bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Relationships Between Absorption, Alterability and Granulation of Coarse Aggregates from Different Lithologies from Southern Brazil
Authors: Ceccato Haline Dugolin , Back Ana Helena , Sagrilo Amanda Vielmo , Nummer Andrea Valli , Pinheiro Rinaldo José Barbosa , Baroni Magnos 
Published: February 2024

This paper studies the mathematical and statistical correlations between absorption, alterability, and granulation of aggregates from different lithological origins in southern Brazil. In order to achieve this goal, a petrographic analysis of the aggregates was carried out, in addition to a qualitative evaluation of granulation/alterability and absorption tests for the 1/2” (12.5 mm), 3/8” (9.5 mm), and #4 (4.75 mm) sieve. Statistical analysis relied on the Shapiro-Wilk and Breusch-Pagan tests, using R-Studio software. The results show that the variables “granulation” and “alteration” exhibit satisfactory correlations with the variable “absorption”, indicating that the larger the grain size the lower the absorption, while the higher the alteration the higher the absorption. The more the particle size decreases, the greater the variable “absorption” can explain “granulation”. Regarding the alteration and absorption degree, the analysis was not feasible, since the analyzed group that included high absorption and low alteration volcanic rocks could modify the trend, contradicting the consensus that the more altered the rock, the more it absorbs. Overall, the employed methodology proved to be satisfactory for the database analyzed, with the suggestion of increasing the number of samples in future studies.
Adaptive Tracking Control of Robotic Manipulator Subjected to Actuator Saturation and Partial Loss of Effectiveness
Authors: Ngo Van-Tam , Liu Yen-Chen 
Published: February 2024

Abstract
This paper introduces an adaptive control design tailored for robotic systems described by Euler–Lagrange equations under actuator saturation and partial loss of effectiveness. The adaptive law put forth not only retains conventional control properties but also extends its scope to effectively address challenges posed by actuator saturation and partial loss of effectiveness. The framework’s primary focus is on bolstering system robustness, thereby ensuring the achievement of uniformly ultimate bounded tracking errors. The stability and convergence of the system’s behavior are rigorously established through the application of the Lyapunov analysis technique. Moreover, the effectiveness and superiority of the introduced framework are compellingly demonstrated through a series of practical simulations and experimental instances.
Investigation on Mechanical and Fracture Behavior of Magnesium Composite Reinforced With Hybrid Fly Ash Particulates Synthesized via Friction Stir Processing Route
Authors: Sagar Prem , Sangwan Sushma , Handa Amit 
Published: February 2024

Abstract
Utilizing waste materials like fly ash in the creation of lightweight magnesium metal matrix composites with a high strength-to-weight ratio is encouraged by the rising demand for in-expensive reinforcements. In the current study, friction stir processing (FSP) was employed to synthesize magnesium surface composites via incorporating hybrid reinforcement particles, including nano titanium carbide and fly ash. The synthesized composite material underwent examination through microscopic images of the stir zone and assessments of microhardness, tensile strength, compressive strength, electrical and thermal conductance, and wear behavior. The results revealed a notable refinement in grain size and a simultaneous improvement in mechanical properties. Notably, there was a substantial increase in wear resistance attributed to the increased hardness and uniform dispersion of hybrid reinforcements within the surface composite. The results demonstrate that the inclusion of reinforcements in magnesium-based alloy led to an enhancement in fracture toughness, mitigation of crack propagation, and an overall improvement in fracture resistance to catastrophic failure.
Combined Cycle Power Plant Economic Evaluation With Hydrogen and Ammonia As Alternate Fuel
Authors: Pichandi Muruganandam , Nandagopal Pugalenthi , Duerr Matthias , Singh Surendra 
Published: February 2024

Abstract
In Power Generation (PG) Industry, the global Original Equipment Manufacturers (OEMs) are focusing to lower their carbon emissions to reduce the impact of global warming to meet the famous Paris agreement goals and targets. At present approximately 25% of Green House Gases (GHG) are emitted during electricity generation, in that 62% contributed by coal & natural gas power plants [1]. Current Gas Turbines (GTs) burn Natural gas (NG) as primary fuel which contains Carbons, obviously emits CO2 as byproduct. The whole industry is investing time and money to research on reducing CO2 emission close to zero by 2040 and checking the feasibilities of using alternate fuels in power generation.
The current study reported here does not consider any design or technology changes required to use H2 or NH3 as an alternate/blending fuel for GTs but attempts to provide some understandings and directions on cost perspective. The approach of this study is to blend the different types of H2 or NH3 with NG as fuel, evaluate the life cycle cost of combined cycle power plant and other benefits like decarbonization advantages, etc. As the H2 or NH3 fuel is classified in different color codes based on the source of production process, the study considered Black/Grey/Blue/Green Hydrogen and Grey/Blue/Green Ammonia types only. PG Industry will focus on availability of Green Hydrogen/Ammonia as the production process does not emit CO2. However, a recent market study points out that Green H2 and NH3 are costlier than NG fuel. The goal of H2 or NH3 industry is to reduce the production cost of Green H2 or NH3 to make cost competitive technologies.
This study will provide insights to Gas Turbine OEMs to predict the feasible H2 or NH3 blend with NG on their engines with the existing technical capabilities by considering the cost benefits and savings based on geographical CO2 penalty rates.
Additionally, OEMs will get understandings on H2 or NH3 fuel selection among different types and can focus to reduce the production cost of green H2 or NH3 to make as economically feasible alternate fuel in GTs.
Experimental Analysis and Reduced Order Modelling of Merging Flames
Authors: Dutta Subrata , Chakraborty Arnab , Mukherjee Auronil , Mondal Sirshendu 
Published: February 2024

