bluuebunny/crossref_metadata_2025_split huggingface dataset:
Processing Multi Component Blade Tip Timing Experimental Data by Independent Component Analysis
Authors: Rizzetto Elena , Carassale Luigi 
Published: October 2022

Abstract
Blade Tip Timing (BTT) is a simple, robust and non-intrusive method for measuring the rotor blade vibrations in turbomachinery. The analysis of vibrations characterized by multiple spectral components typical for example of flutter is challenging. This paper proposes a probabilistic method based on the Independent Component Analysis able to separate and identify multiple harmonic components sampled according to a BTT-like schema. The data are divided into batches of fixed length called snapshots, which are interpreted as realization of random vectors. The statistical property of the subspace spanned by such random vectors is used to identify the number of components present in the signal (i.e. number of active modes), to separate the components and estimate their frequency and amplitude. These results are obtained by applying sequentially the Principal Component Analysis (PCA) and the Independent Component Analysis (ICA) and the Harmonic Matching (HM). The proposed technique is applied to experimental data obtained from a test rig with fixed disk and traveling load. The time-resolved measurements are resampled according to the sampling pattern induced by a specified sensor spacing.
Modeling of Inviscid Flow Shock Formation in a Wedge-Shaped Domain Using a Physics-Informed Neural Network-Based Partial Differential Equation Solver
Authors: Laubscher Ryno , Rousseau Pieter , Meyer Chris 
Published: October 2022

Abstract
Physics-informed neural networks (PINN) can potentially be applied to develop computationally efficient surrogate models, perform anomaly detection, and develop time-series forecasting models. However, predicting small-scale features such as the exact location of shocks and the associated rapid changes in fluid properties across it, have proven to be challenging when using standard PINN architectures, due to spatial biasing during network training. This paper investigates the ability of PINNs to capture these features of an oblique shock by applying Fourier feature network architectures. Four PINN architectures are applied namely a standard PINN architecture with the direct and indirect implementation of the ideal gas equation of state, as well as the direct implementation combined with a standard and modified Fourier feature transformation function. The case study is 2D steady-state compressible Euler flow over a 15° wedge at a Mach number of 5. The PINN predictions are compared to results generated using proven numerical CFD techniques. The results show that the indirect implementation of the equation of state is unable to enforce the prescribed boundary conditions. The application of the Fourier feature up-sampling to the low-dimensional spatial coordinates improves the ability of the PINN model to capture the small-scale features, with the standard implementation performing better than the modified version.
Low Order Heat & Mass Flow Network Modelling for Quasi-Transpiration Cooling Systems
Authors: van de Noort Michael , Murray Alexander V. , Ireland Peter T. 
Published: October 2022

Abstract
Quasi-transpiration cooling schemes such as Double-Wall Effusion Cooling allow the Nozzle Guide Vanes of High Pressure Turbines in modern aeroengines to experience high heat loads whilst maintaining acceptable temperatures. The combination of impingement, pin-fin and effusion cooling in such schemes produces a high convective cooling efficiency, but this is accompanied by large pressure losses that increase vulnerability to coolant migration toward low pressure regions. This can have severely detrimental effects on cooling performance as effusion holes around the Leading Edge can be starved of coolant, producing no local film cooling protection.
This paper presents a Low Order Model (LOM) which rapidly produces pressure, temperature, mass and heat flow distributions throughout Double-Wall Effusion Cooling Schemes, developed from a previously presented Mass Flow Network LOM. These can be found for a variety of flow and geometric conditions, allowing fast analysis of cooling designs. Experiments were conducted using a steady-state facility, from which results were used to validate the new LOM to a satisfactory standard. Using specifically derived dimensionless groups for coolant migration, results from the LOM demonstrate the effect of heat transfer on it as well as the effects of coolant migration on the cooling performance, highlighting design guidelines to reduce such effects and to optimise the component life.
Accurate and Efficient Computation of Heat Transfer Coefficient From CFD Simulations
Authors: Chaquet Jose M. , Perez Carlos , Quintanal Jaime 
Published: October 2022

