bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unsteady Methods to Investigate Inlet Distortion in a Transonic Tail Cone Thruster Fan Stage With Boundary Layer Ingestion
Authors: Giri Ritangshu , Turner Mark G. , Celestina Mark L. 
Published: January 2021

Abstract
Boundary Layer Ingestion (BLI) engines have the potential to offer significantly reduced fuel burn, but the fan stage must be designed to run efficiently with a distorted inflow. It must also be able to withstand unsteady aerodynamic loads resulting from a non-uniform flowfield. In a multidisciplinary turbomachinery design cycle involving such a complicated flowfield, high fidelity numerical solutions are required. Two high fidelity unsteady Reynolds Averaged Navier-Stokes (URANS) methods for accurate analysis of a Tail Cone Thruster (TCT) transonic fan stage subjected to inlet distortion have been implemented. They are frequency domain based non-linear harmonic (NLH) and full-annulus complete time domain based time marching methods. This paper demonstrates that the relevant parameters required to accurately compute aerodynamic performance of a fan stage in distorted conditions can be accurately modelled with a few harmonics using the NLH method in a fraction of time compared to the full annulus time marching method. However, the complete aerodynamics of distortion transfer across different blade rows of a fan stage can only be analyzed using the time marching solution. Several physical mechanisms which govern the fan response to an inlet distortion and how different distortion profiles impact the aerodynamic performance of this fan stage are also explained.
Determining the Optimal Crystallographic Orientation in a Single Crystal Turbine Blade to Increase its Strength Reliability
Authors: Vasilyev Boris , Selivanov Alexander , Semenov Artem , Bortnikov Andrei , Limonova Valentina 
Published: January 2021

Abstract
The high-pressure turbine blades of most modern gas turbine engines are made of single-crystal alloys. Single-crystal materials have significant anisotropy characteristics; therefore, the orientation of the axes of the single crystal relative to the geometrical axes of the blade has a great effect on the stress-strain state, static strength, and dynamic characteristics of the blade.
Here, the necessary optimization of both the axial orientation (the optimal value of which may differ from &lt;001&gt;) and the azimuthal orientation is confirmed. The problem was solved by considering the anisotropic temperature–orientation characteristics of the alloy and the uneven temperature field of the blade. The values of the optimal crystallographic orientations were determined.
Notably, casting tolerances for the deviation of the crystallographic axes must be considered when searching for the optimal position of the axes of the single crystal.
Integration Options for Nuclear Steam Cycle Using Liquid Air Energy Storage
Authors: Heo Jin Young , Lee Won Woong , Park Jung Hwan , Lee Jeong Ik 
Published: January 2021

Abstract
To facilitate the energy transition, the conventional baseload nuclear power must be equipped with flexibility. By integrating grid-scale energy storage systems to the existing nuclear plants, they can curtail their load to avoid surplus generation. Liquid air energy storage (LAES) has been steadily investigated for their advantages, and this paper suggests an integrated layout using mechanical drive steam turbine and packed bed energy storage systems. Possible options for integration of LAES to the existing nuclear steam cycle are considered. The performance of packed bed storage systems is analyzed using transient modeling, and the results are fed into the overall cycle design using an in-house code. The results of the analysis suggests that the concept can reach up to 45.7–59.8% in round-trip efficiency, under much simplified cycle layout than the reference LAES layouts.
Comparative Study of Blades Reduced Order Models With Geometrical Nonlinearities and Contact Interfaces
Authors: Delhez Elise , Nyssen Florence , Golinval Jean-Claude , Batailly Alain 
Published: January 2021

