bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Investigations on Gas Ingestion Mechanism Based on Flow Instabilities in Rim Seal and Cooling Characteristics of Endwall in a 1.5-Stage Axial Turbine
Authors: Cong Qingfeng , Zhang Kaiyuan , Li Zhigang , Li Jun 
Published: September 2022

Abstract
The sealant flow and rim seal at the periphery of cavities formed between rotor and stator disks prevent the high-temperature gas from ingesting into disk cavities and reduce the use of secondary air bleeding from a compressor. The unsteady sealing performance of rim seal and the cooling characteristics of sealant flow on endwall of a 1.5-stage axial turbine are studied by solving the three-dimensional unsteady Reynolds-averaged Navier–Stokes (URANS) equations via shear stress transfer (SST) turbulence model. Besides, mass transfer analogy is introduced to predict the sealant distribution which makes the numerical sealing effectiveness in front and aft cavities agree well with experimental data. The accuracy of the numerical method is verified. The sealing effectiveness in cavities and the flow field in rim seal clearance are analyzed, and the film cooling performance on endwall is explored. The results show that, compared with Φ0=0.0170, the area-averaged sealing effectiveness εc on stator face is increased by 19.05% when Φ0=0.500 in the front cavity, and compared with Φ0=0.0042, the area-averaged sealing effectiveness εc on stator face is increased by 9.82% when Φ0=0.096 in the aft cavity. The nonaxisymmetric pressure on the endwall near rim seal and Kelvin Helmholtz unstable vortices arise due to the circumferential velocity difference between main flow and cavity flow. The flow field in the rim seal clearance is jointly affected by these two factors. The flow pattern in the front rim seal clearance is mainly affected by unstable vortex while the flow pattern in the aft rim seal clearance depends on the circumferential pressure distribution. According to FFT, the most significant frequency of flow field variety is about 1200 Hz and 400 Hz (corresponding to two and six blades passing periods) in front and aft rim seals, respectively. The time-averaged cooling effectiveness increases with the increase of sealant flow on endwall and decreases gradually in the axial direction. The unsteady flow behavior of cooling effectiveness on endwall is also discussed in detail.
A Balance Between Odor Intensity and Odor Perception Range in Odor-Guided Flapping Flight
Authors: Lei Menglong , Li Chengyu 
Published: September 2022

Abstract
Insects rely on their olfactory system to forage, prey, and mate. They can sense odorant plumes emitted from sources of their interests with their bilateral odorant antennae, and track down odor sources using their highly efficient flapping-wing mechanism. The odor-tracking process typically consists of two distinct behaviors: surging upwind at higher velocity and zigzagging crosswind at lower velocity. Despite extensive numerical and experimental studies on odor guided flight in insects, we have limited understandings on the effects of flight velocity on odor plume structure and its associated odor perception. In this study, a fully coupled three-way numerical solver is developed, which solves the 3D Navier-Stokes equations coupled with equations of motion for the passive flapping wings, and the odorant convection-diffusion equation. This numerical solver is applied to resolve the unsteady flow field and the odor plume transport for a fruit fly model at different flight velocities in terms of reduced frequency. Our results show that the odor plume structure and intensity are strong related to reduced frequency. At smaller reduced frequency (larger forward velocity), odor plume is pushed up during downstroke and draw back during upstroke. At larger reduced frequency (smaller forward velocity), the flapping wings induce a shield-like air flow around the antennae which may greatly increase the odor sampling range. Our finding may explain why flight velocity is important in odor guided flight.
Investigation of Volume-of-Fluid Method to Simulate Melting-Solidification of CMAS Particles
Authors: Cavainolo Brendon , Kinzel Michael 
Published: September 2022

