bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance Enhancement Kit for Frame 51 Machine With DLN Combustor
Authors: Soman Abhimanyu , Cocchi Lorenzo , Peddi Mallikarjuna , Avaiya Nikunj , Devi Ravindra , Santhana Gopalakrishnan Babu
Published: February 2024

A Performance Enhancement Kit (PEK) is introduced to infuse the latest technology to MS5001PA fleet there-by existing customers benefit from increased output, extended inspection intervals, improved reliability, and operability. The kit includes advanced-technology combustion system with improved design of hot gas path (HGP) components. The components in the KIT are designed for either enhanced output of 6% or for an increased interval between repairs or increased ‘Mean Time Between Maintenance’ (MTBM) from 24khrs to 35khrs. Initially PEK was introduced as part of MS5001PA in 2016 for standard combustor. Present study shows its application to Dry Low NOx (DLN) combustion system without affecting Maintenance Interval (MI). PEK DLN configuration alters the combustion and in-turn the Stage 1 Nozzle inlet profile. High fidelity CFD computations were performed to evaluate impact of these altered profile on HGP components, especially the thermal distribution and its impact on durability. Adiabatic wall temperatures obtained from CFD were used in developing heat transfer and flow temperature in the flow path locations. These were used to perform thermo-structural assessment for HGP components using ‘Finite Element Analysis’ (FEA) tools. With this evaluation, durability of HGP components in terms of LCF, creep was thoroughly assessed to ensure part life is meeting MI. Detailed high-fidelity FEA shows that, creep, oxidation, and ‘Low Cycle Fatigue’ (LCF) meet the design requirements for both life extension as well as the power increase conditions with DLN combustor profile. To gain confidence, MS5001PA durability results were benchmarked with field experience of ‘Standard’ (STD) and DLN configuration which shows coherent results with Creep and LCF. This gives confidence in thermal profile which was developed for PEK STD and DLN configurations. Based on detailed thermo-structural assessment, the maintenance factor was set to 1. This paper presents the latest methodology used in CFD for aero flow prediction and high-fidelity Finite Element (FE) assessment used for durability prediction of HGP components.
Development of Machine Learning Model to Predict Mechanical Failure of Gas Turbine Disc
Authors: Seth Alok Kumar , Shrivastava Rishabh , Rai Amit Kumar
Published: February 2024

Gas Turbine is a mechanical system which is used for power generation since decades. Its components are highly stressed and exposed to very high temperature. It operates on various environmental condition which experience numerous loading patterns. In all these operating conditions, Gas turbines must operate with higher efficiency to meet changing power requirements. Each component must be assessed for different mechanical failures and predict life during design and development.

Gas Turbine Rotors which comprise of several discs are one of the most critical components in gas turbine. GT rotor is subjected to high temperature and centrifugal load during their operations. In such conditions, predicting the failures becomes utmost priority.

This study aimed to evaluate the effectiveness of Machine Learning (ML) techniques to predict the failure in a gas turbine Rotor Disc. For this study, a simplified geometrical 3D model of Turbine Disc was used along with Cooling holes, Hub geometry with Sealing arm and lifting features. Four input variables i.e., cooling hole mass flow, temperature of cooling air, purge hole mass flow and temperatures of purge air were used as input feature to the machine learning model. Steady-state thermo-mechanical analysis were performed to evaluate the metal temperature and subsequently the stress and life of the component under various load cases.

A machine learning based surrogate model was developed based on the data extracted from 3D thermo-mechanical FEA assessment. The generated dataset was randomly divided into 75:25 ratio for training and testing of ML models respectively. Multiple models based on different algorithms were created for predicting disc LCF life. Then, these were evaluated with test set to select the model using various Evaluation Metric.

Machine Learning techniques such as Logistic Regression, Random Forest and Support Vector Machine algorithms were compared using Precision, Recall and F1 Score. The results were validated through Confusion Matrix and ROC (Receiver Operating Characteristics) curves. This study demonstrates that ML techniques has potential in predicting failures/life of a component.

This study will be helpful for the assessments performed during later stage of product life cycle for example overhaul, lifetime extension or if any manufacturing deviations happen. Mostly these assessments are very critical and time dependent. As we use conventional methods for component assessments, it takes significant time and cost. Therefore, this study and its implementation would make current industrial practices efficient and cost effective.
Spray Interaction in Flat-Fan Injectors and its Effect on Cleaning Effectiveness of Gas Turbine Online Water Washing System
Authors: Kumar Kiran , Sahu Srikrishna , Devi Ravindra G.
Published: February 2024