Abstract
Prediction of thermal loads plays an important role in turbomachinery applications. Accurate results require solving multiphysics phenomena using techniques such as conjugate thermal methods. In this context, CFD solvers allow us to obtain heat fluxes at the wall interfaces with solid domains. An important quantity to properly understand the thermal problem is the heat transfer coefficient (HTC, also called film coefficient) which basically is the proportionality constant between the heat flux and the temperature difference between fluid and solid domains. Methods for computing HTCs have been reported in the literature relying on information at the domain interfaces level. In the present paper a new approach taking advantage of the whole fluid domain is described. This proposed method is efficient since only one CFD solution is required for each instant. Several numerical simulations are presented in order to prove that the computed HTC field is able to mimic the CFD solver while maintaining the same operation conditions. Also it is shown how these surrogate models have partial predictive capabilities to perform cheap simulations at different operation conditions. Comparison of experimental data with numerical results confirms the aforementioned performance of the proposed approach, obtaining similar results as methods incorporating only information at boundary walls.
Effect of Jet-to-Plate Temperature Ratio on Flow and Heat Transfer Features of Active Clearance Control Systems
Authors: Da Soghe Riccardo , Mazzei Lorenzo , Tarchi Lorenzo , Casini Niccolò , Castelli Niccolò , Cocchi Lorenzo , Picchi Alessio , Facchini Bruno , Rotenberg Maxime 
Published: October 2022

Abstract
The goal of the present work is to investigate the effects of target plate temperature on heat transfer features of representative active clearance control (ACC) geometries presenting 0.8 mm circular impingement holes arranged in a single row pattern. The jets generated by such holes cool a flat target surface, which is replicated by a metal plate in the experimental setup. A steady-state technique with controlled wall heat flux is used to measure averaged heat transfer values along the target plate. The target plate is composed by a series of insulated blocks to limit lateral conduction effects and also to assure a fine control of the supplied power. A full characterization of pipe, target plate and flow temperature is obtained using thermocouples and IR camera. Target plate temperature level ranges from 330 K to 570 K, while the manifold inlet temperature is kept at ambient level. The jet-to-target plate temperature ratio (TR) thus ranges from 1 to 2 circa. The investigated jet Reynolds numbers range from 4000 to 10000. The obtained results reveal that heat transfer features are affected by the target plate temperature level, as it plays a role on the interaction between the impingement jets, the spent flow and the manifold surfaces. An in-depth analysis of the obtained results provides valuable information about the extrapolation of ambient test results to engine conditions.
Unsteady Analysis of Aeroengine Intake Distortion Mechanisms: Vortex Dynamics in Crosswind Conditions
Authors: Rao Anirudh Narayan , Sureshkumar Prathiban , Stapelfeldt Sina , Lad Bharat , Lee Kuen-Bae , Puente Rico Ricardo 
Published: October 2022

Abstract
The formation of a ground vortex and its ingestion into an aero-engine intake under crosswind conditions play a significant role in the aerodynamic excitation of the fan. Using steady and unsteady numerical simulations, an analysis of the dynamics of several distortion features is presented. For a simplified intake at high crosswind velocities, there is a substantial movement of the ingested ground vortex at the aerodynamic interface plane (AIP). The ingested ground vortex follows a specific trajectory while varying both in size and strength. The transition from a periodic to an aperiodic regime of the intake distortion at the AIP occurs as the crosswind velocity is increased. Circumferential mode decomposition shows that the largest amplitude of the distortion occurs at the first circumferential mode, and the amplitudes of the higher modes decrease monotonically. Furthermore, the amplitude of the spatial harmonics is time-dependent, which may be an influential feature at the time of assessing fan forced response.
A Resistive Model to Characterize Overall Effectiveness Influenced by Multiple Coolant Temperatures
Authors: Rutledge James L. , Fuqua Matthew N. , Polanka Marc D. , Baker William P. 
Published: October 2022