Abstract
This paper investigates the use of different model reduction methods accounting for geometric nonlinearities. These methods are adapted to retain physical degrees-of-freedom in the reduced space in order to ease contact treatment. These reduction methods are applied to a 3D finite element model of an industrial compressor blade (NASA rotor 37). In order to compare the different reduction methods, a scalar indicator is defined. This performance indicator allows to quantify the accuracy of the predicted displacement both locally (at the blade tip) and globally. The robustness of each method with respect to variations of the external excitation is also assessed. The performances of the reduction methods are then compared in the case of frictional contact between the blade tip and the surrounding casing. This work brings evidence that reduced order models provide a computationally efficient alternative to full order finite element models for the accurate prediction of the time response of structures with both distributed and localized nonlinearities.
An Industrial Methodology for Erosion Analysis of FCC Expander Blades
Authors: Maceli Nicola , Maffulli Gianfranco 
Published: January 2021

Abstract
Fluid Catalytic Cracking (FCC) is a process for the conversion of heavy stocks recovered from different refinery operations into high-octane gasoline, light fuel oils and olefin rich light gases.
Zeolite particles are used as catalyst in the process to facilitate the cracking of long hydro-carbon molecules.
Because of the contact between catalyst and feedstock, coke deposits on the catalyst active surface reducing its activity, air is used to remove it from the catalyst, in the regenerator. The coke burning produces a hot flow of flue gas with a valuable energy content (700°C – 3bar) that can be recovered using a Hot Gas Expander HGE before releasing the exhausts in the atmosphere.
The flue gas is carrying a certain amount of catalyst so the expander hot parts (mainly blades but also the stator vanes) are constantly exposed to an abrasive medium that may compromise the reliability of the asset.
Understanding how the solid particle erosion works is one of the challenges that HGEs designer shall deal with.
To this purpose, a numerical approach was developed to account for some of the factors that are known to play a major role in erosion phenomena: particle velocity, angle of impact, composition and particle size, as well as the mechanical properties of the target surface at the operating temperature.
The methodology was then applied to a cascade blade for which erosion data collected in a stationary erosion test rig are available. The comparison between numerical and experimental data showed a good agreement therefore providing confidence on the proposed methodology.
Finally, the numerical procedure has been applied to a real case to show the effect of the different catalyst load on the life of the blades.
Characterising Hydrogen Micromix Flames: Combustion Model Calibration and Evaluation
Authors: López-Juárez Marcos , Sun Xiaoxiao , Sethi Bobby , Gauthier Pierre , Abbott David 
Published: January 2021

Abstract
Hydrogen micromix combustion is a promising concept to reduce the environmental impact of both aero and land-based gas turbines by delivering carbon-free and ultra-low-NOx combustion without the risk of autoignition or flashback. The ENABLEH2 project aims to demonstrate the feasibility of such a switch to hydrogen for civil aviation, within which the micromix combustion, as a key enabling technology, will be matured to TRL3. The micromix combustor comprises thousands of small diffusion flames for which air and fuel are mixed in a cross-flow pattern. This technology is based on the idea of minimizing the scale of mixing to maximize mixing intensity. The high-reactivity and wide flammability limits of hydrogen in a micromix combustor can produce short and low-temperature small diffusion flames in lean overall equivalence ratios.
For hydrogen-air mixtures there is a need to further characterise the physical importance and calibration process of the laminar Schmidt (Sc), Lewis (Le) and Prandtl (Pr) and turbulent Schmidt (Sc) numbers. In addition, there is limited numerical and experimental data about flame characteristics and emissions of hydrogen micromix combustor at high pressure and temperature conditions.
In this paper, the CFD software STAR-CCM+ was used with the FGM (Kinetic Rate) combustion model to simulate and calibrate hydrogen micromix flames. The research was divided into two parts. In the first part, the values of laminar Schmidt, Lewis and Prandtl numbers for H2 and air, non-reactive, flow mixtures were estimated as 0.22, 0.3 and 0.75 from correlations obtained in the literature. The typical Borghi diagram has been modified to represent this type of diffusion flame, since the assumption of Sc = Le = Pr = 1 can not be applied to hydrogen micromix flames and it is only for premixed flames. This diagram characterizes flame regime based on Damköhler (Da), Karlovitz (Ka) and turbulent Reynolds (Ret) numbers that were calculated from preliminary CFD simulations.
In the second part, the value of laminar Schmidt number was set as constant while laminar Lewis and Prandtl numbers were obtained from the flamelet tables. A Turbulent Schmidt number was then obtained by comparing RANS and LES simulations of a single injector. If Sct &gt; 0.2, the predicted NOx production of RANS simulations approaches that of LES; while Sct &lt; 0.2 provides similar overall flame structure between RANS and LES. It is concluded that, for the current simulations, Sct = 0.2 is a good compromise between flame structure and emissions prediction. Flame characteristics and NOx emissions given by Thickened Flame and FGM Kinetic Rate models in a single injector geometry were also compared.
Micro Gas Turbine Integrated With a Supercritical CO2 Brayton Cycle Turbine: Layout Comparison and Thermodynamic Analysis
Authors: Reale Fabrizio , Sannino Raniero , Tuccillo Raffaele 
Published: January 2021