Compressor fouling due to the deposition of airborne particulates on the compressor blades is a major cause of the degradation of compressor performance and the decline of overall gas turbine efficiency. The online water washing technology refers to an effective method to clean the compressor blades during engine operation. In such systems, typically a series of flat-fan injectors are peripherally located at the entry section of the gas turbine which injects water sprays into the intake air flow. The injected water spray droplets are transported towards the compressor and impinge on the compressor blades, thus removing the foulant. However, such injector arrangement usually leads to the interaction of adjacent sprays which may modify the resulting spray characteristics such as droplet size, velocity, and momentum. Hence, the study of spray interaction in the flat-fan injectors and its effect on the blade cleaning effectiveness is important for the design and development of water washing units. The objective of the present work is to study the spray interaction in two adjacent flat-fan injectors under open atmospheric condition as well as in an experimental test facility that essentially consists of a suction type wind-tunnel that mimics the gas turbine compressor inlet conditions in an optically transparent test section. Different optical diagnostic tools are used to visualize the spray interaction process as well as measure droplet size and velocity. To study the effect of spray interaction on blade cleaning, foulant-coated coupons (SS flat plates) are placed inside the test section of the wind tunnel and are exposed to the sprays for a fixed interval of time. The foulant cleaning efficiency is measured by weighing the coupon before and after the cleaning tests. A parametric investigation is carried out to investigate the cleaning efficiency for different air flow velocities, angle of attack, and injector separation distance. The current experimental results not only further elucidate the understanding of the blade cleaning process in online water wash systems but also provide valuable data for the validation of numerical spray simulations.
Experimental and Numerical Investigation of Velocity Flow Field in a Novel 3D Printed Triple Swirler Burner
Authors: Thombare Mahesh R. , Pillai Sidharth K. , Murugan Raju , Pillai Madhushankar , Balusamy Saravanan
Published: February 2024

Efficient and clean combustion is vital in combustion systems, but achieving perfect fuel-air mixing is challenging. Gas turbine combustors use multiple swirlers to improve mixing and stabilize flames. This study investigates a 3D-printed triple-swirler burner (TSB) to enhance gas turbine combustion systems. The TSB was tested in a vertically configured apparatus, with air passing through before exiting. Experimental and numerical methods were used to study the flow field downstream of the TSB. Different TSB designs with varying swirl numbers and rotational directions were tested at different airflow rates. The experimental data obtained using Stereo Particle Image Velocimetry (SPIV) and the CFD results using Large Eddy Simulation (LES) provided insight into flow physics and helped optimize the design of the TSB. Simulation outcomes are presented and compared with experimental data at the exact locations in the flow field. Results showed that TSB2 had a longer residence time than TSB1. Strong bubble vortex breakdown (BVB) was observed in the upstream region, caused by the counter-rotating tertiary swirler. Downstream, weak conical vortex breakdown (CVB) was observed as the tertiary swirler’s influence diminished.
Conceptualization of a Portable Vacuum Pumping System for Dead Volume Dispensing of Crude Oil From Crude Oil Storage Tanks
Authors: Das Manosh Jyoti , Sahoo Niranjan
Published: February 2024

In crude oil storage-dispensing terminals often problems are encountered regarding dispensing and processing of crude oil at near dead volume capacity of the tanks. Similar problems are encountered while cleanout procedure of tanks for maintenance and repair. In our first consideration processing of crude for treating or dehydration is brought to picture. For crude processing or tank to tank transfer problem arises below dead volume with high flow high pressure circulation pumps. The problems observed are low suction pressure, reduced flow and pressure at discharge end, frequent gas formation at suction, high flow induced vibration at pump suction and frequent failure of dynamic seals. Most pumps used in this scenario are centrifugal pumps (following API 610 codes and API 682 for mechanical seals). For our purpose single stage centrifugal pump is considered. The pump deigns and dead volume level calculation attributes to the problems encountered. Moreover, during the clean-out procedure it becomes difficult for most pumps even with low NPSHR to efficiently pump out the liquid below dead volume level. This creates severe volume build-up and even causes damage to pumps at very low level partial dry run condition. Our aim is to conceptualize and furthermore develop a compact vacuum-pump system which can be used for continuous delivery of fluid even beyond specified dead-volume level. The equipment would have the capability to work on very low-level fluid storage. Again, in traditional vacuum and pump system there is a drawback of swing operation of vacuum and pump system which greatly affects the operation time of any process. This literature will help in identifying the core problem of swing operation and inline draw a concept of the new pump-vacuum system which eliminates need for a swing operation i.e., simultaneous operation of evacuation and pumping can be carried-out. Also, it is aimed to explore further applications of the system for booster application. Vacuum systems consist of vacuum pumps and tanks mounted on a skid or truck. The vacuum pump creates a vacuum in the tank and the oil moves directly through a hose or pipe to the tank from the skimmer or the source of the oil. The oil does not go through the pump, but moves directly from its source into the tank. Vacuum systems can handle debris, viscous oils, and the intake of air or water. The vacuum tank requires emptying, however, which is usually done by opening the entire end of the tank and letting the material move out by gravity [1].
Diameter-to-Chord Ratio Effect on the Aerodynamic Performance of Small-Scale Darrieus-Type Straight-Bladed Vertical Axis Wind Turbine
Authors: Naik Kabita , Sahoo Niranjan
Published: February 2024