Abstract
The ingestion of CMAS (Calcium-Magnesium-Alumino-Silicate) particles into aircraft engines is an issue for both the safety and resilience of aircraft. CMAS ingestion process can erode compressor blades, erode/infiltration thermal barrier coatings, and lead to overheating and stall. To better understand the physical details, this paper presents a novel approach to exploring individual CMAS dynamics in the context of melting particles. The methodology was accomplished by resolving the details of a single CMAS particle using the volume-of-fluid method. To account for thermal properties of the flow and particle, melting-solidification modeling was implemented. The particle was initialized at a stagnant condition with a temperature under its solidus temperature. The flow around the particle was initialized at turbine relevant conditions, including high velocities and temperatures above the particle’s liquidus temperature. Transient conditions were explored in context of non-dimensional numbers (including slip Reynold’s Number, Weber number, and Ohnesorge number), as well as several ratios (ρs/ρg and Ts/T∞). For validation, sensitivity to mesh and input, as well as experimental comparisons were examined. The experimental comparison benchmarked the temperature ratio of particles at varying thermal Stokes numbers against the experimental correlation shown in Bojdo et al. [1].
Evaluation of Flow and Heat Transfer During Compression Stroke in a Porous Material Using MVCEF Solving Method
Authors: Marzougui Inès , Gheith Ramla , Hachem Houda , Aloui Fethi 
Published: September 2022

Abstract
This work deals with CFD modeling method under Fortran 90 with dimensionless setting. A numerical study of flow and heat transfer inside a cylinder partially filled with a porous material and with two pistons is provided during compression stroke. Phase shift between the two pistons is about π/2. Air inside cylinder is considered as Newtonian perfect gas. The flow is supposed to be laminar and steady. The Brinkman-Forcheimer Lapwood theory is adopted to simulate transfer momentum in the porous media. Dimensional governing equations are solved using control volume with finite element method (MVCEF). The obtained results are in good agreement with literature numerical investigations. The effect of the porous media properties (length and porosity) and heat transfer on flow was investigated. Results show that the optimum heat convective flux is achieved for a porosity of 0.9 and a permeability of 0.7. Results show a close relationship between geometry parameters of the regenerator and the pressure drop. An optimum value of regenerator length is expected for each working condition.
FSI of a Cantilever Beam: FVM-FEM and Neural Network Analysis
Authors: Chijioke Clinton , Rodriguez Arturo , Enriquez Andres , Kumar Vinod , Tandon Vivek , Terrazas Jose , Villanueva Daniel , Kotteda V. M. Krushnarao 
Published: September 2022

Abstract
Fluid structure interaction (FSI) problems are becoming highly complex as it has wide range of applications, which assists to model many real-world problems. The finite volume method (FVM) enforces conservation of the governing physics over the designed control volume. Presently, the FVM is the most common discretization technique used within the computational fluid dynamics (CFD) domain. In this day, multiple techniques for simulating the strongly coupled fluid-structure systems numerically is constantly being researched as the CFD analysis approach evolves swiftly. We introduce a segmented neural network-based approach for learning of FSI problems. The FSI simulation domain is discretized into two smaller sub-domains, i.e., fluid (FVM) and solid (FEM) domains and utilize an autonomous neural network for each. A python based scientific library is used to couple the two networks which takes care of boundary data communication, data mapping and equation coupling. The coupled Ansys fluent-transient structural analysis data will be used for training the two neural networks. Changes in the geometrical and material properties of a solid structure such as: bluff/curved - corners/surfaces, physical dimensions, young’s modulus of elasticity and mass moment of inertia will affect the dynamics of the structure.
Effects of Process Parameters on Thin-Wall Substrate WAAM Deposition
Authors: Thien Austen , Goodwin Jesse , Saldana Christopher 
Published: September 2022