Abstract
In an energetic scenario where both distributed energy systems and smart energy grids gain increasing relevance, the research focus is also on the detection of new solutions to increase overall performance of small-scale energy systems. Waste heat recovery (WHR) can represent a good solution to achieve this goal, due to the possibility of converting residual thermal power in thermal engine exhausts into electrical power. The authors, in a recent study, described the opportunities related to the integration of a micro gas turbine (MGT) with a supercritical CO2 Brayton Cycle (sCO2 GT) turbine. The adoption of Supercritical Carbon Dioxide (sCO2) as working fluid in closed Brayton cycles is an old idea, already studied in the 1960s. Only in recent years this topic returned to be of interest for electric power generation (i.e. solar, nuclear, geothermal energy or coupled with traditional thermoelectric power plants as WHR). In this technical paper the authors analyzed the performance variations of different systems layout based on the integration of a topping MGT with a sCO2 GT as bottoming cycle; the performance maps for both topping and bottoming turbomachinery have been included in the thermodynamic model with the aim of investigating the part load working conditions. The MGT considered is a Turbec T100P and its behavior at part load conditions is also described. The potential and critical aspects related to the integration of the sCO2 GT as bottoming cycle are studied also through a comparison between different layouts, in order to establish the optimal compromise between overall efficiencies and complexity of the energy system. The off-design analysis of the integrated system is addressed to evaluate its response to variable electrical and thermal demands.
Structural Dynamic and Inherent Damping Characterization of Additively Manufactured Airfoil Components
Authors: Goldin Andrew , Scott-Emuakpor Onome , George Tommy , Runyon Brian , Cobb Richard 
Published: January 2021

Abstract
The push for low cost and higher performance/efficient turbine engines has introduced a demand for novel technologies to improve robustness to vibrations resulting in High Cycle Fatigue (HCF). There have been many proposed solutions to this, some passive and some active. With the advent of Additive Manufacturing (AM), new damping techniques can now be incorporated directly into the design and manufacture process to suppress the vibrations that cause HCF. Recent work has been investigating new ways of using AM for turbine engine applications. A specifically innovative approach using Laser Powder Bed Fusion (LPBF) is of particular note. The use of internal pockets filled with the build powder but left unfused has proved to have damping quality with &gt; 90% force response reduction. This study will investigate the as-manufactured parts, damping endurance, and structural dynamic changes when this technology is applied to a compressor-like blade. This will be done by using multiple testing methods to investigate the performance and dynamics of the blade. The study will use computed tomography (CT) scans to investigate the pockets, structured light scans to investigate the external geometry, Modal Assurance Criteria (MAC) to investigate the structural dynamics and a sinusoidal strain step test to investigate endurance. This study found similar endurance and damping capabilities as previously observed, in addition to finding that the inclusion of the unfused powder pockets did not affect mode shapes measured by the MAC.
Super Aggressive S-Ducts for Air Breathing Rocket Engines
Authors: Taylor J. V. , Flanagan F. , Dunlop A. , Grimshaw S. D. , Miller R. J. 
Published: January 2021

