bluuebunny/crossref_metadata_2025_split huggingface dataset:
Operational Scenarios of a Gas Turbine Using Exhaust Gas Recirculation for Carbon Capture
Authors: Burnes Dan , Saxena Priyank 
Published: September 2021

Abstract
Finding viable economic solutions to significantly reduce or eliminate greenhouse gas emissions from energy and transportation products in the near future is paramount for the long-term survival of fossil fuel burning systems. One of which, the industrial gas turbine, has proven for decades to be a versatile energy system providing high efficiencies in combined heat and power applications melding well within existing infrastructure. Applying appropriate technology, the industrial gas turbine could be augmented to both sequester carbon and improve efficiency leveraging the full heating value of the fuel. The paper considers a more detailed operational assessment of a gas turbine using exhaust gas recirculation (EGR) to enable cost effective post combustion carbon sequestration and utilization. In this study, the effect of using EGR will be assessed at part load and throughout the operational envelope quantifying component and overall performance, detailed combustion characteristics, and maximizing the utilization of exhaust heat and sequestered carbon in various applications. This study will also attempt to quantify true carbon footprint of gas turbine installations and endeavor to understand the relative change of replacing the gas turbine with an all-electric alternative. Fundamentally, we are looking to see if there is a future to sustain and adapt this significant natural gas (NG) energy infrastructure to a net-zero carbon emissive future by 2050.
A Detailed Loss Analysis Methodology for Centrifugal Compressors
Authors: Zhang Luying , Kritioti Loukia , Wang Peng , Zhang Jiangnan , Zangeneh Mehrdad 
Published: September 2021

Abstract
A deep understanding of loss mechanisms inside a turbomachine is crucial for the design and analysis work. By quantifying the various losses generated from different flow mechanisms, a targeted optimization can be carried out on the blading design. In this paper an evaluation method for computational fluid dynamics simulations has been developed to quantify the loss generation based on entropy production in the flow field. A breakdown of losses caused by different mechanisms (such as skin friction, secondary flow, tip clearance vortex and shock waves) is achieved by separating the flow field into different zones. Each zone is defined by the flow physics rather than by geometrical locations or empirical correlations, which makes the method a more general approach and applicable to different machine types.
The method has been applied to both subsonic and transonic centrifugal compressors, where internal flow is complex due to the Coriolis acceleration and the curvature effect. An evaluation of loss decomposition is obtained at various operational conditions. The impact of design modification is also assessed by applying the same analysis to an optimized design.
Preliminary Study of Heat Pipe Turbine Vane Cooling in the NASA N+3 Reference Engine
Authors: McNichols Ezra O. , Jones Scott M. , Mirhashemi Arman , Juangphanich Paht , Shyam Vikram 
Published: September 2021

Abstract
This paper investigates the effects of implementing Heat Pipe Turbine Vane (HPTV) cooling in the NASA N+3 engine. The HPTV can be thought of as a heat pipe in the shape of a turbine vane, functioning as both an aerodynamic body and heat exchanger. The heat-absorbing section of the HPTV remains fixed in the vanes of the high-pressure turbine (HPT), while the heat-rejecting section can be placed in any stage of the low pressure turbine (LPT) as well as the bypass stream. The optimal location of the condensing (heat-rejecting) section is shown to be in the bypass stream for both HPT stages. The thrust-specific fuel consumption (TSFC) increased by 0.2%, which is mainly attributed to the elimination of air cooling in the second stage HPT vanes combined with the transfer of energy from the main gas path to elsewhere in the cycle. Air cooling is also eliminated in the first stage HPT vanes, but this cooling air is nonchargeable. A preliminary design is proposed and shown to demonstrate the desired performance and operates below the heat flux limitations of the heat pipe.
LES Based CFD Investigation of the Ignition Process in Lean Spray Burner
Authors: Andreini A. , Amerighi M. , Palanti L. , Facchini B. 
Published: September 2021

