bluuebunny/crossref_metadata_2025_split huggingface dataset:
Technical and Economic Viability of an EIS 2050 Geared Open Rotor
Authors: Sebastiampillai Joshua , Rolt Andrew , Nalianda Devaiah , Mastropierro Francesco , Sethi Vishal 
Published: November 2019

Abstract
The aviation sector is projected to grow rapidly over the next two decades and beyond. These projections coupled with ever more stringent environmental legislation call for action within the commercial aviation sector to radically reduce greenhouse gas emissions by 2050. It is perceived that by 2050 current state-of the-art direct-drive turbofans will have evolved into geared turbofans and geared open rotor engines for short haul missions. These changes in engine configuration may be attributed to calls from the Advisory Council for Aviation Research and innovation in Europe to dramatically reduce CO2 generation and greenhouse gas emissions by 2050. The geared open rotor architecture is predicted to significantly reduce fuel burn relative to a typical short-range year-2000 aircraft mission, and greatly reduce CO2 emissions per passenger kilometer. Although relative fuel-burn benefits have been estimated in various studies, the economic feasibility of developing the geared open rotor (GOR) engine configuration for potential manufacturers and operators has not been reported.
Therefore, this paper describes methodologies employed to estimate the relative fuel burn benefit of a short-range year 2050 GOR engine-aircraft configuration. In addition, it details the financial feasibility of year-2050 short-range engine and aircraft concepts, for manufacturers and operators alike. An overview of the technical specifications of a potential ‘GOR2050’ engine configuration is provided. This paper further describes methods employed to predict the unit cost of a year-2050 engine and aircraft concept that might be offered by the manufacturers, as well as a revenue model for manufacturers in the 2050-timeframe. In order to capture the supplier–customer relationship between the OEMs and their customers, direct operating cost (DOC) and representative revenue models have been constructed for the operators.
This paper also analyses the effects that potential future fuel price and taxation policies regarding emissions could have on the operational profitability of such an aircraft and engine combination. Based on a representative set of model inputs, an illustrative test-case for a year-2050 short-haul aircraft and engine combination predicts, with a 50% confidence level, that the minimum number of twin-engine aircraft sales needed to ensure the financial feasibility of the program would be 630 units. Furthermore, with a 50% confidence level, a potential operator could expect an internal rate of return over 7%. The impact of different fuel prices and taxation scenarios are quantified in terms of internal rate of return forecasts.
The Impact of Combustor Turbulence on Turbine Loss Mechanisms
Authors: Folk Masha , Miller Robert J. , Coull John D. 
Published: November 2019

Abstract
A blade row which is located downstream of a combustor has an extremely high turbulence intensity at inlet, typically above 10%. The peak turbulent length scale is also high, at around 20% of the chord of the downstream blade row. In a combustor, the turbulence is created by impinging jets in cross flow. This may result in the turbulence being anisotropic in nature. The aim of this paper is to investigate the effect of combustor turbulence on the loss mechanisms which occur in a turbine blade row. The paper has a number of important findings. The combustor turbulence is characterized and is shown to be isotropic in nature. It shows that, when no pressure gradient is present, combustor turbulence increases the loss of a turbulent boundary layer by 22%. The mechanism responsible for this change is shown to be a deep penetration of the turbulence into the boundary layer. It shows that the presence of combustor turbulence increases the profile loss and endwall loss in the turbine cascade studied by 37% and 47%, respectively. The presence of combustor turbulence also introduces a freestream loss resulting in the total loss of the turbine cascade rising by 47%. When these loss mechanisms were applied to the vane alone, of an engine representative high pressure turbine, it was found to result in a 1.3% reduction in stage efficiency.
Multi-Scale Parallelised CFD Modelling Towards Resolving Manufacturable Roughness
Authors: Kapsis Marios , He Li , Li Yan Sheng , Wells Roger , Valero Omar , Krishnababu Senthil , Gupta Gaurav , Kapat Jayanta , Schaenzer Megan 
Published: November 2019

