bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of a Convolutional Neural Network for Wave Mode Identification in a Rotating Detonation Combustor Using High-Speed Imaging
Authors: Johnson Kristyn B. , Ferguson Donald H. , Tempke Robert S. , Nix Andrew C. 
Published: January 2021

Abstract
Utilizing a neural network, individual down-axis images of combustion waves in a Rotating Detonation Engine (RDE) can be classified according to the number of detonation waves present and their directional behavior. While the ability to identify the number of waves present within individual images might be intuitive, the further classification of wave rotational direction is a result of the detonation wave’s profile, which suggests its angular direction of movement. The application of deep learning is highly adaptive and therefore can be trained for a variety of image collection methods across RDE study platforms. In this study, a supervised approach is employed where a series of manually classified images is provided to a neural network for the purpose of optimizing the classification performance of the network. These images, referred to as the training set, are individually labeled as one of ten modes present in an experimental RDE. Possible classifications include deflagration, clockwise and counterclockwise variants of co-rotational detonation waves with quantities ranging from one to three waves, as well as single, double and triple counter-rotating detonation waves. After training the network, a second set of manually classified images, referred to as the validation set, is used to evaluate the performance of the model. The ability to predict the detonation wave mode in a single image using a trained neural network substantially reduces computational complexity by circumnavigating the need to evaluate the temporal behavior of individual pixels throughout time. Results suggest that while image quality is critical, it is possible to accurately identify the modal behavior of the detonation wave based on only a single image rather than a sequence of images or signal processing. Successful identification of wave behavior using image classification serves as a stepping stone for further machine learning integration in RDE research and comprehensive real-time diagnostics.
Aeromechanical Analysis of a Complete Wind Turbine Using Nonlinear Frequency Domain Solution Method
Authors: Naung Shine Win , Rahmati Mohammad , Farokhi Hamed 
Published: January 2021

Abstract
The high-fidelity computational fluid dynamics (CFD) simulations of a complete wind turbine model usually require significant computational resources. It will require much more resources if the fluid-structure interactions between the blade and the flow are considered, and it has been the major challenge in the industry. The aeromechanical analysis of a complete wind turbine model using a high-fidelity CFD method is discussed in this paper. The distinctiveness of this paper is the application of the nonlinear frequency domain solution method to analyse the forced response and flutter instability of the blade as well as to investigate the unsteady flow field across the wind turbine rotor and the tower. This method also enables the aeromechanical simulations of wind turbines for various inter blade phase angles in a combination with a phase shift solution method. Extensive validations of the nonlinear frequency domain solution method against the conventional time domain solution method reveal that the proposed frequency domain solution method can reduce the computational cost by one to two orders of magnitude.
A Comparison of Unsteady RANS and DES for Simulating an Axial Compressor Stage
Authors: Miller Edward A. , Cave Michael J. , Williams David M. , Thayalakhandan Khandan 
Published: January 2021

Abstract
Computational fluid dynamics (CFD) of industrial-scale, axial compressor geometries has traditionally been performed using steady state methods such as the mixing plane approach. With the surge in the development of large-scale, massively-parallel computing platforms, fully 3D unsteady approaches are rapidly growing in popularity. The fully 3D, unsteady approach involves building a full 3D domain for each blade row, and then coupling the stationary and rotating domains using a sliding interface. In the literature, there are various methods for solving this 3D unsteady problem, such as the Unsteady Reynolds Averaged Navier-Stokes (URANS) and the Detached Eddy Simulation (DES) methods. While these methods are well documented for a variety of real-world problems, there have been limited efforts to compare the effectiveness of these methods for fully 3D, unsteady turbomachinery problems.
In this study, the first stage of an industrial-scale axial compressor was simulated using: i) the URANS approach, and ii) the DES approach. The compressor geometry consisted of an inlet housing, inlet guide vanes (IGV), a rotor, and a stator. The RANS model for both simulations was the k-epsilon model. For both of these cases, sliding mesh interfaces were located between the IGV and rotor, and between the rotor and stator. The results of the URANS and DES approaches were time-averaged and their predictions were compared. Throughout the study, our goal was to provide important insights into the performance of the URANS and DES approaches, and to highlight the essential differences.
Non-Circular and Non-Cylindrical Streamvanes
Authors: Gillespie John , Lowe K. Todd 
Published: January 2021