The growing interest in small-scale Darrieus-type straight-bladed vertical axis wind turbines (SB-VAWTs) presents a novel outlook for the conversion of wind energy, departing from horizontal axis wind turbines. The SB-VAWTs are favourable alternative energy sources to generate independent off-grid electrical power in complex wind environments. The current study aims to explore and understand the effect of blade geometry on the efficiency and self-starting ability of the SB-VAWTs. Therefore, three different diameter-to-chord (D/c) ratios have been investigated at various tip speed ratios (λ). Accordingly, numerical simulation on Darrieus-type SB-VAWTs has been carried out with D/c ratios of 2.5, 3.5 and 4.5 and presented a comparative analysis between their power and torque coefficient. The VAWT with a D/c ratio of 2.5 is conducted in a subsonic wind tunnel of an open circuit type with test section dimensions of 600 mm × 600 mm × 2000 mm to validate and support the numerical findings. The flow physics analysis for all three D/c ratios is also studied by simulations to understand the stability and reliability of SB-VAWTs. An improvement of 13% and 54% is found in the maximum power coefficient by the Darrieus-type SB-VAWT with a D/c ratio of 4.5 as compared to the d/c ratio of 3.5 and 2.5 at λ = 1.8. Smaller D/c ratios exhibit superior self-starting capability in Darrieus-type SB-VAWTs compared to larger D/c ratios at lower λ values. The outcomes revealed that the proper selection of D/c ratios can enhance the aerodynamic performance and starting torque of Darrieus-type SB-VAWT.
Efficiency Assessment of Compressed Air Energy Storage System Coupled With Thermal Energy Storage Unit: Review
Authors: Adamu Assegie Mebratu , Siram Ojing , Kalita Pankaj , Sahoo Niranjan
Published: February 2024

The compressed air energy storage system is one of the emerging storage systems that has recently gained significant attention due to its large storage capacity, eco-friendly, clean technology, and extended life cycle. The present study makes a comprehensive review on the implication of CAES system coupled with TES system. It is noted that when the CAES system is in operation, the cooling system dissipates the majority of the heat produced during compression into the environment, thus reducing its efficiency to 54% or less. Therefore, the post-compression thermal energy can be coupled with an adiabatic thermal energy storage system, which later on can be used to enhance the efficiency of the CAES system. According to its energy and exergy analysis, the adiabatic CAES system can achieve an efficiency of 70% when used in conjunction with a direct-contact type of packed bed (TES) energy system. Past studies demonstrate that the efficiency of A-CAES combined with a heat recuperator increases with more continuous operational cycles and reaches 57% efficiency. In general, it is due to the materials type, geometry, and thermo-physical property, the variation in the thermal efficiency of the TES system is observed that leads to variation in CAES efficiency.
Design and Numerical Analysis of a Lean Burn Combustor Liner Inlet for Micro-Gas Turbine Engine Applications
Authors: Tyagi Vatsal , Divyansh Ayush , Jamod Preetam , K. P. Shanmugadas
Published: February 2024

Lean burn combustion systems of low-emission modern gas turbine engines admit ∼70–80% of the compressed air through the fuel injector and the remaining air is passed through the liner assembly. The paper focuses on developing an intake geometry to accomplish a 70:30 mass flow split between the injector and liner. A lean burn injector and a liner assembly are developed following the existing design rules and extensive numerical simulations are performed to optimize the combustor assembly. The intake geometry is designed considering different operating parameters such as mass flow split ratio, compressor pressure ratio, liner and injector pressure drop. The pressure drop across the injector is limited as 4% and the liner is optimized for a pressure drop of less than 2% across the annulus of the liner. The diffuser section and intake cowl of the combustor are modified to achieve the required flow velocities through the liner and injector. The topology of the central toroidal recirculation zone and effusion flow velocity field are obtained as per the design requirements. The annular liner passage is modified by providing baffle plates to regulate the mass flow and thereby controlling the mass flow split into the intake section. The intake section is designed such that the required flow split is achieved while keeping the pressure drop and other losses to the minimum. Several geometrical iterations are done until the above goal is achieved. Efforts are currently underway for the experimental validation of the test results.
Wind Tunnel Assisted Analysis on the Effect of Span-Wise Separation of Small Wind Turbines: A Near Wake Region Study
Authors: Kumar Ravi , Siram Ojing , Saha Ujjwal K. , Sahoo Niranjan
Published: February 2024

In this work, an in-depth study has been made to examine the benefits of span-wise placed horizontal axis wind turbine configurations. The model turbine rotors have similar configurations with a sectional profile of SG6043, and are tested at low tip speed ratio conditions. The study has been performed for the two span-wise placed rotors having tip-to-tip separation distances of 1R (R being the rotor radius) and 0.5R, and are analyzed within the near-wake regime. The wind turbine wake assessment has been carried out in an open circuit wind tunnel with the help of a constant temperature hotwire anemometry. The downstream velocity deficit assessment shows that the wake of closely placed turbines undergoes faster interaction at short downstream distances, where the whole wake is characterized as an array of localized high velocity-deficit regions associated with each rotor. However, as the wake moves downstream, the rotor wakes start interacting with each other until they eventually form a single wake. The wake recovery rate of the span-wise placed rotors is enhanced by the increase of rotor spacing and wind speed. Furthermore, the tip of the blade generates helical vortices due to which a tangential component of velocity is added in the stream velocity vector. This gives velocity greater than stream velocity in ± 0.75R to ± 1.25R along a lateral direction with respect to wake centre.
Vortex Characterization of Rotor-Stator Cavities Dominated With Radial Flows
Authors: Reddy S. N. Dileep Bushan , Singh Praveen Kumar , Nayak Kali Charan , Scanlon Tim
Published: February 2024

