bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation on Exhaust Energy Recovery System Using Radial Turbine in High-Power Proton Exchange Membrane Fuel Cells
Authors: Jiuxuan Wei , Mingxu Qi , Hong Zhang , Xue Li 
Published: October 2022

Abstract
With the increased power density and capacity of the proton exchange membrane fuel cell (PEMFC) stack, the intake air pressure level is getting higher and can reach up to 3.5bar in some cases, leading to a higher exergy level of the exhaust gas at the fuel cell cathode. To improve the system efficiency of the PEMFC, the energy of the fuel cell exhaust gas at the cathode side can be recovered with a turbine and partially drive the compressor to save part of the power needed by the electric motor. To evaluate the potential capability of the PEMFC exhaust gas recovery, detailed insights regarding the energy recovering capability of the turbine from exhaust gas energy as a result of gas supply pressure, air stoichiometric ratio, current density and operating temperature are presented in the current study. A systematic model of the fuel cell system is established and validated. The model includes the air supply system, electric motor driven turbocharger, fuel cell stack components and necessary pressure drop as well as the gas dynamic model inside the stack. The model can be used to simulate the recovery process of the exhaust gas energy at arbitrary fuel cell operation loadings. It can be used to predict the system energy recovery efficiency once the loading condition of the fuel cell is known. Results indicate that the energy recovery system performance is determined by the fuel cell operating conditions. Results also show that the gas inlet state, current density, electrochemical reaction process and pressure loss play a key role in the recovery efficiency of the turbine and the ratio of recovery power to fuel cell output power. The recovery efficiency is higher at a larger pressure ratio and current. To verify the accuracy of the system model, a high-power fuel cell is used for validation, the rated power of the proton exchange membrane fuel cell stack is calibrated through the electrochemical model from the energy recovery system and good agreement is achieved between the simulation and experiment.
Adjoint Optimization of Centrifugal Compressor Rotor Accounting for Manufacturing Uncertainties
Authors: Aissa Mohamed H. , Racca Alberto , Mueller Lasse , Verstraete Tom , Williams Carnell E. 
Published: October 2022

Abstract
The paper addresses the problem of the design optimization of turbomachinery components while considering the impact of manufacturing uncertainties.
Standard optimization procedures evaluate only the component nominal shape, which is altered till the achievement of the project targets. The verification of the influence of the geometrical tolerances on the robustness of the machine is performed during the late validation phase, thus exposing the design activity to the risk of incurring in unfeasible solutions, when considering the full envelope of real shapes determined by the manufacturing process.
The present work tackles the issue of robust optimizations by developing a strategy based on the Uncertainty Quantification (UQ) method within an adjoint-based multidisciplinary optimization framework. The novel methodology exploits the capability of gradient-based methods in converging to the optimal solution in few design iterations, while the addition of a UQ technique based on an extension of the Probabilistic Collocation method allows the propagation of the uncertainties on the design parameters to the mechanical constraints and the gradients of the constraints.
The methodology is applied to the robust optimization of a turbocharger centrifugal compressor rotor. The proposed approach provides a more reliable design against manufacturing tolerances with a computational overhead exceeding less than 30% the cost of a corresponding deterministic optimization.
Magnetic Resonance Velocimetry of a Turbine Blade With Engine-Representative Internal and Film Cooling Structures
Authors: Ma Haiteng , Liu Yisu , Lai Youkui , Ouyang Hua , Ning Jia , Jiang Xianwang , Xu Qin 
Published: October 2022