Abstract
Wire arc additive manufacturing can produce thin-walled components at much faster rates than conventional subtractive manufacturing processes. The as-built components have a poor surface finish, which requires post-processing via machining. However, tool reach limitations of cutting tools means that the desired component must be produced in sections, where the hybrid manufacturing process is conducted iteratively. A key aspect of this hybrid manufacturing process is the deposition of the first bead onto the previously machined component section, a thin-walled substrate. Since the deposition traverse speed and wire feed rate heavily impact geometry, and therefore the subsequent machining process, this work seeks to analyze the thin-wall substrate deposition geometry resulting from different deposition process parameters. Additionally, this work assesses the impact of the deposition geometry on subsequent machining by assessing the area of excess material which must be removed to achieve net shape geometry. Traverse speed was found to have the largest impact on bead morphology, with wire feed speed having an increased impact at higher traverse speeds. The penetration and remelting geometry of the samples was investigated and found to contribute to the relatively uniform bead height seen in the different samples.
Investigation of the Mechanical Properties of Additively Manufactured Bone Tissue Scaffolds, Composed of Polyamide, Polyolefin, and Cellulose Fibers
Authors: Mandava Paavana Krishna , Joyce Robert , Day James B. , Salary Roozbeh (Ross) 
Published: September 2022

Abstract
The goal of this research work is to fabricate mechanically robust, porous, and biocompatible bone scaffolds with textured surfaces (for cell/tissue adhesion) for the treatment of osseous fractures. The objective of the work is to investigate the mechanical properties of triply periodic minimal surface (TPMS) bone scaffolds, fabricated using fused deposition modeling (FDM) additive manufacturing process, based on a medical grade composite composed of polyamide, polyolefin, and cellulose fibers. FDM has emerged as a high-resolution method for the fabrication of biological tissues and constructs. FDM allows for non-contact, multi-material deposition of functional materials for tissue engineering applications. However, the FDM process is intrinsically complex; the complexity of the process, largely, stems from complex physical phenomena and material-process interactions, which may adversely influence the mechanical properties, the surface morphology, and ultimately the functional characteristics of fabricated bone scaffolds. Consequently, physics-based material and process characterization would be an inevitable need. In this study, seven TPMS bone scaffolds were fabricated, based on the medical-grade polymer composite. The compression properties of the fabricated bone scaffolds were measured using a compression testing machine. The outcomes of this study pave the way for the fabrication of complex composite bone scaffolds with tunable medical and functional properties.
Random Grid-Based DIC Analysis of Plastic Flow Near Interfaces in Deformation Processing
Authors: Gupta Deepika , Viswanathan Koushik 
Published: September 2022

Abstract
Digital Image Correlation (DIC), an in situ analysis technique, has gained widespread popularity within the mechanics community over the past two decades. Despite this, accurate computation of strain and displacement fields, especially at interfaces and free surfaces, remains a central challenge. This problem is particularly acute since material flow near free surfaces and interfaces is paramount for understanding the mechanics of several deformation processing configurations, such as machining and forming. Two common DIC implementations exist, and they exploit either local or global information about the deformation. Local techniques suffer from a lack of continuity across subsets, while global methods, despite ensuring continuity, fail to estimate fields at interfaces accurately. Furthermore, global DIC necessitates grid refinement to capture heterogeneous deformation and can often be computationally expensive. Both local and global methods finally use interpolation schemes to obtain continuous displacement fields, along with a finite difference scheme to compute strains. However, these present additional limitations, such as spurious strains at interfaces and loss of experimental data. In this work, we present a random grid-based scheme that uses local correlation search, while simultaneously exploiting global information. Our algorithm is based on a forward 6-parameter (displacement and its first order derivatives) Newton-Raphson (N-R) search. An underlying random grid is first generated and serves to locate subset centers for the correlation scheme. Second derivatives are then computed using a triangulation method. Multiple random grid realizations enable averaging with minimal data loss, thereby eliminating the need for post-processing. The use of second-order derivatives ensures continuous strain fields, which will otherwise need a twelve-parameter (displacement, its first and second derivatives) based correlation search. We establish the validity of our scheme using standard test cases derived from synthetic non-homogeneous displacement fields and demonstrate its utility in practical machining and deformation processing applications.
Digital Twin-Based Tool State Prognosis Model for Drilling Machines
Authors: Dayam Sunidhi , Desai K. A. 
Published: September 2022

