bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparative Study Between Structured and Unstructured Meshes Applied in Turbopump’s Hydraulic Turbine
Authors: da Silva Tonon Daniel , Takachi Tomita Jesuíno , Castejon Garcia Ezio , Bringhenti Cleverson , Bruno Díaz Rubén , Henrique Lindquist Whitacker Luiz 
Published: January 2021

Abstract
The aim of this work is the evaluation of different mesh types applied in turbomachines area, in this case in an axial turbine stage used in turbopumps (TP) applications. The tip clearance region was considered in this study because it has high influence in turbomachines performance. Due to the complexity of the tip clearance region, structured mesh generation is not always feasible, therefore it is necessary to generate unstructured meshes that allow flow calculation through Computational Fluid Dynamics (CFD) techniques. The use of different mesh type is an interesting topic when different rotor tip geometries are evaluated, in which the desensitization methods are applied. In this work, only the common flat-tip was consider. Thus, as a first step, unstructured tetrahedral meshes (with prismatic layers close to the surfaces) with different y+ values were generated. After this, turbulent 3-D flow calculations were performed at design and off design conditions, based con Reynolds Averaged Navier-Stokes (RANS) equations. The methodology used is to present in a didactic way, for under and graduate students, the advantages and disadvantages of the unstructured mesh in relation to the structured one, already used in previous research. Unstructured meshes were generated using ICEM software (ANSYS), while structured ones were generated using AxCent software developed by CONCEPTS NREC. The machine under study is the first stage of the hydraulic axial turbine used in the Low Pressure Oxidizer Turbopump (LPOTP) of the Space Shuttle Main Engine (SSME), considering 3.0% tip clearance configuration relative to blade height. All simulations were done using CFX program (ANSYS). The result shows the comparison between the two mesh types considering the difficulty and time generation, discretization quality, effect of y+ parameter variation on flowfield, simulation time, and stage performance parameters calculation for different operating points.
Global Reaction Mechanism Optimization for CO Prediction With DARS and HEEDS
Authors: Mahto Navin , Nath Ayan , Kaluri Ramsatish 
Published: January 2021

Abstract
Prediction of carbon monoxide (CO) emission is critical in gas turbine combustion. Compact yet accurate reaction mechanisms are required to predict CO with reasonable computing cost. This study uses SHERPA optimization algorithm to optimize the kinetic rate parameters of a 3-step methane-air global reaction mechanism for improved CO predictions. DARS is used as the chemical kinetics solver. Freely propagating laminar flame and constant pressure reactor solutions with GRI-Mech 3.0 reaction mechanism are used as references for optimization. Tradeoffs in the choice of solution techniques and solver settings for fast and accurate design runs are discussed in the paper. Optimization results and their interpretation for improving the design study is also presented.
The optimal results show significant improvements in predictions compared to the baseline case. The workflow and best practices presented in this paper may be extended to optimize global reaction mechanisms for any given range of operating conditions.
Aero-Thermal Aspects of Film Cooled Nozzle Guide Vane Endwalls: Part 2 — Thermal Measurements
Authors: Alqefl Mahmood H. , Nawathe Kedar P. , Chen Pingting , Zhu Rui , Kim Yong W. , Simon Terrence W. 
Published: January 2021

Abstract
Flow over gas turbine endwalls is complex and highly three-dimensional. As boundaries for modern engine designs are pushed, this already-complex flow is affected by aggressive application of film cooling flows that actively interact. This two-part study describes, experimentally, the aero-thermal interaction of cooling flows near the endwall of a first stage nozzle guide vane passage. The approach flow conditions represent flow exiting a low-NOx combustor. The test section includes geometric and cooling details of a combustor-turbine interface in addition to endwall film cooling flows injected upstream of the passage. The first part of this study describes in detail, the passage aerodynamics as affected by injection of cooling flows. It reveals a system of secondary flows, including the newly-discovered Impingement Vortex, which redefines our understanding of the aerodynamics of flow in a modern, film-cooled, first-stage vane row. The second part investigates, through thermal measurements, the distribution, mixing and disruption of cooling flows over the endwall. Measurements are made with and without active endwall film cooling. Descriptions are made through adiabatic surface effectiveness measurements and correlations with in-passage velocity (presented in part one) and thermal fields. Results show that the newly-discovered impingement vortex has a positive effect on coolant distribution through passage vortex suppression and by carrying the coolant to hard-to-cool regions in the passage, including the pressure surface near the endwall.
Background-Grid Based Mapping Approach to Film Cooling Meshing: Part III — Applications in a Full-Cooled Turbine Vane
Authors: Wang Ruiqin , Yan Xin 
Published: January 2021

