bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Optimization Method for Stiffness and Damping Mistuning Identification From Blade Tip Timing Data
Authors: Krizak Troy , Kurstak Eric , D’Souza Kiran 
Published: August 2024

Abstract
System identification of dynamic properties is of large interest in the turbomachinery industry to create more accurate computational models and more effective designs. Previous identification techniques were able to accurately capture the blade variability, known as mistuning, in the stiffness as well as the average damping of all the blades. Mistuning is vital to accurately identify and study because the symmetry of the system is broken and can lead to vibration localization and high amplitudes. In this work, a new method is proposed to not only capture the stiffness mistuning values, but also the blade-to-blade variability in damping. These damping mistuning values have been shown to have a significant effect on the dynamics of bladed disk systems. Incorporation of the damping mistuning into the computational model can be done utilizing an augmented component mode mistuning method with either structural or proportional damping. The mistuning values for this new identification method were compared to a well-established direct method and a previously studied optimization method. Blade responses were then found using a harmonic analysis and the newly identified mistuning values. These blade responses were then compared to experimental tip timing data from full scale rotating experiments. These comparisons show that the new model is able to better reproduce experimental data using computational models that incorporate both stiffness and damping mistuning values.
NASA HECC Geometry and Performance Review Part 2: Geometric Differences Between the As-Manufactured and Design-Intent Impeller Geometry and Their Effects on the Vaneless Diffuser Configuration Performance
Authors: Robles Vega Gregorio , Bosshart Alec J. , Ni Michael , Ni Ron-Ho , Harrison Herbert M. , Nguyen-Huynh Tammy 
Published: August 2024

Abstract
An investigation of the NASA High Efficiency Centrifugal Compressor (HECC) vaneless diffuser configuration was performed. This multipart investigation focused on validating the computational model against experimental data. The validated model was then used to explore the effects of observed geometric differences between the As-Manufactured and Design-Intent impellers. Lastly, the validated model was used for comparison against an experimental tip clearance study.
Part II of the investigation of the NASA HECC vaneless diffuser configuration focused on understanding the differences in geometry and performance between the As-Manufactured impeller and the Design-Intent impeller. This was achieved through comparison of the As-Manufactured HECC vaneless computational model, developed from the solid model of the impeller and validated in Part I, against a new model developed from the Design-Intent blade sections published in NASA/CR-2014-218114/Rev1. The 1D performance values showed that the As-Manufactured impeller underperformed compared to the Design-Intent for all four speedlines that were simulated. Further investigation of profiles, loading and contours showed consistent underperformance of the As-Manufactured relative to the Design-Intent. An investigation into the source of the performance differences led to the discovery of several significant variations in the impeller geometries. The differences that were observed can be summarized into four categories: fillets, trailing-edge exit radii variation, dissimilarity in the splitter leading-edge geometry and main blade thickness differences. The investigation then shifted its effort to quantify the performance effects caused by geometric differences. The investigation showed that out of the four geometric differences that were explored, the differences in the splitter blade had the largest impact. These differences most notably changed flow physics near the splitter leading edge, especially near the tip of the impeller.
Low Swirl Effect on Compact Spray and Combustion Systems Using Additive Manufactured Dual Airblast Injectors
Authors: Kang Yeonse , Ahn Jihwan , Hampp Fabian 
Published: August 2024