Abstract
Typical turbomachinery aerothermal problems of practical interest are characterised by flow structures of wide-ranging scales, which interact with each other. Such multi-scale interactions can be observed between the flow structures produced by surface roughness and by the bulk flow patterns. Moreover, additive manufacturing may sooner or later open a new chapter in component designs by granting designers the ability to control the surface roughness patterns. As a result, surface finish, which so far has been treated largely as a stochastic trait, can be shifted to a set of design parameters that consist of repetitive, discrete micro-elements on a wall surface (‘manufacturable roughness’).
Considering this prospective capability requirement, the question would arise regarding how surface micro-structures can be incorporated in computational analyses during a design phase in the future. Semi-empirical methods for predicting aerothermal characteristics and the impact of manufacturable roughness could be used to minimise computational cost. However, the lack of element-to-element resolution may lead to erroneous predictions, as the interactions among the roughness micro-elements have been shown to be significant for adequate performance predictions [1].
In this paper a new multi-scale approach based on the novel Block Spectral method is adopted. This method aims to provide efficient resolution of the detailed local flow variation in space and time of the large scale micro-structures. This resolution is provided without resorting to modelling every single ones in detail, as a conventional large scale CFD simulation would demand, but still demonstrating similar time-accurate and time-averaged flow properties. The main emphasis of the present work is to develop a parallelised solver of the method to enable tackling large problems. The work also includes a first of the kind verification and demonstration of the method for wall surfaces with a large number of micro-structured elements.
Flow Characteristics in Aeroengine Bearing Chambers With Shallow Sump
Authors: Chandra Budi , Simmons Kathy 
Published: November 2019

Abstract
In an aeroengine oil is supplied to the bearings for lubrication and cooling. Subsequently, it creates a two phase flow environment in the bearing chamber that may contain droplets, mist, wall film, ligaments, froth or foam and liquid pools. After the oil has served its purpose, it is scavenged out of the chamber and recycled. Effective oil removal is essential as unnecessary working of the oil can lead to excessive heat generation in the chamber, increased risk of seal leakage, and reduced overall efficiency. However the task of oil removal is not trivial as it is entrained in a highly rotating environment induced by the rotating shafts.
Shallow sump variants were investigated using a design of experiments approach. A previous publication discussed the performance of the sump variants using categorization of visualization data relating to the extent of hydraulic uplift in the sump region. Hydraulic uplift was found to be directly related to residence volume in the gravity dominated wall film flow regime. Furthermore, it was found that the flow condition factors such as flow regime and shaft speed are the dominating factors affecting the hydraulic uplift severity. In terms of the geometrical factors, a deeper sump can reduce the hydraulic uplift severity. This reinforces the importance of sump depth, as a deeper sump tends to have lower residence volume but is often not implemented due to space constraint.
This paper presents further results from the experimental study on the shallow sump variants in terms of some important flow characteristics such as upstream flow detachment, upstream flow dry-out, and secondary flow. In addition to the geometrical factors, the flow condition factors such as the flow regime defined by how oil enters the chamber, flow rate, shaft speed, and scavenge ratio were investigated. Upstream flow detachment was observed only for cases where airborne droplets were present and at higher shaft speeds, also known as the windage dominated airborne droplets flow regime. It was noted that the geometrical factors are less important than the flow condition factors for upstream flow detachment as well as upstream flow dry-out and secondary flow.
Gas Path Diagnostics for a Once-Through Steam Generator
Authors: Chen Yu-Zhi , Li Yi-Guang , Newby Mike A. 
Published: November 2019

Abstract
The performance of a once-through steam generator (OTSG) is bound to degrade due to fouling during its operation. The fouling will result in the degradation of the heat transfer between hot gas and water or steam on both sides of the tubes within the OTSG, thereby causing degraded OTSG performance. Such degradation could result in significant economic losses for a power plant where the OTSG plays a key role. Thus, it would be beneficial to develop a diagnostic method to quantify the fouling in an OTSG in order to support the condition monitoring and condition-based maintenance of the plant. In this study, a novel gas path diagnostic method for an OTSG based on Newton-Raphson method was developed to predict the OTSG degradation caused by fouling. The diagnostic method was applied to a model OTSG to test its effectiveness. The impact of measurement noise on the diagnostic accuracy was analyzed and discussed. A comparison between predicted and implanted degradation of a model OTSG demonstrated that the results are promising, and the method is satisfactory. Meanwhile, the diagnostic analysis of an OTSG based on real measurements has further proved that the developed diagnostic method works well and has a great potential to provide useful health information of OTSGs. In theory, the developed diagnostic method has the potential to be applied to different types of OTSGs.
Modeling of Combustor and Turbine Vane Interaction
Authors: Verma Ishan , Zori Laith , Basani Jaydeep , Rida Samir 
Published: November 2019

