bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Educated Guess - Predicting Turbomachinery Efficiencies of Aero Engines During Conceptual Design
Authors: Häßy Jannik , Bolemant Martin , Becker Richard-Gregor 
Published: September 2023

Abstract
Evolutionary advancements and disruptive concepts for future gas turbine-based propulsion systems are researched to reduce the environmental impact of aviation. In the initial design phase, only few data on component efficiencies is available and assumptions have to be introduced. However, comparability and consistency between assumed efficiencies is crucial to benchmark different designs or concepts in a feasible way and to avoid misleading findings. The assumptions made have to reflect the impact of design parameters on efficiency considering underlying physical phenomena. A simple model is developed to predict the design efficiencies of axial flow turbo components of aero engines with the aim to generate traceable, consistent and comparable assumptions for conceptual engine design. The efficiency prediction model combines existing approaches from published sources using a superposition principle and is calibrated by means of available data on engines with an entry into service later than 2010. For a stage-wise evaluation approach, the calibrated model predicts the component efficiencies of database engines with a maximum absolute deviation of 0.1 % for fans, 2.2 % for compressors, 1.4 % for cooled turbines and 0.6 % for low-pressure turbines. The deviations between predictions and database values create a sense for the uncertainty that has to be expected using the calibrated model. The future application of the predictive capability contributes to feasible comparisons between different engine configurations during the conceptual design phase.
Soot Formation and Flame Characterization in a Swirl Kerosene Spray Rich Burn-Quench-Lean Burner at Elevated Pressure
Authors: Perrier Aurélien , Milea Andrei-Silviu , Caceres Marcos , Vandel Alexis , Godard Gilles , Cayre Alain , Collin-Bastiani Félix , Cabot Gilles , Grisch Frédéric 
Published: September 2023

Abstract
Swirl-stabilized, turbulent, non-premixed kerosene-air flames were studied experimentally in an RQL (Rich burn/Quick-quench/Lean-burn) model combustor equipped with large optical accesses. The goal of these studies was to characterize the flame topology as well as soot and NO formation processes in the rich primary zone of the RQL combustor, and to establish a large database for future validation of numerical simulations. The experiments were performed under relevant operating conditions up to 4.5 bar. The aerodynamic flow field was measured by Particle Image Velocimetry, the flame structure, fuel and NO distributions by Planar Laser-induced Fluorescence and soot volume fractions by Planar Laser-induced Incandescence. Additional measurements were performed by a scanning mobility particle sizer technique to record the number of soot particles per unit volume as well as the particles size. Two equivalence ratio conditions were used to study the impact of relevant scalar parameters on NO and soot production. For each condition, instantaneous and average distributions of the measured parameters are presented and discussed. The coupling of the optical and intrusive measurement techniques has finally enabled to highlight the impact of the liquid and gas phases fuel distribution on the flame structure, but also on NO and soot formation.
Investigation of Radial Preswirl Nozzle – Coverplate System Using CFD
Authors: Erdem Erinc , Yalcinkaya Abdulkadir , Sertcakan Mustafa Cem , Sal Sinan , Dogu Yahya 
Published: September 2023

Abstract
This article focuses on a radial preswirler system using CFD, and the effect of different parameters such as the number and the angle of the holes at the preswirl nozzle exit, and the diameter of the preswirl nozzles have been investigated. Three-dimensional steady CFD simulations on a 22.5deg sector model showed a non-monotonic trend of swirl velocity at the inlet of the receiver holes and associated flow angles when different preswirl nozzle configurations are tested. Sudden rise in swirl ratio can be attributed to interactions of adjacent nozzle jets. Due to this flow feature swirl velocities are enhanced up to a certain angle where the interaction starts to diminish. Free vortex assumption in between nozzle exit and receiver inlet holds, as angular momentum of the nozzle jet is much more dominant compared to torques exerted by stator surfaces.
Tacholess Instantaneous Speed Estimation of a Wind Turbine Gearbox Using Vibration Signals
Authors: Sankarankutty Rahul , Rathna Prasad Sagi , Shakya Piyush , Sekhar A. S. 
Published: September 2023