Abstract
As a key technology to ensure the survival of turbine blade, gas turbine cooling encompasses a whole range of cooling strategies with ever-increasing geometric complexities. Flow measurement for turbine blade with such intricate internal and external cooling structures is very challenging, and calls for non-intrusive, three-dimensional measuring techniques. As a response, this work measures the three-dimensional velocity field in a gas turbine blade cooling design by Magnetic Resonance Velocimetry (MRV). A scaled GE-E3 turbine blade with engine-representative internal and film cooling structures was employed. The internal cooling structure includes leading edge impingement cooling, U-shaped serpentine passage with/without turbulence ribs at blade mid-chord and trailing edge pin fins. The external cooling structure includes film holes near the leading edge stagnation point, at the blade tip and in the trailing edge. The experiment was performed using water as the working fluid and the Reynolds number local to the leading edge, mid-chord and trailing edge cooling channels is 1.3 × 103, 5.1 × 103 and 2.3 × 103, respectively, which falls within the range typically found in literature. This is the first time that MRV is used to measure the flow field of a gas turbine blade with all the typical internal and external cooling geometries combined. The results show that MRV has great capacity in measuring the complex fluid flow of a gas turbine blade cooling design. Vortical flow features in leading edge impingement cooling, and at the U-bends of three-pass serpentine channel are captured. Interestingly, internal flow around pin fins at the blade trailing edge redistributes the velocity of external flow injected from trailing edge slots and film holes, indicating strong coupling between the internal and film cooling flow of the turbine blade.
Design Considerations and Validation of a Near Wall Cooled Stator Heat Shield With Sequential Impingement Cooling
Authors: Peschke P. , Naik S. , Henze M. 
Published: October 2022

Abstract
The reduction of cooling air for first stage turbine components plays a vital role in improving the performance of heavy-duty gas turbines. To achieve this goal detailed knowledge of the external heat loads is required as well as introducing novel technologies to reduce the cooling air consumption.
This paper gives an overview of the design considerations and validation for a technology upgrade of an Ansaldo Energia heavy-duty gas turbine first stage stator heat shield.
The heat transfer of the heat shield surface flow is influenced by the complex flow pattern that is created by the interaction of the rotating blade tip with the surface boundary layer, in the presence of leakage air and the wake of the upstream vane trailing edge. The present paper discusses results from CFD computations and laboratory experiments that investigate this interaction, as well as results from full scale engine tests. It is shown that both the wake of the upstream vane and the blade passing have a crucial influence on the heat transfer that needs to be considered during the design phase of the stator heat shield.
Furthermore, the implementation of a novel cooling concept with sequential impingement cooling from laboratory tests to engine ready technology is shown. A comparison of airflow measurements of the new heat shield with a conventional impingement design demonstrates a significant reduction in cooling air flow. Metal temperature measurements in full scale engine test with thermal paint, thermocouples and thermal crystals show similar metal temperatures compared to the conventional design.
Dynamic Response of Stratified Flames to Acoustic Excitation in a Multi-Swirler Model Combustor
Authors: Liu Weijie , Jin Ming , Ge Bing , Xue Ranran , Su He , Zang Shusheng 
Published: October 2022

Abstract
Flame response is a key element in predicting thermoacoustic instabilities in gas turbine combustors. Flame dynamic response of single swirling flames to acoustic excitation was well studied in the past decades, while the unsteady dynamic of multi-swirling flames, such as stratified flames, is not fully reported. This paper presents dynamic response of stratified flames in a multi-swirler combustor which includes a main stage and a pilot stage. The stratified flame contains an outer main flame and an inner pilot flame. The overall Flame Transfer Function (FTF) of the stratified flame is extracted during the experiment. High-speed camera and high-frequency Particle Image Velocimetry (PIV) are used to capture the evolution of the flame and flow structure.
Experimental results show the overall flame transfer function of the stratified flame features several discrete peaks and valleys in a narrow frequency range which is slightly different with a typical simple swirling flame. The main flame is stabilized at the inner shear layer region of the main flow while the pilot flame settles at a position where turbulent flame speed equals to the local pilot flow speed. The effect of the acoustic driving on the topology structure of the stratified flame is not apparent. Proper orthogonal decomposition of the stratified flame shows a wave of alternating positive and negative values across the flame indicating flame fluctuations are in axial modes. Proper orthogonal decomposition of the multi-swirling flow reveals coherent structures are formed in the shear layer of the main flow which dominates the stratified flame response.
Development of a Fuel Flexible H2-Natural Gas Gas Turbine Combustion Technology Platform
Authors: Witzel Benjamin , Moëll Daniel , Parsania Nishant , Yilmaz Ertan , Koenig Michael 
Published: October 2022

