bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Identification of Blade Tip Rub Forces at Engine Relevant Temperatures and Speeds
Authors: Reifsnyder Robin , Mathison Randall , D’Souza Kiran 
Published: August 2024

Abstract
Abradable casing liners are used to safely minimize the clearance between rotating turbomachinery blades and outer casings. Reduced clearance improves engine efficiency but can lead to more blade tip rub events. These blade tip rub interactions need to be well understood at engine relevant speeds and temperatures to safely design the engine. Advancements in experimental capabilities to meet these engine relevant conditions and the corresponding measurement and analysis tools will enable these developments. The Ohio State University Gas Turbine Laboratory, in collaboration with Pratt & Whitney, has expanded its capability in carrying out blade tip rubs to vary the temperature of the casing and blades for temperatures seen in a fan before rubs occur. This expansion of experimental capabilities requires a matching expansion of the methodologies used to analyze and interpret experimental data. In analyzing rubs at varying temperatures, it becomes imperative to understand how the temperature in the rub shoe affects the force transfer functions between the blades contacting the abradable liner and the load cells recording vibrations behind the casing. These transfer functions are necessary for obtaining the actual forces exerted upon the blades during the experiment but are originally obtained at room temperature. This paper examines how the load measuring unit’s frequency response function changes based on different temperature conditions and how force measurements are altered between similar tests at significantly different temperatures.
The Design, Fabrication, and Installation of the Inconel 740H Piping System for a 10 MW sCO2 Pilot Plant
Authors: Cunningham Seth , Rhodes Mitchell , Karg Bulnes Fernando , Wade Jonathan , Khawly George N. 
Published: August 2024

Abstract
The STEP (Supercritical Transformational Electric Power) 10 MWe sCO2 (supercritical CO2) pilot plant operates on a recompression cycle (RCBC) up to 715 °C and 255 bar at the turbine inlet. Initial testing phases for this facility will operate a simple-recuperated cycle with turbine inlet temperatures up to 500 °C as a stepwise risk mitigation. While the uncooled turbine design includes novel thermal management, the surrounding piping must also withstand these conditions. This paper summarizes the design, fabrication, and installation of the high temperature piping throughout the system. These piping sections include pipe materials of the high-nickel alloy, Inconel 740H. Through this experience, supply chain, weld procedures, general handling, and inspection were among key challenges. To support this project the supply chain needed to produce extruded pipe, pipe fittings including elbow and tees along with flanges and flange clamps. The high temperature pipe sections that used the Inconel 704H material utilized Grayloc flanges (clamp type flanges) to connect the piping to the equipment. This project involved pipe sizes and schedules that have not been previously produced with Inconel 740H. Inconel 740H requires careful attention when performing welds to ensure that the weld is not contaminated and that the correct temperatures are used with the proper shielding and purge gas mixture. With the proper weld procedure and attention to detail consistent quality welds can be produced. The paper will detail these challenges and the lessons learned that came from them resulting in a successful installation.
Transient Modeling of an Aero-Engine Using Ammonia As a Fuel Carrier
Authors: Patel Kangana , Goyal Vipul , Cotto Brandon , Otto Marcel , Vesely Ladislav , Kapat Jayanta , Shi Mingxuan 
Published: August 2024

Abstract
The aim of this paper is to reduce aviation emissions by changing the fuel source in a turbofan engine powered by jet fuel to hydrogen derived from ammonia cracking. Because sustainable aviation fuels (SAF) remain partially carbon-intensive, our primary focus centers on hydrogen and ammonia. Storing hydrogen necessitates extreme cryogenic conditions (−253°C) or pressurized tanks, making ammonia a more practical hydrogen carrier. While some studies have simulated continuous hydrogen use throughout a flight in a steady-state analysis, this paper concentrates on transient analysis. As airplane change flight phases, there should be a change to injected fuel mass flow rate, adjustments in bleed flow rates depending upon changes in required thrust along with the ambient conditions according to the flying altitude. The objective of transient analysis is to ascertain if the compressors and combustor’s immediate fuel and stability requirements are met. To achieve this, transient analysis simulations are conducted using Simcenter Amesim, that offers a reduced-order model of gas turbine components that is customized to explore the gas turbine’s transient behavior throughout an entire flight mission within a single simulation. In the baseline study, conventional Kerosene was used for take-off and cruise conditions, achieving a significant match and accuracy in both steady-state and transient analyses. In the latter part of this paper, the engine’s transient behavior is presented when ammonia-cracked hydrogen is employed.
Design Guidelines for Inertial Particle Separators
Authors: Bojdo Nicholas , Filippone Antonio 
Published: August 2024