Abstract
Air breathing rocket engines require turbomachinery and ducting that is substantially lighter than that used in ground based or aerospace gas turbines. In order to reduce the weight of the axial compressor, the design of the inter-spool swan neck duct is targeted. In this paper a circumferential splitter blade is used to reduce loading and diffusion on the duct endwalls. The splitter and duct geometry are coupled and optimised together using 2D CFD. A design is selected that is 30% shorter than ducts that are currently used in aerospace gas turbines and the 3D flow features are investigated in further detail using an experimental rig and 3D CFD.
This paper shows that the “splittered” duct has 3 benefits over a conventional duct design: First, separation of the endwalls is prevented even at short duct lengths, this will reduce distortion into the downstream compressor. Second, losses generated by corner separations on structural struts can be reduced by 20%, enabling short ducts to achieve high performance. Third, splittered ducts are shown to be twice as robust to uncertain inlet flow conditions as conventional ducts. This allows a designer to target high performance short designs with reduced risk.
An Integrated Approach to Simulate Gas Turbine Secondary Air System
Authors: Izadi Ali , Madani Seyed Hossein , Hosseini Seyed Vahid , Chizari Mahmoud 
Published: January 2021

Abstract
One of the most critical parts of a modern gas turbine that its reliability and performance has a great influence on cycle efficiency is the secondary air system (SAS). Modern systems functions to supply not only cooling air flow for turbine blades and vanes but sealing flow for bearing chambers and turbine segments as well as turbine disks’ purge flow in order to eliminate hot gas ingestion. Due to the various interactions between SAS and main gas, consideration of the former is substantially crucial in design and analysis of the whole engine. Geometrical complexities and centrifugal effects of rotating blades and disks, however, make the flow field and heat transfer of the problem so complicated AND too computationally costly to be simulated utilizing full 3-D CFD methods. Therefore, developing 1-D and 0-D tools applying network methods are of great interests.
The present article describes a modular SAS analysis tool that is consisted of a network of elements and nodes. Each flow branch of a whole engine SAS network is substituted with an element and then, various branches (elements) intersect with each other just at their end nodes. These elements which might include some typical components such as labyrinth seals, orifices, stationary/rotating pipes, pre-swirls, and rim-seals, are generally articulated with characteristic curves that are extracted from high fidelity CFD modeling using commercial software such as Flowmaster or ANSYS-CFX. Having these curves, an algorithm is developed to calculate flow parameters at nodes with the aid of iterative methods.
The procedure is based on three main innovative ideas. The first one is related to the network construction by defining a connectivity matrix which could be applied to any arbitrary network such as hydraulic or lubrication networks. In the second one, off-design SAS calculation will be proposed by introducing some SAS elements that their characteristic non-dimensional curves are influenced by their inlet total pressure. The last novelty is the integration of the blades coolant calculation process that incorporates external heat transfer calculation, structural conduction and coolant side modeling with SAS network simulation. Finally, SAS simulation of an industrial gas turbine is presented to illustrate capabilities of the presented tool in design point and off-design conditions.
Optimization of Fan-Shaped Film Cooling Holes for Enhancing Cooling Effectiveness Under Variable Coolant Inlet Pressure Ratios
Authors: Liu Zhansheng , Yang Kefeng , Yang Xing , Liu Zhao , Feng Zhenping 
Published: January 2021