Abstract
Novel low swirl concepts provide a promising approach to ensure stable flame anchoring over an extensive operation condition range, necessary for optimising compact designs for liquid fuel combustors as used in hybrid aero-engine or micro gas turbines in terms of scalability and flexibility. The current study utilises seven different additive manufactured low swirler integrated into a dual airblast injection concept to delineate the influence of high momentum swirling air jet on spray atomization and combustion performance. The developed injector is designed for vane angles from zero to 45° for co- and counter-direction against the orientation of the liquid sheet ejected from the pre-filming pressure swirl injector. The spray atomization in swirl afflicted air jet is demonstrated by phase Doppler interferometry and shadowgraphy. The combustion process is analysed using OH*-chemiluminescence imaging and emission measurements. The results show that a circumferential gaseous flow acting on the wall-film amplifies the radial fuel penetration and atomization. The latter produces robust spray dispersion in response to variations of operational conditions. The effect of low swirl injection on combustion process of kerosene flames leads to a noticeably more compact and intensified heat release zone. In addition, non-monotonic decomposed mode energy with considerable NOx reduction is observed.
Data-Driven Turbulence Modeling for Film Cooling Heat Transport, Part I: Turbulent Heat Transport Property at Wide Flow Conditions
Authors: Zhang Zhen , Hu Kexin , Su Xinrong , Yuan Xin 
Published: August 2024

Abstract
Film cooling is an important cooling technique used in modern gas turbines and air engines. It is a typical jet-in-cross-flow problem, where the jet interacts with the mainstream, leading to complex vortex structures and turbulence properties. In this paper, the deviation between RANS and LES data and the turbulent heat transport of film cooling problems are focused. A data-driven framework based on the physics-informed neural network (PINN) is proposed and used to calculate the distribution of the turbulent Prandtl number (Prt) based on the RANS flow field and the LES temperature field. This Prt is the target of a turbulence heat transport model, and the distribution of this Prt is analyzed in a wide range of film cooling flow conditions. A series of film cooling problems are studied with the variation of the hole geometry, the mainstream Mach number, and the blowing ratio. Results show that the turbulent Prandtl number largely deviates from the default value of 0.85 in most CFD solvers in all flow conditions and different turbulence models also lead to different Prt values, which means the turbulent heat transport model of Prt should be turbulence-model-related.
Simulation Validation of a Coupled Blade-Shaft System Including Non-Linearity and Gravity Effects
Authors: Exposito Iker , Martinez Aja Angel , Price Matthew , Rix Andrew , Schwingshackl Christoph 
Published: August 2024

Abstract
A shaft-bladed-disk rotor configuration has been experimentally subjected to synchronous and asynchronous dynamic excitation using the test rig named Asynchronous Rotor Excitation System (ARES). This work covers validation of an advanced dynamic simulation of the complete system that is formed by this rotor supported on a static frame that provides non-axisymmetric support stiffness. Different sensors have been placed in this installation: displacement sensors at bearings and shaft, and strain gauges at blade roots to derive blade tip displacements. Comparison of test sensors with regard to simulation model results, under prescribed synchronous and asynchronous excitations has been performed, resulting in a very good matching of resonance frequencies and response magnitudes at bearings and shaft. Resultant modes have a significant degree of coupling between blades and shaft.
Gravity load dynamic excitation has been also simulated to match blade tip displacement measurements. Gravity load is a non-axisymmetric static load that promotes dynamic excitation: a rotor blade experiences gravity load as an alternating load due to blade rotation. This type of loading is designated as 0EO (zero engine order) in the stationary frame as it remains at zero frequency at all rotor speeds.
Blade root attachment to disks include non-linear contact effects that can be observed from blade tip displacements obtained from tests. Non-linear modelling of this blade root is also covered with a simplified model in order to explain observed behaviour during testing.
In aircraft engines, due to flexibility of rotor blades and disks, critical modes can be coupled modes of disks and blades with shafts and, also, with static parts. Correct simulation of the complete system should include rotors and static parts in a single model. Rotors should include all steady-state rotatory effects: stress stiffening, spin softening and gyroscopic effect. This advance dynamic simulation technique of these systems has been validated in ARES. Also, specific non-axisymmetric static load conditions at aircraft engines i.e. cross wind scenarios (like gravity) can promote relevant vibrations. This 0EO excitation conducts to a specific dynamic solution that has been also validated in ARES rig through gravity load scenario.
Exergy-Based Analysis of the NASA SDT Configuration
Authors: Boniface Jean-Christophe , Petropoulos Ilias , Berhouni Ilyès 
Published: August 2024