Abstract
The surface temperature of a film cooled turbine hot gas path component is typically nondimensionalized according to the overall effectiveness. This nondimensionalization scheme takes advantage of the fact that the surface temperature must be bounded by the coolant temperature and the freestream recovery temperature. Additional complexity arises when the surface temperature is influenced by the addition of a second coolant stream. While the surface temperature remains bounded by the cooler of the two coolant streams, the presence of the warmer stream means that the resulting overall effectiveness is now a function not only of the appropriately nondimensionalized coolant and freestream flow rates, but an additional nondimensional parameter that describes the relative difference in the two coolant temperatures. Previously, it was thought that experiments or computational fluid dynamics simulations would be required to discern this effect. In the present work, however, we introduce a linear resistive model that is based upon the exact solution to the energy equation and which accounts for the effect of any number of independent sources that influence the surface temperature. The model’s efficacy was demonstrated using experimental data acquired on conducting models in which two rows of holes ejected coolant from two independent plenums at two different temperatures.
Effect of a Reduced Oil Flow Rate on the Static and Dynamic Performance of a Tilting Pad Journal Bearing Running in Both the Flooded and Evacuated Conditions
Authors: San Andrés Luis , Alcantar Andy 
Published: October 2022

Abstract
The mechanical efficiency of rotating machinery improves as drag power losses in bearings reduce; hence, an operation mode that reduces the supplied flow brings immediate benefits. The paper presents measurements of the static and dynamic load performance conducted with a tilting pad journal bearing configured as flooded and evacuated, and supplied with flow rates from 150% to ∼25% (or lesser) of a nominal magnitude, proportional to shaft speed. The lubricant is ISO VG 46 oil supplied at 60 °C. The four pads bearing has center pivots with single orifice feeds for the flooded condition and spray bar injection for the evacuated condition. The shaft, 102 mm in diameter, operates at two speeds, 6 and 12 krpm (= 64 m/s surface speed), while a static load is applied between pads (LBP). The specific loads equal 345, 1,034 and 2,068 kPa. A reduction in flow rate makes both bearings operate more eccentrically. The evacuated bearing operates at a larger eccentricity, which for the lowest flow rate does not align with the direction of the applied load, hence displaying a sizable attitude angle. Pad subsurface temperatures are similar for both bearing configurations, although the evacuated bearing is colder by a few degrees Celsius. Drag power losses derived from the oil exit temperatures show the evacuated bearing produces up to ∼40% lesser power loss than the flooded bearing for a nominal oil flow rate. The bearings direct stiffnesses, Kxx and Kyy, increase with applied load and show little dependency on shaft speed. The evacuated bearing has lower magnitude stiffnesses, 20% or so lesser, than the flooded bearing. Damping coefficients, Cxx ∼ Cyy, reduce in magnitude as the flowrate decreases. In particular for low flow rates, 35% or lower, the evacuated bearing shows rather small (though highly uncertain) damping coefficients. For sufficiently small flow rates, operation at 6 krpm shaft speed and under the smallest applied unit load (345 kPa) produced subsynchronous shaft vibrations with a broad band spectrum (SSV hash). The evacuated bearing produced SSV hash at flow rates equal to 30% or so of nominal, while the flooded bearing demanded very low flow rates (∼15% and lesser of nominal) to produce SSV hash. For both bearings, the SSV amplitude motions were rather small in amplitude. The experimental campaign demonstrates that tilting pad bearings (flooded and evacuated) can safely operate with a reduced flow rate (50% or so of nominal) to produce significant savings in drag power losses and without significant effect on the pads’ metal temperatures that could affect the bearing long-term operation.
Numerical Investigation of Unsteady Inlet Guide Vane-Rotor Interactions in a Transonic Fan Due to Boundary Layer Ingestion
Authors: Giri Ritangshu , Turner Mark G. 
Published: October 2022