Abstract
The present study investigates the dynamics of merging flames, a prevalent phenomenon in reacting flow systems. We employ two different model order reduction techniques to uncover the underlying spatiotemporal features: Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD). These approaches extract dominant flame modes, frequencies, and coherent structures within the reacting zone. We capture the intricate behavior of merging flames by conducting experiments with candle flames, which serve as a simplified yet representative model. By applying DMD to high-dimensional flame data, we successfully extracted coherent structures and dominant modes of variability. This allowed us to characterize the frequencies and spatial structures of the merging flame dynamics in more detail. Additionally, we utilized DMD to construct reduced-order models, which accurately captured the dominant flame modes. These models enable us to predict future flame behavior and design effective control strategies for flame stabilization. The combined use of DMD and POD enhances the analysis by comprehensively understanding the merging flame behavior. DMD uncovers the temporal evolution and characteristic frequencies, while POD identifies the spatial structures and energy distribution among different modes. This integrated approach allows us to construct reduced-order models that accurately capture the dominant flame modes and their corresponding frequencies, facilitating future predictions and control strategies for flame stabilization.
Design of Cooling Air Flow and Thermal Analysis for an Afterburner V-Gutter
Authors: Aadhithya M. Azith , Rao K. V. L. Narayana , Davis Antonio , Degaonkar Girish K. 
Published: February 2024

Abstract
Modern military aircraft engines are designed for high thrust, low specific fuel consumption, small engine size, and high thrust-to-weight ratio. Afterburner is a thrust augmentation device that is used in all modern military aircraft engines. Afterburners are required for aircrafts to take-off from short runways with heavy payloads and to perform combat manoeuvres. Light up and flame stabilization are the key requirements for any afterburner design. From the literature review, V-gutters are known to be the best flame holding devices based on the blockage, flame spread and combustion stability criteria. For the fifth-generation aero engines, the gas temperature at the entry of the afterburner system is higher than the V-gutter material’s allowable limit. Typical turbine entry gas temperatures are of order of 1850 K and reduces to a value of 1100 K at afterburner inlet which necessitates cooling of the V-gutter structure. Uncooled or bare v-gutters are prone to oxidation and damage due to thermal fatigue. The cooling of v-gutter helps to prevent the oxidation and improve the life.
In this work, various cooling design configurations for the given V-gutter have been investigated using jet impingement and film cooling techniques. This study aims to develop a cooling arrangement to reduce the average uncooled V-gutter metal temperature from 950 K to less than 750 K by using the bypass air at 3 bar pressure and 550 K temperature. The corresponding average cooling effectiveness of 0.5 is to be achieved. The design of experiments (DOE) methods used for computational studies like Monte Carlo and Montgomery to validate and analyse the designs are computationally intensive and time consuming. Hence, a parametric approach is used for optimization of cooling flow design to achieve the desired temperatures and cooling effectiveness. Conjugate Heat Transfer (CHT) analysis is performed on four distinct cooling configurations with different cooling hole diameters and their arrangement. The first three cooling configurations 1 to 3 do not meet the design requirement. The metal temperature of the V-gutter for cooling design configuration 4a is in the range of 699 K – 859 K with an average metal temperature of 788 K. The cooling design configuration 4b showed the best cooling performance with the V-gutter metal temperature in the range of 580 K – 840 K and an average temperature of 755 K. The corresponding cooling effectiveness achieved is 0.53 with lowest cooling air mass flow requirement is 0.45% of afterburner inlet flow. Thus, it is concluded that the V-gutter cooling configuration 4b meets the design intend.
Enhancing Turbine Inlet Temperature Prediction in Single Shaft Combined Cycle Power Plants Using Soft Sensor: A Grey-Box Modelling Approach
Authors: Nandagopal Pugalenthi , More Manjunath , Relan Rishi , Singh Gurdev 
Published: February 2024