Abstract
Digital Twin technology can be effectively employed for prognosis and predictive maintenance tasks by establishing interconnections between manufacturing equipment and its virtual counterpart. This paper presents the Tool State Prognosis (TSP) model based on Digital Twin philosophy to perceive the state of a twist drill during the drilling operation. The TSP model estimates the state of a twist drill viz. initial, intermediate, or worn during the operation rather than obtaining the precise wear value. The Digital Twin collects input information as time-series data by establishing an appropriate connection protocol with a drilling machine using vibration and acoustic emission sensors. The Root Mean Square (RMS) approach and Quadratic Support Vector Machine (QSVM) are employed for feature extraction and recognizing the twist drill status with Remaining Useful Life (RUL) prediction from the time-series data. The model also includes integrating a Human Machine Interface (HMI) unit for displaying tool status and RUL information to assist operators in tool replacement decisions. The developed model can be integrated as an edge-level solution with manual and CNC drilling machines without significant hardware changes for perceiving the status of a twist drill. The prediction abilities of the digital twin are corroborated by performing a set of drilling experiments for various cutting tool-workpiece combinations. The confusion matrices demonstrated the effectiveness and generalization abilities of the developed model by comparing predicted and actual classes for each combination. The developed Digital Twin model can quickly respond to tool status and failure with enhanced man-machine interactions and improved prognosis abilities for the drilling machines.
Experimental Study of Microscopic Morphology and Material Property for Recycled Polyamide 12 Powder in Selective Laser Sintering
Authors: Al Amin Mohammad Aman Ullah , Yang Yiran , Kobir Md Humaun , Di Lei 
Published: September 2022

Abstract
Selective laser sintering has become one of the most popular additive manufacturing technologies owing to its great capability of fabricating complex structures with reduced or even eliminated need for the support structure. Meanwhile, an average of 50% to 70% of the consumed powder materials is not directly used for part fabrication. To reduce material waste and enhance material usage efficiency, research studies have been conducted to facilitate the recycling and/or reusing of the waste powder in selective laser sintering. In this research, polyamide 12 powders are studied including virgin powder, waste powder, recycled powder, and mixed powder (with a 30% refresh rate) in terms of their microscopic morphology and material properties. In addition, the location of the powder sampled from the build chamber is also studied for its impact on the powder size and shape. Experimental results show that the average particle size does not change much in different samples, but the standard deviation increases in waste powder. Furthermore, the averaged ultimate tensile strength of test specimens fabricated with virgin powder is around 25% higher than specimens made with mixed powder (30% virgin powder and 70% recycled powder), showing a clear mechanical degradation.
Numerical Studies on Cold Spray Particle Deposition Using a Rectangular Nozzle
Authors: Gabor Ted , Akin Semih , Tsai Jung-Ting , Jo Seunghwan , Al-Najjar Feraas , Jun Martin Byung-Guk 
Published: September 2022

Abstract
Cold spray additive manufacturing (CSAM) is an emerging technique for scalable and rapid deposition of thick metallic coatings on various substrates. Despite great promises, CSAM with no upper limit of coating thickness remains challenging due to the stochastic nature of cold spray (CS) deposition. In particular, using axisymmetric nozzles (i.e., circular supersonic nozzles) lead to a quasi-Gaussian shaped particle distribution on the target surface, which limits the CSAM due to the formation of triangular-shaped (i.e., peak/valley-shaped) coating morphology. Recently, rectangular cold spray nozzles have been applied to CS particle deposition, and found to be promising for CSAM owing to its more uniform particle distribution and wider spray beam. In these studies, however, process-structure properties of cold spray deposition with a rectangular nozzle have not been sufficiently elucidated. Practical expansion of rectangular nozzles in CSAM strictly depends on uncovering process-structure properties of CS deposition phenomenon. To this end, we investigate cold spray deposition of microscale particles using a rectangular nozzle through three-dimensional discrete-phase turbulent flow modeling. The numerical modeling results are experimentally justified using a dual disc anemometer setup. The influence of operating gas conditions on critical particle deposition parameters is studied. An experimental case study of cold spray particle deposition on a polymer (ABS) substrate is also conducted to show the potential of rectangular nozzle in cold-spray based polymer metallization. The results suggest that cold spraying using a rectangular nozzle is beneficial for a more uniform, compact, and higher precision particle distribution on the target surface.
Fused Deposition Modeling of Carbon Fiber Reinforced High-Density Polyethylene: Effects on Microstructure and Mechanical Properties
Authors: Pandit Partha Pratim , Liu Chang , Corti Giancarlo , Hu Yingbin 
Published: September 2022