Abstract
Inertial particle separators are air-cleaning devices integrated in air intakes or engine inlets to remove potentially harmful particles through the action of centrifuging. Their geometry is defined by a mean gas path, which sits at the centroid of a duct cross-section. Advances in additive manufacturing are opening up new opportunities to explore a wider design space and optimise for more mission-specific requirements. The current work presents design guidelines for these devices, and explores the effect of certain geometric parameters on the competing objectives of maximum separation efficiency with minimum pressure loss, through a reduced order model. The model framework computes the centripetal drag force by first transforming the principal mean gas path into the Frenet-Serret reference frame to measure the local radius of curvature, and second, solving the local one-dimensional flow field by application of the isentropic flow equations for ideal gas. Loss in pressure due to wall friction, bends, and rapid area expansion are accounted for at each point along the gas path. The capability of this approach is demonstrated through comparison with a known test case in the literature, followed by application to a hypothetical conceptual design. Primary design parameters of splitter position, throat position, gas path curvature (through spline control points), and scavenge mass flow are chosen for investigation. Key findings are that the IPS cross-sectional area and hump curvature could be used together as effective tuning parameters, to maximise separation efficiency for a given target test dust.
Extracting Meanline Modeling Parameters for Radial Turbomachinery From CFD
Authors: Oliphant Chase , Metten Jason , Gorrell Steve , Maynes Dan , Oliphant Kerry 
Published: August 2024

Abstract
Meanline performance models have a long history of use in the design of radial flow pumps and compressors. Most data used to create correlations are point data such as static pressures and temperature measurements at walls with occasional traverses for more details of the flow field. These point measurements along with limited traverses, while very useful, do not provide details of specific flow characteristics internal to the machine. The Two-Zone model, developed by Japikse and others, is a meanline model based on point measurements that enables prediction of machine performance. The model assumes that the flow at the impeller exit is composed of a primary zone that is isentropic and a secondary zone where losses exist. The Two-Zone model can accurately predict power when the fraction of mass flow in the secondary zone (χ) and the deviation angle in the primary (δ2p) and secondary (δ2s) zones are correctly inferred from the available data. However, it is difficult to ensure that the parameters inferred from the Two-Zone flow model structure are uniquely correct. In this paper, the specific details of the impeller exit flow fields required to generate an accurate prediction using the Two-Zone model are extracted from CFD simulations. Using CFD, flow fields at the impeller exit are obtained and analyzed to calculate the model parameters for 10 radial flow machines. The derived two zone parameters are then used to predict the power for each machine. The Two-Zone predictions match the experimental data with an average error of 3.5%.
Native Multi-GPU Solver for Complex Turbulent Flow Field Requiring Full Wheel Analysis in Turbomachinery
Authors: Patil Sunil , Kelecy Frank , Wise Michael 
Published: August 2024