Abstract
Measuring the turbine inlet temperature (TIT) in gas turbines is daunting due to the exceptionally high temperatures involved. Using thermocouples is not a cost-effective solution for directly measuring TIT, and their durability over extended periods is also a challenge. Online, near real-time accurate prediction of TIT and its close-loop feedback control is critical due to its significant impact on the rate of power generation and on the lifespan of the hot gas path components in gas turbines. Any increase in TIT can cause a reduction in their lifespan, while a decrease can result in a power loss for the customer. To compute TIT, mass and energy balance approaches are used iteratively online in near real-time environment, which relies on continuous measurement of critical signals from gas turbines. These signals include ambient conditions, gas turbine (GT) output, fuel flow, compressor outlet temperature, turbine exit temperature etc.
In a multi-shaft combined cycle power plant, gas turbine power and steam turbine power are measured separately, simplifying the prediction of gas turbine inlet temperature (TIT). However, in a single-shaft power plant, where both turbines’ power output is combined, predicting TIT becomes challenging. Accurate TIT prediction is crucial for effective gas turbine control in single-shaft combined cycle units. Therefore, a rigorous validation methodology using gas turbine fleet data is necessary to ensure efficient operation.
A new approach for predicting TIT in single-shaft power plants has been developed and validated using data from a multi-shaft plant. The paper describes the methodology, called the Heuristic Transfer function, which utilizes prior domain information for TIT prediction and its validation process using fleet data. Despite using the Heuristic Transfer function, the accuracy and variance of the predicted TIT over time did not meet acceptable thresholds.
To address the concerns of prediction inaccuracy and non-stationarity over time, a novel approach is proposed in the paper. It involves combining the baseline heuristic transfer function with a stochastic model to achieve accurate and time-invariant predictions. The stochastic model is developed using residuals from the heuristic transfer function, providing a more robust and reliable TIT prediction method.
High-Speed Centrifugal Compressor Performance Evaluation With Leaning Diffuser Vane Configurations
Authors: Niveditha Porika , Das Shyama Prasad 
Published: February 2024

Abstract
The diffuser vane of the high-speed centrifugal compressor is subjected to lean in the current study’s numerical analyses.Lean can be defined as a shift in the stagger angle in the vane’s span-wise direction. Three different leans, including lean at the vane’s leading edge, trailing edge, and lean with regard to the centroid of the vane, are examined in the current study. When compared to the base scenario, a diffuser with a lean on CG of −4° and +4° improved the isentropic efficiency of the compressor by 4.7% while maintaining a stable operating range. When compared to a vaned diffuser without lean, the maximum flow limit is raised by adding lean to the diffuser. In the case of leading edge lean, static pressure recovery improved by 1.63% and 0.98% at −4° and +4° lean angles, respectively, as compared to a vaned diffuser without lean pressure recovery at the design condition.
Secondary Losses Mitigation using End-Wall Contouring for LPT Nozzle Vane Cascade
Authors: Koiri Maurya Shivkumar , Mistry Chetan S. 
Published: February 2024

Abstract
By applying the inventive forms of the end-wall between the turbine vane/blade passage, known as end-wall contouring, sought to solve the flow aerodynamics near the end-wall area of the vane/blade. The benefits of a contoured end-wall are not restricted to the area immediately adjacent to it; they also contribute to an improvement in the vane/blade’s overall performance. But careful design is necessary due to the LP turbine’s complicated flow and different operating conditions. The primary goals of this paper were to investigate secondary flow creation and its impact on the flow field as well as to identify the region where end-wall contouring placement can help to lessen unfavorable characteristics in terms of losses. The flow behavior close to the end-wall region is significantly impacted by the incidence angle change from negative to positive. Losses are reduced when the incidence angle is negative, while they significantly increase when the incidence angle is positive. Utilizing the curved end-wall, the cross-passage pressure gradient is systematically managed to aid lower losses. Pitch-wise mass flow average secondary kinetic energy and total pressure loss coefficient were used as benchmarks to assess improvements in secondary flow loss. The selected contoured end-wall case showed 25 and 4.68 percent of Pitch-wise mass flow average secondary kinetic energy and total pressure loss coefficient improvement compare to the baseline case without end-wall contouring.
Numerical Simulation and Aerodynamics of a Fuel Flexible Injector for Micro-Gas Turbine Engines
Authors: Uniyal Shivam , Jamod Preetam , Divyansh Ayush , Singh Saket , K. P. Shanmugadas 
Published: February 2024

