bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Analysis of the Effect of Geometric Variations on the Mass Flow Distribution for an Under-Race Lubrication System
Authors: Aguirre Bermudez Daniel Mateo , Abraham Aju , Joshi Shreyas , Schwitzke Corina , Bauer Hans-Jörg 
Published: August 2024

Abstract
Operating conditions of modern aero-engines place a significant demand on oil for the lubrication and cooling of roller bearings. The supply of the required lubricant is often achieved by a system consisting of an oil jet targeted onto a feed geometry machined into the shaft. This cavity leads the oil through a number of equispaced feed holes in the inner race of the bearing, allowing direct lubrication and cooling of the components. This lubrication technique is commonly known as under-race lubrication. Achieving uniformity is of crucial importance for efficient lubrication and cooling. This study explores the effect of key geometric parameters of the shaft cavity on the oil flow distribution for different operating conditions. The analysis is perfomed using Implicit Incompressible Smoothed Particles Hydrodynamics (I-ISPH) simulations, focusing on the variation of groove length, groove depth, groove taper, hole diameter and hole axial distance. The analysis of the results reveals that groove characteristics have a limited impact, while hole diameter and axial distance significantly influence the oil distribution. An investigation of the film thickness inside the cavity is performed, and its correlation with the oil mass flow through the feed holes is discussed.
Effect of Relative Location of Film Cooling Hole With Internal Angled Ribs on the Film Cooling Effectiveness of a Gas Turbine Blade
Authors: Kang Young Jun , Jeong Jin Young , Kim Hyeok Je , Kim Gi Mun , Kwak Jae Su 
Published: August 2024

Abstract
Film cooling effectiveness (FCE) is strongly influenced by film cooling hole geometry, mainstream boundary condition (boundary layer thickness and turbulence intensity), and coolant injection conditions (density ratio and blowing ratio). It is also shown that the flow structure of coolant at the inlet of a cooling hole also affects film cooling performance. In this study, the inlet flow structure resulting from the rib turbulators installed in the internal channel and its effects on the film cooling effectiveness were analyzed numerically. The numerical result was also validated with experimental result obtained with the pressure sensitive paint (PSP) technique. Studies were conducted at 25 relative locations of a fan-shaped hole on the 60-degree angle ribbed channel. Furthermore, the results were compared to cases that coolant was supplied through the plenum chamber. Results showed that the relative location of the film cooling hole with respect to the angled rib significantly altered the flow structure of coolant and the distribution of FCE. Also, FCE with the angled ribbed channel generally showed low FCE compared to the case with a plenum chamber.
Numerical Investigation of the Influence of Tyler-Sofrin Modes on the Increase in Blade Unsteady Pressure in a Subsonic Axial Compressor
Authors: Oshio Tetsuya , Aotsuka Mizuho , Kusuda Shinya , Tateishi Atsushi 
Published: August 2024

Abstract
The present paper describes an investigation on the increase in unsteady pressure on rotor blade due to Tyler-Sofrin modes generated by stator-rotor interaction. The investigation is conducted numerically using CFD, which is unsteady RANS calculation on a quasi-3D model of a single stage cascade extracted from a 3.5 stages subsonic axial compressor. Several parameters such as stator vane count, rotor speed and axial gap between stator and rotor are varied to change characteristics of Tyler-Sofrin modes. As a result, it is found that the pressure amplitude of the 1st-harmonic of vane passing frequency on the blade surface increases at some specific conditions of the vane count and rotor speed. The modal phase velocity of a Tyler-Sofrin mode is related to the pressure amplitude. A parameter called Phase Speed Ratio (PSR) is introduced to express the relationship between the modal phase velocity of Tyler-Sofrin modes and the velocity of acoustic propagation in the circumferential direction. In the region where the PSR is lower than 1.0, the pressure amplitude gradually increases ranging from around 0.5 and peaks around 0.9. Then, the pressure amplitude decreases in the range of PSR from 0.9 to 1.0. After the PSR exceeds 1.0, the pressure amplitude rapidly decreases. This result indicates that the pressure amplitude of the 1st-harmonic of vane passing frequency increases when the modal phase velocity approaches the velocity of acoustic propagation. It is also found that the pressure amplitude peaks close to PSR = 1.0 when the axial gap between stator and rotor is large. It suggests that the non-monotonically increase in the pressure amplitude on the rotor blade is influenced by upstream stator.
Manufacturing and Build Variations Modelling for Multi-Stage Axial Compressors: CFD Aerodynamic Predictions
Authors: Bruni Giuseppe , Krishnababu Senthil K. 
Published: August 2024

