bluuebunny/crossref_metadata_2025_split huggingface dataset:
CFD Modeling of Additively Manufactured Extreme Environment Heat Exchangers for Waste Heat Recuperation
Authors: Duggirala Vyas , Reddy Venkateswara , Muley Arun , Stoia Michael , Vanaffelen Doug 
Published: August 2024

Abstract
Advanced Brayton cycle-based Waste Heat Recovery (WHR) system for a targeted energy efficiency of 20–50%, and gravimetric power densities of 1.6–1.9 kW/kg are attractive propositions for future airplane designs. One of the critical challenges for the maturation of these technologies is the need to achieve highly compact heat exchangers capable of operation under extreme pressure and temperature environments. The current work presents CFD modeling strategies for the design and development of additively manufactured Extreme Environment Heat Exchangers (EEHX). Modeling and simulation-driven design improvements to the heat exchanger (HX) are implemented to achieve a power density of 15 kW/kg under the extreme environment of 800°C inlet temperature and 80 bar pressure with supercritical CO2 as the working fluid. Various CFD based modeling methods are described, starting from selecting, rating, and sizing heat transfer (HT) surfaces, followed by detailed core modeling through periodic and end-section models. Further, a novel porous media-based modeling approach with a high-fidelity manifold model is implemented to generate optimal manifold profiles while minimizing flow maldistribution through the core. Comprehensive physical testing of the additively manufactured heat exchanger prototypes has been used to validate the developed numerical models within 5–10% of pressure drop and heat transfer predictions.
Operation of FT4000® Single Nozzle Combustor With High Hydrogen
Authors: Locke Justin , Kim Wookyung , Smith Lance , Snyder Timothy , Dayton James 
Published: August 2024

Abstract
This paper reports initial results from an effort to develop a retrofittable fuel/air injector for the FT4000® aeroderivative gas turbine that enables use of hydrogen as a carbon-free fuel for efficient power generation. The FT4000 engine’s low-NOx combustor was developed by Pratt & Whitney and RTX Technology Research Center with core technology from the Pratt & Whitney PW4000 turbofan aircraft engine. The work reported here advances the technology readiness level of the FT4000 combustor for operation with hydrogen, starting with an experimental assessment of the current production hardware with increasing hydrogen content mixed with natural gas.
High-pressure single-sector combustor rig tests have been completed, demonstrating the ability for the dual fuel nozzle to operate an FT4000 combustor on 100% hydrogen with low nitrogen oxide (NOx) emissions. Metal temperature measurements and video images of the flame structure from zero to 100% hydrogen highlight opportunities to improve the fuel nozzle robustness for high hydrogen conditions.
The current FT4000 production engine operates on either natural gas or No. 2 fuel oil with water injection to achieve high thermal efficiency and low emissions. This engine is fielded by Mitsubishi Power Aero and delivers 70 MW of power with a simple-cycle efficiency of over 41% when operating with wet compression. Results from this study have cleared the current production FT4000 engines with dual fuel nozzles to operate at baseload power on blends of hydrogen mixed with natural gas and water.
Impact of Input Data Quality on the Uncertainties of a Compressor Blade Parametrization Process
Authors: Schulten Benedikt , Göing Jan , Lück Sebastian , Friedrichs Jens 
Published: August 2024

