bluuebunny/crossref_metadata_2025_split huggingface dataset:
Steady RANS of Flow and Heat Transfer in a Smooth and Pin-Finned U-Duct With a Trapezoidal Cross Section
Authors: Hu Kenny S.-Y. , Chi Xingkai , Shih Tom I-P. , Chyu Minking , Crawford Michael 
Published: August 2018

Steady RANS were performed to examine the ability of four turbulence models — realizable k-ε (k-ε), shear-stress transport (SST), Reynolds stress model with linear pressure strain (RSM-LPS), and stress-omega RSAM (RSM-τω) — to predict the turbulent flow and heat transfer in a U-duct with a trapezoidal cross section and with and without a staggered array of pin fins. Results generated for the heat-transfer coefficient (HTC) were compared with experimentally measured values.
For the smooth U-duct, the maximum relative error in the averaged HTC in the up-leg is 2.5% for k-ε, SST, and RSM-τω and 9% for RSM-LPS. In the turn region, that maximum is 14.5% for RSM-τω, 29% for SST, and 50% for k-ε and RSM-LPS. In the down-leg, SST gave the best predictions and RSM-τω being a close second with maximum relative error less than 10%. The ability to predict the secondary flow in the turn region and the separated flow downstream of the turn dominated in how well the models predict the HTC.
For the U-duct with pin fins, k-ε predicted the lowest and the least accurate HTCs, and SST and RSM-τω predicted the best. For k-ε, the maximum relative error in the averaged HTC is about 25%, whereas it is 15% for the SST and RSM-τω, and they occur in the turn. In the turn region, the staggered array of pin fins was found to behave like guide vanes in turning the flow. The pin fins also reduced the size of the separated region just after the turn.
Aerodynamic and Mechanical Analyses on Manufacturing Variations of a Turbine Blade Row
Authors: Liu Jong-Shang , Zhu Douglas X. , Lew Bryon , Rodriguez Aaron Daniel 
Published: August 2018

Typical turbine blade design systems are based on parametric studies and engineering experience. Best practices use feedback from manufactured hardware to additionally create producible designs and establish tolerances. Often there is a large gap in understanding of true hardware variation and the ability to describe and analyze it without over simplification. Previously, hardware inspections that feed analyses were limited based on Coordinate Measurement Machines (CMM) point inspection, optical measurements or gages designed to measure specific features. Those details were input into parametric models in an attempt to quantify the impact of hardware variation. Each measurement method has its limitations including accuracy and methodology which can affect the evaluation results. With the advent of 3D scanning, the complex 3D nature of airfoil designs can be described accurately with minimal simplification or assumptions. Actual hardware can be analyzed and assessed for design requirement compliance. In this study, 3D structured light inspection technology is used to assess aerodynamic performance and mechanical durability variation on a statistical sample of actual production hardware.
A Honeywell designed auxiliary power unit second stage uncooled turbine rotor was used as a test case for this study. Thirty-five (35) blade castings randomly selected from three different casting mold lots were scanned using structured light to capture manufacturing process variation. The 3D scanning was completed using controls and robust scanning techniques certified for metrology use. Scans were assessed according to manufacturing requirements and correlated to aerodynamic and mechanical requirements using nominal machining geometry based on datum alignments.
Analyses were performed using STAR-CCM+ for aerodynamic performance and ANSYS for mechanical durability. The designed nominal geometry was used as a baseline for comparison. HEEDS was used to automate the aerodynamic analysis process — replacing the baseline model with the scanned data, merging the new geometry with the base model, meshing, applying boundary conditions, and solving in remote Linux clusters. The automation process achieved a significant reduction in cycle time from several weeks to a few days.
Similarly, the same structured light scan data was used to evaluate mechanical durability in ANSYS. Scan data was aligned to machining datums, boolean cut with nominal CAD machining geometry and directly converted to solid models using SpaceClaim. The solid model was meshed in ANSYS and merged onto the baseline FEA model for solving. Macros were used to automate the analysis process of each part scan and output stresses at critical locations for durability assessment.
Using a combination of analytical tools and actual scan hardware, the impact of manufacturing variation could be understood. Integrating scan data directly to analysis reduces engineering assumptions and gives a better understanding of reality.
Application of Conjugate Heat Transfer Analysis to Improvement of Cooled Turbine Vane and Blade for Industrial Gas Turbine
Authors: Horiuchi Takeshi , Taniguchi Tomoki , Tanaka Ryozo , Ryu Masanori , Kazari Masahide 
Published: August 2018