Abstract
We show that desired swirl distributions may be obtained in non-circular and non-cylindrical inlet ducts by tailored vane distributions designed with an a priori method, and further explain dominant physics for the spatial evolution of swirl in expanding or contracting ducts. Virginia Tech has developed the StreamVane™ device for producing swirl distortion, as well as the ScreenVane™ device for producing combined swirl and pressure distortions. Up to now, all StreamVane and ScreenVane devices have designed to fit in a right, circular cylindrical duct. This is usually the simplest geometry to use for testing the response (in terms of performance and stall margin changes, as well as aeromechanics) of turbofan engines to inlet distortion.
However, many potential applications exist for generating or removing swirl distortions in ducts that are not cylindrical. For example, turboshaft engines generally do not have a cylindrical inlet to install a StreamVane in front of. Yet, inlet distortion is still very relevant to the performance of the engine. With a non-cylindrical StreamVane, inlet distortions generated by various flight conditions can be tested in conjunction with the real aircraft inlet. Further applications exist both within and outside of the field of turbomachinery for flow conditioning purposes. Four separate conceptual designs were created and analyzed: a converging duct (nozzle), a diverging duct (diffuser), a square duct, and an annular duct. Twin vortex swirl profiles were specified for all of the cases except the annular duct, which was designed to create a single vortex.
However, in a real application, these swirl profiles would instead be specified by the end-user depending on what is required for the test. As in circular cylindrical StreamVanes, the end-user has the option of selecting any physically consistent swirl profile. All of the concept designs were checked with CFD analysis in ANSYS CFX. The square and annular StreamVanes showed comparable performance to a baseline StreamVane in a cylindrical duct (RMS errors of 1.5° or less). The StreamVanes placed in a nozzle and diffuser demonstrated that swirl patterns may also be created in converging and diverging ducts, and that the varying cross sectional area has a non-negligible influence on the development of the swirl profile. A simple explanation has been made for this altered flow development has been, and is shown to make good quantitative predictions of the changes in swirl with downstream location.
The demonstration of the capability to create StreamVanes for applications that do not use cylindrical ducts should open a variety of possibilities, while building on existing experiences.
Theoretical Study on Static Performance of Herringbone Grooved Aerodynamics Foil Bearing
Authors: Dong ZeDa , Cheng Cheng , Xu Fangcheng 
Published: January 2021

Abstract
In this paper, the mathematical model of herringbone grooved aerodynamic foil bearings is established, and the finite difference method is used to obtain the discretized form of Reynolds equation. The static characteristics of bearings, such as film pressure, film temperature, are obtained by solving the Reynolds equation and energy equation. The bearing load capacity and friction power consumption are obtained by calculating the film thickness and film pressure distribution in the bearing gap. The influence of the bearing operational parameters, such as eccentricity and rotation speed, and the bearing structural parameters, such as groove width, groove depth ratio, groove number and helix angle, on the bearing load capacity and friction power consumption of bearings are analyzed. The methods of improving bearing load capacity and reducing friction power consumption are obtained. Simultaneously, by comparing the bearing load capacity and friction power consumption of herringbone grooved gas foil bearings and gas foil bearings (GFBs) without herringbone grooves, the influence of herringbone grooves on the bearing performance is obtained.
Very Large Eddy Simulation of Film Cooling Effectiveness on Trailing Edge Cutback
Authors: Yan Xin 
Published: January 2021

