bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of Tandem Rotor Dual Wake Interaction With Downstream Stator Under Unsteady Numerical Approach
Authors: Singh Ajey , Mistry Chetan 
Published: February 2024

Abstract
This paper highlights the intricate rotor-stator interaction between a tandem bladed rotor and a single-bladed stator in the light of unsteady numerical simulations. With the promising pressure rise capability of the tandem bladed compressor stage, it becomes obligatory to investigate the rotor-stator interaction owing to its dominant effect on overall stage performance. The multi-passage rotor-stator unsteady simulations have been performed using transformation methods in ANSYS CFX. Due to the presence of two highly loaded rotor blades, the tandem rotor exhibits peculiar rotor-stator interaction in terms of multiple wake impingement on the stator. Incorporating tandem blading on the rotor instead of the stator (which is more common) has some aerodynamic leverage but it also constricts the design envelope in terms of choice of blade axial overlap and percentage pitch. This results in managing the desired loading by varying blade overlap from hub to shroud with careful loading distribution. The variation of aerodynamic loading from hub to tip for both the rotor blades results in spanwise varying wake strength. The initially distinct wake structures merge with a certain frequency resulting into a thicker wake. This changes the incidence on the downstream stator. Additionally, the rotor blades are highly loaded in the tip region which results in the complex interaction between end-wall boundary layer and tip leakage flow. Cumulatively, these conditions constitute a challenging aerodynamic field for the downstream stator. The incidence change caused by the velocity defect at the rotor exit plane affects the aerodynamic loading of the stator. The tip leakage flow behavior is entirely different in a tandem bladed rotor due to the presence of blade overlap. The study focuses on the qualitative interaction between the rotor wakes and blockage with the downstream stator and put forwards some aspects of the tandem rotor-single stator stage design especially for core compressors of aero engine application.
Implementation of Flow Control Methods for Design of Connecting Duct of Annular Sector Cascade Tunnel
Authors: Bhavsar Hardikkumar , Mistry Chetan S. 
Published: February 2024

Abstract
In order to investigate the part clearance leakage flow field through a variable area nozzle turbine (VANT), an experimental setup of the annular sector cascade (ASC) with eight numbers of passages is being developed. The second stage low-pressure turbine stator from Energy Efficient Engine proposed by Pratt and Whitney was selected and modified for the VANT concept. The intermediate turbine duct (ITD) – connecting the high-pressure turbine with the low-pressure turbine was inevitable to be incorporated between the wind tunnel and ASC test section for the following reasons: a) ITD will ensure the geometric continuity on the hub and casing end-walls, and b) it will provide realistic entry flow field with radial pressure gradient. The diverging shape of the ITD with continuously increasing mean radius imposes a major challenge to achieving the required inlet flow angle with periodicity at the entry of the ASC. Hence, the present study focuses on the challenging work of modifying the existing annular ITD to achieve the required inlet flow for ASC. The various geometries of the ITD, including different flow control methods, were numerically analyzed using commercial software ANSYS CFX®. The flow field of the numerical simulations at multiple locations was analyzed using flow angle and its distribution, velocity streamlines, static pressure recovery coefficient, and total pressure loss coefficient. It was found that the IGVs direct the flow through the ITD, and approximately the required flow condition with periodicity was achieved at the entry of the test vane cascade. As an active flow control method, an opening slot was modelled on the casing end-wall at the upstream region of the test vane cascade. However, the numerical analysis shows an adverse effect on the flow angle distribution at the entry of the cascade. The change in axial spacing between IGVs and the test vane cascade shows a negligible effect on the cascade entry flow field.
Influence of Mechanical Properties on Compressor Rotor Blade Fatigue Life : A Reliability Approach
Authors: Muthu S. Esakki , K Ramesh , Degaonkar Girish K , C. A. Neeralagi , Roy Hardik 
Published: February 2024