In this paper, the Conjugate Heat Transfer (CHT) analysis, which utilizes commercial software STAR-CCM+ with detailed models and practical mesh size, was performed to the first stage cooled turbine airfoils for an industrial gas turbine produced by Kawasaki Heavy Industries, Ltd. (KHI). First its estimation accuracy was evaluated by comparing with the measurement results obtained with thermal index paint (TIP) and a pyrometer. After the validation of the CHT analysis, the metal temperature distribution was understood with the flow phenomena associated with it from the analysis results. To the parts where the metal temperature is locally high, then, the improvements of the cooling performance were considered with the CHT analysis and their effects were finally confirmed by measuring the metal temperature in the actual engine.
The investigation reveals that the CHT analysis, which is validated with measurement results, makes it possible for cooling designers to efficiently improve the cooling performance of turbine airfoils with the adequate estimation accuracy, thus enhancing their durability for the reliability of gas turbines.
Development of a Meanline Model for Preliminary Design of Recirculating Casing Treatment in Turbocharger Compressors
Authors: Favaretto Carlos Felipe F. , Anderson Mark R. , Li Shuo , Hu Leon 
Published: August 2018

Recirculating casing treatment is a feature frequently adopted in automotive turbocharger compressor design to extend its operating range. In the low flow region of the map, surge margin can be enhanced by bleeding a fraction of the main flow from the impeller casing back to the stage inlet. In the high flow region, choke margin can be improved by bleeding flow from the stage inlet to a location downstream of the impeller throat. The benefits of recirculating casing treatment are more prominent at higher rotational speeds and are usually accompanied by an associated penalty in efficiency, which may or may not be acceptable. The challenge posed to the designers is to create a recirculating casing cavity configuration which enlarges the map width, while minimizing its impact on efficiency.
In the lack of specialized meanline tools, early stages of recirculating casing cavity design are mostly reliant on results from expensive CFD runs or test data from existing designs, if available. This paper presents the development of a meanline model suitable for preliminary design. The model was compared with CFD results for an automotive turbocharger compressor. The authors believe the proposed model can be a valuable tool for reducing development costs in the preliminary design stages of recirculating casing treatment configurations.
Integration of 3D-CFD Component Simulation Into Overall Engine Performance Analysis for Engine Condition Monitoring Purposes
Authors: Klein C. , Wolters F. , Reitenbach S. , Schönweitz D. 
Published: August 2018

For an efficient detection of single or multiple component damages, the knowledge of their impact on the overall engine performance is crucial. This knowledge can be either built up on measurement data, which is hardly available to non-manufacturers or –maintenance companies, or simulative approaches such as high fidelity component simulation combined with an overall cycle analysis.
Due to a high degree of complexity and computational effort, overall system simulations of jet engines are typically performed as 0-dimensional thermodynamic performance analysis, based on scaled generic component maps. The approach of multi-fidelity simulation, allows the replacement of single components within the thermodynamic cycle model by higher-order simulations. Hence, the component behavior becomes directly linked to the actual hardware state of the component model. Hereby the assessment of component deteriorations in an overall system context is enabled and the resulting impact on the overall system can be quantified.
The purpose of this study is to demonstrate the capabilities of multi fidelity simulation in the context of engine condition monitoring.
For this purpose, a 0D-performance model of the IAE-V2527 engine is combined with a CFD model of the appropriate fan component. The CFD model comprises the rotor as well as the outlet guide vane of the bypass and the inlet guide vane of the core section. As an exemplarily component deterioration, the fan blade tip clearance is increased in multiple steps and the impact on the overall engine performance is assessed for typical engine operating conditions.
The harmonization between both simulation levels is achieved by means of an improved map scaling approach using an optimization strategy leading to practicable simulation times.
On the Identification and Decomposition of the Unsteady Losses in a Turbine Cascade
Authors: Lengani D. , Simoni D. , Pichler R. , Sandberg R. , Michelassi V. , Bertini F. 
Published: August 2018

The present paper describes the application of Proper Orthogonal Decomposition (POD) to Large Eddy Simulation (LES) of the T106A low-pressure-turbine profile with unsteady incoming wakes at two different flow conditions. Conventional data analysis applied to time averaged or phase-locked averaged flow fields is not always able to identify and quantify the different sources of losses in the unsteady flow field as they are able to isolate only the deterministic contribution. A newly developed procedure allows such identification of the unsteady loss contribution due to the migration of the incoming wakes, as well as to construct reduced order models able to highlight unsteady losses due to larger and/or smaller flow structures carried by the wakes in the different parts of the blade boundary layers. This enables a designer to identify the dominant modes (i.e. phenomena) responsible for loss, the associated generation mechanism, their dynamics and spatial location.
The procedure applied to the two cases shows that losses in the fore part of the blade suction side are basically unaffected by the flow unsteadiness, irrespective of the reduced frequency and the flow coefficient. On the other hand, in the rear part of the suction side the unsteadiness contributes to losses prevalently due to the finer scale (higher order POD modes) embedded into the bulk of the incoming wake. The main difference between the two cases has been identified by the losses produced in the core flow region, where both the largest scale structures and the finer ones produces turbulence during migration. The decomposition into POD modes allows the quantification of this latter extra losses generated in the core flow region, providing further inputs to the designers for future optimization strategies.
CMAS Effects on Ship Gas-Turbine Components/Materials
Authors: Shifler D. A. , Choi S. R. 
Published: August 2018

