bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance Analysis of an Engine-Mounted Compression System for Aircraft Environmental Control
Authors: van Heerden Albert S. J. , Ippedico Salvatore , Rajendran David John , Anselmi-Palma Eduardo , Roumeliotis Ioannis , Pachidis Vassilios , Sharpe Richard , Howarth Nicholas 
Published: September 2023

Abstract
Environmental Control Systems (ECS) on civil transport aircraft constitute large portions of the secondary power demand. In this paper, an alternative compression system to the conventional two-port bleed design is presented, which can substantially lower the level of secondary power required for meeting the ECS demand. The concept presented is a novel engine-mounted cabin compression system (EMC2S). The potential benefits of the novel EMC2S over conventional systems are quantified and a multi-disciplinary approach, involving combined engine and aircraft performance analysis, is used to quantify the mission fuel burn of both conventional and novel EMC2S configurations for a reference mission. It is shown that, compared with a conventional system, an EMC2S can achieve up to a 0.72% reduction in fuel burn for a single-aisle short-to-medium-range aircraft with a year 2000 entry-into-service turbofan. Larger savings are expected for higher bypass ratio engines.
High Throughflow Design and Analysis for Streamvane Swirl Distortion Generators
Authors: Hayden Andrew P. , Gillespie John , Hefner Cole , Untaroiu Alexandrina , Lowe Todd 
Published: September 2023

Abstract
In recent years, the StreamVane technology has developed into a mature and streamlined process that can reproduce swirl distortion for ground-test evaluation of fan and compressor performance and durability. A StreamVane device consists of complex turning vanes that accurately output a distorted secondary velocity field at a defined distance downstream. To further advance the applications and conditions in which these devices operate, a research effort was developed and completed to investigate methods to increase critical Mach numbers. The effort was split into three separate stages: 1) Perform high fidelity computational fluid dynamics (CFD) to identify peak Mach number locations within twin and quad swirl vane pack designs; 2) Conduct thorough literature reviews on relevant high throughflow techniques; 3) Design and implement selected techniques to evaluate improvements using the same high-fidelity CFD methods. It was predicted that employing blade lean within high-speed vane junctions increased critical Mach numbers by 6.6%, while blade sweep resulted in a 3.5% increase. The results and conclusions from this effort are presented throughout this paper with a primary focus on comparing Mach numbers and swirl profiles between vane packs with and without high throughflow designs.
Aerodynamic and Rotordynamic Performance of a Multi-Stage Centrifugal Compressor With High Hub Impellers
Authors: Srinivasan Anand , David Tim , Silva Daniel , Rajagopalan Vinayaka , Kurz Rainer 
Published: September 2023

Abstract
Multi-stage centrifugal compressors with single shaft modular rotor designs are used extensively in the oil and gas industry. These compressors are designed to handle a wide range of speeds, flows and discharge pressures, in addition to handling a wide range of gas specific gravities. In this paper, low pressure test results are presented for a multi-stage centrifugal compressor with high hub impellers. Scaled results from a test rig are presented to validate the aerodynamic performance characteristics of a single stage of compression. The results of the scaled test rig are used to generate the performance characteristics of a family of impellers intended for use on the high-pressure compressor product line. A multi-stage compressor was built to validate the full-scale performance and the stage stack-up characteristics. Rotordynamic performance results of the free-free natural frequencies and unbalance response characteristics are presented for the full-scale compressor rotor. These results are used to validate the rotor-bearing models for the compressor rotor. Aerodynamic test results with discharge pressures up to 1,100 psia [76 bara] are presented. Test results obtained on nitrogen and carbon dioxide at multiple machine Mach numbers are also presented. The test results serve as a benchmark for the performance validation prior to intended usage at discharge pressures up to 4,900 psia [337 bara].
Interference of Unbalance on the Dynamic Characteristics of Cracked Rotor: An Experimental Research
Authors: Han Bing , Yan Peigang , Liu Zhansheng , He Peng 
Published: September 2023