Abstract
The landscape of GPU-based scientific computing platforms is rapidly changing and thus is making a strong case for fully native GPU-based industrial CFD solvers. One of key strengths of native GPU-based CFD solvers is their ability to accelerate the solution of large transient problems. In turbomachinery, there are certain classes of problems which necessitate a full wheel, transient analysis, such as inlet distortion, rotating stall, and hot streak migration. Solving these problems with current CPU based hardware can be time consuming and, in general, very resource intensive. Furthermore, the goal of compressing design cycle times requires fast turnaround times for both steady-state and unsteady CFD analyses, for example, computing an entire compressor map.
This paper introduces a new native multi-GPU solver framework designed to fully explore the potential of rapidly evolving GPU hardware. The solver has been developed with the goal of achieving the highest possible parallel scalability and speed on modern GPU high performance computing clusters. The new solver is based on a flexible architecture which allows its compilation and efficient use on a variety of GPU/CPU hardware platforms. In addition to fast execution of CFD solver code, they typically provide an electrical power savings of around a factor of four while reducing hardware costs by a factor of seven when compared to a CPU cluster with 1024 Intel® Xeon® Gold 6242 cores and a 6 x NVIDIA® V100 GPU server.
This paper illustrates the use of a recently developed native multi-GPU solver for two selected full wheel transient turbomachinery simulations. These cases are: (1) a 10MW wind turbine running at a fixed speed, and (2) a high pressure, multistage axial compressor. Comparisons are made with a CPU-based parallel solver which has been well-validated for its accuracy for a wide range of turbomachinery and related flows. This includes evaluating result parity between solvers, accuracy of performance against available data, effective speedup, and scalability of the numerical solutions.
Development of a Power Generation and Economic Model for Micro-Grid Applications
Authors: Pryor Owen , McClung Aaron , Khawly George , Schmitt Joshua , Allison Timothy 
Published: August 2024

Abstract
A model has been developed to explore the possibility of creating self-contained micro-grids using a combination of renewable energy and energy storage. The model, written in Python, uses solar and wind availability over the period of interest to estimate the amount of available renewable energy. It then compares the renewable energy generated to a given electric load profile over the same period to determine when to utilize on-site energy storage. The renewable energy calculations are performed using the NREL System Advisor Model for both solar and wind resources. Using a vector analysis, the model calculates the time periods the system could charge, or discharge energy based on the amount of additional renewable energy that is not directly utilized to the demand profile. The model includes the ability to utilize several different types of storage including lithium-ion batteries, vanadium flow batteries, pumped thermal energy storage (PTES) or any combination of storage technologies. Additional resources have been modeled including an on-site gas engine and a local utility connection. The power generation calculations can then be used to estimate the capital costs, operating costs and the levelized cost of electricity (LCOE) for the microgrid. A case study has been completed examining the Southwest Research Institute (SwRI) campus using their unique economic factors over a 30-year period. The case study shows that the SwRI would only be able to provide up to 43% of their total load using renewable energy alone while decreasing the cost of electricity by around 10%. Increasing renewable penetration and adding storage showed that the system could provide around 50% of the required load without increasing electricity costs and that the SwRI campus could provide up to 60% of its demand with an increase in the LCOE.
A New Non-Linear Time-Domain Flutter Analysis Approach for Distorted Flows
Authors: Corral Roque , Rodríguez-Blanco Salvador , Chennuru Venkata Y. T. , Vahdati Mehdi , Zhao Fanzhou 
Published: August 2024

Abstract
This paper aims to establish an efficient and accurate Computational Fluid Dynamic (CFD) method for calculating the flutter stability of fan blades in the presence of inlet distortion due to crosswind. Due to the asymmetry of the flow and interaction of fan and distortion, this type of analysis will require a whole assembly computational model. Therefore, reducing the computational cost needed to obtain accurate aerodynamic damping values is paramount. Mode-tracking free-flutter analyses are computationally expensive and troublesome due to the presence of many frequencies in the response signals and, hence, require long physical times to converge the aerodynamic damping. Moreover, the unsteady flow field associated with the distortion can be more significant than the one due to flutter, giving rise to additional numerical difficulties. On the other hand, the energy method approach is commonly performed for a single Nodal Diameter (ND) at a time, requiring many computations to establish the least stable ND. This paper proposes an alternative approach based on the multi-ND energy method. The underlying hypothesis is that the unsteady pressure scales linearly with the blade displacements, and the scattering of circumferential modes due to the distortion is negligible. The general method presented here is general, and can be used to compute the aerodynamic damping for other types of distortion (such as downstream distortions due to pylon and structure).
Experimental Investigation of a Physisorption-Based Hydrogen Storage System
Authors: Otto Marcel , Khlyapov Yakym , Fernandez Erik , Schmitt Joshua , Swanger Adam , Kapat Jayanta 
Published: August 2024