Abstract
Early turbine component failures continue to be a problem in the wind energy sector with the gearbox being the costliest subcomponent to maintain. In this study, an in-house wind turbine experimental test rig has been designed to simulate the on-site transient wind speed and load conditions on a scaled-down 3-stage planetary gearbox. A total of 19 different wind profiles from commercial wind farms are validated from the measured vibration data using statistical performance criteria. Tracking the rotational speed, especially in a wind turbine gearbox operating in highly non-stationary environments, is extremely essential. Conventional speed measurement by tachometers or encoders is sensitive to random disturbances, and hence Instantaneous Angular Speed measurement from vibration signals is an alternate approach to estimating the instantaneous frequency of the system from accelerometer data. The present study compares different speed estimation methods based on phase demodulation and time-frequency approaches for their accuracy on various wind speed datasets. A new method is proposed, combining both the time-frequency and demodulation techniques. A performance comparison of the methods is done, and their results are compared with the data collected from an angular encoder.
Virginia Tech Optical Inlet Sensor for Particle Detection: Rolls Royce M250 Turboshaft Demonstration
Authors: Antous Brittney , Byun Gwibo , Lowe K. Todd , Smith C. Fred 
Published: September 2023

Abstract
Propulsion systems are exposed to environmental ingestion hazards that can cause significant damage and decrease performance. Particles are ingested in a wide range of flight environments that can cause immediate engine failure or long-term damage. An accurate measurement technique has been developed to quantify particle ingestion and aid engine health monitoring. This sensor utilizes scattering and extinction techniques along with machine learning models to measure particle characteristics based on a robust and versatile library. The capabilities of this sensor have been demonstrated using solid quartz particles on the Rolls-Royce M250-C20B particle ingestion turboshaft test engine. To the authors’ knowledge, this work presents the first demonstration and validation of optical solid particle sensing in a turbine engine. CSPEC sand (Mil-E-5007C) was ingested for the validation test at two different feed rates using a sand feeder. The sand concentrations were 45mg/m3 and 22mg/m3. The sensor outputs the particle characteristics of aspect ratio (AR), size distribution (σ), Sauter mean diameter (D32), and the particle mass flow rate. The Sauter mean diameter and mass flow rate of ingested sand were calculated using the machine learning model outputs and validated by independent measurements. The sensor produced a 0.1 g/min RMS error compared to the validation measurement.
Elastic and Damping Characterization of Open-Pore Metal Foams Filled or Not With an Elastomer for Vibration Control in Turbomachinery
Authors: Laçaj Endri , Jolly Pascal , Bouyer Jean , Doumalin Pascal 
Published: September 2023

Abstract
In this work, an experimental investigation into vibration damping of elastomer filled open-pore metal foams and their effectiveness as a bearing support in turbomachinery is presented. The polyurethane fillers known for their high-energy absorption capacity were chosen to enhance the damping performance of the metal skeleton. Aluminum (Al), copper (Cu) and nickel-chromium foams (NiCr), with different relative density and pore size were tested dynamically using a dedicated device based on a single degree-of-freedom model. The results indicate that the storage modulus and the loss factor for foam-polymer composites were greater than the combined contribution of both phases taken separately. Foam morphology plays an important role in this effect and it is shown that the increase in performance was more significant for higher specific surface area. Fillers with different properties were also considered. The optimal combination of foam and polymer was selected and tested on a rotor kit test bench. Annular shaped samples were placed between the external race of the ball bearing and the housing. The tests were carried out using a flexible rotor configuration where the vibration amplitudes of the rotor were monitored for foam and foam-polyurethane composites for rotational speeds up to 100 Hz while hammer impact tests were performed using a semi-rigid shaft configuration due to higher resonance frequencies. In the first case, no significant difference was observed between the foam, foam composite and the bearings-only set-up. In the second case, the foam composite resulted with the highest energy dissipation capacity.
Measurements of Turbulence in Compressible Low-Density Flows at the Inlet of a Transonic Linear Cascade With and Without Unsteady Wakes
Authors: Pastorino Giacomo , Simonassi Loris , Lopes Gustavo , Boufidi Elissavet , Fontaneto Fabrizio , Lavagnoli Sergio 
Published: September 2023