Abstract
The effects of boundary layer ingested inlet distortion on the unsteady flowfield between an inlet guide vane (IGV) and rotor of a single stage transonic fan are important, as they result in significant changes in the massflow rate, stagnation pressure rise and stage efficiency. The three dimensional time accurate commercial URANS code EURANUS (Cadence Inc.) was used to generate and analyze periodic quarter annulus simulations of the IGV-Rotor fan stage. A comparison of mixing plane and time averaged solutions showed the unsteadiness of the blade row interactions especially along the interface between the IGV and the rotor. The mixing plane solution predicted a decrease in efficiency of 1.11 % in the fan stage compared to that of a rotor, while a time averaged solution predicted a 1.36 % efficiency decrease in the fan stage compared to that of the rotor. At design speed, significant non-linear interaction was observed with very high levels of unsteady loading occurring at the vane trailing edge region because of it’s interaction with the rotor generated oblique shock waves. These shock waves move upstream and get reflected through the vane passages creating additional fan stage loss. It can also be observed that the strong vortices of the inlet guide vane wake break up the detached rotor bow shock. These shed vortices are chopped by the rotor leading edge and ingested by the rotor. Both the time averaged and the time accurate results show that the wake vortices strongly interact with the rotor blade boundary layer. These cause a decrease in the rotor efficiency and stagnation pressure rise, while the high frequencies of the inlet guide vane wakes can be a potential cause of rotor high cycle fatigue (HCF). Additionally, small flow separations due to shock boundary layer interactions can be observed at the IGV suction surface near the tip and contribute to the IGV flow losses.
Experimental Study on the Combustion Performance of Concentric Staged Lean Direct Injection Combustor With Two Different Swirler Angles of the Pilot Stage
Authors: Zhu Pengfei , Suo Jianqin 
Published: October 2022

Abstract
With the civil aviation engine now developing towards lower pollutant, and the lean direct injection (LDI) combustion proves excellent potential in reducing NOx emission, a concentric staged LDI combustor, both the main and pilot stages are based on LDI combustion concept, is proposed in this paper. It has great potential for an aero engine for a more straightforward structure and smaller size than the Multi-Point Lean Direct Injection (MPLDI) low emission combustor. Experimental research on the combustion and emission characteristics of the concentric staged LDI single-tube combustor with two swirl angles of the pilot stage (Case A: 35°, Case B: 45°) was carried out. The ignition performance was carried out at atmospheric pressure while the total pressure drop was 0.01–0.06, and the combustion and emission characteristics were carried out at different inlet conditions, fuel-air ratios (FAR), and fuel ratios of the main stage. The results indicate that the lowest ignition FAR of both two cases presents the trend of first decreasing and then increasing with the pressure drop, and Case B is lower than Case A at all conditions. The lean blowout FAR of Case B is 0.008, which is reduced by 11.11% than Case A. At the low condition, the inlet temperature is 540K, the NOx emission of the exit presents the trend of increasing with the increase of the FAR while the pilot stage works only. At the condition of the inlet temperature with 653K, both the main and pilot stages work together, and the fuel ratio has a distinct effect on the NOx emission of the combustor. However, when the inlet temperature is 737K, the EINOx of the combustor is almost the same at different fuel ratios. It is identical for both Case A and B. At all conditions, the EINOx of case B is lower than case A, and it is the same for the combustion efficiency. Overall consideration, though the combustion efficiency of Case B is lower than Case A, it is still not less than 99.9% when the main and pilot stages work simultaneously, 90% when the pilot stage works only. All the ignition, lean blowout, and NOx emission performances of Case B are better than A. Case B is better than Case A for a civil aviation engine.
Serviced HGP Parts Assessment Using Microstructure-Based Models for New NovaLT™16 Gas Turbine Validation
Authors: Mastromatteo F. , Romanelli M. , Giovannetti I. , Cinelli C. 
Published: October 2022