Abstract
During the last decades several new technologies were investigated in order to reduce the pollutant emissions and increase the overall engine efficiency. Unluckily, some of them including the lean direct injection spray combustion hinder the ignition performances of the combustor. Moreover, several expensive tests under very challenging operating conditions must be carried out to obtain the required certifications and assess the combustor behaviour with respect to the ignition process. Therefore, a deeper knowledge of the phenomena involved in the flame onset is mandatory to shorten the design process and achieve the required performances from the very beginning. In the last years, CFD simulations established as valid alternative to the experiments to investigate the complex phenomena involved in the ignition process. In fact, several examples are available in scientific literature about the use of simulations to predict the development of the flame starting from an initial kernel. In particular, LES proved to be a reliable tool to uncover new mechanisms of ignition and flame stabilization in gas turbines. In this work, two reactive LES of the ignition process were attempted using ANSYS Fluent 2019R1, with the aim of testing the Thickened Flame Model already implemented in the solver. In fact, compared to the previous versions, a new formulation for the efficiency function based on the pioneering work of Colin was made available. Such promising tool was validated against some detailed experimental results of a lean swirled flame, known as KIAI-CORIA spray flame. At first, a non-reactive and reactive LES were carried out to validate the cold field and the stabilized flame structure respectively. Finally, two ignition simulations were performed, from initial spark deposition up to flame stabilization or kernel quenching. All the obtained results have been extensively compared against the available experimental data showing that the employed simulation setup is fairly capable of describing the phenomena involved in the rig ignition.
A Numerical Sensitivity Study of Modeling Parameters in the Combustion of a Swirler
Authors: Al-Rifai Saja H. , Lin Cheng-Xian , Bohan Brian T. , Polanka Marc D. 
Published: September 2021

Abstract
In this study, a sensitivity analysis based on Reynolds Averaged Navier-Stokes (RANS) equations has been conducted to model the reacting turbulent flow in a swirler used in a (Disk-Oriented) gas-turbine using propane-air mixture. Several popular turbulence models and combustion models have been compared at different equivalence ratios. The effects of simulation parameters such as turbulence intensity, TKE Prandtl number, Schmidt number, and gravity direction have been studied. The contour plots of the species mass fraction (H2, OH) and temperature distributions from the CFD results are compared against the experimental visual results. The results showed that the realizable k-ε model and the steady diffusion flamelet model (SDF) are more suitable to model the turbulence combustion in the swirl domain. The computations further showed that the TKE Prandtl number and gravity are sensitive parameters to model the combustion from the swirler, while the Schmidt number and turbulence intensity showed less sensitivity.
Flamelet Versus Detailed Chemistry LES for a Liquid Fueled Gas-Turbine Combustor: A Comparison of Accuracy and Computational Cost
Authors: Karalus Megan , Thakre Piyush , Goldin Graham , Brandt Dustin 
Published: September 2021

Abstract
A Honeywell liquid-fueled gas turbine test combustor, at idle conditions is numerically investigated in Simcenter STAR-CCM+ version 2020.3. This work presents Large Eddy Simulation (LES) results using both the Flamelet Generated Manifold (FGM) and detailed chemistry combustion models. Both take advantage of a hybrid chemical mechanism (HyChem) which has previously demonstrated very good accuracy for real fuels such as Jet-A with only 47 species. The objective of this work is to investigate the ability of FGM and detailed chemistry modeling to capture pollutant formation in an aero-engine combustor. Comparisons for NOx, CO, Unburned Hydrocarbons, and Soot are made, along with the radial temperature profile.
To fully capture potential emissions, a soot moment model, and Zeldovich NOx model are employed along with radiation. A comparison of results with and without chemistry acceleration techniques for detailed chemistry is included. Then, computational costs are assessed by comparing the performance and scalability of the simulations with each of the combustion models. It is found that the detailed chemistry case with clustering can reproduce nearly identical results to detailed chemistry without any acceleration if CO is added as a clustering variable. With the Lagrangian model settings chosen for this study, the detailed chemistry results compared more favorably with the experimental data than FGM, however there is uncertainty in the secondary breakup parameters. Sensitivity of the results to a key parameter in the spray breakup model are provided for both FGM and Complex Chemistry (CC). By varying this breakup rate, the FGM case can predict CO, NOx, and Unburned Hydrocarbons equally well. The smoke number, however, is predicted most accurately by CC. The cost for running detailed chemistry with clustering is found to be about 4 times that of FGM for this combustor and chemical mechanism.
Power and Compression Analysis of Power-To-Gas Implementations in Natural Gas Pipelines With Up to 100% Hydrogen Concentration
Authors: Allison Timothy C. , Klaerner John , Cich Stefan , Kurz Rainer , McBain Marybeth 
Published: September 2021