Abstract
To cool a high-pressure gas turbine blade, many rows of cooling holes with different arrangements and configurations are manufactured to achieve higher cooling effect and lower aerodynamic loss. To evaluate the heat transfer and film cooling effect in the full-cooled turbine blade, efficient numerical simulations are required in the design and performance optimization processes. From the view of numerical accuracy, the structured grids have to be employed because of higher resolution in flow and heat transfer than the unstructured grids. Because many splitting, attaching and merging manipulations are involved in meshing the cooling features and curved boundaries, it is very complex and time-consuming for a researcher to generate multi-block structured grids for a full-cooled gas turbine blade. As a result, in the industrial applications, almost all researchers preferred to generate unstructured grids instead of structured grids for the full-cooled blade.
Unlike the previous research, the aim of this study is to apply the Background-Grid Based Mapping (BGBM) method proposed in Part I to generate multi-block structured grids for a full-cooled gas turbine vane. With the strategy of BGBM method, meshes were conveniently generated in the computational space with simple geometrical features and plain interfaces, and then were mapped back into physical space to obtain the multi-block structured grids which can be used for numerical simulations. With the experimental data, the present numerical methods and BGBM strategy were carefully validated. Then, the flow and film cooling performance in the full-cooled NASA GE-E3 nozzle guided vane were numerically investigated. The effects of coolant mass flow rate and land extensions on film cooling effectiveness were discussed. The results show that film cooling effectiveness near the stagnation point is the lowest and film cooling effectiveness on the pressure side is slightly higher than that on the suction side. When the coolant mass flow rate increases up to the value of 1.5 design flow, the relative outflow mass flow rates of cooling hole arrays and slots are no longer affected by the increase of the coolant flow rate. At half design flow, the outflow mass flow rates of No.5 hole-array to No.10 hole-array are almost zero, and the area-averaged film cooling effectiveness on vane surface is as low as 0.268. Compared with the cases of half design flow and double design flow, better film cooling performance is obtained in the cases of design flow and 1.5 design flow. Compared with the vane without lands, the area-average cooling effectiveness on vane surface is slightly higher for the vane with lands. Land extensions have a considerable influence on film cooling performance in the cutback region.
A Methodology to Calibrate Gas-Dynamic Models of Turbocharged Petrol Engines With Variable Geometry Turbines and With Focus on Dynamics Prediction During Tip-in Load Transient Tests
Authors: Serrano José Ramón , Arnau Francisco José , De la Morena Joaquín , Gómez-Vilanova Alejandro , Guilain Stephane , Batard Samuel 
Published: January 2021

