bluuebunny/crossref_metadata_2025_split huggingface dataset:
Large-Eddy Simulations of a High-Speed Low-Pressure Turbine Cascade With Purge Flow
Authors: Perkins David W. , Duchaine Florent 
Published: August 2024

Abstract
Future turbofan designs are expected to include gearboxes to allow for the decoupling of the fan and the low-pressure turbine. Doing so will increase overall engine efficiency, but change the design point for low-pressure turbines by allowing to increase the rotation speed. To study these new high-speed turbines, an experimental configuration from the European project SPLEEN, supported by the Von Karman Institute (VKI) and SAFRAN Aircraft Engines, is investigated using Large Eddy Simulation (LES). Three simulations based on the experimental SPLEEN cascade are performed: a baseline case without the purge flow cavity, a case with the purge flow cavity, and a case with the purge flow cavity and 0.9% mass flow rate relative to the main flow. These simulations capture engine-relevant turbulence, transition, and transonic Mach number physics that are expected in this operating regime. The losses in the cascade are analyzed and compared to experiment, showing good predictive capabilities of LES.
Field Performance Testing and Test Codes for Gas Compressors
Authors: Brun Klaus , Kurz Rainer 
Published: August 2024

Abstract
Field testing of gas compressor packages requires the accurate determination of efficiency, capacity, head, and power in sometimes less than ideal working environments. The results of field tests have significant implications for the compressor manufacturers and their customers, as economic considerations demand that the performance and efficiency of an installation are verified to assure a project’s return on investment. Thus, for the compressor manufacturers, as well as for the end-user, an accurate determination of the compressor performance in the field is of vital interest.
While field performance tests have to be executed under conditions dictated by the situation at site, factory test codes like ASME PTC10 and ISO 5389 provide guidance. The former code was recently revised, so a discussion of this revised code in the context of site performance testing is appropriate. A key change in PTC10 is the method to calculate polytropic work, which affects data reduction. It also affirms a method to calculate error propagation and test uncertainties. The discussion includes the appropriate use of Equations of State, and the definition of steady state requirements. Different methods to define valid operating conditions for the test, based on similarity considerations are compared.
However, field tests, unlike factory tests, are ultimately conducted based on the conditions at site which may or may not conform with test codes, Therefore, calculation of test uncertainties, and the use of observations not covered by the codes are emphasized. The paper attempts to provide guidance for the conduct of field performance tests.
Green Methanol Demonstrated as an Alternative Fuel to Decarbonise Gas Turbines
Authors: Clifford Tyler , Booth Charlie , Houde Michel , Fowler Regis , MacLean Cameron , Basu Madhubanti , Witzel Benjamin , Bulat Ghenadie 
Published: August 2024

Abstract
Power generation from gas turbines is responsible for up to 79% of the CO2 emissions generated by the UK Oil and Gas (O&G) industry. Thus, decarbonizing gas turbines is key to reducing emissions in the industry. Siemens Energy, in partnership with The Net Zero Technology Centre (NZTC) and Rolls Wood Group (RWG), successfully demonstrated an SGT-A20 gas turbine running on 100% bio-methanol, reducing the overall CO2 footprint by 60%. The demonstration test was a key milestone in Phase 1 of the Alternative Fuel Gas Turbine project funded by the Scottish government and industry partners. The SGT-A20 bio-methanol test demonstrated the engine operating at various conditions including start-up, shut-down, idle to full power, and transient maneuvers. The engine performed as expected within the standard operating limits. The test also confirmed a reduction in NOx emissions of approximately 80%, a 15% reduction in CO, and elimination of visible smoke in the gas turbine exhaust compared to kerosene fuel.
Prognostics and Health Management for Electrified Aircraft Propulsion: State of the Art and Challenges
Authors: Tang Liang , Saxena Abhinav , Younsi Karim 
Published: August 2024