Abstract
The trailing edge of high pressure gas turbine blade in aeroengine is usually designed as thin as possible to achieve higher aerodynamic efficiency. However, as the inlet temperature of modern gas turbine is continuously increasing, thermal stress in a thin trailing edge will become much significant, resulting in possibilities of erosion and creep problems. To find a balance between these two conflicting goals, one method is the use of pressure-side cutback, which extends into the coolant slot to get film cooling and also achieves a thin trailing edge. Due to the interactions between mainstream and coolant flow, film cooling effect on trailing edge cutback is significantly affected by the vortex shedding downstream the cooling slot. To resolve the coherent flow structures and understand their role on film cooling effect on trailing-edge cutback, this paper implemented a Very Large Eddy Simulation (VLES) model into the solver ANSYS Fluent with user defined functions. By introducing a resolution control factor, the turbulence viscosity predicted by transient SST k-ω model was corrected and the VLES computations were realized in the whole computational region. With the VLES method, film cooling effectiveness distributions on trailing-edge cutback at three blowing ratios were computed and compared against the experimental data. The coherent unsteadiness in cutback region was visualized to reveal the mixing process between mainstream and coolant flow. The numerical accuracies between different unsteady prediction methods, i.e. URANS (Unsteady Reynolds Averaged Navier-Stokes), SAS (Scale-Adaptive Simulation), DES (Detached Eddy Simulation), DDES (Delayed-Detached Eddy Simulation), SBES (Stress-Blended Eddy Simulation), and VLES were compared with respect to the resolutions of cooling effect and vortex shedding. The results show that the periodic vortex shedding induced by the interactions between mainstream and coolant is the main factor that affecting the cooling performance on cutback. VLES method has a comparable accuracy in predicting the film cooling effect on trailing edge cutback with DDES and SBES approaching. In the detached shear layer, VLES method exhibits a good ability to resolve coherent unsteadiness caused by vortex shedding. Compared with URANS and SAS methods, the VLES method has a higher accuracy in resolving the periodic vortex shedding and film cooling effectiveness distributions, especially in low blowing ratio cases.
Uncertainty Quantification of Mass and Aerodynamic Rotor Imbalance for Offshore Wind Turbines
Authors: Ward Nicholas J. , Ekwaro-Osire Stephen , Dias João Paulo 
Published: January 2021

Abstract
One promising way to address turbine durability issues is early detection of mass and aerodynamic imbalances. More probabilistic methods are necessary to improve the accuracy of rotor imbalance diagnostics. The research question that this work addresses is: can current imbalance detection for an offshore wind turbine be improved through uncertainty quantification of its operating conditions? An uncertainty quantification strategy was proposed to model uncertainties in wind speed, pitch angle, and blade mass density using assumed probability density functions based on available data/information. These input parameters served as random variables that were fed into an aeroelastic software to model dynamic and power output variables for multiple imbalance scenarios. 4% variation in wind speed exhibited power differences as much as 500-kW for given imbalance cases. Additionally, the results indicated that a 10% variation in pitch angle, and blade mass density demonstrated power differences of 20-kW and 10-kW respectively due to imbalance in one blade. In addition, probability distributions for power output and dynamic loading indicated that turbine underperformance and excessive blade loading occurred approximately 40–52% and 45–77% of the time respectively depending on the imbalance scenario. This imbalance detection strategy could serve as a useful tool to help minimize turbine operation uncertainties.
Data-Tuned Fuzzy Logic Controller Applied to a Horizontal Axis Wind System
Authors: Dambrosio Lorenzo 
Published: January 2021

