bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance Degradation due to Fouling and Recovery After Washing in a Multistage Test Compressor
Authors: Casari Nicola , Pinelli Michele , Spina Pier Ruggero , Suman Alessio , Vulpio Alessandro 
Published: January 2021

Abstract
Land-based power units have to fulfill even more high levels of production and reliability. In harsh environments (desert and tropical installations, typically), the power unit ingests high amounts of dust that might deposit inside the compressor. In this paper, the analysis of a multistage compressor performance that operates under sandy and humid conditions has been assessed. The compressor units, that equips the Allison 250 C18 compressor, has been subjected to multiple runs under severe conditions of soil dust ingestion. The compressor has been operated according to subsequent runs and at the end of each run, the performance curve was recorded and the performance losses, in terms of pressure ratio, have been measured during the operations. The characteristic curve of each run is representative of the level of contamination of the unit. Finally, the compressor has been washed and the performance curve, in the recovered conditions, has been recorded. The results show the modification and the downward shift of the characteristic curves which lead to a gradual loss of the compressor performance. The curves realized after dust ingestion have been compared with the recovered curve after online washing. The measurement shows a promising recovery of the performances, even if, the compressor flow path appears affected by localized deposits able to resist to the droplet removal action. Detailed photographic reports of the IGV and the first compressor stages have been included in this analysis. After each run, the IGV, the rotor blade and stator vane of the first stage and the hub and the shroud surfaces have been photographed. The pictures show the deposition patterns on the blades and the compressor surfaces. The comparison of the pictures of the internal surfaces, before and after the washing, highlights the parts that are more critical to clean and needy of attention during offline washing and overhaul.
Experimental Analysis of Blade-Casing Contacts in a Centrifugal Compressor: Vibration and Thermal Aspects
Authors: Guérin Nicolas , Gibert Claude , Thouverez Fabrice , Almeida Patricio 
Published: January 2021

Abstract
Due to an increasing need for efficiency of turboengines, rotor–stator clearances are being lowered. Therefore, new designs show higher probability for contacts between rotors and casings. When contacts occur, high dynamic excitation levels as well as high temperatures due to dissipative mechanical phenomena may be expected. While numerical investigations have been proposed in the past, experiments are of high interest to fully understand the underlying phenomena behind rotor-stator contact interactions. In order to assess this situation, and based on former work performed by part of the authors, a rotor–stator contact rig has been used to investigate the mechanical and thermal behavior of a centrifugal low-pressure helicopter engine compressor. This rig operates under vacuum conditions to significantly reduce influence of the air surrounding the studied components. A near-zero gap condition is set at rest, then a rotational speed sweep allows to target the specific operating range of interest. Both structures are fitted with strain gauges, and a torquemeter is installed on the shaft to measure resistive phenomena on the bladed disk. A scanning laser Doppler vibrometer is aimed at the casing through a window to provide additional displacement measurements. Temperatures are measured by an array of thermocouples equally spaced around the casing, close to the expected contact area. Also, using temperature-sensitive markings, overall temperature mappings on the impeller are performed. During the tests, multiple contact phases have been identified through increased vibration and temperature levels, as well as torque and rotational speed variations. A comprehensive analysis of the dynamic and thermal phenomena occurring during these experimental tests is proposed in this paper. Dynamic measurements are analyzed in the time and frequency domains, and nodal diameter contents are evaluated as well through full spectrum analyses. As a result, major influences from synchronous excitations in the frequency range of interest but also of higher modal families are highlighted. Post-trial observations indicate severe contact conditions leading to very high temperatures, abradable coating removal and material transfer between blade and casing.
Experimental and Numerical Assessment of Mistuning Effects on Vibratory Response of a Bladed Disk With Underplatform Dampers
Authors: Pourkiaee S. Mehrdad , Berruti Teresa , Zucca Stefano , Neuville Geoffrey 
Published: January 2021