Abstract
In traditional film cooling design, holes had the same geometry in the same row of the blade and the same zone of the endwall. However, film cooling holes operate at different conditions when the positions are different, even in the same row. Additionally, geometry variables of the film cooling holes with the best cooling performance vary with the aerodynamic conditions. Optimization of film cooling hole geometry and arrangement has been paid much attention in recent years to improve the cooling performance. In this paper, a fan-shaped film cooling hole has been optimized on a plate model under variable coolant inlet pressure ratios to obtain the geometry parameters with better and more robust cooling performance. Two design variables, i.e., injection angle and expand angle were studied in the optimization. The coolant inlet pressure was different for each case during the optimization. The optimization objective was to increase the mean value and decrease the variance value of the area average cooling effectiveness downstream of the hole exit. The optimization system consisted of a self-programming parametric design and mesh generation tool, a CFD solver and a genetic algorithm (GA) coupled with surrogate model. At first, numerical simulation results were validated against the measured data, and agreed well with the experiment results. Range of the design variables were determined according to the sensitive analysis of the design variables. It was indicated that the film cooling hole obtained by the optimization showed remarkably higher cooling effectiveness than that of the original scheme. With the pressure ratio changing, the optimized cooling hole obtained could keep relatively high effectiveness. Additionally, the optimized film cooling hole was applied on a typical gas turbine vane endwall to examine the cooling performance in cascade passage. It could be observed that the optimal film holes performed better than that of the original design.
Performance and Operating Characteristics of Micro Gas Turbine Driven by Pulse, Pressure Gain Combustor
Authors: Sakurai Takashi , Nakamura Shunsuke 
Published: January 2021

Abstract
This paper presents the experimental results of a micro gas turbine driven by pulse, pressure gain combustor. The aim of this study is to demonstrate the improvement of the engine performance by applying the pressure gain combustion. The micro gas turbine is composed of a combustor having two combustion chambers and an automotive turbocharger which is used as a compressor and a turbine. The outlets of two combustion chambers are joined by a confluence part to connect with the turbine. By changing the combustion methods of each combustion chamber, the gas turbine was operated in three modes; normal combustion mode, pulse combustion augmented mode, and fully pulse combustion mode. In the normal combustion mode, two combustion chambers were operated under continuous, constant-pressure combustion. In the pulse combustion augmented mode, one combustion chamber was operated under continuous, constant-pressure combustion and the other was operated under pulse combustion. In the fully pulse combustion mode, two combustion chambers were operated under pulse combustion. The pulse combustion applied in this study was the forced-ignition type, active pulse combustion. Although the pressure increase was attained by the pulse combustion comparing with the normal combustion, the mass-averaged pressure in the combustor showed that the net pressure gain in the combustor was not attained. The engine performance such as thermal efficiency and work and operating characteristics of gas turbine were investigated for two operation modes. In the pulse combustion augmented mode, the gas turbine could successfully sustain its operation as well as normal operation mode. The increase in the combustor pressure affected the air mass flow rate and the compressor performance, resulted in the decrease of performance comparing with the normal combustion mode.
High-Frequency Instability Driving Potential of Premixed Jet Flames in a Tubular Combustor due to Dynamic Compression and Deflection
Authors: Mohammadzadeh Keleshtery Payam , Heilmann Gerrit , Hirsch Christoph , Panek Lukasz , Huth Michael , Sattelmayer Thomas 
Published: January 2021

Abstract
Constructive interference of acoustic oscillations and combustion heat release can result in high-frequency thermoacoustic instabilities in gas turbine combustion chambers with strong pressure pulsations. They may cause component wear and limit the safe operating range of the engine. During the development of stable combustors the influence of design variables on the driving mechanisms of these instabilities is of particular interest. This paper studies the influence of design parameters on the linear growth rates of high-frequency thermoacoustic transverse modes in a tubular combustor of hexagonal cross-section equipped with 12 turbulent premixed jet burners. Two flame dynamics models are used, i. e. the dynamic compression and the deflection mechanisms, which have in the past been validated for turbulent swirl burners. To demonstrate the applicability as well as the shortfalls of these flame dynamics models the impact of different geometrical and flow parameters on the driving potential of high-frequency thermoacoustic modes are considered. A parameter variation study of thermal power, air excess ratio, diameter of the combustor and the radial position of jet burners was performed.
The first transversal eigenmodes and eigenfrequencies were computed by solving the inhomogeneous Helmholtz equation with the flame driving source terms in the frequency domain using the finite element method. The required mean fields of temperature and heat release rate were obtained using a generic flame distribution scaled with respect to the experimental OH* chemiluminescence measurements. The resulting growth rates give a measure for the thermoacoustic driving potential.