bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of Nickel-Based Superalloys for Hot Gas Path Components via Additive Manufacturing
Authors: Callisti Mauro , Dimatteo Antonella 
Published: September 2023

Abstract
High performance Nickel-based superalloys are known to be difficult-to-weld materials due to their complex chemical compositions. Consequently, these alloys become challenging when processed via additive manufacturing (AM) technologies. In this study, new AM Nickel-based superalloys were developed for applications in gas turbines, with particular regard to hot gas path components like turbine vanes for Baker Hughes products. The alloy development was driven by the performance required for the specific components, with emphasis on creep and oxidation resistance.
This paper describes all the steps that led to design and manufacture of an AM alloy free of defects and with required performance. In particular, the alloy design approach based on thermodynamics calculations and fast experimentation is described. AM process parameters development along with post-printing treatments (hot isostatic pressing and heat treatments) are discussed in conjunction with the emerging mechanical properties. An assessment on the oxidation behaviour of a selected alloy is presented.
Improving Performance of a Centrifugal Pump Through a CFD DOE Study of Radial Diffuser Design
Authors: Parmar Basu , Sacks Michael , Jammalamadaka Avinash , Laskowski Gregory 
Published: September 2023

Abstract
Diffuser design significantly affects the performance of a centrifugal pump. To improve the performance of a single stage centrifugal pump, we use RANS CFD simulations to conduct a Latin hypercube DOE study with the diffuser design parameters. The inlet angle, outlet angle, outlet diameter and number of vanes are selected to be key parameters influencing the pump performance. The ERCOFTAC pump is selected as the research model. The CFD simulations and DOE study are conducted using 3DEXPERIENCE® CFD simulations by Dassault Systemes. The results indicate multiple optimal designs for different zones of operation and the choice of response variables to optimize. Pump efficiency is chosen to be the key performance indicator in this paper. The first optimal design for nominal flow rates showed better performance due to an improvement in diffuser static pressure rise coefficient. The second improved design for high flow rates, removes flow separation at high flow rates by reducing the vane inlet and outlet angles. It is found that low values of inlet angle and outlet angle give better pump efficiency at high flow rates and vice versa. We also demonstrate the benefits of RANS CFD over simple 1D analysis.
Compressor Tip Leakage Mechanisms
Authors: Taylor James V. , Dickens Anthony M. J. , Simpson Harry 
Published: September 2023

Abstract
The over tip leakage flow in an unshrouded compressor blade row is highly three-dimensional, yet in order for aerodynamicists to analyse and improve designs they must be able to simplify the problem down to a limited number of mechanisms. In this paper the behaviours of the dominant loss mechanisms are investigated using a multi-order methodology which combines: rapid experimental tests of different geometries, detailed measurements in a large rotating rig, large numbers of industry-standard 3D RANS simulations and a single DNS simulation of the datum geometry.
The three loss mechanisms identified are ultimately caused by mismatches in flow velocity. Separation of the flow as it enters the gap, mixing of the leakage jet with the mainstream close to the suction surface, and endwall shear acting on the jet itself at mid passage. The paper is presented in three sections: First, the loss mechanisms are visualised and examined in detail using experiment, simulation and models. Second, the uncertainty in industry-standard predictions is analysed and improvements to turbulence modelling are presented. Finally, amatrix of blades with different 3D designs is used to investigate the balance of loss mechanisms and a reduction in total loss generation.
Reynolds Number Impact on High Pressure Turbine Flows
Authors: Osusky Michal , Ledezma Gustavo , Sluyter Greg , Shankaran Sriram 
Published: September 2023

Abstract
During operation, turbine blades in aircraft engines can experience flows over a wide range of Reynolds numbers. This range is impacted by engines of different sizes, as well as different operating altitudes, all of which add to the overall range of Reynolds numbers that are relevant for aircraft engine design. Unfortunately, increasing flow Reynolds number has a significant impact on the mesh resolution required for accurately simulating wall-resolved LES models due to the mesh resolution required to capture the near-wall flow physics. During the design process, providing engineers a detailed understanding of the flow physics phenomena, and how they change with Reynolds number, could lead to more efficient and durable turbine designs.
In this paper we present the study of flows around an uncooled high-pressure turbine blade. The simulations are completed with the high-order GENESIS code, which has been successfully applied to thread-parallel compute architectures, such as large computational systems with GPU capability. The simulations cover a range of Reynolds numbers in order to study the impact of Reynolds number increase over a fixed geometry. This allows for examining the impact on flow physics of interest, such as boundary layer evolution, laminar-to-turbulent transition, and wake shedding. The numerical results show that as Reynolds number is increased, a critical value is reached where the shedding behavior of trailing edge vortices changes, resulting in a jump in wake loss. Examination of the local flowfield quantities demonstrates that this change is due to a shift from laminar to turbulent flow on both sides of the airfoil, contributing to destabilization of the shear layer, resulting in larger vortices being shed.
Cross Boundary Design Optimization Using Simulation Process and Data Management
Authors: Malton Ken , Paiva Ricardo , Keskin Akin , Riaz Atif , Mourouzidis Christos 
Published: September 2023

