical configurations for each type of distortion. Then the coupled design strategy is applied on two realistic configuration patterns featuring combined total pressure and swirl distortions.
The experimental testing of the screens and a cross-comparison between design and experimental tests is discussed in the second part of this paper.
Techno-Economic Comparative Assessment of High Temperature Heat Pump Architectures for Industrial Pumped Thermal Energy Storage
Authors: Trevisan Silvia , Buchbjerg Bjarke , Höeg Arne , Guedez Rafael 
Published: August 2024

Abstract
The industrial sector is a key global source of wealth, but it is also recognized as a major challenge toward worldwide decarbonization. Today the industrial sector requires more than 22 % of the global energy demand as thermal energy and produces for this about 40 % of the total CO2 emissions. Solutions to efficiently decarbonize the industrial sector are deemed. This work presents a comparative techno-economic performance assessment of a high temperature heat pump integration within a molten salts based power to heat system for industrial heat flexible generation. The main system performance is reported in terms of required working conditions and temperature for the heat pump and thermal demand size as well as reduction of the attainable levelized cost of heat (LCoH) against non-flexible electric boiler based systems. The impact of different industrial load profiles, electricity prices, heat pump capital cost and heat pump real to Carnot efficiency ratio are also presented.
The results highlight that the proposed system can be cost-competitive, particularly for thermal demand around 10 MW and waste heat temperatures above 80°C. Under these conditions LCoH reduction higher than 15 %, with respect to the considered non-flexible electric boiler alternative, are attainable. These LCoH reductions are primarily driven by savings in electrical consumption as high as 30 %. This study sets the ground for further power-to-heat techno-economic investigations addressing different industrial sectors and identifies main system and components design strategies, integrations, and targets.
State-of-Charge (SoC) Management of PTES Coupled Industrial Cogeneration Systems
Authors: Albay Alp , Zhu Zhennan , Mercangöz Mehmet 
Published: August 2024

Abstract
We present a novel optimization-based state-of-charge (SoC) management solution for pumpedthermal energy storage (PTES) systems capable of charging and discharging with electrical power and discharging high temperature heat — for integration with industrial processes. The considered PTES system in the study uses a supercritical CO2 recuperative Brayton cycle (SCBC) utilizing molten salt and water as hot and cold storage materials respectively. A SoC balancing heat exchanger is integrated along with a utility heat exchanger to the base design to accommodate withdrawal of high temperature heat. The study builds on a detailed part-load study to extract the SoC dynamics as a function of the electrical power as well as the heat withdrawal rate. These functions are used for modelling SoC management as an optimization problem considering three case studies; a base case for only electrical operation given an electricity price profile, a flexible operation study with electrical and heat price profiles, and a continuous heat supply case where the system delivers heat to a process. The results indicate that the proposed approach can enable optimized operation while respecting SoC constraints under different scenarios and illustrate the potential for the integration of PTES systems with industrial processes for the decarbonization of heat provision.