Abstract
In the present work, hot-wire anemometry was employed for the characterization of the turbulent field at the inlet of a high-speed low-pressure turbine cascade, in terms of turbulence intensity and integral length scales. This work addresses two major topics relevant to the turbomachinery field: the application of hot-wire anemometry in transonic and rarefied flow regimes and the decoupling of the deterministic and the stochastic fluctuations when measuring unsteady phenomena. In compressible and rarefied flows, a hot-wire is strongly sensitive to both density and velocity fluctuations, and the commonly used Nusselt-Reynolds correlations are not valid. In this paper, a non-dimensional calibration methodology, based on Nusselt, Reynolds and Knudsen numbers, was coupled with a sensitivity analysis and employed to post-process the experimental dataset, allowing to decouple the fluctuations of density and velocity and compute the turbulence parameters. In the presence of unsteady wakes generated upstream of the cascade, two different phase-locked averaging techniques were employed to distinguish the wake deterministic fluctuations from the background turbulence intensity.
Investigation of Rotor Stator Cavity Flowfield at Downstream of a High Pressure Turbine Disk
Authors: Yazan A. , Karasu Z. T. , Yilmaz S. , Erdem E. , Sal S. 
Published: September 2023

Abstract
The present study aims to investigate the flow field of the cavity, that is bordered by HPT rotor disk and LPT stator disk, via CFD and 1D flow solver for a symbolic engine geometry. The cavity has two outlet regions, namely disk rim side and labyrinth seal side, and one inlet that is located at the middle of the stator surface. The test rig data, that is used for validating CFD method in the study, from Kilic and Owen [5] is performed at various disk speeds. It is intended to demonstrate unorthodox rotor-stator flow physics, in which rotor pumping is hindered by an impinged air on to the rotor surface. In order to expand the scope, analyses are conducted by varying turbulent flow parameters. The explanations, which are constructed on stream lines, temperatures, swirl ratios and pressures, on the results are carried out based on physicals concepts such as free & force vortex behaviour and windage effect. The outcomes of the unfamiliar rotor-stator behavior in the study is expected to be a guide for the ones who have an interest in rotor-stator designing in terms of thermal /flow discipline.
Spray Combustion and Emissions of a Hydrothermal Liquefaction Biofuel for Gas Turbine Applications
Authors: Broumand Mohsen , Shahzeb Khan Muhammad , Thomson Murray J. , Singh Devinder , Yun Sean , Hong Zekai 
Published: September 2023

Abstract
Biomass liquefaction oil (BLO), obtained from biomass resources through thermochemical processes like fast pyrolysis (FP) or hydrothermal liquefaction (HTL), is widely regarded as one of the most economically feasible energy solutions in our future sustainable energy mix. However, the utilization of BLO as a drop-in fuel in the current in-line gas turbines has encountered several challenges due mainly to the difficulties in atomization and ignition, originating from the fuel’s chemical composition and physicochemical properties. The present study compares the combustion performance and gas- and solid-phase emissions of a HTL oil (also called biocrude), as well as its diesel blends, with those of a conventional FP oil (also called bio-oil). Considering diesel as a baseline fuel, the properties and combustion performance of the HTL oil compare favorably with those of the FP oil. An anchored spray flame using the 100% HTL oil is achieved in the experiments with much smaller degrees of fuel coking and nozzle clogging problems and a lower amount of particulate matter (PM) emissions. However, its CO and NO emissions are measured higher by more than two times. The insights drawn from the present study indicates the potentials of high quality HTL oils as sustainable fuels to replace fossil fuels in gas turbines and other energy conversion systems.
Investigation of Rear Blisk Drum Dynamics Under Consideration of Multi-Stage Coupling
Authors: Gambitta Marco , Beirow Bernd , Klauke Thomas 
Published: September 2023