Abstract
When the rotor of an aeroengine or gas turbine contains cracks, it produces abnormal vibrations. The abnormal vibration behavior of the cracked rotor can be used as the basis for crack fault diagnosis. However, in practice, the rotor itself cannot achieve absolute dynamic balance. Also, the operating environment in which the rotor is placed may contain unbalanced excitation. During the rotation of the cracked rotor, the existence of unbalance interferes with these abnormal vibration characteristics. Therefore, studying this process is of great significance for solving the issue of rotor crack fault diagnosis under unbalanced disturbance in engineering.
This study aimed to monitor the dynamic characteristics of a multi-disk rotor system with transverse cracks. An unbalanced mass was imposed at the disk. Precision wire cutting was used to prefabricate cracks on the rotor to maximize the simulation of fatigue cracks in the real industrial environment. During the test, the crack depth was from shallow to deep and the direction of the crack opening remained unchanged, while the direction of unbalanced force changed 360° along the circumferential direction of the disk. The experimental results showed that when the angle between the unbalanced force direction and the crack opening direction changed, the crack fault characteristics changed to different degrees. The effect of unbalance on crack fault characteristics was more obvious with the increase in crack depth.
The Effect of Unsteady Inlet Boundary Conditions on the Aero-Thermal Behavior of High-Pressure Turbine Vanes: A Numerical Study Using Scale-Resolving Simulations
Authors: Gründler Jonathan , Lehmann Knut , Schiffer Heinz-Peter 
Published: September 2023

Abstract
This paper presents the application of a novel method to prescribe unsteady boundary conditions to transient, scale-resolving Computational Fluid Dynamics simulations of the high-pressure turbine in modern jet engines. The methodology is based on the compression of the interface data at the Combustor Turbine Interface, using Proper Orthogonal Decomposition and Fourier Series (PODFS). Doing so can reduce the stored data at the interface drastically. The capability of the PODFS method to produce realistic inlet boundary conditions was demonstrated in previous work. Here, the method is applied to a turbine case. The outlet data of a combustor simulation is used to create the PODFS boundary conditions for a scale-resolving simulation of a simplified first Nozzle Guide Vane of the high-pressure turbine. This simulation is compared with simulations with steady-state boundary conditions to show the effect of unsteadiness in the inlet boundary condition on the aerodynamic and thermal behavior of the turbine. While the aerodynamics show minor sensitivity against the way of applying the inlet boundary conditions, the thermal behavior of the vanes is strongly affected by the modeling of combustor unsteadiness.
Shape Optimization of a Cooling Hole Using Improved Metamodeling Techniques and Workflow
Authors: Norman Adam , Arguinzoni Carlo , Sharma Kalyan , Cunningham Pat , Joshi Dibesh 
Published: September 2023

Abstract
In modern day gas turbine hot sections, active cooling of liner walls is critical due to extremely high temperatures and long continuous operation. A secondary flow can be introduced that shields the metal surfaces by forming a film increasing the durability and life of the liner. Typically, this cooling flow is mixed with the mainstream by a series of holes or slots along the length of the liner wall. In the past, typically, these effusion holes were cylindrical. However, as the hot section temperature increases, more advanced hole designs are necessary for increased cooling effects.
Determining an optimal hole design is costly and time-consuming if approached with standard experimental trial-and-error techniques. Numerical tools can aide in optimization studies, but for complex transient flows requiring scale-resolving methods, simple optimization methodologies require thousands of design points and can take extended periods of time to complete.
In this study, a metamodel-based optimization of a shaped cooling hole is demonstrated in an automated workflow. The automated workflow consists of six geometrical hole parameters being investigated at flow conditions akin to the hot section at a constant blowing ratio. These six parameters completely define the shape of the hole leading to a complete optimized design for maximum cooling effectiveness. The metamodel is based on data from a stress-blended eddy simulation (SBES). To construct the meta-model, an adaptive technique is used that employs machine learning (ML) algorithms to minimize the number of required design points by dynamically modifying the design space sampling based on the gradients in the response. As part of the metamodel generation, a sensitivity analysis is performed to eliminate geometry parameters which do not influence the cooling effectiveness.
The optimization study is done in two parts: the first part involves an evolutionary algorithm-based optimizer which runs the fast-running metamodel through multiple design points to identify potential optimal solution candidates; the second part involves validating the candidate designs using actual solver calls. This two-pronged approach drastically reduces the time to achieve optimal effusion hole design while ensuring that the design space is explored thoroughly. Overall, this work demonstrates the enhanced optimization capabilities and timeline compression of a shaped cooling hole.
Performance Evaluation of Additively Manufactured and Hybrid Indexable Milling Tools in Machining of AISI4140+QT and Ti-6Al-4V
Authors: Kelliger Tobias , Meurer Markus , Bergs Thomas 
Published: September 2023

