bluuebunny/crossref_metadata_2025_split huggingface dataset:
Revolutionary Vertical Lift Technology (RVLT) Side-by-Side Hybrid Concept Vehicle Powertrain Dynamic Model
Authors: Bianco Santino J. , Chevalier Christine T. , Litt Jonathan S. , Smith Joshua K. , Chapman Jeffryes W. , Kratz Jonathan L. 
Published: September 2021

Abstract
The Side-by-Side (SBS) Hybrid is one of several Revolutionary Vertical Lift Technology (RVLT) concept aircraft identified by NASA to investigate Urban Air Mobility (UAM) requirements. This paper presents a dynamic model of the SBS Hybrid powertrain built using the Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS) and the Electrical Modeling and Thermal Analysis Toolbox (EMTAT). The model consists of the rotors, electrical power system, and turboshaft engines connected through freewheeling clutches, gearboxes, and multiple shafts. This research effort models the complex behavior of the powertrain, including the operation of the freewheeling clutches and electrical power system at the simulation time scale of the shaft dynamics. Several simulations highlight the key features present in the model and demonstrate its operation.
Reduced-Order Models for Effusion Modelling in Gas Turbine Combustors
Authors: Paccati S. , Mazzei L. , Andreini A. , Facchini B. 
Published: September 2021

Abstract
Effusion cooling represents the state-of-the-art for liner cooling technology in modern combustion chambers, combining a more uniform film protection of the wall and a significant heat sink effect by forced convection through a huge number of small holes. From a numerical point of view, a high computational cost is required in a conjugate CFD analysis of an entire combustor for a proper discretization of effusion holes in order to obtain accurate results in terms of liner temperature and effectiveness distributions. Consequently, simplified CFD approaches to model the various phenomena associated are required, especially during the design process.
For this purpose, 2D boundary sources models are attractive, replacing the effusion hole with an inlet (hot side) and an outlet (cold side) patches to consider the related coolant injection. However, proper velocity profiles at the inlet patch together with the correct mass flow rate is mandatory to accurately predict the interaction and the mixing between coolant air and hot gases as well as temperature and effectiveness distributions on the liners. In this sense, reduced-order models techniques from the Machine Learning framework can be employed to derive a Surrogate Model (SM) for the prediction of these velocity profiles with a reduced computational cost, starting from a limited number of CFD simulations of a single effusion hole at different operating conditions.
In this work, an application of these approaches will be presented to model the effusion system of a non-reactive single-sector linear combustor simulator equipped with a swirler and a multi-perforated plate, combining ANSYS Fluent with a MATLAB code. The employed Surrogate Model has been constructed on a training set of CFD simulations of the single effusion hole with operating conditions sampled in the model parameter space and subsequently assessed on a different validation set.
Predicting EBC Temperature Limits for Industrial Gas Turbines
Authors: Pint Bruce A. , Stack Padraig , Kane Kenneth A. 
Published: September 2021

Abstract
Higher turbine inlet temperatures may require the use of ceramic matrix composites (CMC) such as SiC/SIC, which require environmental barrier coatings (EBCs) to protect them against the detrimental effect of water vapor. The goal of this project is to determine the maximum bond coating temperature for EBCs for land-based turbines, where the minimum coating lifetime is 25,000 h. If the temperature exceeds the 1414°C melting point of the Si bond coating, then coatings without a bond coating also need to be evaluated. Thus, current Yb2Si2O7 EBCs with a Si bond coating and next-generation EBCs without a Si bond coating are being evaluated in laboratory testing using 1-h cycles in air+90%H2O. For this initial work, coatings were deposited on CVD SiC coupons. Reaction kinetics at 1250°, 1300° and 1350°C have been evaluated by measuring the thickness of the thermally grown silica scale after 100–500 h exposures. For comparison, scale growth rates for uncoated SiC and Si specimens in dry and wet environments were included as minimum and maximum values, respectively. Based on a critical scale thickness failure criteria, estimated maximum temperatures were calculated for both EBC systems using this initial data.
Effect of Rotation on Heat Transfer in AR = 2:1 and AR = 4:1 Channels Connected by a Series of Crossover Jets
Authors: Madhavan Srivatsan , Singh Prashant , Ekkad Srinath V. 
Published: September 2021