Abstract
The numerical prediction of multi-stage compressor flows has historically been a challenge for CFD models, due to their complex, turbulent and three-dimensional nature. High-fidelity models such as LES and DNS have shown promising results, but their application is limited by the high computational cost, while steady-state RANS simulations are still used for the majority of applications in the industry. Over the years, engine manufacturers have developed best-practices and guidelines for multi-stage axial compressor simulations, providing reliable CFD models capable of predictions comparable to test data, both with regards to performance and surge margin at different operating conditions. However, even with state-of-the-art models, several discrepancies can be observed and are generally addressed with calibration based on operational experience. These discrepancies are partially due to known limitations of steady-state CFD, as well as to modelling assumptions and the use of idealised geometries. This paper demonstrates how the accuracy of CFD predictions can be greatly improved by modelling the effect of manufacturing and build variations, such as tip clearances, surface roughness and in-tolerance geometry variations. The resulting engine-build specific models show greatly improved agreement with engine test data, with no increase in computational cost. These models can be used as part of the design process, to develop robust axial compressor designs desensitized to these variations. Moreover, the results from the analyses can be used to re-define tolerance ranges and drawing specifications, to reduce the potential impact on build-to-build engine performance scatter.
Analysis of the Instantaneous Film Cooling Effectiveness on Showerhead Film Cooling Using Fast Response Pressure Sensitive Paint (Fast-PSP)
Authors: Sounik Jeremy L. , Wright Lesley M. 
Published: August 2024

Abstract
The instantaneous effect of unsteady wakes on film cooling effectiveness using a fast response pressure sensitive paint (PSP) was studied. Testing was performed in a five passage, low speed wind tunnel using five times scaled versions of typical high pressure blades (axial chord of 17 cm). The blowing ratios studied include 0.8 and 1.2, with a density ratio of 1.0 and 1.5 at each blowing ratio. Upstream unsteady wakes were produced by a spoked wheel type wake generator. The wake generator, utilizing a varying number of rods and rotational speeds, produced Strouhal numbers of 0.1 and 0.3 while the wind tunnel inlet mainstream Reynolds number was held at a constant value of 300,000 (mainstream velocity of 21 m/s) for every test case. For each Strouhal number, blowing ratio and density ratio studied, several positions within the period between rods, and the resulting wakes, were recorded. Results show that the location of the wake along a blade’s surface had a significant impact on the film cooling effectiveness in the immediate location of the wake. An overall fluctuation of up to 69% in film cooling effectiveness was observed within the wake period. Conclusions also show that while mainstream flows with higher Strouhal numbers tend to decrease film cooling effectiveness, the fluctuation of film cooling effectiveness at higher Strouhal numbers was reduced when compared to results utilizing lower Strouhal numbers. A comparison of results from tests at different density ratios showed a much smaller change in the instantaneous film cooling effectiveness between test cases.
Flow Disturbance by Intrusive Instrumentation: Part 2 – Protrusions on the Suction Side of HP Compressor Vanes
Authors: Schäflein Lukas , Jung Daniel , Jeschke Peter , Wunderer Roland 
Published: August 2024