Abstract
In recent years, the aviation industry has witnessed a transformative wave of innovation in electrified aircraft propulsion (EAP), driven by sustainability and efficiency goals. Integration of novel electrical subsystems, including high-voltage power electronics, motors/generators, and energy storage devices, has introduced intricate complexities. In this context, an intensified focus on Prognostics and Health Management (PHM) is imperative, considering the heightened reliability needs in a transportation propulsion application. This paper extensively analyzes the current state-of-the-art in PHM applicable to various EAP systems and components crucial for the functioning of electric aircraft. Typical fault modes and fault management strategies are analyzed at various levels of systems hierarchy. An integral aspect of our investigation involves the identification of critical gaps within existing PHM frameworks, guiding the research agenda for enhanced reliability and performance. Moreover, the distributed nature and increasing complexity of electric propulsion systems underscore the importance of Model-Based Systems Engineering (MBSE). We advocate for the exploration of MBSE not only to inform the design and implementation of PHM solutions but also to facilitate certification and Verification and Validation (V&V) activities. Additionally, the paper offers insights into existing tools and simulation software packages capable of integrating traditional gas turbine modules with electric subsystems, as well as simulating various faulty conditions in EAP relevant to PHM development. Key gaps in these tools are emphasized, drawing attention to areas that require further refinement and development. This comprehensive exploration aims to pave the way for future advancements in PHM tailored for the unique challenges posed by electric aircraft propulsion systems.
Thermodynamic Modelling of Air Management System for Commercial Aircraft Environmental Control Systems
Authors: Spurthy Subramanya , Joksimović Aleksandar , Carbonneau Xavier , Rebholz Sarah , Tong-Yette Frederic 
Published: August 2024

Abstract
For a short-medium-range aircraft at cruise, the Environmental Control System (ECS) consumes about 75% of the total extracted engine bleed air on average. The Air Management System (AMS) of the ECS significantly reduces the bleed air pressure and temperature to meet the inlet requirements of the Pressurized Air Conditioning Kit (PACK). This paper aims to understand the impact of the conventional AMS on the engine performance and proposes an alternative AMS architecture for effective utilization of the bleed off-take pressure and temperature. Subsequently, a steady-state 0D thermodynamic analysis of the conventional and alternative AMS architectures is carried out using PROOSIS™ software, to study their impact on engine performance for different mission phases. Based on this preliminary thermodynamic analysis the alternative AMS shows a potential improvement of the engine performance mainly in terms of the TSFC, up to 0.7% across different mission phases.
Reconstruction of the Reflection Coefficient Downstream of a Flame From Dual SISO Flame Response Measurements
Authors: Ganji Hamed F. , Kornilov Viktor , van Oijen Jeroen , Lopez Arteaga Ines 
Published: August 2024

Abstract
This study introduces an innovative approach to assess the thermoacoustic characteristics of components downstream of a flame, employing two sets of distinct Single-Input-Single-Output (SISO) acoustic measurements. Conventional direct assessments of downstream reflection coefficients face challenges due to the need for measurements in the high-temperature downstream region and complexities arising from heat inflow from the flame. To address these challenges, we leverage the widely adopted dispersion relation format from the theory of radio-frequency circuits. In the current methodology, the flame transfer function (TF) technique, as a well-established tool in thermoacoustics, is used. The second method utilizes a standard impedance tube test based on a one-port acoustic reflection test, conducted on the upstream/cold side with a flame present. To demonstrate the effectiveness of our approach, we applied the method to a ducted premixed burner-stabilized Bunsen-type flame. The straightforward reconstruction of downstream reflection coefficients revealed strong sensitivity to noise and uncertainty, particularly in higher frequencies, necessitating specialized data treatment. To mitigate this sensitivity, we conducted multiple tests with slight changes in operating conditions, creating a dataset expected to yield nearly identical downstream reflection coefficients. We then formulated an over-determined system of linear equations, employing the least-squares method to minimize errors and sensitivity. This work showcases a significant reduction in sensitivity through the use of multiple tests and data treatment techniques. The reconstructed downstream acoustics were employed to construct the reflection coefficient measured at upstream side of active subsystem and flame TF at a thermal power close to that corresponding to the reconstructed downstream acoustics, demonstrating substantial improvements in accuracy and reliability.
Unsteady Flow Structure of Rotating Instability in a 1.5-Stage Axial Compressor
Authors: Fujisawa Nobumichi , Ohta Yutaka , Yamagami Mai , Goto Takashi , Kato Dai 
Published: August 2024