Recent inspection of shipboard gas-turbine components under the platform has indicated the apparent presence of CMAS (calcium, magnesium, alumino-silicate) and its related attack. This type of attack has often been observed in aero gas turbine engines when sand and similar siliceous matter is ingested into the engine and the sand debris melts due to high engine operating temperature greater than 1150°C. Initial chemical analysis shows that the CMAS-affected areas of ship engine components versus aero engine components are similar. However, this phenomenon commonly observed in advanced aeroengines are not supposed to occur in the ship engine components since their probable temperature is known to be much lower than 1150°C (i.e., melting temperature of CMAS). As a consequence, some important questions arise as to: What caused this “CMAS” attack in ship engine components? Was this initiated by hot corrosion, which created a molten salt pool at a sufficient temperature to trigger CMAS attack? Did sodium chloride mixed with dust and debris lower the temperature at which molten CMAS would initiate?
Past research provides a basic understanding of hot corrosion, but may ignore other reactants and other species inherently associated with ‘natural CMAS’ and mechanisms contributing to hot corrosion or CMAS attack. Further examination of ship and aero components will discern the local structure chemical profile of the component coatings, the chemical compositions of the alloy substrates, and the interface between the coating and the molten “CMAS” by several methods. Integrated computational materials engineering (ICME) and validating experiments will assist in developing degradation mechanisms.
The environment complexity is also to be taken into account to determine whether salt-induced CMAS attack or CaO-induced hot corrosion may be dominant. The mechanisms need to be further studied and defined. The current work will address a series of systematic approaches to the aforementioned CMAS issues and will also present some recent results on CMAS-related effects on components and an elected alloy material system.
Development of a Steady-State Experimental Facility for the Analysis of Double-Wall Effusion Cooling Geometries
Authors: Murray Alexander V. , Ireland Peter T. , Romero Eduardo 
Published: August 2018

The continuous drive for ever higher turbine entry temperatures is leading to considerable interest in high performance cooling systems which offer high cooling effectiveness with low coolant utilisation.
The double-wall system discussed here, is an optimised amalgamation of more conventional cooling methods including impingement cooling, pedestals, and film cooling holes in a more closely packed array characteristic of effusion cooling. The system entails two walls, one with the impingement holes, and the other with the film holes. These are mechanically connected via the bank of pedestal thereby allowing conduction between the walls and increasing coolant wetted area and turbulent flow. However, in the open literature, data — and particularly experimental data — on such systems is sparse.
This study presents a newly commissioned experimental heat transfer facility designed to investigate double-wall cooling geometries. The paper discusses some of the key features of the steady-state facility, including the use of infrared thermography to obtain overall cooling effectiveness measurements. The facility is designed to achieve both Reynolds and Biot (to within 10%) number similarity to those seen at engine conditions.
The facility is used to obtain overall cooling effectiveness measurements for a circular pedestal, double-wall test piece at three coolant mass-flow conditions with the results presented and discussed. A fully conjugate CFD model of the facility was also developed providing greater insight into the internal flow field. Additionally, a computationally efficient, decoupled conjugate method developed by the authors for analysing such double-wall systems is run at conditions to match the experiments. The results of the simulations are encouraging, particularly given how computationally efficient the method is, with area-weighted, averaged overall effectiveness within a small margin of those obtained from the experimental facility.
Unsteady Conjugate Heat Transfer Investigation of a Multistage Steam Turbine in Warm-Keeping Operation With Hot Air
Authors: Łuczyński Piotr , Toebben Dennis , Wirsum Manfred , Mohr Wolfgang F. D. , Helbig Klaus 
Published: August 2018