Abstract
This paper presents experimental and numerical investigation of mistuned forced responses of an integrally bladed disk with full set of underplatform dampers (UPDs). This research aims at providing:
1. An experimental benchmark for nonlinear dynamics of a mistuned bladed disks with UPDs.
2. A numerical model that can account for features of a mistuned forced response level.
Accordingly, a detailed experimental campaign is conducted on a static test rig called Octopus. This rig is specifically designed to investigate the dynamics of a full-scale integrally bladed disk (blisk) with UPDs in a noncontact manner so that the dynamic response of the system is not modified.
The effect of mistuning on experimental forced response levels is assessed and a linearized model is proposed to predict the modulation of frequency response functions (FRFs) due to the frequency splitting.
In the development of the model, the mistuning pattern identified from the linear blisk without UPDs is used and it is assumed that adding the dampers does not change the structural mistuning of the blisk. In this study, the fundamental mistuning model identification (FMM ID) was employed to identify the mistuning pattern of the blisk.
It is shown that the proposed model successfully predicts the modulation of linear mistuned FRFs. The linearized model is also able to predict the modulation of nonlinear mistuned FRFs in stick condition (when nonlinear friction damping is negligible) with a good accuracy validating this assumption that adding the dampers does not change the mistuning pattern.
Laminar Flame Speed Measurements of Kerosene-Based Fuels Accounting for Uncertainties in Mixture Average Molecular Weight
Authors: Keesee Charles L. , Guo Bing , Petersen Eric L. 
Published: January 2021

Abstract
New laminar flame speed experiments have been collected for some kerosene-based liquid fuels: Jet-A, RP-1, and Diesel Fuel #2. Accurately understanding the combustion characteristics of these, and all kerosene-based fuels in general, is an important step in developing new chemical kinetics mechanisms that can be applied to these fuels. It is well known that the precise composition of these fuels changes from one production batch to the next, leading to significant uncertainty in the mixture average properties. For example, uncertainty in a fuel blend’s molecular weight can have a noticeable effect on defining an equivalence ratio for a typical fuel-air mixture, on the order of 15%. Because of these uncertainties, fuel mole fraction, Xfuel, is shown to be a more appropriate parameter for comparison between different batches of fuel. Additionally, a strong linear correlation was detected between the burned-gas Markstein length and the equivalence ratio. This correlation is shown to be useful in determining the acceptability and accuracy of individual data points. Spherically expanding flames were measured over a range of fuel mole fractions corresponding to equivalence ratios of φ = 0.7 to φ = 1.5, at initial conditions of 1 atm and 403 K in the high-temperature, high-pressure constant volume vessel at Texas A&M University. These new results are compared with the limited set of laminar flame speed data currently available in the literature for this fuel.
Hidden Advantages and Strategic Leaps for CODAG, CODELAG, CODELOG and Hybrid Propulsion Systems
Authors: Hendry Morgan L. , Bellamy Nicholas 
Published: January 2021

Abstract
Navies worldwide are increasingly considering and adopting propulsion plants with electric propulsion for cruise and ship silent operation, and gas turbines for boost propulsion for high speed. These propulsion plants, often referred to as hybrid propulsion, utilize water jets, controllable pitch propellers, or fixed pitch propellers, and have design and overall configuration to fit into naval ships with various size hulls such as would be the case with corvettes, frigates, destroyers, cruisers, etc. Therefore, size, weight, and space of the propulsion plant is important, but equally important is limiting associated machinery which must be used with a particular hybrid propulsion plant design selected.
In addition, propulsion design engineers, in conjunction with naval architects, shipyards and navies, must consider fuel efficiencies, machinery efficiencies, weight of all the associated machinery, placement in the hull, first time cost, and life cycle maintenance with associated cost when selecting the configuration of the propulsion system’s associated machinery. Manning levels are dictated by these parameters and in the end, it must be realized that the purpose of the ship mission can be compromised if reliability is not high and premature failures occur.
This paper is a more in depth analysis of hybrid propulsion systems for naval ships of various sizes, and analysis of the associate machinery emphasizing ship weight and space savings, fuel savings, cost savings, mean time between failures and mean time to repair which results in lower manning requirements and increased mission readiness.
By the time this paper is published, more than 250 SSS Clutches will be installed in US Navy Arleigh Burke Destroyers, 32 are operating in low speed propeller shafts of British Navy Type 23 ships, 2 in the Japanese Navy’s Asuka Class and 16 in low speed propeller shafts of Royal Korean Navy FFX Batch II frigates. At the time of abstract submission, all three programs referenced above have cumulatively had zero defects attributable to SSS Clutch material, function, design, or quality. While the US Navy are given occasional reminders of why alternative clutch designs remain ineffective, unreliable and remarkedly inefficient, other nations’ vertically tiered supply chains and inexperienced engineers are shielded from similar issues.
Aeroelastic Modelling of Three-Dimensional Lifting Bodies With an Accelerated Boundary Element Method
Authors: Könnecke Ludwig , Saverin Joseph 
Published: January 2021