Abstract
Siemens Energy is developing the required technologies to operate its gas turbines on up to 100% H2 by 2030 to support the target of limiting global warming to 1.5 degrees Celsius. A focused effort has been undertaken to develop a technology platform for the Siemens Energy GT portfolio which will enable GT operation across the entire range H2/natural gas blends within emissions compliance. A first engine demonstration of these technologies in an industrial application will be conducted in an SGT-400 engine in 2023 as part of HYFLEXPOWER, an EU Horizon 2020 funded consortium project.
This paper will present the results of numerical and experimental investigations of several candidate dry low NOx technologies. The candidate technologies are all lean, premixed designs and include: a swirled flame primary stage, a jet-based flame primary stage and an axial stage. The experimental results are conducted at elevated pressure and temperature conditions representative of the Siemens Energy gas turbine fleet. Additionally, a comparison of different kinetics mechanisms which offer the potential to accurately model flames burning H2, natural gases, and combinations of these fuels will be presented. The mechanisms include GRI 3.0 as well as three mechanisms which have been previously developed to improve the accuracy with high H2 content fuels.
Experimental and Numerical Investigation of a Novel Method for Gradient Temperature Measurement
Authors: Schönheit Markus , Thiele Marcus , Ginzbursky Edward , Thomas Anastasia 
Published: October 2022

Abstract
Hot gas temperature and mass flow rates are continuously increasing to meet future gas turbine power, efficiency and emission targets. Moreover, expectations for flexible operating capability can add conditions for frequent cold starts and load changes. To realize such gas turbine developments, improved cooling concepts are required to guarantee the lifetime of thermally highly loaded components such as turbine blades, vanes, blisks and combustor rings. In addition to design and metallurgical adjustments to the components, this also requires validated calculation and design methods. As described by Thiele et. al. [1], a visco-plastic material model has been developed which shows the significant influence of superimposed thermal gradients on the low-cycle failure life. Reliable temperature gradient measurements are required to validate the material models, FEM and CFD simulations and the fatigue life. Accurate in-situ measurement capability in real engine conditions is particularly challenging which existing measurement methods only cover to a limited extent.
A novel application using Uniform Crystal Temperature Sensors (UCTS) with two different minimally invasive application methods is proposed and evaluated here. The sensor installation package is micro size, with a diameter that can be less than 1mm and a length that can be adjusted to the available wall thickness of the part and the expected gradient through the wall. Experimental work to validate the measurement accuracy of the UCTS was carried out using a highly efficient, patented radiation furnace reported in GTP-18-1482, which can apply a heat flux of q ≥ 1.5 MW/m2 and a thermal wall gradient of up to 65 K/mm.
In order to validate the novel measurement system both experimentally and numerically, measurements with calibrated thermocouples and thermo-mechanical simulations were performed. For the temperature gradient data generation, the UCTS were integrated in a MAR-M247 hollow cylinder specimen in various configurations. The conventional cast nickel based alloy MAR-M247 is a typical turbine blade material. Its thermo-physical properties are well studied and it has been part of thermally loaded and temperature gradient investigations for several years. The paper focuses on the validation and application of the UCTS measurement system and shows its potential for investigating actual operating conditions of highly thermally loaded real engine components. Information from this study will be applicable to gas turbine design and development engineers needing in situ gradient measurements for rig or real engine testing programs.
Life-Cycle-Assessment for Rough Machining of Inconel 718 Comparing Ceramic to Cemented Carbide End Mills
Authors: Fricke Kilian , Zimmermann Richard , Ganser Philipp , Gierlings Sascha , Bergs Thomas 
Published: October 2022