Abstract
This study discusses a practical system utilizing the principle of physisorption where hydrogen is weakly bound to the surface of a nanoporous silica aerogel blanket as an alternative to high-pressure and cryogenic hydrogen storage.
Three different experiments are conducted to simulate various scenarios of such a storage method: change in pressure and change of scale. Transient responses of the charging and discharging cycles are of particular interest. It is observed that hydrogen uptake can be increased by up to 36–38 % at ambient conditions and 77 K when utilizing the aerogel blankets. Packing density, or the artificial increase of surface per volume, increases storage capacity as it is a mainly surface-driven phenomenon. High-pressure testing up to 50 bar showed benefits of the aerogel addition whereas the maximum uptake improvement was observed for 2 bar with a 105.3 % improvement over an empty vessel at identical conditions corresponding to 6.43 wt%.
The scale-up of the system is highly sensitive to the design of the internal cooling design as aerogels are poor thermal conductors reducing the transient response of such systems. Furthermore, the high mass of metal-based pressure vessels further delays the thermal response. This makes the system suitable for day to week-long hydrogen storage but not for peak-shaving or load balancing.
Quantitative Measurements in the Exhaust Flow of a Rotating Detonation Combustor Using Rainbow Schlieren Deflectometry
Authors: Gupta Apurav , Miller Robert S. , Bell Kayla M. , Langner Dalton G. , Agrawal Ajay K. 
Published: August 2024

Abstract
This study employs Rainbow Schlieren Deflectometry (RSD) to characterize the unsteady, supersonic/subsonic exhaust plume of a Rotating Detonation Combustor (RDC). Firstly, RSD images are analyzed to quantify the frequency and strength of flow oscillations and their relationship to the detonation wave. Secondly, a 3D tomographic algorithm is used to obtain the local 3D density field across the whole region of interest (ROI). The tomographic analysis relies upon wave rotation to infer projection data of the 3D exhaust plume at multiple view angles using a single RSD/camera system and was previously validated using phantom data from computational fluid dynamics analysis of an RDC. The annular RDC operated on methane and 2/3 O2 – 1/3 N2 oxidizer mixture is equipped with a converging nozzle to pressurize the combustion chamber. The product flow exiting the nozzle throat expands across an unoptimized conical aerospike attached to the center body of the RDC. RSD images provide a temporal resolution of 369 ns and spatial resolution of 100 μm in a 6.4 high and 25.6 mm wide ROI of the exhaust plume. A rainbow filter is calibrated to convert hue in color schlieren images into deflection angle data. This data is used to characterize the unsteady flow oscillations that show excellent agreement with PCB pressure probe measurements acquired inside the combustion chamber. Tomographic analysis yields a 3D local density field that shows distinct features, consistent with published numerical simulations of the RDC exhaust plume. For the first time, this work demonstrates the ability of high-speed non-intrusive RSD diagnostics to acquire whole-field density measurements in an operational RDC. Such data would be valuable to validate high-fidelity numerical simulations and gain a further understanding of the exhaust flow to help with RDE-turbine integration. Further improvements to the RSD hardware and analysis procedures would enhance present capabilities to ultimately infer other thermodynamic properties such as temperature and pressure from density measurements.
Characterization of the Upgraded NASA GRC Single Stage Axial Compressor and Fan Facility
Authors: Stephens Julia E. , Lucci Barbara , Mirhashemi Arman 
Published: August 2024