Abstract
The variable geometry turbines (VGT) technology has been proved as beneficious for diesel engines turbocharging, becoming the standard for passenger car diesel engines when high boosting pressure and short transient response are pursued.
It has not been until recent times that OEMs and turbocharger manufacturers are able to explore the advantages of VGTs in petrol engines. The high exhaust gases temperature and the low boost pressure prevented the introduction of petrol VGTs up to now. In modern direct injection petrol engines relevant fuel consumption benefits have been obtained from significant to moderate boosting pressure (thanks to downsizing strategies). This benefit joint with the advances in materials and turbocharger cooling technologies have fostered exploring the limits of VGT technology in petrol engines.
Consequently, the 1-D and gas-dynamic modelling of turbocharged petrol engines for matching, benchmarking or analysis purposes has become a significantly more complex task. The reason is the energy loop interaction between VGT, petrol engine and compressor; which makes that all relevant system variables (boosting pressure, back-pressure, VGT inlet gas temperature, residuals, volumetric efficiency, etc) are coupled among them. In this case, a proper simulation strategy of the whole system with existing 1-D gas-dynamic codes, i.e.: avoiding excessive use of spurious-non-physical fitting coefficients, has not been enough explored either described in the literature yet.
In addition, proper models of the turbocharger (both compressor and VGT) are more relevant now, since the VGT mechanism is a new variable with a first order influence. It can be destabilizing or tricking the whole system, depending on the engine operative conditions and turbo-model quality.
In this paper, a systematic methodology, with physical perspective, for calibrating 1D codes of petrol engines with VGTs is clearly described. The methodology can be easily followed by other engineers or researchers in their modelling activities. In addition, the importance of the turbocharger sub-model for achieving successfully previous objectives is depicted. Standard characteristic maps used as look-up tables are shown to be a poor source of information when compared with pre-processed adiabatic and extrapolated maps. The focus is kept in low end torque at full load steady state and transient tip-in, for being the most challenging situations. Being, low-end torque simulation in steady state the baseline point for the transient simulation.
Comparative Life Cycle Assessment of Different Gas Turbine Axial Compressor Water Washing Systems
Authors: Dominizi Ilaria , Gabriele Serena , Serra Angela , Borello Domenico 
Published: January 2021

Abstract
Nowadays the climate change is widely recognized as a global threat by both public opinion and industries. Actions to mitigate its causes are gaining momentum within all industries. In the energy field, there is the necessity to reduce emissions and to improve technologies to preserve the environment. LCA analyses of products are fundamental in this context.
In the present work, a life cycle assessment has been carried out to calculate the carbon footprint of different water washing processes, as well as their effectiveness in recovering Gas Turbine efficiency losses. Field data have been collected and analyzed to make a comparison of the GT operating conditions before and after the introduction of an innovative high flow online water washing technique. The assessments have been performed using SimaPro software and cover the entire Gas Turbine and Water Washing skids operations, including the airborne emissions, skid pump, the water treatment and the heaters.
Sensitivity Analysis and Uncertainty Quantification for Rim Seal Ingestion With 1-D Network Models
Authors: Pozo Dominguez Alejandro , Hills Nicholas , Marques Simao 
Published: January 2021

Abstract
Accurate prediction of turbine rim seal ingestion remains a challenge, even sophisticated unsteady computational models have had limited success due to the complexity and uncertainties present in this type of problems. For this reason, it is of interest to perform stochastic analysis taking into account the variability in the input parameters as well as uncertainties and assumptions associated with a given model of choice. This study focuses on a Secondary Air System (SAS) of a gas turbine, considering a generic cavity in a high pressure turbine (HPT) in which hot gas ingestion occurs and uncertainty in geometrical, operational and modelling parameters is present. Several statistical methods are applied to a 1D gas network model in order to evaluate the impact of the tolerances of the main geometrical parameters in the output, followed by a broader analysis including other operational and modelling variables. Results indicate that most influential parameters are the sealant mass flow rate, a modelling constant and the minimum gap of the wheelspace cavity.
Blade Root Joint Modelling and Analysis of Effects of Their Geometry Variability on the Nonlinear Forced Response of Tuned and Mistuned Bladed Disks
Authors: Koscso Adam , Petrov E. P. 
Published: January 2021