Abstract
Unsteady flow structure of the rotating instability (RI) in a 1.5-stage axial compressor is investigated through experimental and numerical analyses. In the tested compressor, the total pressure rise of the rotor stagnates at a certain flow coefficient before it increases again towards lower flow rate in a case involving a wide tip clearance. The RI appears beyond this stagnant point as the compressor is throttled. The RI indicates a gentle hump in the frequency spectra of wall pressure or the flow velocity near the tip in a range approximately 20 to 40% of the blade-passing frequency. As the flow rate decreases, the mode order of the RI increases, in contrast to more commonly reported tendency, while the propagation velocity remains constant. These features are well captured by DES of the half-annulus model, with which the unsteady flow structure is further investigated. At its onset, RI is formed by the collision of the tip leakage vortex onto the pressure surface of the adjacent blade and subsequent vortex segmentation. This vortex structure spans two blade passages and propagates in the direction opposite to the rotor rotation. As the compressor is throttled, RI becomes more dominated by the circumferential propagation of vortex breakdown of tip leakage vortices, which occur simultaneously among neighboring passages with slight phase differences. The mechanism is discussed in relation to the temporal change in the blade tip loading. The frequency of vortex shedding increases with the reduction in flow rate and thus the increase in the number of RI disturbances.
TPMS Turbojet Precooler Design Methodology and Case Study
Authors: Cerantola David J. , Schmidt Graeme , Handford Daniel , Dass Pradeep 
Published: August 2024

Abstract
Turbojet precoolers can benefit from additively manufactured triply periodic minimal surfaces (TPMS). Although literature has quantified heat exchanger performance improvements with specifically gyroid or diamond lattice structures and how to utilize optimization frameworks, pressure loss and heat-transfer correlations appear to be geometry-specific and a precooler design methodology is not apparent. Parametric steady-RANS CFD studies that employed the SST turbulence model with a zero-thickness shell interface were conducted on 50-50 and 80-20 volume ratio cross-flow gyroid and diamond arrays where air was the hot fluid and hydrogen gas was the cold fluid between the Reynolds numbers of 5,000 and 2e5. Better fits for drag coefficient and Nusselt number occurred when tortuosity and viscosity ratio were included as independent parameters. Given compressor inlet temperature and H2 pressure loss constraints, a methodology was proposed to determine the optimal volume ratio for an unit cell. A cross-flow precooler case study showed that weight was minimum as TPMS cell size Δx decreased whereas pressure loss was minimum at Δx = 4.5cm.
Integration a Rotary Pressure Exchanger in Transcritical CO2 Refrigeration System: Modeling and Annual Energy Saving Estimation
Authors: Sarawate Neelesh , Deshmukh Arnav , Thatte Azam 
Published: August 2024