Abstract
Nickel-based alloys such as Inconel 718 belong to the group of heat-resistant super alloys. Combined with good mechanical properties over a wide range of temperatures nickel alloys are used extensively in the aero engine sections exposed to elevated temperatures. Besides turbine blades and discs, integrally designed compressor rotors (Blisks) in the high-pressure compressor (HPC) are increasingly made of Ni-alloys. This is the result of an efficiency-driven increase in temperature levels in the rear compressor stages. The machining of these hard-to-machine materials is characterized by low productivity and high tool wear. Compared to the machining with conventional cemented carbide end mills, innovative SiAlON ceramics offer a significant potential to increase the performance of these machining processes while saving cooling-lubricants. Besides an increase in productivity, the evaluation of the overall environmental impact of specific manufacturing processes is gaining importance in the context of more sustainable product life-cycles. This paper focuses on the comparison of different milling strategies in the production of high-pressure compressor rotors made from Inconel 718 in a cradle-to-gate assessment based on DIN EN ISO 14040/44. Thus, the ecological impact of both the state-of-the-art and the novel SiAlON roughing strategy are evaluated considering the consumption of energy, water and compressed air as well as the tool wear. The Life-Cycle-Impact-Analysis (LCIA) will be performed as a midpoint analysis taking multiple indicators into account such as the Global Warming Potential (GWP).
Performance of FGM in Bluff-Body Stabilized H2-CO Diffusion Flame
Authors: Hofsteenge Jesse W. , Kok Jim B. W. 
Published: October 2022

Abstract
Blends of H2 with CH4 and/or CO have become of interest with hydrogen as sustainable fuel. In the past, numerical models were derived to simulate combustion of H2-CO (syngas) mixtures. This paper compares the performance of a newly implemented Flamelet Generated Manifold (FGM) combustion model to an earlier model by Correa and Pope and experimental data in the bluff-body stabilized syngas flame by Correa and Gulati. The FGM in the presented model consists of premixed flamelets stretching the flammable region, parametrized by mixture fraction and Computational Singular Perturbation-based reaction progress variable. RANS simulations are performed in Fluent with k-ε, k-ω SST and Reynolds Stress Model turbulence modelling. Radial and axial profile plots of temperature and major species concentrations showed generally improved results with the FGM model, although locally deviations occur. Causes for these deviations are scrutinized: the use of premixed opposed to diffusion flamelets and the unity Lewis number assumption.
Aerothermal Performance of Axially Varying Winglet-Squealer Blade Tips
Authors: Garg Anmol , Vadlamani Nagabhushana Rao , Srinivasan Balaji 
Published: October 2022

Abstract
High-pressure turbine blades are usually susceptible to secondary flow losses due to fluid flow between the casing and the blade tip. In this study, we have evaluated the performance of several blade tip designs for different combinations of winglets and squealer geometries towards mitigating tip leakage losses. The effects of considering Relative Casing Motion (RCM) on the aerothermal performance is also brought out. In particular, we have considered three different blade tip designs which include winglets, Top Winglet Bottom Squealer (TWBS) and Top Squealer Bottom Winglet (TSBW). Inspired by the partial winglet configurations studied in the literature, we have also examined designs with partial squealers and winglets. The performance of all the designs and the dynamics within the tip gap are discussed through the distributions of total pressure loss within the tip gap and Nusselt number over the blade tips. Of all the blade tip designs, aerothermal performance of a 100% TWBS design is demonstrated to be superior, both with and without relative casing motion. When compared to a flat tip design, a 100% TWBS design showed a 15% reduction in total pressure loss and a 22% reduction in the average Nusselt number over the blade tip. For this design, accounting for the relative casing motion showed a marked reduction in the total pressure loss and the heat transferred to the blade tip. In particular, RCM is shown to suppress the ‘hot-spot’ associated with a cavity vortex within the squealer cavity.
Comprehensive Analysis of a Cycloidal Rotor With Different Types of Blade Profiles
Authors: Staśko Tomasz , Majkut Mirosław , Dykas Sławomir , Smołka Krystian 
Published: October 2022