Abstract
Additively manufactured (AM) cutting tools enable new design concepts in tool development concerning lightweight construction, damping behavior and internal cutting fluid supply. So far, the impact of the layer-by-layer manufacturing technique onto the tool performance during machining of aerospace materials is widely unknown. In this study, the performance characteristics of AM indexable milling tools were investigated and compared to a conventionally manufactured tool of the same geometry. The AM tools were manufactured by Laser Powder Bed Fusion (LPBF) from a newly developed bainitic steel alloy. All tools were analyzed with two main focuses. Outside the machine tool, geometrical characteristics and mechanical properties were taken into account. Inside the machine tool, during roughing of AISI4140+QT (42CrMo4+QT) and Ti-6Al-4V (ASTM Ti-Grade 5), tool wear, cutting forces, surface roughness and vibration behavior were evaluated. Three tool concepts were compared, a conventional tool, an AM tool and a hybrid tool with a conventionally manufactured preform and an AM head. Differences in the performance behavior could be traced back mainly to geometrical inaccuracies caused during post-processing of the tools. Thus, LPBF manufactured basic bodies seem to meet the requirements as application for indexable milling tools. Based on this work, future investigations using AM cutting tools can be carried out assuming a negligible influence of the manufacturing technique onto the tool performance during machining.
Supercritical Carbon Dioxide Shock Behaviour Near the Critical Point
Authors: Wang Jinhong , Cao Teng , Martinez-Botas Ricardo 
Published: September 2023

Abstract
This paper aims to provide an understanding of sCO2 inviscid adiabatic normal shock behaviour near the critical point and to develop an explicit tool for faster prediction of the shock relations that can aid the supercritical turbomachinery design process. An iterative algorithm was developed to compute shockwave behaviours for non-ideal fluids. Three important shock behaviour parameters were investigated: post-shock Mach number, shock strength, and polytropic efficiency. A comparative study was carried out between air (ideal gas assumption), ideal gas CO2 (ideal gas assumption), and non-ideal fluid CO2 (Span-Wagner equation of state). The distinct differences show the inadequacy of the perfect gas shock relations when predicting sCO2 shock behaviour near the critical point. The results of non-ideal fluid calculations show a general trend of stronger shock strengths and higher polytropic efficiencies towards lower pre-shock entropy conditions. This is also distinctive near the critical point due to the reduced speed of sound. Finally, explicit expressions for these parameters were retrieved using symbolic regression. The fitted models have significant improvements compared to the prediction from perfect gas shock relations with a 5–20% point reduction in relative errors. This study also shows the potential for machine learning to be applied in non-ideal fluids effects modelling and the methodology developed in this paper can be easily introduced to other working fluids in their ranges of interest.
Challenges in the Application of Hot-Wire Anemometry for the Investigation of Transient Temperature Fluctuations in a High-Speed Research Compressor
Authors: Schäffer Christian , Rabl Alexander , Speck Konstantin , Boetzel Kiyan , Helcig Christian , Gümmer Volker 
Published: September 2023