Abstract
Modern aero-engines are characterized by compact components (fan, compressor, combustor, and turbine). Such proximity creates a complex interaction between the components and poses a modeling challenge due to the difficulties in identifying a clear interface between components since they are usually modeled separately. From a numerical point of view, the simulation of a complex compact aero-engine system requires interaction between these individual components, especially the combustor-turbine interaction. The combustor is characterized by a subsonic chemically reacting and swirling flow while the high-pressure turbine (HPT) stage has flow which is transonic. Furthermore, the simulation of combustor-turbine interactions is more challenging due to aggressive flow conditions such as non-uniform temperature, non-uniform total-pressure, strong swirl, and high turbulence intensity. The simulation of aero-engines, where combustor-turbine interactions are important, requires a methodology that can be used in a real engine framework while ensuring numerical requirements of accuracy and stability. Conventionally, such a simulation is carried out using one of the two approaches: a combined simulation (or joint-simulation) of the combustor and the HPT geometries, or a co-simulation between the combustor and the turbine with the exchange of boundary conditions between these two separate domains.
The primary objective of this paper is to assess the effectiveness of the joint simulation versus the co-simulation and propose a more practical approach for modeling combustor and turbine interactions. First, a detailed grid independence study with hexahedral and polyhedral meshes is performed to select the required polyhedral mesh. Then, an optimal location of the interface between the combustor and the nozzle guide vane (NGV) is identified. Co-simulations are then performed by exchanging information between the combustor and the NGV at the interface, wherein the combustor is solved using LES while the NGV is solved using RANS. The joint combustor-NGV simulations are solved using LES. The effect of the combustor-NGV interaction on the flow field and hot streak migration is analyzed. The results suggest that the joint simulation is computationally efficient and more accurate since both components are modelled together.
Design Considerations for High Pressure Boil-Off Gas (BOG) Centrifugal Compressors With Synchronous Motor Drives in LNG Liquefaction Plants
Authors: Taher Matt , Meher-Homji Cyrus B. 
Published: November 2019

Abstract
The increased size of Liquefied Natural Gas (LNG) plants worldwide has led to an increase in boil-off gas (BOG) flows. The BOG can be either liquefied again to LNG or compressed to higher pressure levels for use as fuel gas. Single shaft multistage centrifugal compressors are used to compress large volume of BOG at high pressures. This paper reviews design considerations for synchronous motor driven BOG centrifugal compressors operating at high discharge pressures. Several design features including compressor selection and sizing, auxiliary system, performance characteristics and testing are reviewed. The use of leading power factor synchronous motors to improve the power factor of the LNG plant is discussed. Capability curves of API 546 synchronous motors for operation in VAR control mode — for maintaining constant reactive power — are explained. The choice between the use of speed control or adjustable guide vanes for BOG compressors is discussed.
A General Study of Counterflow Diffusion Flames for Supercritical CO2 Mixtures
Authors: Manikantachari K. R. V. , Martin Scott , Rahman Ramees K. , Velez Carlos , Vasu Subith 
Published: November 2019

Abstract
A counterflow diffusion flame for supercritical CO2 combustion is investigated at various CO2 dilution levels and pressures by accounting for realgas effects into both thermal and transport properties. The UCF 1.1 24-species mechanism is used to account the chemistry. The nature of important non-premixed combustion characteristics such as Prandtl number, thermal diffusivity, Lewis number, stoichiometric scalar dissipation rate, flame thickness, and Damköhler number are investigated with respect to CO2 dilution and pressure. The result show that, the aforementioned parameters are influenced by both dilution and pressure; the dilution effect is more dominant. Further, result shows that Prandtl number increases with CO2 dilution and at ninety percent CO2 dilution, the difference between the Prandtl number of the inlet jets and the flame is minimal. Also, the common assumption of unity Lewis number in the theory and modeling of non-premixed combustion does not hold reasonable for sCO2 applications due to large difference of Lewis number across the flame and the Lewis number on the flame drop significantly with increase in the CO2 dilution. An interesting relation between Lewis number and CO2 dilution is observed. The Lewis number of species drops by 15% when increasing the CO2 dilution by 30%. Increasing the CO2 dilution increases both the flow and chemical timescales; however chemical timescale increases faster than the flow time scales. The magnitudes of the Damköhler number signifies the need to consider finite rate chemistry for sCO2 applications. Further, the Damköhler numbers at 90% sCO2 dilution are very small, hence laminar flamelet assumptions in turbulent combustion simulations are not physically correct for this application. Also, it is observed that the Damköhler number drops non-linearly with increasing CO2 dilution in the oxidizer stream. This is a very important observation for the operation of sCO2 combustors. Further, the flame thickness is found to increase with CO2 dilution and reduce with pressure.
Development of a 250-kWe Class Supercritical Carbon Dioxide Rankine Cycle Power Generation System and its Core Components
Authors: Seo JeongMin , Choi Won Chul , Lim HyungSoo , Park MooRyong , Kim Dong Ho , Lee KongHoon , Yoon EuiSoo 
Published: November 2019