Rotor-Stator cavities are quite common and an important feature in the turbomachinery application. The static pressure and total temperature change in the rotor-stator cavities play a critical role in the design of the secondary air system, bearing load and component life. Hence understanding the vortex characteristics and windage heating is vital to accurately estimate the swirl velocity, static pressure, and air temperature surrounding rotor/stator structures. This paper describes the development of a numerical methodology aimed at studying the vortex dynamics and windage heating in rotor-stator cavities. Specifically, a 2D axisymmetric validated CFD model is developed utilizing commercial finite volume-based software incorporating the Reynolds Stress turbulence model. Using the validated model, a broad parametric study is conducted by varying the aspect ratio of the cavity, inlet swirl fraction and mass flow rate at a constant rotor speed. Finally, the radial variation of swirl velocity, static pressure and total temperature are studied for the radial inward and outward flows. The nature of the vortices is found to be very complex and they cannot be categorized into either free or forced vortex. The vortices change radially in the cavity with change in the flow, inlet swirl and cavity aspect ratio. Practically it is difficult and cumbersome to arrive at a universal characteristic equation for the range of flow conditions for a cavity of interest. In this paper an attempt is made to arrive at the universal characteristic equation using machine learning based surrogate model for the rotor-stator cavity. A polynomial regression is developed using the CFD generated data sets by suitably training and testing the model. Feature engineering and hyperparameter tuning techniques are used to select the important features from the input parameters to make the model simple without significant accuracy loss. The results from the surrogate model show accuracy of 97% with an independent set of CFD data used in validation. Understanding of the vortex dynamics from CFD and the polynomial vortex characteristic equations will be instrumental in the design of secondary air system, bearing load and component life in turbomachinery.
Methodology to Optimize the Location of Osteosynthesis Material for 3D Printed Cranial Implants Based on Force Analysis
Authors: Perero Segarra Bryan S. , Helguero Carlos G. , Maldonado Fausto , Amaya R. Jorge Luis , Saldarriaga Carlos , Loayza Francis
Published: February 2024

Cranioplasties are highly complex surgical processes where surgeons try to repair skull bone defects in patients. An aspect that needs to be addressed in this procedure is the precise location of osteosynthesis material, such as screws and plates, for successful implant fixation. These must meet the technical requirements and biocompatibility with the organism to avoid rejection. Currently, the positioning of the anchor points (A.P.) is exclusively based on the surgeon’s expertise, and there are no precise measurement tools or any criteria for the accurate location of this fixing material, depending on the patient’s case. This work proposes a method to establish where the A.P. will be located before surgery, reaching their maximum resistance in service using a mathematical tool to define the location of the osteosynthesis material. This study reduces the time in surgery, ensuring its correct positioning and behavior against specific loads using indentation guides designed according to the patient’s case before admission to the operating room. Information based on a cranial implant case study was obtained to determine the maximum impact force the system would withstand. The validation was done by simulation showing the general behavior before an external stimulus with previously defined A.P.
A Travelling Wave Ferro-Microfluidic Device Platform for Potential Cell Separation and Sorting
Authors: Hewlin Rodward L. , Edwards Maegan
Published: February 2024

This paper presents the design and development of a simple traveling wave ferro-microfluidic device platform and rig purposed for the potential manipulation and magnetophoretic separation of cells in water-based ferrofluids. This paper details in full the development of the ferro-microfluidic device for potentially separating cells and magnetic nanoparticles as well as the design and development of a system rig for producing the electric field within the ferro-microfluidic channel device for magnetizing and manipulating nonmagnetic particles in the ferro-microfluidic channel. The results reported in this work demonstrate proof of concept for magnetophoretic manipulation and separation of magnetic and non-magnetic particles within a water based ferrofluid confined in a simple ferro-microfluidic device with a programmable chip platform.
Thermal Analysis of Thermosyphon for Waste Heat Recovery From Auto Exhaust Using Limited Fluid Charge
Authors: Xiao Bin
Published: February 2024