Abstract
In the wake of the push towards knowledge-based maintenance of jet engines, a process for analysing and evaluating the performance of deteriorated aero engine components was developed. This process automatically generates CFD-simulations from 3D-scans of compressor blades and inputs the calculated performance maps into a gath-path analysis of the jet engine. The uncertainties of such a process are important for the interpretation of its results. Therefore, the uncertainties of a specific part of the process, the geometric analysis, are investigated. Special focus is put on the impact the input data quality has on the uncertainties and how the specific process implementation responds to variations in quality. Test procedures are developed to calculate the uncertainties of individual process steps for specific input data qualities. It is shown, that the noise level of the 3D-scans has a significant impact on the uncertainties. The point-cloud density also has an influence on the uncertainties, which however is small as long as a certain minimum threshold of 189 per profile section is reached. It is also shown that the uncertainties are sufficiently small to capture real geometric variances of deteriorated compressor blades when input data with noise levels of 15 μm and 316 profile points or better is used.
Cooling System of a High-Pressure Centrifugal Compressor: Development and Impact on Wheel Temperatures
Authors: Weihard Stefan , Willeke Tobias , Božek Lukáš , Hort Vladimír , Münch Stefan , Spengler Sebastian , Winter Thomas 
Published: August 2024

Abstract
High power density, low fuel consumption, and a compact design with competitive total costs of ownership are key requirements for internal combustion engines for conventional fuels and carbon-free or carbon-neutral future fuels. These requirements influence the development targets of charging systems and call for single-stage charging systems with increased charge air pressures. However, high compressor pressure ratios of the turbocharger lead to challenging material temperatures in aluminum alloy wheels. Consequently, creep becomes the fundamental lifetime-limiting damage mechanism for these wheels. In order to meet customer requirements regarding total costs of ownership, the lifetime is of major importance for the development of aluminum compressor wheels for turbochargers with pressure ratios beyond 6. This paper focuses on a high-pressure compressor design with a water-cooling system for a new turbocharger generation. The development of its components and their validation based on numerically predicted and measured compressor wheel temperatures are discussed. After introducing the need for high-pressure ratios and the accompanying lifetime challenges, the paper presents the design strategy and methods of the development process. Finally, the paper summarizes the achievements obtained by this procedure. Detailed and rarely before documented temperature measurements from the rotating compressor wheel are published. As will be shown, the temperature measurements confirm the predictions from the pre-development phase. A comparison of the temperature measurements from the recently developed compressor wheel with measurements carried out for a state-of-the-art wheel reveals the technological improvements achieved by this new generation of high-pressure compressor wheels.
Bayesian Inference for the Calibration of Progressive Damage Model of Dovetail Specimens From Laminated Composite Fan Blade
Authors: Tang Xu , Chen Yong 
Published: August 2024

Abstract
Composite fan blades are the preferred alternative for the fan stage of most advanced high bypass ratio turbofan engines in the world. Under service operating conditions, the dovetail part bears a significant centrifugal load, and the ability of the dovetail to safely bear this load is one of the key points of the multi-level “test pyramid” approach of compliance demonstration for special airworthiness regulation. Debonding between adjacent layers is the main damage mode of laminated composite fan blades, and the Cohesive Zone Material model (CZM) is widely applied to characterize its elastic and progressive damage behavior. However, there is difficulty in measuring the as-manufactured interlaminar mechanical properties used in finite element models. In this study, tensile loading was applied to simulate the interacting centrifugal force and capture mixed-mode damage evolution. Structural responses and material damages were calibrated with measured tensile loads through Bayesian inversion, where interface and contact elements with distinct bilinear behavior were selected. Posterior probability distributions of maximum interface tractions and contact stresses were solved using Markov chain Monte Carlo sampler. Results indicated that the two bilinear cohesive material models had a capacity of predicting empirical means of longitudinal reaction forces as that in test considering additional discrepancy term (0.035 kN and 0.96 kN respectively), while they made an significant impact on the prediction of tensile load history especially when two delamination cracks initiated and propagated. Interface elements provided a higher matching quality in predicting loading history and capturing damage mechanism in association with in-plane progressive damage analysis. This calibrated parameter set could be functioned as benchmark in numerically determining the ultimate tensile load of dovetail elements and reducing the necessary number of physical tests at elemental length level.
Reverse Thrust Aerodynamics of Variable Pitch Fans With Inlet Distortion
Authors: Ma Kwun Yeung , Hall Cesare A. , Wang Tianhou , Williams Tim S. 
Published: August 2024