Abstract
Korea Institute of Machinery & Materials (KIMM) investigated a supercritical carbon dioxide (sCO2) cycle for a heat recovery power generation system for several years. The objective of the study focuses on the development of the technologies and the establishment of the development procedure of turbomachinery, heat exchangers, and auxiliary equipment for the sCO2 power cycle. A motor-driven centrifugal starter pump with an inducer is developed for startup operation. The main pump-drive turbine module adopts magnetic bearings as axial and radial bearings to remove oil lubrication and exhibits a hermetic structure to eliminate leakage problems. The power turbine and a generator are linked via a gearbox in the power turbine-generator module. An oil bearing and floating ring seal with dry gas injection are applied to minimize sCO2 leakage. The recuperator is developed as a printed circuit heat exchanger (PCHE) owing to its high efficiency and compactness.
The integrated test facility is designed as a 250-kWe class sCO2 recuperated Rankine cycle to evaluate the performance of the core modules as opposed to demonstrating the viability of a particular sCO2 cycle. The test facility is proven to successfully operate in startup mode and self-sustaining mode using the starter pump and the main pump-drive turbine module. An overview of the operation of the startup mode and self-sustaining mode is presented.
Numerical Investigation of Ignition Sequence in a Multi-Burner Methane-Air Swirl Combustor Using Flamelet Generated Manifold Combustion Model
Authors: Nakod Pravin , Shrivastava Sourabh , Patwardhan Saurabh , Orsino Stefano , Yadav Rakesh 
Published: November 2019

Abstract
Low emission gas turbine engines, operating under fuel lean conditions, are susceptible to light-around issues. Traditionally, gas turbine manufacturers rely on experimentation and testing to understand the relight characteristics of a combustor. However, since the last decade, numerical simulations are gaining popularity in performance evaluation of the light-around characteristics of the gas turbine combustors. In the present work, assessment of the Flamelet Generated Manifold (FGM) combustion model is carried out to understand its performance for capturing the correct ignition sequence in a linear multi-burner methane-air swirl combustor designed by COmplexe de Recherche Interprof essionnel en Aérothermochimie (CORIA) in the context of Knowledge for Ignition, Acoustics, and Instabilities (KIAI) project. The present work uses linear five, four and two swirled injector configurations for the validation of the simulation results. Non-reacting and reacting Large Eddy Simulations (LES) are performed for three injector arrangements to predict the main flow structure, mixing, flame propagation and ignition sequence. Non-reacting time-averaged flow quantities such as mean axial and radial velocities are data-sampled and compared with the experimental results. The predicted results show a good comparison between simulation and experimental data. Ignition sequence and timing predicted from the reacting LES for all the three configurations studied in this work, also compare well with the experimental data. This numerical investigation confirms that the FGM combustion model used in the LES framework can be successfully employed for the prediction of the relight characteristics of the gas turbine engines.
Impacts of H2 Blending on Capacity and Efficiency on a Gas Transport Network
Authors: Bainier Francis , Kurz Rainer 
Published: November 2019

Abstract
Gas Transport System Operators (TSO1) are considering injecting hydrogen gas in their networks. Blending hydrogen into the existing natural gas pipeline network appears to be a strategy for storing and delivering renewable energy to markets [1], [2],[3].
In comparison to methane, hydrogen gas (dihydrogen or molecular hydrogen) has a higher mass calorific value than methane gas. Because of this property, molecular hydrogen is appreciated for space shuttle engines. A second property is that hydrogen gas has a lower mass density than methane gas. The result of the second property is that the volume calorific value is in favor of methane gas. The list of differences between methane and hydrogen is long. In the relevant range of pressures and temperatures, the Joule-Thomson coefficient has a different sign for hydrogen and methane, and the compressibility factor has the opposite trend when the gas is compressed. The dynamic viscosity is also significantly different, and finally, heat capacity, isentropic exponent, and the thermal conductivity are also different.
What are the impacts of these hydrogen characteristics on the transport capacity and its efficiency in the case of blending in a gas transport network?
The first part of the paper is a review of the differences in characteristics between Hydrogen Gas and a Typical Natural Gas in Europe and their impact on the gas flow performance in a pipeline network equipped with compressors.
The second part of the paper is dedicated to pipe segments. And in the third part, compressor stations are introduced between each pipe segment. At each step, an analysis of a mixed gas from one hundred per cent pure natural gas to one hundred per cent pure hydrogen is done.
The paper provides some results for 10 %, 40 %, and 100 % of hydrogen blending in an international pipeline. The study shows that the energy quantity transported at the same pressure ratio is reduced respectively by 4 %, 14 %, and 15 to 20 %, and energy requirement for compression increases respectively by 7 %, 30 %, and 210 % (i.e. it more than triples). To transport the same quantity of energy in a network, assuming the resizing to the same level of optimizations, the energy requirement increases by 11 %, 52 %, and 280 %. In other words, it takes 4 times the energy to transport a given amount of energy if the gas is pure hydrogen than it takes if the gas is pure natural gas.
The paper does not address the issue of equipment or material, it only compares the influence of hydrogen gas on the network capacity and the transport efficiency. This paper doesn’t take into account the limits of the equipment. All equipment is considered as compatible with any load of hydrogen blending.