Abstract
The compressor blade which operates at higher pressure and higher temperature conditions are made out of titanium alloys. The fatigue life of the compressor blade depends on load, geometry and material. In material, parameters like Young’s modulus, ultimate tensile strength and fatigue strength plays a vital role in fatigue life. The scatter / variation in each parameter’s influence the fatigue life. The compressor rotor blade under study is analyzed for material properties scatter. The stress scatter and corresponding material parameters were used to estimate the fatigue life scatter. The reliability analysis was carried out on fatigue scatter. The influence of each material parameter was studied on fatigue life of the blade. The parametric analysis was done to find out the influence of each mechanical properties effect on compressor blade fatigue life.
Effect of Variable Tip Clearance at the Inlet and Exit of a Radial In-Flow Turbine
Authors: Harish D. , Bharathan R. D. , Kumar C. Kishore , Kapil Sharad , Jehoash Jatin Kumar , Prasad D. Kishore , Ramana Murty S. V. 
Published: February 2024

Abstract
Radial inflow turbines are widely used in turbochargers, in which they drive the centrifugal compressor, and in auxiliary power units (APUs). Losses in a radial inflow turbine are comprised of profile losses, secondary losses and clearance losses. Therefore, in order to increase the efficiency of the radial inflow turbine, it is necessary to keep the losses due to clearance too as low as possible. There are two clearances in a typical radial turbine — Tip clearance and Hub clearance. The effects of variable tip clearance at the inlet and exit of a radial turbine are investigated, and the relative losses associated with each clearance variation are quantified. Hub clearance is formed due to scalloping. This is carried out to decrease the hub stress and polar moment of inertia, which leads to additional losses. In this paper, the effect of variable tip clearance and scalloping on the performance of a radial turbine is studied through use of numerical simulation.
Non-Axisymmetric Stator Hub Endwall Contouring for Tandem Bladed Axial Compressor Stage
Authors: S. Priyanka , Mistry Chetan S. , Roy Arnab 
Published: February 2024

Abstract
Secondary flow within the compressor stator passage induces 3D flow separation and reduces the flow passage which in turn decreases the efficiency, operating range and pressure rise capacity of the compressor stage. The aim of this study is to reduce the effects of secondary flow losses near the lower span region by implementing a Non-Axisymmetric Hub Endwall contour. The linear stator hub cascade is used by utilizing point displacement method in conjunction with optimization. The numerical simulation was performed using ANSYS CFX® to solve steady state 3D-RANS equation with SST K-ω turbulence model for a single blade passage with translational periodicity, Parameterization of Hub endwall was done using commercial software CAESES® using control points based NURBS curves. The optimization for the NAEW was performed using ANSYS Direct optimization by availing the ASO (Adaptive Single Objective) optimization method, which is the combination of optimal space filling, kriging response surfaces and MISQP (Mixed-integer sequential quadratic programming). The optimization has been done for the design incidence case, which resulted in the reduction of total pressure loss coefficient of maximum 1.2%. The same optimized endwall contour has been numerically studied for the different incidence angles of −4 degree and +4 degree. It was found at the −4 degree incidence angle, the blade stall has been removed completely. The change in the endwall pressure gradient and thereby spanwise pressure gradient bring the change in the flow structure. Reduction of total pressure loss coefficient increases with the increase in the positive incidence angle which is due to the reduction of loss coefficient along the spanwise direction increases. The endwall contour of Design A found to be more favorable compared to other profiles.
Numerical Investigation on the Optimization of Angled Effusion Holes of Liner Assembly of Micro Gas Turbine Engine Combustor
Authors: Shahi Nivedita , Divyansh Ayush , Tyagi Vatsal , K. P. Shanmugadas 
Published: February 2024