Abstract
Variable pitch fans can improve the operability of low pressure ratio fan systems by repitching the rotor blades. If a variable pitch fan can generate sufficient reverse thrust on landing it also eliminates the need for heavy, cascade-type thrust reversers. However, any reverse thrust generation is impacted by high levels of inlet distortion generated as air is drawn into the exhaust nozzle. This paper uses both RANS computations and low-speed rig experiments to explore how a representative inlet distortion from the engine installation affects the aerodynamics and performance of a variable pitch fan operating in reverse thrust mode. The simulations and the experiments both show that the distortion from the engine installation leads to a highly three-dimensional flow field with a large recirculation region within the bypass duct. This is in contrast to the primarily axial flow that is produced for a case with uniform freestream inlet conditions. The distortion substantially redistributes the mass flow, thrust and power in the engine. Streamline tracking combined with a power balance analysis reveals that there is highly radial flow within the fan rotor and almost all of the power from the fan is used to drive the recirculating flow in the bypass duct, which generates high loss and has a high total temperature. The recirculation reduces the net mass flow through the engine to around 5% of a uniform inflow case and the effective reverse thrust is greatly reduced. With uniform inflow the net reverse thrust was found to be 35% of the nominal takeoff thrust. With inlet distortion present this was reduced to 20%. This demonstrates the importance of designing and operating variable pitch fan systems to minimise the reverse thrust inlet distortion.
Simulation of Sand Erosion in a Transonic Fan Stage
Authors: Ghenaiet Adel 
Published: August 2024

Abstract
In desert regions, there is a high concentration of dust and sand particles carried by storms and sucked into aircraft engines, leading to severe erosion. This numerical study simulates the movement of sand particles and erosion process in the front components of a high-bypass turbofan engine (HBTFE). The components include the Pitot intake, spinner, fan, core flow inlet guide vanes (IGVs), and secondary flow outlet guide vanes (OGVs). The study focuses on the engine operating conditions during takeoff from a Saharan airfield. The flow field data is obtained separately, and exported to an in-house particle tracking code based on the Lagrangian approach. The finite element method (FEM) is used to track the particles as they move through the mesh cells and determine the precise impacts and conditions to calculate the local erosion rates and material removal.
The obtained results indicate large numbers of sand particles impacting the fan blade at high frequency from the hub up to approximately 80% of the span, due to their deflection by the Pitot intake lip and outer contour. The pressure side (PS) of the fan blade experiences extreme erosion rates, while the highest erosion rates occur at the leading edge (LE) and towards the trailing edge (TE). At the exit of fan blade a significant amount of particles pass through the OGVs and typically erode its PS, while fewer particles from the lower sections of the fan pass through the IGVs. These findings reveal the erosion-prone areas that need a special coating protection.
Steam Boiler Integrity Strategy for Complex Steam Generators in Thermal Operation Facility
Authors: Al Fazari Mohamed , Aulaqi Muatasam 
Published: August 2024