Abstract
This paper presents the use of a rotary gas pressure exchanger (PX) in enhancing the efficiency of transcritical CO2 refrigeration systems. Pressure Exchanger based system utilizes the high-pressure discharge from the condenser/gas cooler as a driving fluid, effectively compressing the low-pressure gas (either from flash gas in receiver or from a bypass source) with minimal external energy. This process significantly lowers the power consumption of the main compressor. Concurrently, the PX expands the high-pressure supercritical/liquid CO2 into a two-phase state, preparing it for heat absorption and thereby mirroring the role of a standard high-pressure expansion valve.
The study delves deeper into the architecture of CO2 refrigeration systems that incorporate the PX as a mechanical subcooler. The source of high-pressure fluid is derived from the gas cooler, while the low-pressure gas originates from a bypass line connected to the main gas cooler exit flow. This bypassed flow undergoes expansion and is then utilized to lower the temperature of the flow exiting the main gas cooler, achieved through a counter-flow heat exchanger. The superheated flow from the bypass serves as the low-pressure inlet to the PX. Such integration markedly diminishes the flash gas presence in the receiver, leading to a reduction in the overall workload of the compressor and a consequent boost in energy efficiency. The paper presents a detailed modeling approach that addresses the simultaneous energy and mass balance equations integral to the cycle when integrated with PX G. It also establishes mass flow constraints, which are contingent on the internal physics of PX G and the density ratio of the low and high-pressure streams as they enter PX G.
The analysis encompasses various performance metrics such as the overall system Coefficient of Performance (COP), the work done by medium-temperature (MT) and low-temperature (LT) compressors, liquid content post-expansion through PX G, flash gas production, and superheat control. These factors are evaluated across a broad spectrum of conditions, including diverse ambient temperatures, evaporator duties, and load splits between MT and LT evaporators.
Additionally, the paper discusses multiple techno-economic scenarios considering different system parameters and architectures. These architectures include an adiabatic gas cooler, a parallel compressor, and an internal heat exchanger. An analysis of annualized work savings across various geographical locations in North America and Europe is presented, highlighting the variance in temperature patterns. The findings demonstrate that PX presence enables the system to operate more frequently under extreme temperatures and reduces the likelihood of operational shutdowns during heatwaves, particularly on hot summer days. A single PX unit can approximately add about 5.4 m3/hr or a 20% capacity increase to a standard 150 kW store.
Investigation of Methanol Spray Combustion in a Swirling Hot Coflow
Authors: Alam Zafar , Patel Riya , Bhatia Bharat , De Ashoke 
Published: August 2024

Abstract
Clean combustion technologies and efficient energy harvesting methods are the focal points of current combustion research. The swirling flows are employed to achieve a well-mixed, homogenous fuel-air mixture for an efficient combustion in a gas turbine engine. The current study simulates an air-diluted methanol spray in a swirling hot co-flow. Atomization, the phase change of liquid fuel, and the mixing of the gaseous fuel with the oxidizer are essential physical processes that must be modeled to simulate liquid fuel combustion. The study involves using an Eulerian-Lagrangian method, a common technique in multiphase simulations, wherein it resolves the continuous gas phase using the Eulerian approach. In contrast, the dispersed liquid phase is handled using the Lagrangian approach. The Flamelet Generated Manifold (FGM), a computationally efficient yet accurate combustion model, simulates the gas-phase reactions within the multiphase simulations. An increase in swirl provides better fuel-oxidizer mixing and higher turbulence to the flow. The former is desirable for efficient combustion; the increase in the latter may tend to cause local flame extinction or delayed auto-ignition. Analysis of swirl numbers between 0.2 and 0.6 is carried out to analyze its effect on the auto-ignition and flame stability. It is noted that the lift-off height increases as the swirl number increases due to a delayed ignition. Further, Proper Orthogonal Decomposition (POD) is used to analyze the ignition kernel and flame propagation around different vortical structures contributing to the evolution of the swirl-dominated flow field.
A Carbon Footprint Comparison Through LCA of Forging vs. Wire Arc Additive Manufacturing (WAAM) Processes for the Internal Casing of a Gas Turbine
Authors: Orlandi Rachele , Pucciarelli Martina , Ragni Giacomo , Serra Angela , Fantozzi Francesco 
Published: August 2024