Abstract
Detailed heat transfer measurements using transient liquid crystal thermography were performed on a novel cooling design covering the mid-chord and trailing edge region of a typical gas turbine blade under stationary and rotating conditions. The test section comprised of two channels with aspect ratio (AR) of 2:1 (mid-chord) and 4:1 (trailing edge), where the coolant was fed into the AR = 2:1 channel from the root. Rib turbulators with a pitch-to-rib height ratio (p/e) of 10 and rib height-to-channel hydraulic diameter ratio (e/Dh) of 0.075 were placed in the AR = 2:1 channel at an angle of 60° relative to the direction of flow. The coolant after entering this section was routed to the AR = 4:1 section through a set of crossover jets. The purpose of the crossover jets was to induce sideways impingement onto the pin fins that were placed in the 4:1 section to enhance heat transfer. The 4:1 section had a realistic trapezoidal shape that mimics the trailing edge of an actual gas turbine blade. The pin fins were arranged in a staggered array with a center-to-center spacing of 2.5 times the pin diameter in both spanwise and streamwise directions. The trailing edge section consisted of both radial and cutback exit holes for flow exit. Experiments were performed for a Reynolds number (ReDh(AR = 2:1)) of 20,000 at Rotation numbers (RoDh(AR = 2:1)) of 0, 0.1 and 0.14. The channel averaged heat transfer coefficient on trailing side was ∼28% (AR = 2:1) and ∼7.6% (AR = 4:1) higher than the leading side for Rotation number (Ro) of 0.1. It is shown that the combination of crossover jets and pin-fins can be an effective method for cooling wedge shaped trailing edge channels over axial cooling flow designs.
Turbomachinery Loss Analysis: The Relationship Between Mechanical Work Potential and Entropy Analyses
Authors: Leggett John , Zhao Yaomin , Richardson Edward S. , Sandberg Richard D. 
Published: September 2021

Abstract
Physics-based loss analysis methods have been developed to interpret the detailed three-dimensional and time-dependent predictions of turbomachinery CFD simulations. This paper contrasts two analysis methods for assessing loss: entropy loss analysis (Zhao & Sandberg, GT2019-90126) and mechanical work potential analysis (Miller, GT2013-95488). The two individual analyses are applied to high-fidelity simulation data for linear high-pressure compressor and high-pressure turbine cascades. The results show each analysis captures the loss generating processes in different ways, corresponding to different terms in their equations. The key loss generation processes are shown to be turbulent and mean viscous dissipation in the mechanical work potential analysis, and mean viscous dissipation and turbulence production in the entropy loss analysis. A relationship between the two approaches is derived rigorously, providing a means to convert between the results of the two approaches, enabling designers to assess individual stage performance using the entropy-based analysis and multiple stages in terms of mechanical work potential, by using the same reference pressure.
On the Challenge of Determining the Surge Limit of Turbocharger Compressors: Part 1 – Experimental and Numerical Analysis of the Operating Limits
Authors: Dielenschneider T. , Ratz J. , Leichtfuß S. , Schiffer H.-P. , Eißler W. 
Published: September 2021