Abstract
Even at the preliminary level, Multidisciplinary Design Optimization (MDO) of a novel aircraft concept is a challenging prospect. There, the interaction between airframe design and propulsion design tasks is particularly strong and can simultaneously be a weak link if not dealt with adequately. In the case of civil aviation, the constraints around sharing of data and tools (i.e., Intellectual Property) across organizational boundaries usually preclude an effective communication between the airframer and propulsor supplier. As such, the design of the airframe and propulsion system are usually done in isolation with occasional transfers of limited amounts of data, often leading to suboptimal results due to sequential subsystem optimization having effectively taken place rather than an overall and fully integrated system optimization.
In the present work, the Simulation Process and Data Management (SPDM) paradigm is employed to explore the benefits of automated encapsulation, transfer and ultimately storage of data during the design exploration process of an aircraft concept while ensuring compatibility of attributes between airframe design and engine design disciplines at each iteration, i.e. fully converged airframe-propulsor iterates, where the propulsion system provides exactly the thrust the airframe requires and the design of the latter is fully aware of the performance of the engine in the flight envelope it is being required to operate within.
Acoustic and Optical Investigations of the Flame Dynamics of Rich and Lean Kerosene Flames in the Primary Zone of an Air-Staged Combustion Test-Rig
Authors: March Martin , Renner Julian , Sattelmayer Thomas 
Published: September 2023

Abstract
In this study the thermoacoustic behavior of non-premixed kerosene flames from rich to lean combustion conditions is investigated. Flame-transfer-functions measured purely acoustically are compared with results based on flame chemiluminescence. OH*, CH*, C2* and CO2* were selected as potential measures for representing steady and fluctuating heat release when burning non-premixed kerosene. In addition, their ability for the quantification of equivalence ratio fluctuations will be highlighted. The measurements were performed in the primary zone of an atmospheric rich-quench-lean (RQL) combustion test-rig. The new experimental approach allows a characterization of the primary zone independent of the secondary zone. Rich and lean operating points were analyzed by fueling an aero-engine prototype injector with and without acoustic excitation. To improve the quality of the acoustic wavefield reconstruction a thermocouple correction method was implemented. The flame dynamics determined with the multimicrophone method exhibit a frequency and equivalence ratio depending effect for rich combustion conditions. The results for the steady behavior of the chosen radicals by altering equivalence ratio and thermal power indicate proportionality of the chemiluminescence to thermal power. Furthermore, the CH*/C2* ratio is found to be a promising indicator for the global equivalence ratio in the combustion chamber. The flame-transfer-functions based on chemiluminescence show a good qualitative agreement with the multimicrophone method. Based on the experimental findings a calibration curve for the different radicals to obtain quantitatively correct flame-transfer-functions from chemiluminescence is presented.
Effect of the Position of the Centerbody on Thermoacoustic Instabilities in a Central-Staged Model Combustor
Authors: Han Meng , Han Xiao , Gan Zhichao 
Published: September 2023

Abstract
The present study investigates the effect of the position of the centerbody on thermoacoustic instabilities in a central-staged model combustor with a dual-swirl layout. The position of the centerbody significantly influences the combustor’s vortex breakdown and combustion performance, such as combustion instability. In this paper, three different axial positions of the center body are studied experimentally under atmospheric pressure and temperature with premixed methane-air mixtures. The result shows that the position of the center body alters the pilot flame shape, and then the overall flame shape changes, no lifted flames have been discovered in the case of the center body in the Down-5mm. The degradation of the centerbody also could increase the amplitudes of pressure oscillation in the combustor. Moreover, the dominant frequency of oscillation is different with different positions of the center body. The beating oscillations are also found in three positions of the center body. Flame dynamics are further analyzed using the Dynamic Mode Decomposition method. It is concluded that the cases of the center body downstream have the best thermoacoustic stability within the tested range of three cases. The flow mechanisms of three different center body positions have been revealed using the numerical simulation of RANS. It is found that the degradation of the center body could decrease its ability of stabilized the pilot flame and then decrease the thermoacoustic stability.
Numerical Investigation of NH3 Doped Fuels From Biomass Gasification on Fuel-Bound NOx Formation at Gas Turbine Conditions
Authors: Yang Silin , Raslan Ahmed , Durocher Antoine , Güthe Felix , Bergthorson Jeffrey 
Published: September 2023