Abstract
In the continuation of ongoing works at ONERA, aiming at performing exergy-based analyses of steady numerical solutions corresponding to complex internal or external flows, this paper presents a first application to the performance investigation of the NASA SDT configuration. Different operating conditions at take-off rotational speed were considered in the analysis. Links between losses and their physical origins are clearly highlighted in exergy-based analyses, which provide decompositions between reversible/irreversible losses and between mechanical/thermal effects. Attention is given to the decomposition of irreversible losses due to shock waves, viscous and thermal effects. In addition, it is shown that drastically lowering the numerical dissipation by strongly increasing the accuracy of the space discretization does not have a significant impact on the exergy balance in terms of mechanical and thermocompressible exergy outflow components, but has non-negligible effects on the anergy generation characterizing irreversible losses.
Collaborative Design in Context for Whole Engine Mechanical Design
Authors: Wang Leran , Toal David , Anobile Alessandro , Stanley Felix 
Published: August 2024

Abstract
Decomposition is often required to make the design of complex mechanical systems tractable. However, often the resulting sub-systems are designed in isolation with little indication as to the impact of design decisions on system level performance. The following paper demonstrates the increased risk of rework resulting from the naive recombination of such seemingly optimal sub-systems and goes on to demonstrate two approaches which can potentially help. The first proposes the adoption of a design in context based approach, where sub-systems are aware of the potential impact of their decisions on the wider system. The second augments this approach with a system level coordination step employing a surrogate model. The performance of each strategy is demonstrated using a realistic whole engine mechanical model for an ultra high bypass ratio (UHBR) gas turbine as a case study. The design in context approach is demonstrated to considerably reduce the level of infeasibility at the system level, while including some system level coordination not only reduces the level of infeasibility but improves the quality of the final system design and the rate of convergence towards it.
Dissipation in Skewed Boundary Layers
Authors: Peacock Robert , Pullan Graham , Folk Masha 
Published: August 2024

Abstract
The entropy generation within a turbulent, collateral boundary layer is well understood and is characterised by a dissipation coefficient, Cd. However, it is common for the transverse pressure gradients in turbomachines to create highly skewed boundary layers, where the velocity varies in direction as well as magnitude. A combined experimental and high-fidelity computational approach is used to quantify the effect of skew on the dissipation coefficient for the first time. At a nominal condition of 14 degrees of skew and Reθ of 1000, the increase in dissipation coefficient is 20% as determined from direct numerical simulation, and 28% from experimental measurements, relative to the collateral boundary layer. Experimental data over a range of skew angles and Reθ values show that Cd increases approximately linearly with skew so that, at a skew of 25°, loss is 70% greater than in the collateral boundary layer. The implications for loss estimation are examined by evaluating boundary layer loss, in the Harrison turbine cascade, with and without the influence of skew on Cd. By accounting for the skew in the boundary layer, a new proposed model has been used to calculate the loss coefficient in the Harrison cascade to within 4% of the experimentally measured value.
Supersonic Convergent-Divergent Vaned Nozzles Design Algorithm and Respective Discharge Coefficient Model
Authors: Moroz Leonid , Burlaka Maksym , Frolov Borys , Dyzenko Tetiana 
Published: August 2024