Abstract
Investigated was the aeroelastic treatment of a three-dimensional NACA0006 wing by coupling the boundary element method (panel method) for the aerodynamic solution with a beam model (Chrono) for the structural-elastic solution to obtain an aeroelastic solution. Aerodynamic information is interpolated to the structural model by using radial basis functions. As a validation case an analytical model was set up by calculating the lift force from the lifting-line theory and the resulting deflection and torsion predicted with a linear beam theory. This analytical model considers a purely torsional aeroelastic case which is comparable with the simulation results. The distribution of the lift force over the span position of the simulation and the analytical model agrees well, particularly in comparison to the purely torsional case.
CO and OH Imaging in Flames Using a Single Broadband Femtosecond Laser Pulse
Authors: Parajuli Pradeep , Jain Ayush , Kulatilaka Waruna D. 
Published: January 2021

Abstract
Carbon monoxide (CO) and hydroxyl (OH) are the two key intermediate species formed during chemical reactions inside gas turbine combustors. Spatiotemporal information and a detailed understanding of CO formation in the reaction zone are important during the combustion processes as a major part of the heat release is obtained from the oxidation of CO to CO2. Turbulent flame structures and reaction zone in different flame conditions can also be visualized through the spatial distribution profiles of OH. In the current study, both these species are excited simultaneously using a single ultrashort, broad spectral bandwidth of approximately 100-femtosecond (fs) duration laser pulse at λ = 283.8 nm. Subsequent fluorescence signals are separated through spectral filters of appropriate bandwidth and imaged using two cameras. This present study was performed in a McKenna flat-flame burner with ethylene/air as a pilot flame and non-premixed turbulent ethylene jet at the center. The partial spectral overlap of CO–X (4,0) and OH A–X (1,0) transitions are utilized for simultaneous excitation, thereby characterize the overall flame structure (via OH) and regions of oxidation reactions (via CO) in a range of flame conditions. Besides, CO and OH profiles follow the trends obtained from model predictions for a range of equivalence ratios in ethylene/air flames stabilized over the Hencken calibration burner. These results are used for obtaining quantitative calibrations of CO and OH signals. Overall, the present study extends the applicability of a single, broadband fs laser pulse for simultaneous imaging of multiple chemical species in flame.
Effects of Inlet Distortion Patterns on Induced Swirl in a Highly Loaded Fan Stage
Authors: Orme Andrew D. , Gorrell Steven E. , Pulsipher Addison C. 
Published: January 2021