Abstract
In this study, we investigate the aerodynamic impact of spanwise pressure tubes located on the suction side of a high-pressure compressor stator vane. For our experiments in a linear cascade wind tunnel, we modeled the pressure tubes as simplified protrusions. The experiments were conducted at a Mach number of ∼0.5 and a Reynolds number of 790,000. By testing six configurations with protrusion widths between 8% to 24% of the chord lengths and heights of 33% and 66% of the maximum vane thickness, we find that increasing the protrusion height as well as reducing the protrusion width leads to an increase of the total pressure loss. Consequently, the narrowest and highest protrusion with a width of 8% and a height of 66% represents the worst case with a total pressure loss increase of factor 5.7 compared to a nominal vane. In the best case, the protrusion with a width of 24% and a height of 33% leads to an increase in the total pressure loss of factor 2.1 compared to a nominal vane. Oil flow visualization and CFD simulations reveal complete flow separation downstream of higher protrusions, creating large recirculation zones. For lower protrusions the flow mostly reattaches at the top of the protrusions. The study offers insights for engineers designing intrusive instrumentation on compressor vanes, enabling them to minimize additional total pressure loss.
Break-Up and Atomization Characteristics of N-Dodecane in High-Temperature Crossflow
Authors: Johny Tom , Bhatia Bharat , De Ashoke 
Published: August 2024

Abstract
The present study numerically investigates the break-up and atomization characteristics of n-dodecane, a widely used surrogate for jet fuels and diesel, under high pressure and temperature conditions of crossflow. This research can provide valuable insight into optimizing fuel injection processes and reducing emissions in gas turbine engines. Simulated test conditions range from 3.8 to 10 bar and at temperatures of473K, varying the momentum flux ratios (q) in the range of 6–30 and Weber number (We) in the range of 100–1200. An OpenFOAM-based compressible VOF-LPT coupled framework is developed to simulate the high-temperature evaporating spray problem. Numerical validation of the developed framework is done based on the high-temperature experimental data from Amighi and Ashgriz [1,2] for water. It is further utilized to simulate n-dodecane injections in a crossflow. The validation is performed regarding liquid jet penetration and droplet sizes, finding accurate agreement with experimental data. The effect of temperature and pressure on break-up and atomization, liquid jet penetration, and droplet size characteristics are also discussed. An increased fine droplet production is observed for dodecane at high temperatures, potentially due to enhanced break-up and heat transfer rates. Further, the variation of droplet sizes downstream of injection for n-dodecane fuel under different pressure conditions is also discussed. Determination of quantitative droplet size distribution highlights the solver’s utility in understanding atomization, evaporation, and mixing under high-temperature crossflow environments.
Power Analysis of Wave Speed Coincidence Stability and the Effect of Asymmetry
Authors: Ma Chris , Garvey Seamus D. , Kamesh Punithavathy , Rix Andrew I. J. 
Published: August 2024

Abstract
This paper considers the interaction between a rotating bladed-disc and static casing, specifically a synchronisation phenomenon called wave speed coincidence. Through tip rub, travelling waves in the bladed-disc and casing can interact and cause large amplitudes of vibration. Previous work has analysed this phenomenon using time integration methods, which are often too computationally expensive for early design stages, and frequency domain approaches such as the harmonic balance method, which require simplification in the periodicity of the problem limiting the usefulness of such methods. This paper demonstrates the use of a power method and consideration of periodicity over a contact cycle. This allows the problem to still be considered as a periodic behaviour, but without the loss of generality associated with conditional harmonic balance methods. This is useful as a faster screening method for preliminary design stages and a way to down-select high risk cases, where further time integration analyses can be performed. The method is also applied to cases with asymmetric casings, allowing quantitative assessment of the effect of asymmetry in the future. In this case, as a result of the asymmetry, the interaction quickly became non-wave speed coincidence. Nevertheless positive power into the casing continued to be observed in some cases, suggesting potential instability from the subsequent blade rubs.
Research on Calculation Method of Variable Specific Heat Performance of Wide-Speed Range Aeroengine
Authors: Du Huipeng , Liu Chuankai 
Published: August 2024