Abstract
As our society transitioning away from fossil fuel-based energy system to reduce carbon emissions, renewable energy sources are needed to meet the increasing energy demand in the near future. Biomass, consisting mostly of plant-based organic materials, is a promising alternative to fossil fuels for carbon-neutral energy production. Unfortunately, during the gasification process, the nitrogen content in biomass is converted to NH3, which is then oxidized in the combustion process, leading to high NOx emissions through the fuel-NO pathway. The high NOx emissions from NH3 and NH3-containing fuels have prevented their implementation at scale. Depending on the gasification process, source of biomass, and combustion technology, the NH3 and water content can vary greatly. This works focuses on blends of 2% (mol) NH3 in CH4, diluted by up to 55% (mass) water. The combustion process is modelled by freeflame connected to a plug flow reactor (PFR), achieving a total residence time of 100 ms. Major chemistry involved in the fuel NO pathway were identified from reaction pathway analysis. NOx emissions were investigated under different equivalence ratios (Φ = 0.45–2.2) and inlet pressures (1 atm, 40 atm). NO concentration increases rapidly as NH3 is added to the fuel mixture, as expected. Under fuel rich conditions, NO decreases after the initial increase, and this reduction becomes more pronounced at elevated pressure and long residence times. At the same time, unburned NH3 and other reactive N species increase as NO decreases. The optimal conditions that minimize the total NOx and NH3 emissions were found to be slightly fuel rich, high pressure, and long residence time. Under these conditions, additional pathways involving NNH and N2O promotes the conversion of NH3 to N2. Large discrepancies among different thermochemical mechanisms highlight areas that still need to be researched. Results from the current study can assist in the modelling and design of low-emissions engines fuelled by biomass and NH3, thereby contributing to a carbon-neutral economy.
Towards Scales Resolving Direct Simulation of a Hydrogen/Air Lean Premixed Flame With Swirler-Induced Turbulence
Authors: Xiao Gan , Palies Paul 
Published: September 2023

Abstract
This article introduces a computational tool for scales resolving simulations of chemically reacting flows applicable to moderately complex geometries and relevant operating conditions. The advantage of the presented methodology is to retain finite rate chemistry with single step chemical kinetic mechanism coupled with detailed transport to solve for turbulence flow scales, both integral and Kolmogorov scales, as well as flame scales. This enables to limit the cost associated with complex chemical mechanisms. The approach is applied here to an atmospheric laboratory-scale configuration to study high-swirled 100% H2/Air fully premixed flame ignition, a key knowledge gap in the literature. This configuration includes the geometry effects from the swirler that have an essential role in turbulence scale generation driving the flame wrinkling. The computational tool is based on open-source codes, the finite volume OpenFOAM9 solver where detailed transport data from Cantera are integrated. The paper presents the transport model validation, the single-step kinetic mechanism development, the high-performance computing scaling study, the premixed turbulent combustion regime assessment, the geometry, the mesh, and the numerical settings. The non-reacting flowfield and ignition transient sequence numerical results obtained are discussed. Key non-reacting establishing swirling flow features, inner recirculation zone and swirling jet, are captured. The ignition method strategy is devised from 1D premixed flame ignitions tests. It is next applied to the 3D configuration to ignite the premixture. This provides a computational capability to assess multiple ignition scenarios to initiate flame propagation.
Methods and Apparatus for Real-Time Seal Clearances Assessment Using a Pressure Measurement
Authors: Kim Taehong 
Published: September 2023

Abstract
Today’s aircraft turbine engines are exposed to higher temperatures, higher pressure with the need of increased rotor life to meet customer demand with higher thrust and better fuel efficiency. The case structure and rotating parts have different thermal and mechanical expansion and contraction which drive clearances to be excessive. In most of commercial engines, interstage seals (ISS) and mid-seals connected to tip clearance control system are designed to schedule seal clearances to maintain cavity pressures and balance purge flow. The system is designed to manage the gap for efficiency but prevent hot gas ingestion from overheating during engine operation.
Measurement of seal clearances would be a crucial way to understand seal clearance changes and to design purge flow for secondary flow and thermal design. For example, real time measurement would provide a way to adjust seal gaps to maintain turbine efficiency in new and deteriorated conditions. However, there is no promising method or an apparatus to sense and measure seal clearances in actual engine test or operation because ISS and mid-seals are located at inner flow path, such as buffer cavities through vane or nozzle, which are not favorable to directly install clearance probes and sensors.
This study is to review flight test data of turbine mid-seal clearance and radial tip clearances measurement and demonstrate its linear correlation between pressure and temperature against clearance changes during test of different operating conditions such as power calibration test at low and high altitudes and Active Clearance Control (ACC) valve swing test at high power. As a result, the study proposes new methods to assess seal clearances using conventional pressure sensors at forward and aft cavities with the linear conversion curves. The conversion method was developed for new engines tests, but it can be applicable for deteriorated conditions of production engines to improve efficiency and operability if independent seal clearance control system is developed and adapted.
A Method for Preliminary Design of Variable Geometry Vaned Diffuser for Centrifugal Compressor
Authors: Tamaki Hideaki , Yamaguchi Satoshi 
Published: September 2023