Abstract
The present work focuses on developing a novel injector concept for a fuel-flexible micro gas turbine engine that is sized for 1 kN thrust requirements. The lean burn fuel injection design is adopted from the available modern aero-engine combustors. The injector hardware comprises an assembly of pilot and main swirlers, which are arranged in clockwise and counter-clockwise directions having multiple fuel passages in between. The pilot consists of two axial swirlers arranged in clockwise and counterclockwise direction and main consists of one axial and two radial swirlers arranged in clockwise and counter-clockwise direction. As the name suggests both the liquid and gaseous fuel can be used in the assembly either separately or simultaneously. Both the fuels can be alternatively used depending on the thrust or required power operating conditions. The injector is designed using based on the area mass flow split ratio. The mass flow split of 24:76 is distributed between the pilot and main geometry. A simplex nozzle is used for atomizing the liquid fuel with an annular channel having plurality of swirling vanes around it for gaseous fuel makes up the pilot. The main injector has annular toroidal passageways for both liquid and gaseous fuel after an air resist path, which prevents the impingement of main liquid fuel on the wall of pilot. By iterating through several swirler geometrical parameters, numerical studies are made to optimize the recirculation zone structure that can atomize the liquid phase. The CFD formulation is based on the Reynolds-Averaged Navier-Stokes (RANS) equations for accounting turbulence with 0.075 kg/s mass flow rate having a pressure drop of 4% with the atmospheric pressure inside the injector as operating conditions. Standard k-ε model is practiced in computing and optimizing the results. The computational domain of diameter 100 mm, length 80 mm for the inlet and 200 mm, 160 mm for the outlet is used for capturing the aerodynamics of pilot. For main, the computational domain of diameter 100 mm, length 120 mm for the inlet and 200 mm, 200 mm for the outlet is used. The grid independence study for the injector assembly is also performed with varying number of elements from 1.7 million to 6.6 million and employing hybrid meshing method in order to get a suitable mesh for all the iterations. Recirculation zones are captured pilot, main and injector individually. After optimization and variation through various parameters mentioned below, the pilot and main is combined which formed a central toroidal recirculation zone (CTRZ) having a forward and a backward stagnation point with a counter-rotating shear layer at the injector exit. The crucial parameters for the formation of CTRZ’s optimization is the distance that acts as a mixing length between the exit pilot flare and main venturi exits and flow split between the pilot and main injector swirlers.
Internal and External Flow Characteristics on Variation of Swirl Strength for a Fuel Flexible Injector for Micro Gas Turbine Engines
Authors: Verma Abhishek , Jamod Preetam , Uniyal Shivam , Divyansh Ayush , K. P. Shanmugadas 
Published: February 2024

Abstract
The internal and external aerodynamics of fuel flexible lean burn gas turbine injector is numerically investigated to obtain a detailed understanding of the recirculation zone and shear layer characteristics. The injector geometry consists of a main and pilot swirlers that are organized in clockwise and anticlockwise orientations, with several fuel tubes interspersed. Two axial swirlers are positioned in the pilot in a clockwise and anticlockwise direction, while one axial and two radial swirlers are arranged in the main in a clockwise and anticlockwise manner. The area mass flow split ratio is used to construct the injector. There is a 30:70 mass flow split between the main geometry and the pilot geometry. The central toroidal recirculation zone (CTRZ) characteristics are captured for different swirl numbers, for pilot, main and the full injector. Individual recirculation zones are formed at the pilot and main mixers and they combine to form the required single CTRZ at full injector exit. The swirl number of swirlers of main and pilot was varied keeping other parameters constant and it is observed that a slight change in swirl number can impact changes in flow characteristics and CTRZ formation of both mixers of injector.
Aerodynamic Design Improvement of Centrifugal Compressor for Turbocharger Application
Authors: Purushothaman Kirubakaran , Varghese David , Chandramohan Kishore Kumar , Pandurangi Vidyadheesh , Pratap Ajay , Prasad D. Kishore 
Published: February 2024

Abstract
This paper focuses on the design improvement of a baseline centrifugal compressor used in a turbocharger. Centrifugal compressors are favored for their compactness, high pressure ratio output, and wide operating range. The baseline compressor was initially tested and achieved 72% efficiency and 17% surge margin. However, scope for improvement of efficiency and choke mass flow was identified in the new design. Geometric modifications were made to geometric parameters such as impeller blade angle progressions, impeller sweep back angle, vane wrap angle, and impeller exit width. The volute cross-section area was also reduced to improve overall efficiency. Through these modifications, a 5% improvement in efficiency and 3% improvement in choke mass flow were achieved. The modified compressor, tested in a gas stand facility, demonstrated an efficiency of 77% compared to the baseline’s 72% efficiency. These results highlight the importance of geometric parameters in optimizing the performance of centrifugal compressors in turbocharger applications.