An experimental investigation was carried out to analyze the thermal performance of a thermosyphon that recovers waste heat from automobile exhaust using a limited fluid charge in this study. The thermosyphon was constructed from Inconel alloy 625. The outer diameter of the thermosyphon measures 27 mm, with a thickness of 2.6 mm, and an overall length of 483 mm, which includes a 180-mm evaporator, a 70-mm adiabatic section, a 223-mm condenser, and a 97-mm finned exchanger. The study involved directing exhaust gas onto the evaporator end cap at a flow rate ranging from 0–10 g/sec, with temperatures varying from 300–900°C. The impact of three parameters, namely the inclination angle (ranging from 5°–45°), water mass (ranging from 2 g–5.3 g), and the amount of non-condensable gas Argon (ranging from 0 g–0.6 g), were analyzed to determine their effects on the thermal performance of the thermosyphon. Based on the experimental results, it was observed that when the thermosyphon contained 3 g of water and 0.0564g of argon, the condenser achieved a maximum temperature of approximately 200°C. The optimal fuel loading rate for the thermosyphon lies within the range of 0.2 g/s to 0.7 g/s. Furthermore, outer wall temperatures of the thermosyphon increase as inclination angles increase due to the explicit expansion of the actual heating area within the evaporation section of the thermosyphon, accompanied by an augmented gravitational component of the water flux. An increase in the quantity of non-condensable gas (NCG) can diminish temperature gradients on the outer wall of the thermosyphon, leading to a reduction in the thermosyphon’s performance. The insulation applied at the adiabatic section proved effective in increasing temperature gradients on the outer wall of the thermosyphon and thereby enhancing the performance of the thermosyphon. With an increase in the water charge within the thermosyphon, heat transfer rates from the exhaust to the thermosyphon and from the thermosyphon to the fuel increase.
Collapsible Origami-Based, Drop-Deployable Micro Air Gliders
Authors: Kolano Hannah , Lao Miranda , Patel Anil , Wei Maxmilian , Xu Jingyi , Lee Christopher L.
Published: February 2024

This paper reports on the design, fabrication, and testing of two micro-air-vehicles (MAVs) with origami-based fixed wings which were inspired by foldable wings found in nature that are not controlled by muscles but by joints that have bi-stable open-closed positions. The wings have a folding pattern that allows them to collapse and expand via flexible joints. The first MAV was designed to land quickly in a controlled manner while the second was designed to glide over a longer period of time. Both wing configurations were designed so that the MAVs can be stored and deployed in compact form by minimizing their wingspan. Upon release, the wings self-reconfigure enabling the MAVs to fly. Flight tests were conducted to evaluate the performance. Both qualitative and quantitative results are presented that evaluate gliding capability. Qualitative evaluations describe how well the MAVs level out from a vertical to horizontal position and the straightness of their flight paths. Quantitatively, the time the MAVs took to level out and then to land on the ground was recorded. The flight tests demonstrate that the prototypes can be deployed in a collapsed configuration then open successfully and glide to the ground.
CFD With Fluid Structure Interaction Analysis of Lung Alveolar Sacs and its Applications in Emphysema Study
Authors: Carotenuto Carlo , Orlandi Francesco , Montorsi Luca , Milani Massimo
Published: February 2024

Emphysema, a chronic lung disease characterized by respiratory distress and reduced lung function, poses significant challenges. Computational Fluid Dynamics (CFD) coupled with fluid structure interaction (FSI) is a highly effective simulation technique that offers valuable insights into the mechanics of lung function and the influence of diseases like emphysema. The intricate lung alveolar sacs play a vital role in gas exchange, and CFD with FSI enables the simulation of mechanical forces that shape and impact their functionality. By employing CFD with FSI, we can simulate the fluid dynamics of emphysema and acquire a comprehensive understanding of disease progression. These simulations allow us to explore the contributions of tidal breathing and surface tension forces. This study has demonstrated through FSI that a lung alveolus affected by pulmonary emphysema, and therefore collapsed, causes reduced air intake with each breath. This is due to the significantly compromised deformability of the alveolar wall. Ultimately, this technique plays a critical role in developing therapeutic interventions to improve patient outcomes.
An ANOVA Based Study of Variations in Circularity Form Error Due to Mathematical Methods and Measuring Instrument Eccentricity
Authors: Sahay Chittaranjan , Ghosh Suhash , Venkatesh Nithish Adhithya
Published: February 2024

One of the most important fundamental forms for engineering components is the circular cross-section. Circular forms arise in many applications, particularly in bearing surfaces such as rotating shafts and ball bearings. The importance of studying roundness form deviations of circular and cylindrical features is to avoid the excessive lateral or axial runout deviations of the rotating and reciprocating parts during dynamic operations. Of all the methods of measuring these form errors, the most precise is the one with accurate spindle and turntable type measuring instrument. Considering the precision that industries require now and will require in the future, the authors of this article have chosen roundness (also called circularity per ASME Standards) as the measurable parameter. Based on reference circles, this paper focuses on the four modeling methods of roundness, namely, (1) Least Squares Circle (LSC), (2) Maximum Inscribed Circle (MIC), (3) Minimum Circumscribed Circle (MCC) and (4) Minimum Zone or Minimum Radial Separation (MRS) Circles. In this article, the authors have conducted an ANOVA (Analysis of Variance) study of variations in roundness measurements based on these mathematical methods, instrument’s centering and tilt error (also known as eccentricity) and filter type and filter size. In order to arrive at precise results, the roundness of a near-to-perfect cylinder is measured at selected heights on an accurate spindle and turn-table type measuring instrument, Mahr MMQ200. Other instrument settings, namely, probe size and probe angle were kept the same throughout. This statistical investigation provides key insights to determine the variances due to the different sources of variation and determine the percentage contribution due to each source. This helps the instrument users to pay close attention to the variables that would influence the final results the most, leading to develop a better control in the beginning of the measurement process.
Improvements to a Friction Stir Extrusion Machine
Authors: Emblom William J. , Antoine Ethan , Dartez Zachary , Faucheaux John , Hendrix Stephen , Simon Austin , Theriot Blake , Darby Paul , Wagner Scott W.
Published: February 2024