Abstract
This paper deals with the control problem concerning the output voltage frequency and amplitude regulation of a wind system power plant not connected to the supply grid. The wind system configuration includes a horizontal-axis wind-turbine which drives a synchronous generator. An appropriate modeling approach has been adopted for both the wind-turbine and the synchronous generator. The proposed controller makes use of the fuzzy logic environment in order to take advantage of the wind plant system informations integrated into a limited number of equilibrium condition points (input variable - output variable pairs). The fuzzy logic controller described in the present paper merges the most appropriate fuzzy rules clusters, based on the steady state working conditions. Then, thanks to a Least Square Estimator algorithm, the proposed control algorithm evaluates, for each sample time, the linear relation between control law correction and control tracking error levels. In order to demonstrate robustness of the suggested fuzzy control algorithm, two sets of results have been provided: the first one consider a fuzzy base with equally spaced rules, whereas, in the second set results, the number of fuzzy rules is reduced by a 25%.
Gas Turbine Direct Exhaust Gas Integration in Process Industry: Applications Review
Authors: Cichocki Marek , Salamonik Ilona , Bielecki Marcin , Fadlun Ever , Rusowicz Artur 
Published: January 2021

Abstract
The typical combined heat and power plants requires the introduction of additional heating medium. The alternative solution is the direct integration of the exhaust gases from heat engine. High temperature, surplus oxygen and low water content of the Gas Turbines exhaust gases enabled the successful integration at industrial scale as: preheated combustion air for industrial furnaces, heat source for drying and for absorption chillers. The article comprises the reference list for direct exhaust gas integration of GTs produced by Baker Hughes formerly GE), the processes overview, GTs selection criteria, as well as the review of documented GTs applications in process industry focusing on technical and economic considerations.
Majority of referenced applications for industrial furnace are in the steam methane reformers used in fertilizer industry, as well as steam crackers in petrochemical industries. Several GTs were integrated with crude oil furnace in refinery. Direct drying utilizing exhaust gas from GT, is commonly applied in ceramic, wood derivative, pulp & paper and inorganic chemicals industries. Integrating GTs with absorption chillers was introduced to serve the district heating and cooling system.
The described solutions allowed to reduce specific energy consumption by 7–20% or the costs of energy consumption associated with large volume production by 15–30%. The reduction of specific energy consumption allows to decrease the amount of CO2 emitted. The overall efficiency of cogeneration plant above 90% was achieved.
The Influence of Element Thermal Conductivity, Shape, and Density on Heat Transfer in a Rough Wall Turbulent Boundary Layer With Strong Pressure Gradients
Authors: Gramespacher Christoph , Albiez Holger , Stripf Mattias , Bauer Hans-Jörg 
Published: January 2021

Abstract
Formation mechanisms for turbine roughness are manifold, including erosion, corrosion, deposition, and spallation or more recently additive manufacturing processes. Consequently, the resulting surfaces differ remarkably not only in roughness shape, height, and density, but also in element thermal conductivity. Because the roughness elements extend into the boundary layer, their temperature distribution has a direct influence on the thermal boundary layer and thus on the resulting convective heat transfer. In the current study, heat transfer distributions along a flat plate with more than 20 deterministic rough surface topographies that differ in element eccentricity, height and density are measured. For each surface roughness, measurements are conducted using two different element thermal conductivities (0.2 W/(mK) and 30 W/(mK)), two pressure distributions, four Reynolds numbers between 3 × 105 and 7.5 × 105 and various inlet turbulence intensities in the range of 1.5% to 8%. The pressure distributions resemble a typical suction and pressure side, respectively. Results show a heat transfer increase of up to 60% for the high thermal conductivity surfaces and up to 50% for the low conductivity ones. While heat transfer on the high conductivity surfaces is always higher than on the low conductivity ones, the difference becomes smaller with decreasing element density.
Monitoring Damage in Non-Oxide Composites at High Temperatures Using Carbon-Containing CVD SiC Monofilament Fibers As Embedded Electrical Resistance Sensors
Authors: Panakarajupally Ragav P. , Elrassi Joseph , Manigandan K. , Singh Yogesh P. , Morscher Gregory N. 
Published: January 2021