Abstract
NovaLT™16 is a new high-efficiency gas turbine developed by Baker Hughes for mechanical drive and power generation applications in the 16MW market range.
The Fleet Leader engine of this GT class underwent a planned stop which has been used to check the status of the most critical components and validate the engine design.
Hot Gas Path (HGP) components specifically have been object of a detailed assessment of their post-service conditions which included NDT inspections, dimensional measurements, air and water flow checks of cooling circuits. Selected components have been also destructively examined to check their microstructure condition and assess the level of service-induced base material and coating alteration.
The set of assessments carried out did not highlight any criticality in the engine overall condition or unexpected behavior with respect to design intent.
For High Pressure (HP) buckets a quantitative assessment of the service temperature has been also obtained leveraging a microstructure-based model specifically developed by Baker Hughes for bucket base material René N4, a first-generation single crystal superalloy. This model takes into account the time-temperature dependent alterations of the γ/γ’ material structure and namely the growth of the periodicity width lambda (λ), measured along the [001] lattice direction of the single crystal structure.
A Review of High-Speed Rotating HP Turbine Heat Transfer and Cooling Studies Over the Last Decade in the Oxford Turbine Research Facility
Authors: Falsetti Chiara , Beard Paul F. , Cardwell David N. , Chana Kam S. 
Published: October 2022

Abstract
Over the last years, advanced experiments under engine-representative conditions have been performed in the Oxford Turbine Research Facility (OTRF) to obtain high-quality aero-thermal data that are essential for developing novel cooling designs and for validating computational models.
Thanks to its unique experimental capabilities, the OTRF plays a crucial role in the advancement of HP turbines, which are life limiting components of modern gas turbines due to the harsh high temperature environment.
The OTRF continues to be developed for additional capability to achieve more engine-representative conditions. Major upgrades include: (i) a combustor simulator able to produce engine radial and circumferential temperature profiles and inlet swirl simultaneously to study combustor-turbine interaction, (ii) fully film-cooled HP turbine designs and 1.5 stage configurations with a low-turning strut, (iii) novel rotor casing effusion cooling concepts, (iv) an advanced in-shaft data acquisition electronics system.
More recently, the enhanced capabilities of additive manufacturing have been used in the facility to investigate the performance of novel blade tips and full annular effusion cooling concepts. This allowed complex cooling features and geometries to be implemented and assessed in the facility. The aero-thermal performance of cooled and uncooled blades for three variants of squealer tip design and a next-generation effusion cooling designs have been recently evaluated.
Assessing the Structural Integrity of Plasma-Sprayed Multilayer Thermal Barrier Coatings
Authors: Adam Marcel , Kontermann Christian , Oechsner Matthias 
Published: October 2022

Abstract
The majority of lifetime models associates the failure of thermal barrier coatings to an oxidation of the bond coat. A thickening of the thermally grown oxide leads to a conversion of stresses at the undulated ceramic-metal interface, supporting the propagation of existing micro cracks. However, in plasma-sprayed multilayer thermal barrier coatings consisting of gadolinium zir-conate (GZO) and yttria-stabilized zirconia (YSZ) a shift of the failure site from the ceramic-metal interface to the GZO-YSZ interface has been observed. Thus, an exclusively oxide-based formulation is not sufficient to describe the damage transition phenomena. Therefore, this paper outlines a mechanism-based approach for assessing the structural integrity, considering all relevant thermally activated processes as well as the interaction between thermal and elastic misfits. Oxidation of bond coat, creep of composite materials and sintering of ceramics are modeled in terms of temperature and exposure time. Finite element analysis of GZO-YSZ pairings with different microstructures reveal a strong influence of the initial porosities on the sintering behavior and thus on the resulting mechanical stresses and potential crack driving forces at the bi-material interfaces.