Abstract
Given the escalating demand for hypersonic maneuverability in forthcoming times, it is imperative to advance wide-speed range engine technology, while acknowledging that diverse incoming flow conditions exert a substantial influence on aerothermal processes. The conventional method for calculating aerodynamic performance, which assumes constant specific heat and employs a velocity coefficient parameter, is no longer applicable to aeroengines operating across a wide range of speeds. Therefore, it is crucial to develop an appropriate calculation method for variable specific heat in this type of engine and establish a comprehensive physical property library based on object-oriented programming methodology to cater to the future calculation requirements of diverse engine components. The present study employs polynomial fitting to determine engineering thermodynamic properties, while incorporating the Qin Jiushao (or Horner) algorithm to enhance computational efficiency. The novel approach of utilizing energy conservation and isentropic process principles, in conjunction with numerical methods such as false position, has been employed to ensure the convergence of aerodynamic properties across a wide range of speeds. Subsequently, a novel algorithm is developed for two crucial processes within the intake and exhaust system: the stagnation process and expansion process. Furthermore, a comparative analysis is conducted to discern disparities between these algorithms. Concurrently, employing global sensitivity analysis methodology enables an examination of the impact of altitude and Mach number on the calculated total parameter results. The results indicate that during the stagnation process at 30km, 5Ma, there is an approximate temperature difference of 10% between the two algorithms, while the total pressure difference exceeds 25%. The impact of Mach number on the total temperature is significant, as is the influence of Mach number and altitude on the total pressure. During the expansion process, the critical temperature exhibit minimal difference, but exhaust velocity is dependent on the temperature difference.
High-Fidelity Simulation of an Industrial Low-Pressure Pump of Helicopter Using Coupled LES/CAA Method
Authors: Bénez Pierre , Moureau Vincent , Cailler Mélody , Ribert Guillaume , Mingret Pascal , Robin Marine 
Published: August 2024

Abstract
This paper is devoted to the simulation of an industrial hybrid regenerative liquid-ring pump in pure liquid conditions. An hybrid Large-Eddy Simulation (LES) / Computational AeroAcoustic (CAA) coupled method, based on the association between a low-Mach number flow solver and an implicit linear acoustic solver, is used to rebuild efficiently the hydro-acoustic pressure fluctuations generated by the flow. The acoustic effects are solved implicitly to avoid being limited by the acoustic time step at low-Mach number. This fully coupled strategy, already validated in a body-fitted formalism, is adapted here to an immersed-boundary formalism for the modeling of the pump rotor motion. The LES/CAA simulation of the pump is used to investigate the potential impact of the acoustics on the pump performances and the fuel vaporization risks.
Computational Study of Additively Manufactured Internally Cooled Airfoils for Industrial Gas Turbine Applications
Authors: Krull Matthew , Lynch Stephen , Searle Matthew , Floyd Timothy , Ames Forrest E. , Straub Douglas 
Published: August 2024

Abstract
Internal cooling features such as pin-fins, impingement jets, and rib-turbulators are necessary to keep turbine components cool, but if sufficiently advanced can potentially also eliminate the need for film cooling on turbine blades particularly in industrial gas turbines where temperatures are not extreme. Furthermore, by leveraging additive manufacturing (AM), other advanced designs such as lattice and incremental impingement configurations are possible and have recently been experimentally tested. While the performance of such configurations has been quantified recently through means of overall cooling effectiveness, it is not as clear why certain designs were better than others, or what the mechanisms were behind the observed external cooling patterns. The purpose of this study was to computationally analyze different advanced turbine blade internal cooling designs previously tested by the National Energy Technology Laboratory. Conjugate steady Reynolds Averaged Navier Stokes (RANS) simulations were performed on three symmetric blades with different internal cooling configurations: a baseline cooling design with pin-fin arrays, a double wall design with impingement jets and serpentine channels, and an incremental impingement design. The computational results were compared to previously obtained experimental data and were further studied to understand the advantages and disadvantages of different cooling configurations. This study found that the double wall design had better overall cooling than the baseline design, as found in the experiment, because of increased convective heat transfer in the double-wall region. However, the computational model based on design-intent geometry indicated a higher rate of coolant flow in the trailing edge as compared to the experiment resulting in an overprediction of cooling. Additionally, the incremental impingement design had the highest overall cooling effectiveness of the various designs. This was attributed to the impingement jets in the incremental impingement design that produced relatively uniformly distributed high internal heat transfer coefficients.
Unsteady Flow Simulations of a Transonic Low-Pressure Turbine Cascade
Authors: Hullin Liza , Gonzalez-Martino Ignacio , Bonnal Benoît 
Published: August 2024