Abstract
One of the major sources of the damping of the forced vibration for bladed disk structures is the micro-slip motion at the contact interfaces of blade-disk joints. In this paper, the modeling strategies of nonlinear contact interactions at blade roots are examined using high-fidelity modelling of bladed disk assemblies and the nonlinear contact interactions at blade-disk contact patches. The analysis is performed in the frequency domain using multiharmonic harmonic balance method and analytically formulated node-to-node contact elements modelling frictional and gap nonlinear interactions.
The effect of the number, location and distribution of nonlinear contact elements are analyzed using cyclically symmetric bladed disks. The possibility of using the number of the contact elements noticeably smaller than the total number of nodes in the finite element mesh created at the contact interface for the high-fidelity bladed disk model is demonstrated. The parameters for the modeling of the root damping are analysed for tuned and mistuned bladed disks.
The geometric shapes of blade roots and corresponding slots in disks cannot be manufactured perfectly and there is inevitable root joint geometry variability within the manufacturing tolerances. Based on these tolerances, the extreme cases of the geometry variation are defined and the assessment of the possible effects of the root geometry variation on the nonlinear forced response are performed based on a set of these extreme cases.
Feasibility Study of a Radical Vane-Integrated Heat Exchanger for Turbofan Engine Applications
Authors: Jonsson Isak , Xisto Carlos , Abedi Hamidreza , Grönstedt Tomas , Lejon Marcus 
Published: January 2021

Abstract
In the present study, a compact heat exchanger for cryogenically fueled gas turbine engine applications is introduced. The proposed concept can be integrated into one or various vanes that comprise the compression system and uses the existing vane surface to reject core heat to the cryogenic fuel. The requirements for the heat exchanger are defined for a large geared-turbofan engine operating on liquid hydrogen. The resulting preliminary conceptual design is integrated into a modified interconnecting duct and connected to the last stage of a publicly available low-pressure compressor geometry. The feasibility of different designs is investigated numerically, providing a first insight on the parameters that govern the design of such a component.
Redesign of the TG20 Heavy-Duty Gas Turbine to Increase Turbine Inlet Temperature and Global Efficiency
Authors: Baratta Mirko , Cardile Francesco , Misul Daniela Anna , Rosafio Nicola , Salvadori Simone , Forno Luca , Toppino Marco 
Published: January 2021

Abstract
The even more stringent limitations set by the European Commission on pollutant emissions are forcing gas turbine manufacturers towards the redesign of the most important components to increase efficiency and specific power. Current trends in gas turbine design include an increased attention to the design of cooling systems and enhanced best practices for the study of components interaction. At the same time, the recent crisis suffered by the oil and gas industry reduced the interest in brand new gas turbines, thus increasing the service market. Therefore, original equipment manufacturers would rather propose the replacement of specific components within the gas turbine plant during its maintenance with compatible elements that are likely to guarantee increased performance and longer residual lifetime at a more desirable nominal working point.
In the present activity the cooling system of the TG20 heavy-duty gas turbine has been redesigned to increase the turbine inlet temperature while contemporaneously reducing the total amount of coolant mass-flow. Specifically, the cooling scheme of the rotating blade of the first turbine row has been reviewed at the Department of Energy (DENERG) of Politecnico di Torino in cooperation with EthosEnergy Italia S.p.a.. The paper presents a new design, which, starting from the original solution featuring fifteen smooth pipes, adopts an improved geometry characterized by the presence of turbulators.
The activity has been carried out using Computational Fluid Dynamics (CFD) for the coolant/blade interaction and one-dimensional models developed at EthosEnergy for the redistribution of the cooling flows in the cavities. The mutual effects between the coolant fluid and the blade are analyzed using a Conjugate Heat Transfer (CHT) approach with Star-CCM+. The validation of the computational approach has been performed exploiting the experimental data available for the NASA C3X test case. The TG20 rotating blade of the first turbine row has been analyzed considering the two different coolant configurations. The impact of the main flow on the thermal field has initially been included by imposing a temperature field on the blade surface. The latter field has in turn been obtained by means of a separate computation for the solid only. Full CHT simulations has hence been performed, thus quantifying the accuracy of the proposed approach. The obtained results are discussed in terms of thermo-fluid-dynamic effects.
An Investigation of Reversing Axial Turbomachinery for Thermal Energy Storage Application
Authors: Harris Paul , Wolf Tom , Kesseli Jim , Laughlin Robert B. 
Published: January 2021