Abstract
From the historical point of view, the research on cyclorotors has been focused on aviation applications, such as propulsion systems for UAVs. There is a need for studies on the use of a cycloidal rotor fan (CRF) in internal-flow applications, such as power or HVAC applications. This paper presents considerations of the cycloidal rotor application for a fan. The possibility to change the flow angle and its direction makes the CRF a potential solution in HVAC systems. A very desirable feature is the lack of a diffuser, which simplifies construction and the ability to operate the CRF as a puller or a pusher fan in rectangular ventilation ducts. Two variants of the CRF were tested numerically and experimentally. The first variant was equipped with asymmetrical CLARK Y blades and the second one — with symmetrical NACA0012 blades. The blades were selected based on the universality of their use and their popularity in scientific research. For each rotor, experimental tests were carried out for the blade amplitude of 40 degrees, and rotational speed of 1000 rpm. The experimental results were compared with those obtained from numerical calculations, and the comparison results were satisfactory. Due to the small size of the fan, no significant differences were noticed in the speed profiles for the two rotor variants.
LES-CHT for a Rotating Cavity with Axial Throughflow
Authors: Hickling Tom , He Li 
Published: October 2022

Abstract
The flow and heat transfer within rotating cavities is often discussed as a conjugate problem: the temperature distribution within the cavity disks drives the large-scale flow structure within the cavity, and the cavity aerodynamics influence the heat transfer to the disks. However, most simulations of rotating cavities only consider the fluid domain in isolation. This is particularly true for turbulence resolving approaches such as large eddy simulation (LES).
The large timescale disparity between the fluid time steps used in LES and the characteristic solid time-scale complicates the use of LES with conjugate heat transfer (CHT). A further issue is that an under-resolved solid domain mesh can artificially amplify higher frequency temperature fluctuations in the fluid domain.
This paper addresses these challenges with a new method for LES-CHT where the low-frequency temperature fluctuation caused by the large-scale flow structure is accounted for using a multi-scale frequency domain approach. We investigate two cases: axially heated disks made of a low conductivity material and disks made from a higher conductivity material with a temperature set by radial conduction from the shroud.
The formation of small-scale flow structures on both the disk and shroud is dependent on the heating configuration of the cavity — this interaction indicates that high-fidelity thermal boundary conditions should be used when simulating rotating cavities. The formation of heating induced vortical flow structures on the disk is particularly interesting, as this is unexpected from the laminar Ekman layer modelling argument usually used to consider this region of the flow.
Market Opportunities for Power-to-X Solutions for Combined Cycles Flexibilization
Authors: Barberis Stefano , Cuneo Alessandra , Bellotti Daria , Sorce Alessandro , Vannoni Alberto 
Published: October 2022

Abstract
Power-to-X solutions are getting year by year more and more market interest in the present and future Renewable (RES) driven energy market scenario. Their potential coupling with Combined Cycles Gas Turbine (CCGT), which have to be present together with RES as back-bone to guarantee grid resilience and stability, is currently under investigation also in order to enhance CCGT flexibility as short-/middle-term storage solutions.
The H2020 EU Funded PUMP-HEAT and FLEXnCONFU projects1 study two different types of Power-to-X solutions: the former a power-to-heat concept by heat pump coupling and the latter a power-to-hydrogen/ammonia system via Electrolyser coupling), both targeting flexibility enhancement and emissions reduction. This paper presents and compares the market potential of Power-to-X solutions proposed in the two projects presenting guidelines for the upscale of the proposed Power-to-X solutions derived from a techno-economic assessment of the two Power-to-X solutions.
These guidelines will bring to a preliminary assessment of the flexibility and electric market potential of Power-to-X solutions coupled with CCGTs, presenting specific features per both of them such as the most techno-economic viable sizes or market characteristics to leverage Power-to-X potential. Furthermore, the market potential is presented by analysing bottlenecks and drivers (in current and future EU scenarios) that could facilitate or hamper the widespread of the proposed technologies.