Friction stir extrusion is a variation of friction stir processing, of which the most well-known is friction stir welding where a non-cutting rotating probe comes into contact with two metal sheets or plates. For friction stir welding, the friction between a rotating probe and the two metal sheets generates heat so that the temperature of the sheets increases above the recrystallization temperature and the material of the two metal sheets are stirred and upon cooling, results in a joined sheet. Within the stir zone, the grain structure is an ultrafine.

For friction stir extrusion, the rotating probe is plunged into a work piece and the resulting heat raises the work piece to above the recrystallization temperature as either a solid or hollow cylindrical rod is formed.

The previous version of the custom-built machine friction stir machine had significant vibration present during tests, difficulty in mounting the tooling on to the machine, errors in the workpiece temperature readings, alignment of the probe and work piece, and other manufacturing defects that made the machine difficult to be used for research and testing.

This paper documents improvements to the friction stir machine and provides preliminary test data prior to a full-scale investigation of friction stir extrusion processes. Data in the paper includes observations, pictures, and force and temperature results.
Turbulent Heat Transfer From an Isothermal Half-Cylinder Positioned Parallel to Airflow
Authors: Rarick Nathan A. , Molki Majid
Published: February 2024

Turbulent heat transfer and fluid flow characteristics for an isothermal half-cylinder oriented parallel to a uniform flow are investigated numerically. The computational results of the local and average heat transfer coefficients are compared with the available experimental data. The semi-circular cylinder, which has a length-to-diameter ratio of 1, is compared to full cylinders of similar dimensions. Though not identical, the current results agree with full cylinder axial flow analysis in that the convective heat transfer coefficient increases to its maximum towards the edge of the front face. Computations are carried out over a range of Reynolds numbers from 5,000 to 42,000, using air as the working fluid. Results showing the convective heat transfer coefficient distribution across each face and the influences attributed to flow separation and flow recirculation are presented. The Nusselt number at the stagnation point is compared with experimental results. No vortex shedding was seen, and a steady state flow condition was observed, contrary to that seen in cylinders in cross-flow. The k-ω SST turbulence model is implemented as adverse pressure gradient situations are expected. Contour plots of heat flux and plots of the local and average Nusselt numbers are provided as results.
Electro-Mechanical Studies of Multi-Functional Glass Fiber and Carbon Fiber Composites Exposed to Seawater/Freshwater and Cold Temperatures
Authors: O’Donnell Jacob , Cavallaro Paul , Smith Michael P. , Valm Nicholas , Legris Joseph , Warner Eric , Chalivendra Vijaya
Published: February 2024

A detailed experimental study is performed on the piezo-resistive damage sensing capability of electrically conductive carbon fiber and carbon nanotube-infused glass fiber composites after freshwater and saltwater ingression under quasi-static tension and under low temperatures. The electrical resistance is recorded via a two-point probe measurement technique for carbon fiber and a four-point probe measurement technique for glass fiber.

The carbon fiber composites on average absorbed 1.7% of their initial mass as either freshwater or saltwater. The glass fiber composites absorbed 2.1% on average of their initial mass as freshwater or saltwater. Mechanical and electrical properties of carbon fiber composites showed a dependency on both water ingression and testing temperature.

Water-infused carbon fiber composites exhibited a unique electrical behavior where, after severe delamination the frayed lamina fibers could bridge the delamination and regenerate lost electrical connections. Lower temperatures allowed more severe delamination to occur within the composite. The glass fiber composites infused with 0.5% by weight (wt) and 95% purity carbon nanotubes were not conductive and did not detect internal damages.
XTENTH-CAR: A Proportionally Scaled Experimental Vehicle Platform for Connected Autonomy and All-Terrain Research
Authors: Sivashangaran Shathushan , Eskandarian Azim
Published: February 2024