Abstract
The present work investigates the flow topology generated by the angled effusion holes of a compact combustor liner assembly. The combustor geometry is designed in a way that the flow conditions are selected corresponding to a 1 KN thrust for a micro gas turbine engine. The combustor operates based on a lean burn combustion technology in which 70% of the air is admitted through the injector and the remaining is sent to the annulus passage of the liner assembly which aids in cooling the liner walls. The angled effusion holes were designed initially on the basis of existing empirical formulas and further iterated according to the numerical analysis to provide an optimum cooling pattern across the combustor length. Optimization of the cooling hole geometry is critical to achieve the desired film cooling effectiveness. The various parameters with important effect on film cooling effectiveness include positioning of holes, dimension, shape (elliptical, circular, or other), number of holes. A detailed parametric study is conducted on a number of geometrical features related to the liner holes such as hole diameter, shape, angle with respect to liner axis, the position of holes, number of rows of holes, the transverse and axial pitch. The combustor is operating at a maximum pressure of 14 bar with a mass flow rate 0.2206 Kg/s coming from the compressor at a temperature of 595K based on the Brayton cycle analysis done for 1kN thrust. The combustor liner is operated at zero pressure drop focusing the geometry in absence of injector where 4 % pressure drop is considered through annulus passage. The combustor is having 70-30 % mass flow split and a uniform temperature of 900K is taken inside the combustion chamber. The combustor cooling is optimized for the minimum pressure drop across the liner. The study is carried out using numerical analysis on the lean burn liner system designed to optimize wall temperature conditions to have control over temperature of emissions reaching the turbine blades and have better service life as a result.
The circular holes of 1.82 mm diameter inclined at an angle of 18-degree result in the best film cooling effectiveness among all geometries. This is decided basis of the temperature plots, pressure drop through holes, and pressure drop across the entry and exit of holes favorable for optimal film cooling effectiveness.
Heat Transfer Radiation Coefficient Measurements on Different Shaped Sections of a Piping System
Authors: Elsharafi Mahmoud , Criss Ty , Vora Nevil , Alkathiri Abdullah 
Published: February 2024

Abstract
The understanding of heat transfer is very important to the success of any project or product dealing with thermal processes whether as a product or an unintended byproduct. There are three subcategories within heat transfer. These are convection, conduction, and radiation. Radiation, which is the purpose of our research, deals with electromagnetic waves being emitted as the charges within the particles themselves move. These waves radiate to other surfaces or the atmosphere which transfer thermal energy from which it was generated. Radiation is dependent on several factors, such as shape, and material properties. The goal of this project was to create a model of the temperature and heat losses associated with a typical piping system consisting of different shaped pipes. This would allow improvement in existing systems through the recommendations gathered from our research to increase efficiency and maximize or minimize thermal energy loss depending on the goal of the specific piping system. To do this, an apparatus consisting of three different shaped pipes will have a heated gaseous medium flowing through it, in which the temperature will be recorded, and analyzed. The focal point of the data would be the measured temperature from thermocouples on each shaped pipe. By designing a piping system consistent with those in industry, we can discover more efficient ways to contain and/or utilize thermal energy in productive ways through the use of unconventional geometrical shaped pipes.
A Computational Fluid Dynamics Approach for Hospitalization at Home During the Pandemic
Authors: Al-Rawi Mohammad , Wang Lulu , Zhou Hong 
Published: February 2024