Abstract
This paper investigates the feasibility of reversing axial turbomachinery for a thermal energy storage application. Under the proposed concept, the direction of flow and spool rotation is reversed when changing from electrical generation to heat pump mode, and the axial turbomachinery components function as either a compressor or turbine depending on the energy storage system’s mode of operation. Such reversing pump-turbines are widely used in pumped hydro installations but have not been employed for compressible flow applications to our knowledge to date. The preliminary aerodynamic design approach for the reversing blade geometry is described, followed by a CFD-based evaluation of turbomachinery performance for the case of a 50MW thermal storage plant. The demand for high efficiency in both modes leads to an unconventional design with a large number of stages for a given pressure ratio. A statorless counter-rotating architecture is utilized for efficiency considerations, and to reduce the overall number of turbomachinery components. Initial CFD results indicate that the reversing axial turbomachinery is capable of achieving high efficiency in both modes of operation, and of satisfying the performance goals of the thermal energy storage application.
Numerical and Experimental Research of the Highly Loaded Compressor 1st Stage: Part 1 — Aerodynamics
Authors: Druzhinin Iaroslav , Mileshin Victor , Petrovichev Alexander , Stepanov Alexander 
Published: January 2021

Abstract
Investigation object is a 1.5-stage with wide-cord rotor blades modeling a full-scale first stage of advanced highly loaded high pressure compressor. Overall total pressure ratio of the stage in the design point is 2.28.
Numerical part of the investigation includes a series of the simulations in 3D RANS statement to assess the integral performances of the stage. The simulation is carried out using the blade geometries defined with taking into account pressure distribution at the blade sides. The second part of the simulation is devoted to the analysis of unsteady row interaction in URANS statements at the design rotational speed. Finite volume grid covering full-annulus blade rows was generated. Total numbers of meshed passages are: 3 blades of inlet struts, 29 inlet guide vanes, 29 rotor blades, 58 stator vanes. Through flow simulation is carried out using dual time-stepping scheme with physical time step corresponding the movement by approximately 1 cell at the rotor-stator interface at 1 time step. The calculation continues until the flow parameters become periodic in time. The analysis of instantaneous and time averaged flow distributions is carried out. Viscous wakes propagation from struts, vanes and rotor blades through the flowpath is studied. The comparison between time averaged flow fields and the distribution from steady RANS shows some features in different problem statement. Unsteady pressure distribution at blade sides is extracted at each time step for mechanical analysis.
Experimental part of the investigation consists of series of tests at CIAM compressor test rig at wide range of rotational speed. The instrumentation of the stage allows to measure steady and unsteady flow parameters and to control mechanical behavior of rotor blades by strain gages and tip timing method.
Finally, the comparison between measured data is performed in integral performances and flow distributions.
Defining Key Environmental Performance Factors (KEPF) for Gas Turbines Eco-Design and Production Through Life Cycle Assessment
Authors: Musacchio Alessandro , Corona Andrea , Cencioni Luca , Serra Angela , Bartocci Pietro , Fantozzi Francesco 
Published: January 2021

Abstract
Nowadays environmental impact assessment of a new product is necessary to meet rising sustainability requirements also in the Oil & Gas and Power Generation markets, especially for industrial gas turbines. From the conceptual phase to the detailed design, engineer’s work is supported by a wide range of tools aimed to define and evaluate typical parameters such as performances, life and costs, etc. However, considering environmental impact aspects from the early stages of product development may not be easy if the involved engineers are not provided by a specific Life Cycle Assessment (LCA) knowledge.
Scope of this paper is to introduce and explain the development of a methodology aimed to define and evaluate the Key Environmental Performance Factors (KEPF) during the whole design process. The proposed methodology enables easy and fast eco-design evaluations and supports sustainable design assessments. Preliminary analysis of the entire processes involved in gas turbine (GT) design and production as well as testing and commissioning phases were performed to evaluate which factors affect mostly the Carbon Footprint of each process, referred to their specific functional unit. Extrapolating the KEPF from Cradle-to-Gate LCA they can be combined with case-specific qualitative and quantitative information such as material selection, manufacturing processes, mass quantity, presence of coatings etc. to provide environmental assessments.
A case study of LCA applied to a heavy-duty GT is presented to outline the relative weight of each KEPF.