Abstract
The introduction of hydrogen or synthetic natural gas produced from renewable electricity into gas pipelines is being considered to enable decarbonization and energy storage. Prior published studies show that hydrogen concentrations over 20–30% are likely to require significant infrastructure modifications and that significant concentrations of hydrogen will decrease energy transport capacity and/or reduce transport efficiency due to higher compression work. A comparative analysis of four power-to-gas implementations utilizing alkaline electrolysis, steam methane reforming, and catalytic methanation at hydrogen concentrations from 0–100% is performed in order to quantify production and transport power requirements utilizing pipeline or electrical transport. The pipeline transport analysis evaluates the pipeline transport capacity, efficiency, and emissions at various hydrogen concentrations and their sensitivity to pipeline diameter and compressor station spacing. The results show that production costs for hydrogen and synthetic natural gas dominate the overall energy requirement, requiring more power to create product than will be delivered for end use. Pipeline transport power requirements also increase by a maximum factor of 6–8 depending on surface roughness at high hydrogen percentages, but pipeline transport losses are less than electrical transmission losses in all cases. The increased pipeline compression power increases CO2 emissions along the pipeline up to a peak value of 240% relative to pure methane at a mole fraction of 65% hydrogen, above which CO2 emissions reduce. An analysis of pipeline compression conditions shows that flow requirements for all cases exceed the capabilities of reciprocating compressors but are mostly within the capabilities of centrifugal compressors, although multiple bodies may be required at hydrogen concentrations exceeding approximately 40–85%.
Optimization of an Additively Manufactured U-Bend Channel Using A Surrogate-Based Bayesian Method
Authors: Ghosh Shinjan , Mondal Sudeepta , Wardell Ryan , Fernandez Erik , Kapat Jayanta S. , Ray Asok 
Published: September 2021

Abstract
CFD-based design optimization of turbulent flow scenarios is usually computationally expensive due to requirement of high-fidelity simulations. Previous studies prove that one way to reduce computational resource usage is to employ Machine Learning/Surrogate Modeling approaches for intelligent sampling of data points in the design space and is also an active area of research, but lacks enough experimental validation. Such a method has been used to optimize the shape of a U-bend channel for the minimization of pressure drop. U-bends are an integral part of serpentine cooling channels inside gas turbine blades but also contribute to total pressure drop by more than 20%. Reducing this pressure loss can help in more efficient cooling at low pumping power. A ‘U-bend’ or 180-degree bend shape has been used from literature, and a 16-dimensional design space has been created using parametrized spline curves, which creates a variety of shapes inside a given bounding box. A Latin Hypercube Sampling (LHS) was carried out for populating the initial design space with output data from the CFD simulation. After training a surrogate model on this data set, Bayesian updates were used to search for an optimum using an exploration vs exploitation approach. The resulting optimum shape showed that pressure drop was lowered by almost 30%, when compared to the baseline. The aim of this study is to experimentally validate this method using 3D printed models of the baseline and optimum channels respectively. Pressure taps placed across stream-wise locations on these channels helped to create a pressure profile for turbulent flow at a Reynolds number of 17000, for comparison to CFD results.
Adjoint Based Heat Conduction Optimization of Struts Parameters Within Hollow Blade
Authors: Ruan Yougang , Feng Zhenping 
Published: September 2021

Abstract
In gas turbine, the interaction between hot gas mainstream and blade solid region becomes more and more obvious as the turbine inlet temperature increases, thus heat conduction within the blade solid regions should be taken into consideration in optimization design process. In this paper, an adjoint-based optimization method for heat conduction problems in the solid region was built based on ANSYS Fluent and OpenFOAM Solver. The continuous adjoint equation and the corresponding boundary conditions for three typical conduction boundary conditions were derived in detail. To validate the correctness of this method, inverse design problems within the hollow cylinder and hollow blade were calculated, respectively. Inner shape inverse design of the hollow cylinder and the blade thickness inverse design were performed, and the target values were found successfully. Adjoint gradients were compared with finite-difference method or theoretical results. Then a Conjugate Heat Transfer (CHT) calculation was performed using ANSYS Fluent software, and the numerical methods were validated against the experimental results. An optimization of the struts place and thickness within hollow blade for average temperature was performed based on the CHT calculation results. Average temperature within the solid region of the optimized blade decreased 11.1K as compared to the original case.
Probabilistic Approach for Optimizing Uncertainties of Input Variables to Reach a Desired Confidence Level
Authors: Prots Andriy , Voigt Matthias , Mailach Ronald , Magin Philip , Danner Florian 
Published: September 2021