Abstract
Recently due to the COVID-19 pandemic, caused by the SARS-COV-2 virus which spreads via airborne transmission, there has been greater attention on the concept of acute hospitalization at home (HaH). Whilst HaH has been investigated for over three decades, the need for development of this method was highlighted by the pandemic which overloaded tertiary (hospital) health care services. HaH requires advanced medical equipment that is not always readily available for non-wealthy households; however middle-class households have the means to purchase less advanced ventilation equipment to treat the air, for example, using HEPA filters in a particulate air cleaner (CC 410). To assess the ventilation efficiency, Computational Fluid Dynamics (CFD) modelling using ANSYS CFX 2022 R2 is applied and then validated experimentally to ensure the reduction of CO2 concentration in the HaH space in terms of age of air (AoA). Additionally, thermal comfort parameters were assessed using CFD modelling and validated experimentally. The predicted mean vote (PMV) and percentage dissatisfaction (PPD) while running the device were aligned with the ASHRAE 55 standard to ensure users would not switch off the device based on dissatisfaction or discomfort. The results show that the device improved the AoA in 105 seconds of the time of CO2 produced by one of the occupants in the room. This type of analysis is helpful to reduce the time during a crucial period of treatment, when infected occupants are hospitalized at home up to a maximum space of 140 m2.
Mesh Independency Analysis for Aorta Geometry Using a Computational Modelling Approach
Authors: AL-Rawi Mohammad , Belkacemi Djelloul , Al-Jumaily Ahmed M. 
Published: February 2024

Abstract
Cardiovascular diseases have been investigated computationally by biomedical engineers to find new diagnoses for these diseases. Computationally simulating diseases occurring at the aorta artery and more specifically aortic arch, requires a comprehensive workstation computer with an advanced processor and graphics card to create a suitable mesh for the elements. The mesh process is essential: sufficient granularity of the mesh increases simulation accuracy, providing the ability to solve the governing partial differential equations in an increasingly realistic three-dimensional form in the allocated cell. For the complicated geometry of an artery, it is essential to reach a suitable mesh, validated with clinical data, to ensure the computational fluid dynamics model (CFD) has minimal error. Therefore, in this study we investigated different types of mesh, applying different element sizes, and comparing the results with clinical data for a healthy aorta using ANSYS 2021 R1-Fluent. Tetrahedral and Polyhedral meshes were applied for the same element size (1.0, 0.8 and 0.6 mm) with a growth rate of 1.2 and 10 boundary layers for the artery wall using the same boundary conditions to investigate the pressure, velocity waveforms and wall shear stress (WSS) at the aortic arch. The boundary conditions used in this study are the blood flow waveform applied at the ascending aorta and iliac pressure waveform applied at the iliac bifurcation based on clinical data. The results show that the Tetrahedral mesh obtained higher average pressure values with 2.8% at the systolic; however, the diastolic pressure values are the same for the 1 mm element size. Comparing that to the element size of 0.8 and 0.6 mm, the pressure difference was 2.9% and 3.1% respectively for the systolic pressure with a phase time of 0.01 s.
Targeted Particle Fractionation Technologies: Proof of Concept
Authors: Minette Michael J. , Burns Carolyn A. , Phillips Nathan R. J. , Davidson Casie L. , Bamberger Judith A. , Serkowski Jason E. , Pease Leonard F. 
Published: February 2024

Abstract
Most methods of particle-size separation involve particle fractionation which is often done by filtration or the use of screens. This paper provides proof-of-concept testing for new in-pipe particle fractionation technologies that can be used at laboratory to industrial scales. These technologies are extensions of recent advancements in bump arrays as well as testing of new inline angled-to-the-flow-slats separation technologies.
Experiments were conducted for three targeted particle fractionation technologies to evaluate the in-pipe removal of oversized sands in Newtonian slurries prior to the introduction to bump arrays. This mesofluidic system uses an array of staggered posts at controlled offset angle to establish flow streams within the device. The methods and results of these experiments are described in this paper. This information could be applied in most industrial and laboratory systems to rapidly remove oversized particles from a flowing slurry.
Determination of Material Parameters of In740H Under Different Experimental Situations Using Chaboche Model
Authors: Haddadi Elnaz , Zimnoch Michael , Tabarraei Alireza 
Published: February 2024