Connected Autonomous Vehicles (CAVs) are key components of the Intelligent Transportation System (ITS), and all-terrain Autonomous Ground Vehicles (AGVs) are indispensable tools for a wide range of applications such as disaster response, automated mining, agriculture, military operations, search and rescue missions, and planetary exploration. Experimental validation is a requisite for CAV and AGV research, but requires a large, safe experimental environment when using full-size vehicles which is time-consuming and expensive. To address these challenges, we developed XTENTH-CAR (eXperimental one-TENTH scaled vehicle platform for Connected autonomy and All-terrain Research), an open-source, cost-effective proportionally one-tenth scaled experimental vehicle platform governed by the same physics as a full-size on-road vehicle. XTENTH-CAR is equipped with the best-in-class NVIDIA Jetson AGX Orin System on Module (SOM), stereo camera, 2D LiDAR and open-source Electronic Speed Controller (ESC) with drivers written for both versions of the Robot Operating System (ROS 1 & ROS 2) to facilitate experimental CAV and AGV perception, motion planning and control research, that incorporate state-of-the-art computationally expensive algorithms such as Deep Reinforcement Learning (DRL). XTENTH-CAR is designed for compact experimental environments, and aims to increase the accessibility of experimental CAV and AGV research with low upfront costs, and complete Autonomous Vehicle (AV) hardware and software architectures similar to the full-sized X-CAR experimental vehicle platform, enabling efficient cross-platform development between small-scale and full-scale vehicles.
The Demonstration of a Low-Cost Tabletop Microscale Hydroforming System With a Self-Aligning Sealing System
Authors: Emblom William J. , Frederick Connor L. , Carline Grant R. , Earles Kenneth , Taylor Collin , Tran Diep , Cambre Brock , Castille Bradley , Olayinka Ayotunde , Darby Paul , Wagner Scott W. , Ferdowsi Farzad
Published: February 2024

A microscale/multiscale tube hydroforming tabletop test bed that includes the tabletop testbed, PLC controller, and high-pressure hydraulic pump has been developed. Currently, feedback and controls are being implemented along with adapting previously built open-die tooling as part of a collaborative initiative between researchers in Louisiana and at Michigan Technological University.

The tooling utilizes the floating die concept and was designed and built based upon conventional macroscale manufacturing processes to produce microscale components.

At this point in the system development, the objective is to implement controlled expansion of AISI 304 tubing with an OD of 2-mm using an existing floating rigid die. Later modifications to the system will allow the production of tubing with complex geometry such as tee-sections that can be used in microfluidic devices such as fuel cells, microscale heat exchangers, and MEMS.

Preliminary results for formed sample tubes are discussed.
Investigation of Frequency Coupling in a Restricted Pulsatile Flow
Authors: Barbosa Gonzalez Alexandra , Goldmann Felix , Ahmed Fadhil , Byers Clayton P.
Published: February 2024

A parametric study of the influence of flow restriction and Reynolds number on the acoustic spectrum is performed. By altering the boundary conditions of the pulsatile flow, changes in frequency coupling can be investigated. To mimic aortic valve stenosis in a resting heart, the pulsing frequency is set to 70 beats per minute (1.17 Hz), while the physical size of the restriction and fluid volume pumped is altered. An 8 × 8 data matrix is collected for different Reynolds numbers (4500–9831) and restriction severity (0–82% restricted), in steps based on ratings from the American Society of Echocardiography. Utilizing both the power spectrum and the bicoherence, which is a measure of frequency coupling, a quantitative measure of restriction severity based on the dominant frequencies present is sought. While the forcing frequency is present throughout all results, normalization and a focus on triadic interactions exposes characteristic frequency bands that can be correlated to restriction severity. Across all Reynolds numbers, the band of frequencies from 100–150 Hz appears significant for moderate to severe restrictions, and a band surrounding 270 Hz increases in prominence with increasing restriction. The bicoherence indicates phase coupling decreases with increasing restriction, providing another quantitative measure of restriction intensity.
A Study on the Vibro-Acoustic Analysis Technology About the Transformer Load-Noise
Authors: Yun Minok , Lee Kanghyuok , Ahn Changhoon , Lee Jinwoo , Kang Jeehwoon , Kim Changwook , Choi Hyunseok
Published: February 2024

Recently, the importance of low-noise design on transformers has been growing. This is due to increasing requirements from customers whose substations are being installed nearby downtowns. Increasingly stringent noise emission limits are therefore being placed on transformers by both regulators and utility operators. However, the absence of adequate modelling tools to predict noise levels of transformers during the design phase is leading to difficulties in consistently meeting the acoustic specifications for the manufacturers. This paper presents a numerical methodology to identify the vibration characteristics and predict the sound pressure levels from the load-noise of large power transformers. The methodology involves development of the vibro-acoustic finite element model of a transformer including the excitations of the forces present in a transformer’s active part. Additionally, the application of the vibro-acoustic modelling methodology with regard to the computer-aided design of transformers has been presented through a sensitivity analysis. The validation of the vibro-acoustic modelling scheme detailed in this paper has been conducted with appropriate experimental measurements. The measurements were conducted on several manufactured transformers. Specifically, it has been shown that experimentally determined modal tests and sound pressure levels are in good agreement with numerical results. Through this process, the analysis technology suggested in this paper was validated.
Plasma Interaction and Dynamic Monitoring of Hybrid Laser-Arc Welding of Large-Length Continuous Welds in Large Cruise Ships
Authors: Li Liangfeng , Shen Jie , Zhang Yansong
Published: February 2024