Abstract
Electrical resistance has become a technique of interest for monitoring SiC-based ceramic composites. The typical constituents of SiC fiber-reinforced SiC matrix composites, SiC, Si and/or C, are semi-conducive to some degree resulting in the fact that when damage occurs in the form of matrix cracking or fiber breakage, the resistance increases. For aero engine applications, SiC fiber reinforced SiC, sometimes Si-containing, matrix with a BN interphase are often the main constituents. The resistivity of Si and SiC is highly temperature dependent. For high temperature tests, electrical lead attachment must be in a cold region which results in strong temperature effects on baseline measurements of resistance. This can be instructive as to test conditions; however, there is interest in focusing the resistance measurement in the hot section where damage monitoring is desired. The resistivity of C has a milder temperature dependence than that of Si or SiC. In addition, if the C is penetrated by damage, it would result in rapid oxidation of the C, presumably resulting in a change in resistance. One approach considered here is to insert carbon “rods” in the form of CVD SiC monofilaments with a C core to try and better sense change in resistance as it pertains to matrix crack growth in an elevated temperature test condition. The monofilaments were strategically placed in two non-oxide composite systems to understand the sensitivity of ER in damage detection at room temperature as well as elevated temperatures. Two material systems were considered for this study. The first composite system consisted of a Hi-Nicalon woven fibers, a BN interphase and a matrix processed via polymer infiltration and pyrolysis (PIP) which had SCS-6 monofilaments providing the C core. The second composite system was a melt-infiltrated (MI) pre-preg laminate which contained Hi-Nicalon Type S fibers with BN interphases with SCS-Ultra monofilaments providing the C core. The two composite matrix systems represent two extremes in resistance, the PIP matrix being orders of magnitude higher in resistance than the Si-containing pre-preg MI matrix. Single notch tension-tension fatigue tests were performed at 815°C to stimulate crack growth. Acoustic emission (AE) was used along with electrical resistance (ER) to monitor the damage initiation and progression during the test. Post-test microscopy was performed on the fracture specimen to understand the oxidation kinetics and carbon recession length in the monofilaments.
Structural Analysis of a Gas Turbine Axial Compressor Blade Eroded by Online Water Washing
Authors: Cinelli Rossella , Maggiani Gianluca , Gabriele Serena , Castorrini Alessio , Agati Giuliano , Rispoli Franco 
Published: January 2021

Abstract
The Gas Turbine (GT) Axial Compressor (AXCO) can absorb up to the 30% of the power produced by the GT, being the component with the largest impact over the performances. The axial compressor blades might undergo the fouling phenomena as a consequence of the unwanted material locally accumulating during the machine operations. The presence of such polluting substances reduces the aerodynamic efficiency as well as the air intake causing the drop of performances and the increase of the fuel consumption. To address the above-mentioned critical issues, several washing strategies have been implemented so far, among the most promising ones, High Flow On-Line Water Washing (HFOLWW) is worth to mention. Exploiting this technique, the performance levels are preserved, whereas the stops for maintenance should be reduced. Nevertheless, this comes at the cost of a long-term erosion exposure caused by the impact of water washing droplets. Hence, it was deemed necessary to carry out a finite element method (FEM) structural analysis of the first rotor stage of the compressor of an aeroderivative GT, integrated into the HFOLWW scheme, in order to evaluate the fatigue strength of the component subjected to the erosion; possibly along with its acceptability limits. The first step requires the determination of the blade areas affected by erosion, using computational fluid dynamics (CFD) simulations, followed by the creation and the 3D modelling of the damaged geometry. The final step consists in the evaluation of the static stress and the dynamic agents, to perform a fatigue analysis through the Goodman relation and carrying out a simulation of damage propagation exploiting the theory of fracture mechanics. This procedure has been extended to the damage-free baseline component to set-up a model suitable for comparison. The structural analysis confirms the design of the blade, moreover dynamic and static evaluation of the eroded profiles haven’t outlined any working, nor mechanical, issue. This entitles the structural choice of HFOLWW as a system which guarantees full performance levels of the compressor.