Abstract
This paper presents an investigation into the principles of unsteady total temperature measurement with a parallel hot-wire while also examining potential challenges that might occur when using a custom-made hot-wire in a High-Speed Research Compressor.
After modifying the institute’s open free-stream calibration tunnel with a pressure chamber to enable the calibration of hot-wires at compressor-representative conditions, different approaches for extracting the total temperature from the hot-wire raw data were evaluated. The comparison of the ‘optimized King’s law’, ‘Lienhard & Helland method’ and a new polynomial approach revealed reasonable results with similar accuracy, whereas the polynomial concept requires less calibration effort. When measuring with the hot-wire in the research compressor, significant disturbances were caused due to vibrations. After several mechanical modifications at the prongs, probe holder and probe guidance, followed by a visual inspection with a high-speed camera, it was concluded, that wire strain gauging occurred due to prong vibrations. This difficulty could be avoided by welding the wires with less tension and a noticeable slack.
Finally, the effect of wire contamination was investigated. After two hours of testing, particle accumulation shows potential of having a significant effect on the measurement results in open-loop test rigs.
Numerical Investigation of the Influence of the Degree of Reaction in an Axial Compressor Stage With Tandem Vanes
Authors: Giannini Samuele , Luz Guilherme M. , von Jeinsen Philipp , Straccia Mattia , Gümmer Volker 
Published: September 2023

Abstract
Many investigations have defined Smith-type diagrams to guide the preliminary designs of conventional axial compressor stages on the choice of loading, flow coefficient, and degree of reaction. The recent development of unconventional axial compressor stages with tandem vanes has not been accompanied by similar works aimed at tailoring existing correlations to the new type of vanes. While it is clear that axial compressor stages with tandem vanes operate in higher working ranges than conventional stages, it is less clear how the choice of reaction affects the aerodynamic behavior of such setups. Recent works have shown that higher work coefficients would require higher degrees of reaction thanks to the centrifugal effects’ beneficial influence on the rotor’s boundary layer. However, the interaction of tandem vanes with such phenomena is still not fully understood. For this purpose, this paper numerically investigates a low-speed axial compressor stage developed at the Technical University of Munich with different degrees of reaction for increasing loading levels. The metal angles of the unshrouded rotor and the shrouded stator are modified to ensure that the other design parameters of the stage, namely the work and flow coefficients, are kept constant and that the influence of the degree of reaction is isolated. The investigation starts with Q2D simulations of the reference midspan aerofoils, and it is then extended to a 3D configuration by maintaining the radial distribution of the aerofoil parameters together with the lean and bow distributions of the reference 3D vanes. New correlations are presented, aiming to show how the performance of the stage in terms of efficiency, total pressure losses, and loading coefficients of the vanes are influenced by the different degrees of reaction investigated. This paper therefore provides insight into the preliminary choices of parameters for the design of axial compressor stages with tandem vanes.
Flame Speed Measurements of Ammonia-Hydrogen Mixtures for Gas-Turbines
Authors: Yovino Louis , Kim Gihun , Rahman Ramees K. , Pierro Michael , Vasu Subith S. , Winquist Mark , Subbaraman Ganesan , Steele Robert 
Published: September 2023