Abstract
In order to meet the emissions and efficiency goals established by the aviation community, next generation aircraft engines will require low pressure ratio, distortion tolerant fans. Maturation of the necessary technologies will require facilities which are capable of accurately testing the fan performance. To achieve this, the Single Stage Axial Compressor and Fan facility at NASA Glenn Research Center was upgraded. Details of the goals and upgrades undertaken were documented in the 2022 Turbo Expo paper, “Upgrades to the Single Stage Axial Compressor and Fan Facility for Low Pressure Ratio Boundary Layer Ingesting Fan Research.” The performance of the upgraded facility will be documented in this paper.
This paper will review the challenges associated with testing low pressure ratio and distortion tolerant fans and briefly review the upgrades undertaken and their goals. Then the performance of the facility upgrades and the extent to which they were able to achieve the stated goals will be discussed. This includes mass flow measurements, test section temperature, pressure, flow angle at two axial locations, and turbulence levels at the inlet and test section. The paper also documents the performance of distortion generating swirl vanes and total pressure screens to achieve desired distorted conditions at the Aerodynamic Interface Plane.
An Advanced Sine-Hyperbolic Creep-Damage Model Incorporating Threshold Strength
Authors: Hossain Md Abir , Haque Mohammad Shafinul , Pellicotte Jacob , Stewart Calvin M. 
Published: August 2024

Abstract
This study aims at improving the classic Sine-Hyperbolic (Sinh) creep-damage model to predict minimum-creep-strain-rate (MCSR), rupture, damage, and creep deformation. The Sinh model employs a continuum-damage-mechanics-based framework to model secondary and tertiary creep regimes. In Sinh, the creep strain and damage rate equations exhibit an implicit threshold stress that arises during numerical optimization. Herein, the Sinh model is modified to include an explicit threshold strength as a material property and the tensile strength. Threshold strength is defined as the lower limit for creep activation at a given temperature. Stresses are applied below the threshold, resulting in infinite life. The advanced Sinh offers several advantages including a physical significance of stress ratios where the onset of creep is defined by threshold strength, a closed-form solution where the rate equations remain finite at any combination of stress and temperature, and adaptability in finite element analysis where the solution space remains numerically stable.
Experimental creep data of 304SS at multiple isotherms are gathered from prior literature. The advanced Sinh is calibrated to the MCSR and SR data of 304SS. The calibration of threshold strength follows a standard procedure from literature and is observed to be realistic for stainless steel at elevated temperatures. The MCSR and SR predictions illustrate the Sigmoidal bend and demonstrate zero creep rate and infinite life at or below threshold strength. The creep deformation and damage predictions exhibit agreement with experimental data. The advanced Sinh is validated by employing finite element simulation to ensure the applicability of the model across a range of applications. The advanced Sinh improved creep response prediction and added physical realism to the model’s framework.
Small Volume Fatigue Testing of Additively Manufactured Hybrid IN718/XH67 and IN939 Ni Based Superalloys
Authors: Awale Deepshree , Shah Naimish , Srinivasan Dheepa , Balila Nagamani Jaya 
Published: August 2024

Abstract
Additively manufactured alloys are known to possess sufficient tensile strength-ductility combinations, matching their conventionally processed counterparts, and yet fail to perform under cyclic loading conditions. The complex, heterogeneous microstructure, resulting anisotropy and porosity distribution, as well as the surface roughness in additively manufactured alloys result in reduced fatigue life. Evaluation of fatigue behavior of these materials, especially during the alloy development stage, necessitates small-volume fatigue testing, to mimic the component geometry. It is also very pertinent during repair and component lifing, in Hybrid alloys, owing to the small sampling volume. This study explores a novel technique of small-scale fatigue specimens, for evaluating the fatigue behavior of a new Hybrid XH67–IN718 manufactured by the powder bed fusion-laser beam technique, in the as-printed condition, at room temperature. Comparisons are made with a high gamma prime (γ′) IN939 Ni based superalloy used in gas turbine hot section components. Miniature fatigue test specimens were designed to determine the fatigue life with the loading at 0.95 % yield strength, for both the Hybrid and the monolithic alloy, in the as-printed condition. Results will be discussed in the context of the observed failure mechanism, tensile properties, and the hierarchical microstructure.