Abstract
The European Commission is increasingly investing efforts on regulating and standardizing Environmental Footprint (EF) assessment for both Products and Organizations. In the framework of UN Agenda 2030, proactivity in performing Life Cycle Assessment (LCA) on products is becoming of vital importance for companies, as well as having internal initiatives for carbon reduction and implementation of eco-design practices. Energy and turbomachinery industries are focal points in this context, and these industries should pioneer such initiatives. For such consolidated industries, it is important to assess the environmental impact of their more traditional processes and products, such as gas turbines (GT), in comparison to innovative ones. As a case study, this paper showcases a Life Cycle Assessment evaluation of two different manufacturing processes, taking internal case of gas turbines as an example. These items are commonly manufactured by forging process. The aim of this paper is to compare the carbon footprint of producing these components through forging or Wire Arc Additive Manufacturing (WAAM) process. The applied methodology is Life Cycle Assessment as per ISO 14040:2006 and ISO 14044:2006, using EF 1.03 as calculation method. Modelling was performed on SimaPro software and for background data Ecoinvent (vv. 3.5) was employed. In addition, uncertainty of the results of both the technologies have been assessed using the pedigree matrix.
Development of High-Temperature, Interlaminar Tension (ILT) Test Methodology for Ceramic Matrix Composites (CMCs)
Authors: Mattison Jacob T. , Faucett David C. , Choi Sung R. 
Published: August 2024

Abstract
This paper was to present how an affordable, high-temperature, interlaminar tension (ILT) strength testing method was explored and developed for ceramic matrix composites (CMCs), leading to development of a diametral-compression test methodology. The test methodology was first delved and verified at ambient temperature by employing a model, 2D-woven polymer matrix composite (PMC) with various test-specimen configurations. The test method was then applied to and confirmed with two different gas-turbine grade CMCs of 2D MI SiC/SiC and 2D N720/alumina oxide/oxide at both ambient and elevated temperatures. Life prediction testing was also conducted at 1316°C for the MI SiC/SiC to validate the effectiveness of test method for a long-term life prediction testing. All of the results on strength and life prediction testing indicated an applicability and feasibility as an appropriate high-temperature ILT test methodology in CMCs with provisions of simplicity, affordability, and technical soundness.
Expanding the Capability of a Legacy Combustion Flametube to Test High Temperature Engine Materials in Relevant Environments
Authors: Harder Bryan J. , Liebfried Carl W. , Luginbuhl Thomas R. , Smith Andrew D. , Stalker Amy R. , Presby Michael J. 
Published: August 2024

Abstract
New materials and component designs are needed to advance gas turbine engine technology and provide the performance and efficiency needs for future applications. In order to advance these materials, testing in combustion environments is a critical step prior to engine testing. In this work, we detail the design and the fabrication of a materials test sector in a flametube combustor facility. The facility simulates a combustion environment similar to that experienced by components in gas turbine engines. The flow regime is characterized by a combination of high-temperature, high-heat flux, and high-velocity that components experience in gas turbine engines. Exposure of components in this facility allows for the study of combined environmental effects and the impact on both coating and substrate durability. The test facility may operate across a wide range of pressures from 275–400 psig (1,896–2,758 kPa) and an airflow rate of 5 lb/s (2.27 kg/s). While combustion gas temperature is expected in excess of 3,000°F (1,649°C), 900°F (482°C) cooling air may be supplied to the backside of components or test articles. The flametube combustor was previously used to evaluate fuel injectors and combustion products, and the new test configuration will also allow for materials exposure to complex, engine-like conditions. The interior of the Test Section was additively manufactured from GRCop-84 and cryogenically fit and brazed to a stainless steel 304 housing. The use of a copper liner minimizes welds and with active cooling, is expected to provide better durability over traditional hardware using stainless steel or Inconel with a ceramic liner. The Test Section has two opposing 9.5” × 3.125” (241 mm × 80 mm) removable windows that can accommodate articles up to 3.5” (89 mm) tall. This modular design allows for custom platforms to hold coupons, panels, or airfoil shapes to be tested with minimal re-engineering or fabrication. The bolted joint and sealing remains consistent, so any new testing only needs to work within the existing design footprint. This paper will provide an overview of the facility capabilities, design considerations, as well as thermal and structural analysis of the hardware. Future testing of ceramic matrix composite (CMC) airfoils and advanced environmental barrier coatings (EBCs) will also be discussed.