Abstract
To continue the series of already published articles on supersonic drilled nozzles [GT2022-83387, GT2023-101760], this publication is devoted to another type of supersonic nozzles, which are formed by vanes providing an annular row of convergent-divergent supersonic channels. This type of supersonic vaned nozzles, as well as the drilled nozzles, are used in numerous high-loaded turbine applications. Published data on this type of nozzles and turbine stages with them have very limited information on both the design methodology and calculation methods and thus do not allow these data to be systematized and implemented into the turbine design and calculation tool. The work carried out in this direction includes all the algorithms and models required for the supersonic vaned nozzle design and calculations: (1) The design algorithm of a highly efficient supersonic vaned nozzle, (2) the discharge coefficient model, (3) loss model, (4) flow angle deviation model. In this article, we focus on design model (1) and discharge coefficient (2) items. A list of geometric parameters that uniquely determine the 3D geometry of the nozzle channel that is used in the design algorithm is discussed. The approaches to building convergent and divergent parts of the supersonic nozzle are elaborated. Besides, the model of the discharge coefficient through the critical section of the nozzle is described in detail. The developed discharge coefficient model demonstrated a maximal deviation of 0.6% and an average of 0.18% from CFD results in a wide range of configurations of the nozzle channel.
Operations Optimisation of a Gas-Lift Compression System Using a Digital-Twin Approach
Authors: Mucino Marco , Savage John 
Published: August 2024

Abstract
The Oil and Gas industry is facing complex challenges including spiralling exploration and development costs, aging assets, long lead times on equipment, shortage of skilled people, among others. As such, it is imperative existing assets are operated efficiently and properly maintained to maximise production. A typical approach to achieve this objective considers industry best practices, international standards, manufacturer recommendations and condition monitoring techniques such as oil analysis, vibration, thermography, ultrasound, etc.
However, the advent of Industry 4.0 has promoted the development and adoption of advanced techniques: a prominent example being the Digital-Twin concept. A Digital-Twin is a virtual model developed using advanced modelling and data handling techniques to replicate and predict the behaviour of individual equipment or entire production systems. A Digital-Twin approach can deliver predictive monitoring capabilities; analysis of complex systems; define solutions to operational issues; virtual testing and confirmation of proposed modifications; etc.
This paper presents the development of a Digital-Twin for troubleshooting and operations optimisation of a motor-driven three-stage gas-lift compression system with a long history of unstable operation, recurrent emergency shutdown events and low availability. The multidisciplinary approach includes analysis of the control system architecture, assessment of field instrumentation, data validation, performance benchmarking, dynamic modelling and off-line control system testing. A cost-effective solution with only minor software modifications was designed, tested and demonstrated before its implementation. The successful outcome of the project reduced the need for constant operator intervention, reduced emergency shutdown events, increased availability of the gas compression system from 86% to 98.2%, reduced gas imports, increased gas exports and enhanced oil production.
An Experimental Investigation of the Corner Separation Control in a Compressor Cascade Using Spatially Oscillating Jet
Authors: Yang Pengcheng , Chen Shaowen , Liu Guanyu , Wang Shiqi 
Published: August 2024

Abstract
In the present study, an actuator with the ability to generate spatially oscillating jets, known as the sweeping jet actuator (SJA), is employed to manage the corner separation in a CDA profile. Experiments were performed in a low-speed wind tunnel with an inflow Mach number of 0.23. Measurements using a five-hole probe, dynamic pressure sensors, and oil flow visualizations were carried out to get insight into the performance and physics of the flow field. SJA was integrated into the cascade endwall through 3D printing, with dimensions constrained within 15mm, and reaching a maximum operating frequency of approximately 1400Hz. Parameters such as axial injection location, jet momentum, and operating frequency were systematically investigated to determine the optimal active flow control strategy. The results show that the spatially sweeping jet significantly suppresses the migration of low-energy fluids on the endwall surface, leading to a reduction of more than 30% in the spanwise extent of corner separation and a 14.2% decrease in the integrated total pressure loss coefficient, with 0.13% of the cascade throughflow. The study of the influence of jet momentum on control effect indicates that the sweeping jet could enforce the low-energy fluids without a significant increase in mixing losses between jets and mainstream even at a large jet momentum, which is attributing to the rapid decay of the unsteady sweeping jet velocity in mainstream. The results highlight the superior characteristics of the SJA in managing the corner separation.
Performance of Heavily Loaded Textured Gas Foil Bearings Based on the Multigrid Method
Authors: Han Jiazhen , Zhang Guanghui , Xu Kefan , Gong Wenjie , Sun Wenlong , Huang Zhongwen 
Published: August 2024