Abstract
The analysis of the structural dynamics of multistage cyclic structures as linked components is required to model the interstage coupling. In turbomachinery, this can result in a collaboration between different compressor or turbine stages. This paper investigates the coupling between two rear drum blade integrated disk stages of an axial compressor to support the mechanical design process.
Considering the vibration modeshapes of a multistage system, different components may co-participate in the dynamics. For this reason, a criteria to identify the modes affected by the coupling and to quantify this coupling is defined. This allows to distinguish between modes with inter-stage coupling, requiring the multistage system for their description, and uncoupled modes, involving a single stage. In addition, it is of interest to research methods to reduce the impact of the coupling on the vibrating system without drastically altering the geometry of the components.
The vibration analyses of a two-stage compressor generalized geometry, representative of a compressor rear drum blisk, is presented as a study case. The use of a reducing method allows to describe the behavior of the nominal multistage system with a computationally efficient technique, enabling a parametric analysis of the stages’ coupling. The investigation considers the effect of a set of geometrical and mechanical parameters on the dynamics, identifying the driving parameters of the coupled vibration characteristics.
Development of a Novel Steam Turbine Low Pressure Section for Variable Speed Application
Authors: Auciello Jury , Maceli Nicola , Arcangeli Lorenzo , Cosi Lorenzo 
Published: September 2023

Abstract
Low Pressure (LP) stage design characteristics play a key role in Steam Turbine (ST) product line as they typically set limits to the maximum turbine flow and rotating speed and have a strong influence on the overall turbine efficiency.
LP stages design presents a combination of structural and aerodynamics challenges that obliges the manufacturers to develop and test the design well in advance with respect to the turbine design schedule.
For the same reason (development complexity) an LP stages design is usually scaled to cover a wide range of rotating speed and annulus area. The set of scaled LP stage is referred to as LP stage family.
The author’s company has started the design of a new family of LP stages for power generation and mechanical drive application. The initial phase of the development has focused on the design of the master size, development of the entire family and manufacturing process qualification.
This paper will present a comprehensive review of all the phases of development with the intent to share an OEM perspective of the key technical aspects involved in the development of these components.
Analysis of Infiltration and Solidification of Brazing Materials Into Porous Hastelloy X Feltmetal Using Differential Scanning Calorimetry
Authors: Motyka Elaine , Kweder Jonathan , Noyes Tyler , Roeseler Stefan , Schricker Robert 
Published: September 2023

Abstract
The diffusional solidification of high-temperature brazing compound interacting with open-pore metallic Feltmetal materials were investigated using simultaneous differential scanning calorimetry analysis with thermogravimetric analysis (DSC-TGA). Feltmetal is an abradable seal material primarily used to sustain pressure differentials between stages gas turbines. It is a sintered particle material with an open-pore structure and high total pore volume, typically 80%. Because Feltmetal is commonly brazed into the turbine stage directly to the outer shroud, the effect of the braze layer on the pore structure and on the properties of the seal material is important to the seal function. The characteristics of non-vacuum brazed Feltmetal is of particular interest in this work, as we explore processes for overhaul and repair of Feltmetal abradable seals while in-field and away from a particular service center. The ability to repair these seals in-situ, could provide a faster and less expensive route for an engine back into service. The DSC-TGA responses of a Ni-based Feltmetal material and a Fe-based Feltmetal material with one braze material AMS 4777 were examined. The DSC-TGA data to 1200°C were used to identify elemental diffusion, eutectic melting, and high temperature oxidation reactions. The target microstructure consists of a porous matrix of Feltmetal fibers where fibers and pores adjacent to the braze have reacted with the braze alloy to make a metallurgical bond. This research demonstrates that thermal analysis methods can indicate key process reactions, such as onset of oxidation and eutectic phase transformation, during atmospheric brazing process development. The results of this work are used to aid in the development of in-field seal installation where full system disassembly, and vacuum brazing, is not practical.
On the Feasibility of Helicity-Based Corrections of Turbulence Models for Improving RANS Predictions of Centrifugal Compressor Stages
Authors: Pela Alessandro , Marconcini Michele , Arnone Andrea , Toni Lorenzo , Valente Roberto , Agnolucci Andrea , Grimaldi Angelo , Pacciani Roberto 
Published: September 2023