Abstract
Characterization of distortion transfer and generation through fans with distorted inlet conditions enables progress towards designs with improved distortion tolerance. The abruptness of transition from undistorted to distorted total pressure regions at the inlet impacts the induced swirl profile and therefore the distortion transfer and generation. These impacts are characterized using URANS simulations of PBS Rotor 4 geometry under a variety of inlet distortion profiles. A 90° and a 135° sector, both of 15% total pressure distortion, are considered. Variants of each sector size, with decreasing levels of distortion transition abruptness, are each applied to the fan. Fourier-based distortion descriptors are used to quantify levels of distortion transfer and generation at axial locations through the fan, principally at the stator inlet. It is shown that a gradual transition in distortion at the inlet results in decreased levels of distortion transfer and generation. The flow physics resulting in this reduction are explored.
Effects of Shock Wave Development on Secondary Flow Behavior in Linear Turbine Cascade at Transonic Condition
Authors: Tsujita Hoshio , Kaneko Masanao 
Published: January 2021

Abstract
Gas turbines widely applied to power generation and aerospace propulsion systems are continuously enhanced in efficiency for the reduction of environmental load. The energy recovery efficiency from working fluid in a turbine component constituting gas turbines can be enhanced by the increase of turbine blade loading. However, the increase of turbine blade loading inevitably intensifies the secondary flows, and consequently increases the associated loss generation. The development of the passage vortex is strongly influenced by the pitchwise pressure gradient on the endwall in the cascade passage. In addition, a practical high pressure turbine stage is generally driven under transonic flow conditions where the shock wave strongly influences the pressure distribution on the endwall. Therefore, it becomes very important to clarify the effects of the shock wave formation on the secondary flow behavior in order to increase the turbine blade loading without the deterioration of efficiency.
In this study, the two-dimensional and the three-dimensional transonic flows in the HS1A linear turbine cascade at the design incidence angle were analyzed numerically by using the commercial CFD code with the assumption of steady compressible flow. The isentropic exit Mach number was varied from the subsonic to the supersonic conditions in order to examine the effects of development of shock wave caused by the increase of exit Mach number on the secondary flow behavior. The increase of exit Mach number induced the shock across the passage and increased its obliqueness. The increase of obliqueness reduced the cross flow on the endwall by moving the local minimum point of static pressure along the suction surface toward the trailing edge. As a consequence, the increase of exit Mach number attenuated the passage vortex.
Combustion Tuning for a Gas Turbine Power Plant Using Data-Driven and Machine Learning Approach
Authors: Li Suhui , Zhu Huaxin , Zhu Min , Zhao Gang , Wei Xiaofeng 
Published: January 2021

Abstract
In this paper, we present a cross-disciplinary study on the combustion tuning of an F-class gas turbine that combines machine learning with physics understanding. An artificial-neural-network-based (ANN) model is developed to predict the combustion performance (outputs), including NOx emissions, combustion dynamics, combustor acceleration, and turbine exhaust temperature. The inputs of the ANN model are identified by analyzing the key operating variables that impact the combustion performance, such as the pilot and the premixed fuel flow, and the inlet guide vane angle. The ANN model is trained by field data from an F-class gas turbine power plant. The trained model is able to describe the combustion performance at an acceptable accuracy in a wide range of operating conditions. In combination with the genetic algorithm, the model is applied to optimize the combustion performance of the gas turbine. Results demonstrate that the data-driven method offers a promising alternative for combustion tuning at a low cost and fast turn-around.
Recirculation Zones During the Centrifugal Compressor Surge Cycle: CFD Simulation
Authors: Kulak Michał , Grapow Filip , Liśkiewicz Grzegorz 
Published: January 2021

Abstract
In this paper the flow recirculation regions during the full surge cycle were described. It is a known fact that the surge cycle consists of two periods: backflow and recovery. The aim of this paper is to add spatial dimension to this analysis. Therefore, the main target is to identify the regions of backflow and recirculation throughout the surge cycle. The full surge cycle modelled with an application of unsteady RANS methods is demonstrated — the significant push was put to realistic boundary conditions definition, narrowed to establishing pressure setting at both inlet and outlet positions located far from the impeller. The results show that all the backflow appears in the recirculation zones that grow and diminish throughout the surge cycle. The regions of inflow and backflow can concurrently exist at different stages of the surge. The analysis includes areas occupied by both structures and mass flowrates associated with them. Presented research is a part of a project aiming at design and construction of more efficient anti-surge systems. Its overall target is to eventually introduce the anti-surge systems that are made to fit the particular machine. Therefore, the understanding of local flows during and prior to surge are one of the key issues that need to be interpreted.
Phantom Cooling Effects on Rotor Blade Surface Heat Flux in a Transonic Full Scale 1+1/2 Stage Rotating Turbine
Authors: Anthony Richard J. , Finnegan John , Clark John P. 
Published: January 2021