Abstract
Surface texturing technology is a novel avenue for enhancing gas foil bearing performance. For the cases of heavily loaded foil bearing, the static equilibrium eccentricity ratio may exceed 1.0, even 4.0, which will result in poor convergence for the numerical algorithm. The introduction of textures and numerical calculations under heavy load conditions have heightened the complexity of the solution, and the multigrid method offers an efficient resolution to this challenge. This paper established the pressure governing equation considering the effects of gas rarefaction. The cumulative eccentricity method was applied to analyze the bearing’s behavior under heavy-load operating conditions. Additionally, the numerical solution efficiency of the direct, iterative, and multigrid methods was analyzed. Furthermore, the Newton-Raphson method and the perturbation method are utilized to determine the static and dynamic characteristics under large eccentricity conditions.
The results indicate that the multigrid method offers up to a 77% increase in computational efficiency compared to the direct solution method. The bearing exhibits maximum load capacity when the axial texture ratio is above 0.7 and the circumferential texture ratio is within the range of 0.3 to 0.4. As the eccentricity ratio increases from 0.1 to 4, the enhancing effect of surface texturing on load capacity decreases by 6.78%, while the friction-reduction effect increases by 4.25%. Furthermore, critical mass calculations indicate improved bearing stability with a large eccentricity. This study shows that suitable texture parameters effectively improve the bearing performance under heavy-load conditions, while the multigrid method can efficiently solve the above problems.
Analysis of Heat Transfer Within Buoyancy Dominated Rotating Cavities of H.P Compressors
Authors: Fazeli Seyed Mostafa , Kanjirakkad Vasudevan , Long Christopher 
Published: August 2024

Abstract
A detailed knowledge of the flow structure and the heat transfer within blade-disc cavities is required for designing safe and efficient aero-engine compressors with a useful operating range. This paper presents the results from temperature field measurements obtained from the Multiple Cavity test facility at the University of Sussex. This emulates part of the secondary air system in an aircraft engine high-pressure compressor. It comprises four externally heated disc-cavities and is supplied by a cool bore flow. The heat transfer is studied with the help of a finite-element method using measured temperatures as boundary conditions. A validated 2D steady-state heat conduction analysis methodology is presented. Results are presented for a range of values of Rossby number, rotational and axial Reynolds numbers and the buoyancy parameter. The curve-fit type that is best suited for the temperature boundary condition specification is established using an independent Ansys APDL based study. The sensitivity of the overall cavity heat transfer to major driving mechanisms has been described. The Monte-Carlo analysis is used to reveal how a ±0.5 K uncertainty in temperature affected the Nu estimation.
The Safety Design Method for the Rotor System With Fan Blade Off
Authors: Zhao Zhenyao , Zhang Dayi , Yang Cheng , Zhang Qicheng 
Published: August 2024

Abstract
A safety optimization design method for the rotor system with fan blade off is established by taking the time-varying parameters such as rotor speed and support stiffness as the optimization variables, and the vibration response at the key position of the rotor as the optimization objective. The reduction in the number of optimization objective functions is achieved through correlation analysis and influence rule analysis. The optimization problem of rotor system dynamics is addressed by employing finite element model and radial basis function response surface surrogate model, integrated with NSGA-II genetic algorithm. The results show that the optimization method based on the response surface surrogate model can greatly save the computational time and obtain a smoother Pareto frontier solution. The Pareto solution set of the rotor system with fan blade off can be divided into two regions, corresponding to the structural design ideas of “partial fusing design” and “complete fusing design” respectively. In addition to the steady-state amplitude of the fan disk, the other three objective functions can be reduced by more than 45.0% after optimization. In general, the optimal solution of the corresponding area of “complete fusing design” is better than that of “partial fusing design”.