Abstract
The development of jet engines is typically accompanied by measurement campaigns to mitigate technical risks at an early design stage and to validate the specified performance. Often different configurations are compared in order to determine the superior one. But due to uncertainties in boundary conditions, geometry, and sensors, the derived performance values are subject to uncertainty as well. Assuming that the desired difference in performance metrics is small compared to the associated uncertainty, it can consequently be hard to conclude on the superiority of the configurations.
In this paper, a probabilistic approach is used to estimate the uncertainties of the output values of interest. For that, the measurement process is executed virtually taking the low-speed research compressor of Technische Universität Dresden as a test case. In the first step, a sampling for the uncertainties associated with boundary conditions and geometry is created. Then, Computational Fluid Dynamics (CFD) calculations for these samples are executed. Afterwards, virtual measurements are performed, for which the unbiased value of the measurement quantity of interest is extracted from the CFD calculation and then merged with a measurement uncertainty. Finally, these virtual measurements are evaluated in the same way as it is done for real measurements to derive the output values.
Evaluating the samples allows to obtain the associated uncertainties and hence the confidence levels of a measurement campaign which are to be optimized. The system behavior is first approximated with an inner meta model. This surrogate can be used to create an outer meta model describing the relationship between the variance of the input variables and the uncertainties of the output variables. By evaluating the outer meta model it is possible to identify important input variables effecting the uncertainty of the output variables. Finally, the outer meta model is used to find combinations of input variances, which on one hand lead to the desired output uncertainties and on the other hand are optimal with respect to the associated cost.
A Quantitative Approach for the Estimation of the Fouling Rate on the Stationary Parts of a Multistage Test Compressor
Authors: Vulpio Alessandro , Suman Alessio , Casari Nicola , Pinelli Michele 
Published: September 2021

Abstract
Gas turbine particle ingestion may lead to the deposition of contaminants in the compressor section, inducing the performance losses of the whole engine. The economic losses derived from this issue push great interest in the investigation of such a phenomenon from a numerical and experimental standpoint. This paper describes a quantitative approach to predict particle deposition on the vanes of an axial compressor starting from the flow field obtained employing CFD simulations. The results are then compared to the experiments performed on the Allison 250 C18 compressor unit subject to particle ingestion under controlled conditions. The results derived from the experimental and numerical investigations are presented, providing insight into the mass deposited on the vanes and the corresponding zones most affected by the particle deposition issue. The numerical model showed good agreement in the estimation of the predicted values of the deposited mass and the corresponding patterns through the compressor stages. The low-complexity approach proposed here, helps the designer to predict the contamination of the stationary rows starting from a simple set of single-phase numerical results. Furthermore, with the implementation of this approach into the design path, the designer could reduce the impact of fouling, looking at the effects of their solutions under the fouling-reduction light.
Non-Equilibrium Turbulence Modelling for Compressor Corner Separation Flows
Authors: Sun Wei 
Published: September 2021

Abstract
Corner separation is one type of the three-dimensional (3D) separated flows which is commonly observed at the junction of the blade suction surface and endwall of an axial compressor. The commonly used Reynolds-Averaged Navier-Stokes (RANS) turbulence models, namely Spalart-Allmaras (SA) and Menter’s Shear Stress Transport (SST) models, have been found to overpredict the size of corner separation. The physical reason is partly attributed to the underestimation of turbulence mixing between the mainstream flow and the endwall boundary-layer flow. This makes the endwall boundary layer unable to withstand the bulk adverse pressure gradients, and in turn leads to its premature separation from the endwall surface during its migration towards the endwall/blade suction surface corner.
The endwall flow characteristics within the compressor stator cascade are then studied to facilitate understanding the physical mechanisms that drive the formation of 3D flow structures, and the physical reasons that lead to RANS modelling uncertainties. It is found that the insufficient near-wall boundary layer mixing is partly due to the failure of both SA and SST models to reasonably model the non-equilibrium turbulence behaviors inside the endwall boundary layer, which is caused by the boundary layer skewness.
Based on the understanding of the skew-induced turbulence characteristics and its effect on mixing, a detailed effort is presented towards the physical-based modelling of the skew-induced non-equilibrium wall-bounded turbulence. The source terms in the SA and SST models that control mixing are identified and modified, in order to enhance mixing and strengthen the endwall boundary layer. The improved turbulence models are then validated against the compressor corner separation flows under various operating conditions to prove that the location and extent of the corner separation are more realistically predicted.
Electrochemical Defect Analysis (EC-D) of Additive Manufactured Components
Authors: Sous Florian , Herrig Tim , Bergs Thomas , Karges Florian , Feiling Nicole , Zeis Markus 
Published: September 2021

Abstract
Due to more freedom in design and flexibility in production, parts produced by additive manufacturing technologies (AM) offer a huge potential for the manufacture of turbomachinery components. Because of the layer by layer built structure, internal defects like cracks or gaseous pores can occur. These defects considerably reduce the mechanical properties and increase the importance of quality control, especially in the field of turbomachinery. Therefore, in this study, an electrochemical defect analysis (EC-D) of additive manufactured components is introduced, performed and validated in comparison to a nondestructive X-ray testing of the same part. A test rig was developed, which allows an alternation between electrochemical machining and subsequent optical documentation of each removed layer. The documentation of the surface and the macroscopic defects in the AM-parts are captured by an integrated camera system.