Abstract
An experimental and numerical investigation of phantom cooling effects on cooled and uncooled rotating high pressure turbine blades in a full scale 1+1/2 stage turbine test is carried out. Objectives set to capture, separate, and quantify the effects of upstream vane film-cooling and leakage flows on the downstream rotor blade surface heat flux. Multiple series of 1+1/2 stage rotating high pressure turbine tests were carried out in the Air Force Research Laboratory, Turbine Research Facility, at Wright-Patterson Air Force Base, Ohio. A non-proprietary research turbine test article is uniquely instrumented with high frequency double-sided thin film heat flux gauges custom made at AFRL. High bandwidth, time resolved surface heat flux is measured on multiple film-cooled and non-film-cooled HPT rotor blades downstream of both film-cooled and non-film-cooled vane sectors. Upstream wake passing and heat flux is characterized on both rotor pressure and suction side surfaces, along with quantifying rotor phantom cooling effects from nonuniform 1st stage vane film cooling and leakage flows.
Fast response heat flux measurements quantify how rotor phantom cooling impacts the blade pressure side greatest; increasing along the pressure side towards the trailing edge. It is discovered upstream vane film-cooling alone can account for 50% of the rotor blade cooling effect, and even outweigh the rotor blade film cooling effect far from the blade showerhead holes. Added unsteady aero numerical simulation demonstrate how variations in inlet total temperature and incidence angle can also contribute to circumferentially non-uniform rotor heat flux.
Better understanding from this investigation aids modelling and design efforts in optimizing film cooling performance in real high pressure turbine flow fields. Understanding the behavior of such non-uniform circumferential rotor phantom cooling effects can be critical to optimize the efficiency, fuel consumption, range, and durability of advanced turbomachines.
Multidisciplinary Design of a Low-Noise Propeller: Part II — Efficient Aero-Acoustic-Mechanical Design Methodology Exploiting Surrogate Models in an Adaptive Design Space
Authors: Baert Lieven , Dumont Chloé , Beauthier Charlotte , Sainvitu Caroline , Lepot Ingrid , Blanchard Julien 
Published: January 2021

Abstract
The regional aircraft segment plays a crucial role in achieving the EU Flightpath 2050 objectives (increase connectivity through Europe, enforce Europe’s industrial leadership, and significantly reduce the environmental impact of aviation). Despite an outdated perception by the general public, turboprop aircraft are typically less expensive to operate than regional jets. The impact of new technologies is therefore even more evident. Achieving a significant reduction in perceived noise levels remains however a challenge for the success of further turboprop deployment.
This twofold paper discusses the design of an innovative low-noise propeller in the framework of the Clean Sky 2 Regional Aircraft IADP, with a focus on the design methodology itself in this second part. The design is inherently multidisciplinary — aerodynamic, acoustic, mechanical — with multiple flight conditions and a wind tunnel condition to be considered. In order to limit the number of expensive high-fidelity computations, an online surrogate-based optimisation (SBO) approach has been deployed. A high-dimensional design space has been considered to enable to identify disruptive low-noise concepts. By exploiting the results of low-fidelity tools (see the first part of the paper), combined with efficient machine learning techniques and data mining capabilities, a gradual increment of the design space from 57 to 111 design parameters has been considered. A significant noise reduction of about 6.5 dB has been achieved without major degradation of the aerodynamic efficiency — fully aligned with the objectives for the Regional Aircraft IADP.