Abstract
Centrifugal compressors require a wide operating range as well as high efficiency. Typical active control forms to enhance the operating range are suction throttling with a valve in a suction line, discharge throttling with a ring installed in a vaneless diffuser, variable inlet guide vanes, and variable geometry vaned diffuser. This study focuses on the design of a variable geometry vaned diffuser (VVD) whose vane rotates around a pivot to adjust its opening and proposes a method to estimate the main parameters of a VVD at the preliminary design stage. The design method here is based on matching the diffuser vane inlet angles with the flow angles at the diffuser inlet. If the designed VVD can maintain low incidence at the diffuser vane leading edge over the whole movable range of the vane is evaluated. A graph, which indicates the relation between the diffuser vane inlet angles and the flow angles at the diffuser inlet at diffuser choking and diffuser stalling, makes the evaluation easy. The proposed procedures were applied to select the number of vanes of a VVD for a turbocharger compressor. Tests for the validation of the design procedures were conducted by using fixed vaned diffusers that simulated the VVDs installed on the turbocharger with an 85mm-diameter impeller. The results showed the effectiveness of the proposed design procedures. This paper first presents examples of applications of the typical active methods extending centrifugal compressors’ operating range for real machines and then discusses the design of VVD.
Rotor-Rotor Cavity Flowfield in the Presence of Radially Inward Flow With Different Co-Rotational Speeds
Authors: Erdem Erinc , Karasu Zeki Tugberk , Yilmaz Sefa , Yazan Alican , Sal Sinan 
Published: September 2023

Abstract
This article aims at the investigation of rotor-rotor cavity flowfield using CFD and one-dimensional flow solver for a representative engine configuration. The numerical approach is validated against the test data of Firuzian et. al. for a simpler rotor-rotor cavity geometry, in terms of the location of zero radial velocity signifying the extent of entraining source region and the swirl ratio distributions in radial direction, for three different λT values. Afterwards the flowfield in the current configuration is numerically predicted using the same numerical approach at various engine thrust settings corresponding to a wide range of dissimilar rotational speed ratios (0.34–0.67). Zero radial velocity location is observed on the high-pressure structure and it moves from low radii at low thrust levels to medium radii at high thrust levels. On the low-pressure disk side, the flow is radially inward for all the cases. At low thrust settings the flowfield resembles a forced vortex-like flow, where torques generated on both disks prevent tangential acceleration of the flow.
Extension and Validation of the Turbomachinery Capabilities of SU2 Open Source CFD Code
Authors: Yan Chuanxiang , Wang Baotong , He Xiao , Zhao Fanzhou , Zheng Xuedong , Vahdati Mehdi , Zheng Xinqian 
Published: September 2023

Abstract
Computational Fluid Dynamic (CFD) tools have revolutionized the way to design engineering systems, but most established codes are proprietary and closed-source, making it difficult, if not impossible, to modify, debug or add new features to the code. To provide a freely available open-source CFD code for turbomachinery aerodynamics and aeroelasticity, this paper enhances the turbomachinery capabilities of the open-source SU2 code and demonstrates its capabilities of single-passage steady simulation, full-annulus unsteady simulation and aeroelasticity analysis in two high-speed compressors, namely NASA Stage 35 and TUDa-GLR-OpenStage, and a linear cascade SC1. For the single-passage steady simulation of NASA Stage 35, the SU2 results are validated against the measured data and verified against the commercial solver Ansys CFX, and the performance characteristics results are in reasonably good agreement with each other. For the single-passage steady simulation of TUDa-GLR-OpenStage, grid and turbulence model sensitivity studies are performed and results are validated against the measured data, and SU2 can predict both the performance characteristics and the radial profiles with sufficient accuracy. For the full-annulus unsteady simulation of NASA Stage 35, it is demonstrated that SU2 can predict the propagation of inlet distortion equally well as Ansys CFX. For the linear cascade, SU2 can predict the unsteady pressure and aerodynamic damping coefficient accurately. The presented results demonstrate the turbomachinery aerodynamics and aeroelasticity capabilities of SU2. The major modifications of SU2 made in this work will be shared with the code maintainer and the community in the future.