Abstract
Owing to its superior durability, good biocompatibility, and high recycling capability, high-density polyethylene (HDPE) has been widely applied into making prosthetic implants, liquid permeable membranes, corrosion-resistant pipes, etc., and gains its popularity in packaging, consumer goods, and chemical industries. Injection molding and blow molding are two most common conventional processes of making HDPE products. These conventional processes, however, are considered time-consuming and labor-intensive since molds are usually needed prior to fabricating parts. Moreover, manufacturing complex-structured parts (such as lattice and cellular structures) is a challenge for these conventional manufacturing processes. Facing these problems, it is crucial to find a time- and labor-saving process, which can be used to manufacture complicated structures in a cost-effective way. Additive manufacturing (AM) is such a process that needs no mold and is more affordable to create complex and highly customized parts. Among all types of AM processes, fused deposition modeling (FDM), which is primarily designed for thermoplastic materials, seemed to be a benevolent process for fabricating HDPE parts. Based on reported publications, however, it is difficult to print HDPE materials using FDM due to the problems of warping, shrinking, and weak bonding between printed HDPE parts and the substrate. In addition, the FDM-printed HDPE parts can demonstrate defects of porosities and delamination. To improve the printability of FDM, we conducted preliminary experiments and optimized processing parameters. For the first time, we added carbon fiber (CF) into HDPE to make CF-reinforced HDPE composites (CF-HDPE) using FDM and investigated the effects of CF on part quality, microstructure characteristics, and mechanical properties (including tensile properties and dynamic mechanical properties) of CF-reinforced HDPE composites. Experimental results show that the addition of CF was beneficial for not only improving the printability of FDM and quality of printed composite parts, but also for enhancing mechanical properties (such as Young’s Modulus and ultimate tensile strength) of the parts.
Why Did Lord Novgorod the Great Fall? The Novgorod Republic and Its Neighbors in 1470–1471
Authors: Lukin P. V. , Polekhov S. V. 
Published: September 2022

Abstract
This article is devoted to the last decades of the existence of the independent Novgorod Republic and its fall. The events of 1470–1471, namely, the attempts to call into service a prince from Lithuania, to conclude an alliance with Lithuania and with the Teutonic Order in Livonia, and the campaign of Ivan III and the military defeat of Lord Novgorod the Great, have been considered on a wide background of social and political development of Novgorod the Great throughout the fifteenth century, in the context of the history of its foreign relations and the position of its neighbors, the organization of its armed forces, with a comprehensive account of a variety of sources (not only chronicles but also charters, epistolary and literary sources, etc.) and a rich research literature. In contrast to the approaches widespread in historiography, emphasis has been placed on contemporary reliable sources rather than on later ideological interpretations. Analysis of the chronicles also involves textual criticism. The authors have come to the conclusion that the defeat of the Novgorod Republic was caused not only by social, particularly religious, conflicts that were emphasized by the Moscow side but rather by the complex international situation, which the military and political organization of Novgorod was no longer consistent with, and the inability of the opposing pro-Moscow and pro-Lithuanian parties to offer a convincing ideological line and, consequently, strategy of action in these circumstances.
The Agony of the “Yoke”: The Great Horde as a Fading Threat to Muscovite Rus
Authors: Trepavlov V. V. 
Published: September 2022

Abstract
The last period of the existence of the Golden Horde and its relations with Muscovite Rus and the Polish–Lithuanian state have been considered, and the gradual degradation of the Horde statehood has been shown, including the change in the relations of the Tatar rulers with former Russian tributaries.