Abstract
Petroleum Development Oman LLC (PDO) is Oman’s premier oil producer and operates several fields. Thermal Development is one of key enablers in Oman for significant Oil Recovery. “A” facility is designed to receive Aquifer Pump-off (APO) water from a reservoir and utilize it for steam generation once treated in Water Treatment Plant (WTP).
Thermal Enhanced Oil Recovery application in Oman has been first operated in Gulf region back in 2012 with enormous lesson learned insights on selecting and operating water treatment facilities.
The Purpose of Water Treatment plant is to remove hardness of APO Well Water to make it suitable for Steam generation. The processes involve the removal of suspended solids and, traces of oil and dissolved minerals from water.
Quality of boiler (steam generator) feedwater is of critical importance in steam injection projects. Field experience indicates that most generators downtime is caused by water treatment performance concerns, hence operating outside water quality specification results in damaging mechanisms of the boiler tubes i.e., corrosion and scaling deposition.
The project steam consists of 10 steam boilers of various type with total steam production of 20k tones/day responsible to produce 30k net oil/day. Steam availability has been the most significant challenge for meeting oil productions target for Steam Enhanced Oil Recovery Fields. However, maintaining safe operation of boilers at “A” facility has come with huge annual OPEX cost of &gt; $3mln annually from boilers inspection, tube repair, and associated oil deferment due to steam unavailability during maintenance.
A comprehensive engineering approach through setting detailed boiler integrity strategy and traffic lights criteria assessments development of API-530/ASME assessment while integrating that with detailed corrosion rate calculation and proper utilization of Fitness for Service API-579 in the right context.
The objective of this paper is to generate a robust integrity strategy management of steam boilers along with significant economic benefits of cost savings around $1.5mn/year. This has proven to be the standard boilers integrity strategy to be implemented for first time in Oman and has been cascaded for all other EOR applications.
Design and Verification of a Fully Interchangeable Additively Manufactured Production Injector
Authors: Ehlig Ryan , Fahme Tony , Ryan Daniel , Evans Timothy 
Published: August 2024

Abstract
The development of additively manufactured (AM) components via Powder Bed Fusion - Laser Beam (PBF-LB) has accelerated in recent years within the gas turbine industry. A desire to reduce manufacturing steps, assembly complexity, supply chain dependency, and development cycle time are all driven by efforts within the industry to reduce cost. At Solar Turbines®, AM technology development has focused on the design, print, and verification of AM injectors that can match the established performance of the legacy DLE production counterpart. The motivation for this focus is full interchangeability between the AM and non-AM produced injectors, allowing customers to either use existing injectors available off the shelf, on-demand AM produced injectors, or a combination of both.
Accordingly, the team has recently designed, 3D printed, and verified an AM produced injector that matches the performance of the production DLE counterpart. Using in-house developed AM technology that is not constrained by the traditional AM design rule of a 45° build angle limit, AM was used to produce matching flow feature geometries that are otherwise very difficult to print with traditional AM methods. Key combustion parameters were also matched, such as fuel-air mixing profiles, velocity profiles, and combustion exit profiles. These parameters all play an important role in emissions performance, lifing of downstream turbine hardware, and impact the potential for encountering thermoacoustic oscillations during engine operation. Through rig and full-scale engine testing, the design team has verified the interchangeability of AM and non-AM injectors and demonstrated that equivalent performance and emissions capability can be achieved with AM produced injectors without the need to compromise due to the complexity of the design.
Unsupervised Methodology for the Prognostics of Gas Turbine Abrupt Faults
Authors: Losi Enzo , Venturini Mauro , Manservigi Lucrezia , Bechini Giovanni 
Published: August 2024

Abstract
The current energy market requires that gas turbines (GTs) run efficiently and reliably, thus improving their sustainability. To this aim, condition monitoring is fundamental for GT manufacturers to track performance degradation and ensure fault detection in advance.
Thanks to the huge amount of data acquired during GT operation, data-driven methodologies can be successfully employed for fault detection and prediction.
Therefore, this paper develops an unsupervised data-driven methodology for the prognostics of GT abrupt faults. The methodology comprises i) an autoencoder (AE) neural network aimed at modeling GT operation in the absence of fault symptoms and ii) a threshold-based criterion for the detection of anomalous deviations between actual data and AE predictions. A sensitivity analysis on the anomaly threshold is carried out to identify the optimal set-up of the methodology.
The paper considers GT trip as archetypal of an abrupt fault. Since no labeled data are available in the case of trip occurrence, the time point at which trip symptoms arise has to be identified. Furthermore, the paper also investigates which measurable variables are most effective for predicting GT trip, in order to provide useful insights on trip prediction.
The methodology is validated by considering a real-world case study comprising data collected from six GTs before trip occurrence. The results prove that the optimally tuned methodology correctly classifies the 80% of data. Another relevant result is that fuel mass flow rate, exhaust gas temperature, and compressor discharge temperature are the most useful measurable variables for the detection of trip symptoms.
Numerical Investigation on the Robustness Assessment and Enhancement of Labyrinth Seal With Axial Displacement and Clearance Deviation
Authors: Jin Xin , Liu Chuankai , Liu Peng , Li Zijun , Ding Shuiting 
Published: August 2024