Abstract
The surge limit of compressors is one key parameter in the design process of modern turbocharger compressors for automotive applications. Since the compressor is operated close to the surge limit, the determination of the surge limit is of high importance. Unfortunately, the determination of the surge limit with any numerical method with high accuracy is still an unsolved challenge. The numerical surge limit is often determined by the operating point with the minimum converged mass flow rate. But, as this investigation will clearly show, this cannot be used as a surge limit of the investigated compressor configuration. In this paper it will be shown that a more differentiated approach is required when it comes to operating limits. Especially, two different operating limits can be determined. A methodology for the determination of each limit will be presented. One is based on the system approach defined by Greitzer and the other one is based on the analysis of the low momentum fluid in the shroud region of the compressor wheel. Finally, experimental data will be used as benchmark data for both limits. The determination of the experimental surge limit is based on the analysis of transient experimental pressure signals. This is achieved through a fourier analysis of the unsteady compressor outlet pressure signal for transient surge runs.
A Stochastic Model for Nanoparticle Deposits Growth
Authors: Suman Alessio , Vulpio Alessandro , Casari Nicola , Pinelli Michele 
Published: September 2021

Abstract
Natural events and human activities are responsible for the generation and transport of large amounts of micro-sized particles, which could contaminate several engineering devices like solar panels, wind turbines, and aero-engines. In industrial processes, systems as heat exchangers, fans, and dust collectors are continuously affected by nanoparticles’ interaction. For several applications, the adhesion of such nanoparticles is detrimental, generating safety and performance issues. Particle-to-particle and particle-to-surface interactions are well known, even if a general explanation of nanoparticle deposit growth is still unknown.
In the present paper, an interpretation of deposit growth due to nanoparticle deposition can predict particle adhesion, and layer accretion is proposed. A statistical model and a set of coefficients are used to generalize nanoparticle deposits’ growth by an S-shaped function. In particular, the nanoparticle deposits grow analogously to a typical autonomous population settlement in a virgin area following statistical rule, which includes the initial growth, the successive stable condition (development), and catastrophic events able to destroy the layer. This approach generalizes nanoparticle adhesion/deposition behavior, overpassing the constraints reported in common deposition models, mainly focused on the mechanical aspect of the nanoparticle impact event. The catastrophic events, such as layer detachment, are modeled with a Poisson’s distribution, related to material characteristics and impact conditions.
This innovative approach, analogies, and coefficients applied to common engineering applications may be the starting point for improving the prediction capability of nanoparticle deposition.
Progresses in Particle-Laden Flows Simulations in Multistage Turbomachinery With OpenFOAM
Authors: Oliani Stefano , Friso Riccardo , Casari Nicola , Pinelli Michele , Suman Alessio , Carnevale Mauro 
Published: September 2021

Abstract
Numerical simulations of particle-laden flows have received growing attention in the last decade, due to the broad spectrum of industrial applications in which discrete phases prediction is of interest. Among these, ingestion of particles by turbomachinery is an area that is seeing vivid research and studies. The most common technique to tackle this kind of problem is the Eulerian-Lagrangian method, in which individual particles are tracked inside the domain. At the same time, in multi-stage turbomachinery simulations interfaces are needed to couple the flow solution in adjacent domains in relative motion. In this work, an open-source extension for Lagrangian simulations in multistage rotating machines is presented in the foam-extend environment. Firstly, a thorough discussion of the implementation is presented, with particular emphasis on particle passage through General Grid Interfaces (GGI) and mixing planes. Moreover, a mass-conservative particle redistribution technique is described, as such a property is requested at interfaces between Multiple Reference Frame (MRF). The peculiarities of the algorithm are then shown on a relevant test-case. Eventually, three turbomachinery applications are presented, with growing complexity, to show the capabilities of the numerical code in real-life applications. Simulation results in terms of erosion and impacts on aerodynamic surfaces are also presented as examples of possible parameters of interest in particle-laden flow computations.
A Novel Energy Storage System Based on Carbon Dioxide Unique Thermodynamic Properties
Authors: Astolfi Marco , Rizzi Dario , Macchi Ennio , Spadacini Claudio 
Published: September 2021