Abstract
In order to face the challenges of energy transition, turbomachinery designers claim for appropriate numerical tools able to keep up with robust, and fast design iterations.
High fidelity analyses are becoming feasible for assessing the performance of selected geometries, however RANS-based CFD codes are still the workhorse exploited for daily design and optimization iterations when a large number of geometrical configurations are needed to scrutinize a wide and complex design space. The proper selection of the numerical framework, and in particular of the turbulence model, is always critical in order to guarantee a sufficient confidence level in the predicted results, and, at the same time, robustness and numerical stability with quick simulations. Major sources of inaccuracy are often associated with 3D flow features, secondary flows, flow separations, and shock wave boundary layer interaction.
The present work proposes helicity-based corrections for the production terms of two-equation turbulence models as a mean of improving predictions of the aforementioned flow features. A discussion on the treatment of helicity-based terms when changing frame of reference represents one novelty aspect of the paper.
The numerical framework is first validated on a transonic axial fan test case (NASA Rotor 67) and then applied to the analysis of two centrifugal compressor stages for in the high peripheral Mach number regime.
The feasibility of the helicity-based approach is proven via a comparison with the available experimental data in terms of spanwise distributions of flow quantities and performance characteristics of work input and polytropic efficiency. The impact of turbulence modeling on the prediction of the flow field details is investigated, to assess the capability of a steady state numerical approach to identify the physical mechanisms that limit the operating range at low mass flows.
Part II: Validation and Verification of CFD Analysis for NASA SDT Transonic Fan Stage Coupled With Nacelle
Authors: Lee Daryl Y. , Robles Vega Gregorio , Ni Michael , Ni Ron-Ho 
Published: September 2023

Abstract
The airframe and engine are a tightly coupled system but are generally designed in isolation. It is only during final installation testing that the interaction effects of the airframe and the engine are quantified. There are many reasons for the separation of effort, but one blocker is the availability of a validated modeling approach that incorporates best practice methodologies for both components while providing an estimate of the coupling effects within a time reasonable for the design cycle.
In Part I, a CFD code validation was completed on the NASA SDT (Source Diagnostic Test) with the focus on the turbomachinery components. The turbomachinery model was compared against two experimental data sets that consisted of seven speedlines, an operating line and 2D radial profiles each. The outcome of Part I showed good agreement with the experimental data. In this paper, the turbomachinery model is integrated with the SDT nacelle geometry with baseline nozzle area from Part I. By not changing the modeling approach for the turbomachinery components and simply connecting the model from Part I to the nacelle, nacelle installation effects can be isolated. These simulations predict lower adiabatic efficiency due to the inclusion of the nacelle and the CFD model illustrates the reasons for the loss.
In addition, four freestream operating conditions from Mach 0.05 to Mach 0.2 are analyzed, and fan stage distortion sensitivity is evaluated across an entire operating line to understand the effects on the nacelle behavior from different flight operating conditions. The coupled nacelle analysis shows that the effects of higher boundary layer buildup and changes in the stagnation point of flow entering the nacelle can cause efficiency losses between 1% to 3% or more and increases as the Mach number is decreased.
The methodologies developed in this paper, could be applied within the design cycle to understand inlet and engine coupling effects prior to test for future aircraft designs. The rapid evaluation of different design choices offered by this methodology provides designers with another tool to optimize the coupling effects caused by the various design parameters.