Abstract
This paper presents the development and validation of a Chaboche unified viscoplastic constitutive model, incorporating both nonlinear isotropic and kinematic hardening rules, to accurately predict the stress-strain behavior of Inconel Alloy 740H. Inconel 740H is a high-temperature, nickel-based superalloy known for its exceptional mechanical strength, creep resistance, and corrosion resistance, making it highly suitable for extreme environmental applications. The research focuses on determining the material parameters of the unified Chaboche constitutive model and validating its accuracy using experimental data obtained from uniaxial strain-controlled loading tests. The experimental data covers a wide temperature range from room temperature up to 1112 °F, with strain ranges spanning from 0.75% to 1%. The results demonstrate the model’s effectiveness in capturing the complex mechanical behavior of Inconel Alloy 740H under varying conditions, providing a valuable tool for design and engineering applications in high-temperature environments.
Assessing Acoustic Piping Vibration on a Naphtha Splitter Column Overhead Line
Authors: Herrera Sierralta Carlos , Alsokairan Ibraheem Saud 
Published: February 2024

Abstract
In gas piping systems exposed to pressure drops, the high frequency generated by the flow could provoke acoustic induced vibration.
Acoustic induced fatigue is a particular concern as it could lead to catastrophic failure of piping components in a significant short period of time in some cases in a matter of days, hours or minutes. The reason being that this type of excitation can generate high frequency vibration of the pipe wall which takes the form of pipe wall flexural modes, resulting in high dynamic stresses with the potential of generate fatigue at circumferential discontinuities on pipe wall.
The typical approach of the designers is to conduct the acoustic induced vibration (AIV) screening by calculating the acoustic power level at the source (PWL) as per the Energy Institute’s screening method.
Alternatively, there is a different methodology proposed by Eisinger, which is based on an acoustic induced vibration fatigue chart corresponding to the relationship between the acoustic energy parameter in terms of the downstream Mach number, pressure drop, diameter and wall thickness.
While the aforementioned screening methods can be deemed sufficient during the detailed engineering phase of the facility, practitioners are advised to bear in mind, that any anomaly detected during commissioning and start-up after construction of the piping system should be thoroughly assessed by a dedicated study, including the verification that the “as-built” matches the issued for construction documentation and the thorough analysis of vibration data, etc. collected at field.
This paper describes a case study of a piping system that during the start-up of the facility was observed with abnormal levels of noise and it was perceived with a relatively high frequency piping vibration.
The system in question was a particular concern as the AIV screening methods were circa the border line of the acceptability criteria for both the Energy Institute and Eisinger Method, this finding plus the abnormal vibration and noise at field raised the doubt of the owner of whether or not the system was at risk of having an acoustic induced fatigue failure.
Consequently, the system was thoroughly studied by collecting and analyzing vibration and strain gauges data from the field to primordially corroborate the original detailed design, and to conduct fatigue life predictions that allowed to determine that the system was not at risk of fatigue.
Challenges of Purging Air With Natural Gas and Hydrogen Blends in Pipe Segments
Authors: Botros Kamal K. , Hill Colin , Ziade Paul , Johansen Craig , Van Boven Greg 
Published: February 2024

Abstract
The aspiration for blending hydrogen (H2) into natural gas (NG) in gas transmission systems is high and is happening globally. However, several design and operational aspects need to be developed to ensure the safe and reliable delivery of these blends to the end users. One of these aspects is the development of an effective purging procedure of air with NG+H2 blends during the commissioning of a pipe section. The present research examines various aspects of the purging procedures and attempts to address salient parameters and conditions when the NG+H2 blend is the purging gas. Three principal aspects were investigated, namely: 1) The stratification velocities of the air and gas wave fronts for different NG+H2 blend ratios, 2) The interfacial turbulent diffusivity coefficients between air and NG+H2 blends that determine the extent of the mixing spread as purging progresses, and 3) The applicability of the minimum stratification velocity to smaller pipe sizes ≤ NPS 4. The present investigation found that the stratification velocity of the air wave is higher than that of the NG+H2 wave, and both deviate from the classical value corresponding to Fr # = 0.707 assumed in AGA Purging Principles and Practices. Initial results of the diffusivity coefficients show an upward deviation from that currently in use in the gas transmission industry.