Abstract
This paper focuses on the thermodynamic performance and techno-economic assessment of a novel electrical energy storage technology using carbon dioxide as working fluid. This technology, named CO2 battery and recently patented by Energy Dome SpA., addresses to an energy market which has great need of energy storage solutions able to handle the increasing share of non-dispatchable renewable energy sources like photovoltaic and wind energy. After a brief introduction, the present study presents the concept of CO2 batteries and their operation. Then the detailed numerical model developed for the accurate calculation of system round trip efficiency is presented with the adopted assumptions and the optimization routine description. Results on the reference case and following sensitivity analysis confirm a RTE of around 77% (±2%) which makes CO2 batteries a very promising technology with respect to other energy storage systems based on thermodynamic cycles like compressed air and liquid air energy storage thanks to the high performance and the easiness of installation. Finally, calculation of system footprint, capital investment cost and levelized cost of storage are discussed.
A Rapid Viscous-Inviscid Interaction Method for the Preliminary Design of S-Shaped Transition Ducts
Authors: Veyrat A. , Carrotte J. F. , Walker A. D. , Hall C. , Simpson H. 
Published: September 2021

Abstract
For preliminary design of compressor transition ducts, knowledge-based tools for the rapid assessment of aerodynamic performance of S-shaped ducts are not currently available in the open literature. This is due to the highly complex flow developing under the combined influence of pressure gradients and streamline curvature. This paper presents a new approach enabling an agile design process avoiding premature use of time-consuming high-fidelity CFD calculations. The features of a 2D axisymmetric incompressible steady flow field are captured with a semi-analytical viscous inviscid interaction method. A potential core, based on streamline curvature and implicit velocity profile by parametric spline reconstruction, is coupled to an integral method predicting the turbulent boundary layer growth up to separation. The shear stress distribution is generated by a modified mixing length model for strongly curved flows and wall shear stress closure is performed by inverse calculation of a composite law-of-the-wall. When compared to CFD, the aerodynamic loading is generally predicted to within ±3% but convergence is achieved 20 times faster.
Hot Turbine Guide Vane Performance Improvement With Metal Additive Manufacturing at Siemens Energy
Authors: Fedorov Ilya , Barhanko Dikran , Hallberg Magnus , Lindbaeck Martin 
Published: September 2021

Abstract
Additive manufacturing (AM) of gas turbine components has been suggested as a measure to improve performance and create other value additions in several research papers. This paper focuses on application of AM for gas turbine performance improvement considering industrial scale of this activity at Siemens Energy.
Efficient cooling designs, made possible by AM, are considered not only from the standpoint of cooling characteristics, but also inherent challenges, arising in the complete chain of manufacturing processes: from powder removal to coating. Practical limitations of cooling scheme complexity are discussed and the benefits of in-wall cooling, enabled by AM, are described. It is shown that thin cooled trailing edges, enabled by the AM, provide considerable reduction of losses. It is demonstrated that production challenges can be successfully overcome, and the components can be manufactured with the required quantity and according to the original design intent.
The sequence and progress of AM components long-term validation in the field engines are discussed and illustrated with actual operation experience. The development of the AM vane was executed in line with the roadmap of AM portfolio development in Siemens Energy and supports the strategy of commercial validation and full commercial release of AM components..
Impact of Mistuned Underplatform Dampers on the Nonlinear Vibration of Bladed Disks
Authors: Quaegebeur Samuel , Chouvion Benjamin , Thouverez Fabrice 
Published: September 2021

Abstract
Before the final experimental validation and certification of a turboengine, designers perform a numerical simulation of its vibratory properties, among other things, in order to estimate its lifespan and adjust the design in an optimization process. One possible practical solution to decrease the vibratory response is to add underplatform dampers to the system. These components dissipate energy by friction and are widely employed in turbomachinery. However, a specific underplatform damper is usually efficient only for a specific mode. The purpose of this work is to investigate the possibility of adding different kinds of underplatform dampers to the cyclic structure in order to decrease the vibratory energy over a larger panel of modes. Different methods exist to determine the vibrations of nonlinear cyclic symmetric systems, but creating a robust methodology to account for the additional effect of mistuning remains a big challenge in the community. In this paper, the structure is mistuned through the friction coefficient of the dampers and not by altering its geometry, as is usually done in the literature. First, assuming a cyclic symmetric structure, the performance of the dampers is assessed for specific modes. Then, employing a method recently developed, the efficiency of an intentional mistuning pattern of underplatform dampers is studied and an optimal pattern proposed.
Steam Turbine Casing Analyses to Determine Pressure and Temperature Limits
Authors: Smith Paul T. , Griffin Daniel J. 
Published: September 2021