Abstract
Recent findings from the US Energy Information Administration (EIA) project an increase in domestic fossil fuel consumption (e.g., petroleum, natural gas) and global greenhouse gas (GHG) emissions through 2050 [1]. Consequently, advanced combustion research aims to identify fuels to mitigate fossil fuel consumption while minimizing exhaust emissions. Ammonia (NH3) is one of these candidates, as it has historically been shown to provide high energy potential and zero carbon emission (CO and CO2) [2]. As a hydrogen (H2) carrier, NH3 serves as a possible solution to the U.S. Department of Energy’s (DOE) Hydrogen Program Plan by providing efficient H2 storage and conservation capabilities [3]. As a result, applied turbine-combustion research of NH3 and H2 fuel has been conducted to identify combustion performance parameters that aid in the design of sustainable turbomachinery [4]. One of these key combustion parameters is the laminar burning speed (LBS). While abundant literature exists on the combustion of NH3 and H2 fuels, there is not sufficient evidence in high-pressure environments to provide a comprehensive understanding of NH3 and H2 combustion phenomena in turbine-combustor settings. To advance the state of the knowledge, NH3, and H2 mixtures were ignited in a spherical chamber across a range of equivalence ratios at 296 K and 5.07 Bar (5 atm) to understand their flame characteristics and LBS which was determined using a multizone constant-volume method. The experimental conditions were selected according to primary turbine-combustor conditions, as much research is needed to support NH3-H2 applicability in turbomachinery for power generation. The effect of H2 addition to NH3 fuel was observed by comparing the LBS for various NH3-H2 mixture compositions. Experimental results revealed increased LBS values for H2 enriched NH3, with the maximum LBS occurring at stoichiometry. The experimental data were accurately predicted by the UCF NH3-H2 mechanism developed for this investigation, while NUI 1.1 simulations overestimated recorded LBS data by a significant margin. This study demonstrates and quantifies the enhancing effect of H2 addition to NH3 fuels via LBS and strengthens the literature surrounding NH3-H2 combustion reactions for future work.
Novel Additively-Manufactured and Internally-Cooled Airfoils for Increasing Small Industrial Gas Turbine Efficiency
Authors: Searle Matthew , Roy Arnab , Ramesh Sridharan , Floyd Timothy , Ames Forrest E. , Straub Douglas 
Published: September 2023

Abstract
The U.S. Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) has tested the cooling performance of baseline and advanced additively manufactured (AM) airfoils for small industrial gas turbines. This study is a first step to increase market penetration of gas turbine-based combined heat and power (CHP) systems by increasing gas turbine efficiency through a 100 °C increase in turbine inlet temperature, where the turbine inlet temperature gain is enabled by AM cooling architectures. The baseline designs consisted of state-of-the-art blade and vane designs, while advanced concepts included the NETL Double Wall, incremental impingement, and lattice designs.
Tests were performed at NETL in the conjugate aerothermal test (CAT) facility, which is a visually-accessible, heated, wind tunnel with an independent coolant plenum. Spatially resolved overall cooling effectiveness was measured using infrared (IR) imaging, and the results accounted for reflection and IR window transmission losses.
To evaluate the design performance, baseline (0.28) and advanced overall cooling effectiveness (0.37), targets were established from system models. Results for overall cooling effectiveness (both average and 99th-percentile) for the baseline and advanced designs (five total) were plotted versus a non-dimensional heat load parameter (HLP) varying from 0.5 to 3.5. The minimum HLP to keep 99% of the blade surface temperature of the baseline blade, incremental impingement, and NETL Double Wall at or below the maximum metal temperature for the advanced target was 3.22, 2.83, and 1.36, respectively.
The success of the NETL Double Wall was attributed to the staged coolant addition along the airfoil chord. Poor cooling performance on the leading edge of the incremental impingement design due to inadequate leading edge plenum sizing prompted a redesign, which will be reported in future work.
A CFD-Based Small-Scale Combustor Design Optimization Utilizing a Many-Objective Evolutionary Algorithm
Authors: Briones Alejandro M. , Paxton Brendan T. , Rankin Brent A. 
Published: September 2023

Abstract
This work demonstrates the capability of an open-source autonomous computational fluid dynamics (CFD) meta-modeling environment (OpenACME) for optimizing small-scale combustor designs. OpenACME couples several object-oriented programming open-source codes for CFD-assisted design using a decomposition-based many-objective evolutionary algorithm (MaOEA). The CFD is based on steady, incompressible, three-dimensional simulations with k-ω SST RANS and flamelet/progress variable combustion model. There are five unconstrained design variables based on combustor liner dilution hole diameters. The CFD results are compared with existing experimental data in terms of combustion efficiency as a function of severity. The comparison demonstrates that the CFD methods capture combustion efficiency trends. Next, more than 500 combustor designs are evaluated with OpenACME. A Pareto Frontier is generated in terms of combustion efficiency, pattern factor, and total pressure losses. Pseudo weights are used to select a non-dominated Pareto Frontier design point for future fabrication and experimental testing. OpenACME is demonstrated to be a viable tool for small-scale combustor design optimization.