Hybrid laser-arc welding, which combines the advantages of arc and laser welding, is a typical small heat input welding method for thin-walled structures like large cruise ships. In hybrid laser-arc welding, the interaction of the laser and arc plasma can improve the thermal efficiency of welding and reduce the plasma shielding effect in laser ablation. However, the length of welds in cruise ships is usually several meters long, making the shielding effect of plasma on laser far more complicated than that of short welds. The molten pool and plasma become inconsistent during the welding process of large-scale continuous welds due to thermal accumulation and parameter fluctuation, which increases the plasma’s shielding effect and may cause welding defects such as undercuts and poor shape. In this paper, large cruise structures with a length of 300 mm to 3000 mm were examined for welding quality consistency in the laser-arc hybrid welding process, and the mechanism of weld morphology change in continuous welding is revealed. A high-speed camera was used to capture images of the instantaneous plasma during the hybrid laser-arc welding of these large cruise ship structures. Various methods such as machine vision and SVR models were employed to analyze the dynamic characteristics of plasma and the plasma shielding effect during welding. Finally, the effect of weld length on plasma interaction during hybrid laser-arc welding was discussed. The results revealed that the dynamic changes of plasma were closely related to the length of welds. During continuous welding of a 3m-long seam, the maximum reduction rate of weld width can reach 26.8%. It is necessary to adjust the welding parameters during the welding process to ensure the quality of the weld when performing long-seam continuous welding. The use of high-speed cameras provides a straightforward and efficient approach to monitoring the plasma interaction during welding.
Comparing Experimental Results for Large Particle Separation From Non-Newtonian Slurries Using Full and Tapered Bump Arrays
Authors: Bamberger Judith Ann , Pease Leonard F. , Serkowski Jason E. , Minette Michael J. , Burns Carolyn A.
Published: February 2024

To separate particles from carrier fluids, arrays of staggered posts inserted into the flow stream can be employed. The smaller particles follow the flow stream while the larger particles move laterally to one side. During flow, the concentration of particulate increases in one direction and decreases in the other traverse direction. This technique separates the particles from the carrier fluid.

Experiments using a slurry with non-Newtonian rheology were conducted to evaluate large particle separation from the non-Newtonian carrier fluid using bump arrays. Bentonite kaolin clay slurry with non-Newtonian rheology was spiked with large diameter inert glass particles. Experiments with flow through lateral displacement arrays evaluated the performance of particle separation using two array configurations: a full array with all posts and a tapered array with posts removed in a triangular portion of the array past the rows of anticipated particle of separation. The posts are staggered to promote particle segregation to one side of the flow channel. Using this type of array to remove particles from non-Newtonian yield stress slurries is novel and we present unique results. In this paper, the performance of full and tapered arrays are compared. These results have many industrial applications including removing particles from slurries of nuclear waste. Large particle removal could be an important step in waste processing.
Louver Fin Design for Condensate Management in Dehumidifying Heat Exchangers
Authors: Jones Alan L. , Park Younggil
Published: February 2024

The thermal-hydraulic performance of flat-tube, louver-fin heat exchangers is generally superior to their round-tube counterparts. However, under a dehumidifying condition, a flat-tube, louver-fin heat exchanger suffers a significant reduction of sensible heat transfer coefficient. Typical brazed aluminum heat exchangers have narrow airflow passages that make the core susceptible for the formation of condensate blockages. In this paper, the possibility of mitigating the performance degradation of wet louver-fin heat exchangers are explored by a modeling analysis. If louver spacing, a key length scale responsible for wet performance degradation, is increased beyond a critical value, the formation of condensate blockage between the louvers can be suppressed.

A simplified modeling of 2D capillary interface for condensate bridge is used to identify the critical condition for condensate blockage elimination, which is presented as a stability map. From exploring 486 louver fin heat exchanger designs, several promising designs are identified that are free of condensate inter-louver bridges. The performance of these promising designs are compared with sample heat exchaners reported in the literature using heat exchanger correlations in the literature and selected heat exchanger performance evaluation criteria (PEC).
Application of Sparse Estimation for Best Estimate Plus Uncertainty Analysis of a Small Break LOCA in PWRs
Authors: Kinoshita Ikuo
Published: February 2024

To reduce the computational demand in the Best Estimate Plus Uncertainty analysis, an accurate and inexpensive surrogate model is expected to be used to replace the RELAP5 code for rapid determination of the uncertainties on the figure of merit of interest. One of the problems associated with the application of a surrogate model is overfitting. To ensure confidence in the model prediction, it is crucial to assess the generalized performance of the surrogate model. In this study, a surrogate model was generated from a small sample of a RELAP5 code uncertainty analysis on peak cladding temperature (PCT) for a small break LOCA scenario in PWRs. The surrogate model was constructed using second order polynomial regression combined with the Lasso method and the cross validation technique. The accuracy of uncertainty quantification of PCT by the surrogate model was investigated by comparing its results with the RELAP5 analysis results. Appropriate selection and use of the hyperparameter of the L1 regularization overcame overfitting for the regression model and made the model more generalized for predicting the 95th percentile value of PCT by the RELAP5 analysis results. The cross validation method was used for the training data set to select the hyperparameter with which the Lasso regression achieves higher generalization performance for predicting the cumulative distribution function of PCTs. It was confirmed that using the hyperparameter with which the 95th percentile PCT error was estimated to be the smallest by cross validation, the predicted 95th percentile value of PCT by the Lasso regression agreed well with the 95th percentile value of PCT by the RELAP5 analysis results.