Abstract
To ensure safe and reliable operation, steam turbine casings must have acceptable stresses and maintain sealing when subjected to internal pressures and temperatures. To show turbine casings acceptable, analysts conduct structural evaluations using finite element analysis (FEA) techniques. This paper outlines the analytical methods used to perform these types of analyses, provides analysis examples, and summarizes the process to create pressure and temperature limit maps.
Finite element models of the main casing and steam chest are used to determine stresses and sealing of the casing horizontal split line and steam chest cover during normal operation. The sealing evaluations consider the sealing capabilities of the bolted joints when the casing is subjected to internal steam pressure and consider the effects of bolt stress relaxation at elevated temperatures, joint contact surface separation, and penetration of the internal pressure into the sealing surface. The acceptance criteria for the bolted joint sealing is based on the minimum width of the contacting surface and the minimum joint contact pressure.
A series of analyses were conducted on the various models to create pressure and temperature limit maps, so that the design can be applied for the appropriate conditions. These maps plot maximum allowable working pressure (MAWP) versus maximum allowable working temperature (MAWT), and allow an application engineer to easily determine the acceptability of the casing for a particular application. An explanation of the process used to create the limit maps is presented.
The EPRI Gas Turbine Digital Twin – a Platform for Operator Focused Integrated Diagnostics and Performance Forecasting
Authors: Lim Jamie , Perullo Christopher A. , Milton Joe , Whitacre Rachel , Jackson Chris , Griffin Chris , Noble David , Boche Lea , Seachman Steve , Angello Leonard , Maley Susan , Lieuwen Timothy C. 
Published: September 2021

Abstract
EPRI has been developing a digital twin of simple and combined cycle gas turbines over the last 5+ years to provide owners and operators with improved capabilities that typically reside in the expert domain of OEMs and 3rd party service providers. The digital twin is a digital model, a physics-based representation of the actual asset. The model is thermodynamic and is created with the intent to support 5 M&D areas:
• Integrate with existing M&D tools such as advanced pattern recognition (APR)
• Power plant performance prediction and trending such as day, week, and month ahead performance prediction for capacity and generation planning
• Health Monitoring and Fault Diagnostics to support asset management with additional health scores and virtual instrumentation enabled by the digital twin model
• Monitoring and prediction of both base and part-load performance. Many gas turbine tools have been simplified to work only at full load conditions. To be useful and to improve utilization of collected data, part-load conditions should also be considered.
• Outage and repair impacts, including “what-if” capability to understand and quantify potential root causes of less than expected performance improvement or recovery after outage and repairs.
This paper presents current progress in creating an EPRI Digital Twin applicable to gas turbines. The formulation, methodology, and real-world use cases are presented. To date, digital twins have been created and tested for both E and F class frames. This paper describes the process of generating closed-form equations capable of transforming existing, measured historian data into the health parameters and virtual sensors needed to better track unit health and monitor faulted performance. These equations encapsulate the digital twin physical model and provide end-users with a methodology to calibrate to their specific unit and efficiently use their choice of monitoring software. Tests have been performed using operator data and have shown good accuracy at detecting anomalous operation and predicting week ahead performance with excellent accuracy. Post-outage impact analysis is also assessed.
Real-world application cases for the digital twin are also presented. Examples include using the digital twin to identify causes of post-outage emissions and performance issues, expected impact of degradation and fault conditions, and simulating improvements to operation through part repair and upgrades.