Abstract
The labyrinth is widely used in aero-engine, which experiences axial displacement and radial deformation due to the interaction of mechanical, aerodynamic, and thermal loads. The axial displacement and radial clearance variation of the labyrinth have a direct effect on its operating condition and then on the functions of the secondary air system. In order to evaluate the effect of axial displacement and radial clearance deviations on the mass flow rate of the labyrinth and the functions of the secondary air system, based on the fluid network method and the modular modeling method, this paper developed a low-dimensional simulation method of rotor axial displacement. In order to improve the robustness of the stepped labyrinth to axial displacement and radial clearance deviations, a new stepped labyrinth with negative feedback is proposed. Then, the effect of the structural parameters on the flow characteristics is studied, and the sealing performance of the new stepped labyrinth and the conventional stepped labyrinth is compared under different axial displacements and clearances. Finally, the robustness evaluation is performed in terms of the labyrinth sealing performance in the isolated boundaries and the environment of the secondary air system fluid network, respectively. The results show that the mass flow of the new stepped labyrinth is more sensitive to the axial displacement deviation than that of the conventional stepped labyrinth in the isolated boundaries. While in the fluid network environment, the mass flow rate and the axial bearing load variation range of the secondary air system with the new negative feedback stepped labyrinth are significantly smaller than that with the conventional stepped labyrinth. This shows that the new negative feedback stepped labyrinth has better robustness compared to the conventional stepped labyrinth when faced with axial displacement in a fluid network environment.
Investigation of NOx and Ammonia Slip in an Ammonia and Hydrogen Powered Aviation Gas Turbine Using Chemical Reactor Network Modelling
Authors: Garai Priyankar , Bobi Shahzad , Rahman Ramees K. , Zamora David , Ahmed Marzuqa , Urso Justin , Vasu Subith S. 
Published: August 2024

Abstract
Ammonia is a promising green fuel with several favorable attributes that could make it a replacement for current nonrenewable aviation fuels. The feasibility of using an NH3-H2 blend as the fuel in terms of the NOx emitted has been explored in this work, consisting of residence times of 10 ms and 5 ms which represent the residence times in modern aviation gas turbine combustors. Chemical reactor network (CRN) models have been simulated using the Ansys Chemkin-Pro software, implementing air-staging techniques like RQL (Rich-Quench-Lean) to efficiently combust the fuel and bring down the NOx while also minimizing ammonia slip. Various CRN configurations have been investigated for operating conditions reflecting take-off, while varying crucial parameters such as equivalence ratio, NH3-H2 fuel fraction, inlet temperature, and pressure. This exploration aims to understand the trends in NOx emissions and ammonia slip while ensuring that the reactor exit temperature remains within the cycle requirements to prevent any material damage to the components post combustion. The effect of varying the residence times in the individual CRN components on the NOx and ammonia slip was also investigated and discussed. The minimal NOx possible while varying the parameters was about 20 ppm for the 10 ms overall residence time simulations, and about 30 ppm for the 5 ms overall residence time simulations. The trends obtained from the parametric variations along with the understanding of the different CRN models explored can help in optimizing the NOx minimization further and assist in obtaining the optimal conditions for the NH3-H2 blend used, not just for take-off, but additionally for other flight operating conditions as well. Understanding the parametric trends for minimizing NOx emissions and controlling the NH3 slip from this study can help establish an understanding of using ammonia as aviation combustor fuel, serving as a basis for further computational and experimental research.