In recent decades, the rising share of commonly subsidized renewable energy especially affects the operational strategy of conventional power plants. In pursuit of flexibility improvements, extension of life cycle, in addition to a reduction in start-up time, General Electric has developed a product to warm-keep high/intermediate pressure steam turbines using hot air. In order to optimize the warm-keeping operation and to gain knowledge about the dominant heat transfer phenomena and flow structures, detailed numerical investigations are required. Considering specific warm-keeping operating conditions characterized by high turbulent flows, it is required to conduct calculations based on time-consuming unsteady conjugate heat transfer (CHT) simulations.
In order to investigate the warm-keeping process as found in the presented research, single and multistage numerical turbine models were developed. Furthermore, an innovative calculation approach called the Equalized Timescales Method (ET) was applied for the modeling of unsteady conjugate heat transfer (CHT). The unsteady approach improves the accuracy of the stationary simulations and enables the determination of the multistage turbine models. In the course of the research, two particular input variables of the ET approach — speed up factor (SF) and time step (TS) — have been additionally investigated with regard to their high impact on the calculation time and the quality of the results. Using the ET method, the mass flow rate and the rotational speed were varied to generate a database of warm-keeping operating points.
The main goal of this work is to provide a comprehensive knowledge of the flow field and heat transfer in a wide range of turbine warm-keeping operations and to characterize the flow patterns observed at these operating points. For varying values of flow coefficient and angle of incidence, the secondary flow phenomena change from well-known vortex systems occurring in design operation (such as passage, horseshoe and corner vortices) to effects typical for windage, like patterns of alternating vortices and strong backflows. Furthermore, the identified flow patterns have been compared to vortex systems described in cited literature and summarized in the so-called blade vortex diagram. The comparison of heat transfer in the form of charts showing the variation of the Nusselt-numbers with respect to changes in angle of incidence and flow coefficients at specific operating points is additionally provided.
Criteria for Best Performance of Pre-Optimized Solid Dampers
Authors: Gastaldi Chiara , Gola Muzio M. 
Published: August 2018

This paper furthers recent research by these authors. The starting point is the pre-optimization of solid dampers, which ensures that all dampers bound to misbehave are excluded since the early design stage. The authors now enlarge the scope of their investigations to explore those damper configurations selected inside the admissible design area. The purpose of the paper is to present a set of criteria apt to select a damper configuration which not only avoids unwanted situations, but in addition guarantees high performance under different design conditions.
The analysis starts with the definition of a set of requirements a high performance damper should meet. In detail the present investigation seeks to answer the following questions:
– in the low excitation regime, what is the frequency shift and the stiffening effect each damper can provide?
– for increasing excitation levels, which damper will start slipping sooner?
– in the high excitation regime, which damper provides the maximum dissipation?
Like pre-optimization, it does not involve nonlinear Finite Element calculations, and unlike existing optimization procedures, is not linked to a specific set of blades the damper may be coupled to. The numerical prediction of the blade-damper coupled dynamics is here used only for validation purposes.
The approach on which this paper rests is fully numerical, however real contact parameters are taken from extensive experimental investigations made possible by those purposely developed test rigs which are the distinctive mark of the AERMEC Lab of Politecnico di Torino.
Model Based Diagnostics of AE-T100 Micro Humid Air Turbine Cycle
Authors: Mahmood Mariam , Martini Alessio , Massardo Aristide F. , De Paepe Ward 
Published: August 2018

Micro gas turbines (mGT) are emerging power sources for distributed generation facilities with promising features like environment friendliness, high fuel flexibility, cost effectiveness and efficient cogeneration of heat and power (CHP). However, curtailed heat demand during summers reduces the plant operating hours per year and negatively affects the overall economic feasibility of a CHP project. The micro Humid Air Turbine (mHAT) cycle is one of the novel cycles to increase the electrical efficiency of the gas turbine by utilizing the exhaust gas heat in periods of low heat demand, thus avoiding the system shutdown. However, the water injection system can introduce additional pressure losses in the mGT cycle, which may lead to compressor surge and it may also affect the recuperator performance in the long run due to corrosion. Hence, numerical simulation and diagnostic tools are essential for cycle optimization of mHAT and prediction of performance degradation.
This work is focused on the real time application of the AE-T100 model for the mHAT system located at the Vrije Universiteit Brussel (VUB), which is based on the T100 mGT equipped with a spray saturation tower. The AE-T100 model is a steady-state simulation tool for mGT cycles, which has been developed within a collaboration between the University of Genova (Unige) and Ansaldo Energia, and has been successfully applied at the Ansaldo Enegia test rig (AE-T100) for the diagnostic purpose. For this study, the basic AE-T100 model has been modified to simulate the humidified cycle according to the VUB plant configuration. The modified AE-T100 model has been validated against the experimental data obtained from the mHAT unit at nominal and part load.
Once the model was validated using real operating conditions, it has been used for monitoring the recuperator performance over large number of tests in dry mode, conducted over the past five years, as well as initial tests in wet mode, from the VUB-mHAT system. This work has proved the modeling capability of the AE-T100 tool to simulate the mHAT cycle with reasonable accuracy and first diagnostic application of the AE-T100 tool, in dry mode. However, the lack of data available at present in wet mode does not allow to provide a complete and robust diagnostics of this novel cycle under wet operation.
Hence, this preliminary analysis will provide basis for more detail diagnostics of the mHAT cycle using AE-T100 tool, over a longer time period under wet operation, in future.