Abstract
High-speed low-pressure turbine blades (HS-LPT) are a key component in the development of high-efficiency geared engine architectures. High-fidelity CFD simulations are progressively being integrated into the design process of engine components, to get a better insight in the complex flow behavior and guide the shape optimization process. The current study presents Very-Large Eddy Simulations (VLES) of the flow across a HS-LPT, using Lattice-Boltzmann Methods (LBM). Different solvers of the commercial software SIMULIA PowerFLOW® have been used for this study. The selected benchmark case is the SPLEEN cascade, a next-generation HS-LPT cascade rig developed by Von Karman Institute and Safran Aircraft Engines, as part of a large European collaborative project. A subset of the large amount of available test rig data has been used here to benchmark the CFD solver. Hence, the study aims at assessing the ability of this numerical methodology to predict several complex flow phenomena occurring at engine relevant Mach and Reynolds numbers. For instance, we observed (1) unsteady transonic flows, (2) laminar separation bubble, (3) natural laminar-to-turbulent transition, (4) unsteady bypass transition due to wake impingement coming from upstream turbulence, (5) endwall 3D effects, (6) corner stall separation and (7) fluctuation of the flow due to periodic wakes coming from translating bars representing wakes of upstream rotor.
Numerical Investigation of Two-Phase N-Decane/Air Rotating Detonation Engines With Different Numbers of Fuel Orifices
Authors: Shao Xiaofeng , Zhao Ningbo , Zhang Wei , Zheng Hongtao 
Published: August 2024

Abstract
In this study, n-decane/air two-phase rotating detonation is numerically investigated based on Eulerian-Lagrangian method. Three-dimensional rotating detonation chamber (RDC) with various numbers of fuel orifices (30, 45, 60 and 90) is considered. The effects of numbers of fuel orifices on the fuel mixing characteristics, the flow field structures and the propagation characteristics of the rotating detonation wave (RDW) are analyzed. The results show that the liquid fuel mixing is influenced by the fuel jets and the incoming air shear. The former mainly affects the mixing uniformity, while the latter has a great influence on the Sauter mean diameter. Specifically, increasing the numbers of fuel orifices improves the mixing uniformity but slightly rises the Sauter mean diameter. Besides, the number of fuel orifices has a significant impact on the propagation mode of RDW. Single-wave mode is established in RDC except for the 30 orifices. Furthermore, a dimensionless kinematic parameter (α) is used to represent the fuel reactivity and predict the propagation mode of RDW. Moreover, the propagation parameters of RDW vary greatly with different numbers of fuel orifices. As the number of orifices increased, the formation time to stable operation of RDW decreases. The research results can provide guidance for the design of two-phase RDE.
Generative Design of a Gas Turbine Combustor Using Invertible Neural Networks
Authors: Krüger Patrick , Gottschalk Hanno , Werdelmann Bastian , Krebs Werner 
Published: August 2024

Abstract
The need to burn 100% H2 in high efficient gas turbines featuring low NOx combustion in premix mode require the complete redesign of the combustion system to ensure stable operation without any flashback. Since all engine frames featuring a power range from 4 MW up to 600 MW are affected, a huge design effort is expected. To reduce this effort, especially to transfer knowledge between the different engine classes, generative design methods using latest AI technology will provide promising potential.
In this work, this challenge is approached utilizing the current advances in generative artificial intelligence. We train an In-vertible Neural Network (INN) on an expandable database of geometrically parameterized combustor designs with simulated performance labels. Utilizing the INN in its inverse direction, multiple design proposals are generated which fulfill specified performance labels.