bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrogen Compression - Towards a New Strategy for the Design of Hydrogen Compressors
Authors: Tiainen Jonna , Turunen-Saaresti Teemu , Mäki-Iso Mikko , Schuster Sebastian , Brillert Dieter 
Published: October 2022

Abstract
The growth of renewable energy resources increases the need for energy storage. Excessive energy could be stored into hydrogen, but its transportation in pipelines requires compression up to pressures of 70 bar and high volume flows. Due to several benefits, centrifugal compressors could be considered for hydrogen transportation.
Previous investigations indicate that the achievement of the required pressure rise needs high tip speeds, resulting in high mechanical stresses. This paper proposes forward-swept impeller blades to reduce the tip speed. 1D methods are used to design compressors with different outlet blade angles. The performance of three compressors is analyzed numerically. The performance maps are computed with an Euler-based through-flow approach. The results indicate that the forward-swept impeller with −15° could reduce the tip speed by 5% compared to the unswept impeller without negatively impacting the efficiency.
Numerical Observations of a Stall Phenomenon in the NASA CC3 Compressor
Authors: Ni Michael , Robles Vega Gregorio , Ni Ron Ho , Clark John , List Michael 
Published: October 2022

Abstract
Numerical analysis of the transonic NASA CC3 centrifugal compressor stage with vaned diffuser is undertaken and the mechanism for the onset of stall investigated. The analysis methodology employs standard practice numerical methods, the mixing-plane approximation at the rotor-stator interface and periodic boundary conditions within a given row. Simulation results were then compared against full annulus time accurate simulations and the methodologies evaluated for estimation for the onset of stall.
In the study, steady state and full annulus time accurate simulations were conducted at the 100% design speed, from choke to stall. Many time-resolved simulations “stalled” at pressure ratios where steady state mixing-plane solutions converged. One observation from the time-resolved simulations is that the number of revolutions required for the flow to stall was over 5 revolutions and increased to 9 revolutions closer to the last stable point.
Integrations of the time-resolved solutions at the onset of stall reveal that the flow field of both the impellers and diffusers are not circumferentially uniform, and a stall “cell” is rotating in the opposite direction of the rotor. However, the “cell” is stationary in the stationary frame of reference thus, it is not a conventional rotating stall.
There is a notable difference in choke flow between experiment and CFD results, which has been seen by others for this configuration. The reason for the miss is not a focus of this paper, and the numerically predicted unsteady stall point should not be viewed as the exact mechanism for stall within the NASA CC3 experiment, instead this work is to provide a review of standard practice numerical approximations and how cost effective full wheel unsteady analysis can be used to improve transonic compressor design.
Computational Fluid Dynamics Modeling of Fuel Properties Impact on Lean Blowout in the ARC-M1 Combustor
Authors: Dasgupta Debolina , Som Sibendu , Wood Eric , Lee Tonghun , Mayhew Eric , Temme Jacob , Kweon Chol-Bum 
Published: October 2022

Abstract
The flow and flame dynamics within liquid fueled gas turbine combustors are complex due to the interactions between the highly turbulent flow, spray dynamics and combustion. Computational tools help understand these governing processes. A computational fluid dynamics model for Army Research Combustor Midsize (ARC-M1) is developed to characterize the complex turbulent flow, multi-phase spray physics and hydrocarbon chemistry. Using high-quality X-ray data for the combustor, the spray is initialized in the near nozzle region. To understand the overall impact of liquid properties, the liquid properties corresponding to Jet-A and F-24 are tested. It is observed that F-24 has a higher LBO liquid flow rate compared to Jet A. To understand the impact of individual properties, liquid properties such as density, viscosity, specific heat, heat of vaporization, are changed one at a time. It was observed that an increase in density, viscosity, heat of vaporization and specific heat w.r.t Jet-A tends to increase the LBO liquid flow rate i.e. makes the flame blow-off at higher equivalence ratios. This is attributed to the altered flame shapes and the impact of these properties on fuel heating and its subsequent vaporization.
Internal Heat Transfer Measurement on Metal-Based Additively Manufactured Channels Using a Transient Technique
Authors: Lüscher Patrick , Deflorin Marin , Voggesser Manuel , Stuber Peter , Galoul Vincent , Ko Minseok 
Published: October 2022

Abstract
The advancements in additive manufacturing (AM) of metals open new possibilities in the design of gas turbine parts. Especially the cooling efficiency of internal channels can be improved with more complex geometries. Naturally, AM channels have a higher surface roughness than conventionally manufactured parts, which influences the cooling air pressure loss as well as the heat transfer. Implementing novel cooling designs using AM can be possible only if the effect of increased surface roughness on the flow and on the heat transfer can be predicted with an appropriate accuracy. The objective of the current study was to measure these parameters experimentally in simple AM channels to build a database for designing complex and efficient cooling designs using the AM technique. A test rig and post-processing method was elaborated to derive the local internal heat transfer distribution of metal-based AM channels. Six circular single channel coupons made by selective laser melting (SLM) were tested for Reynolds numbers ranging from 20000 to 50000. The coupon with the lowest relative roughness shows good agreement with the Dittus-Boelter correlation. All the other coupons show a consistent increase of internal heat transfer and flow friction with the increase of the internal surface roughness.
Validation of Hydrogen Boundary Layer Flashback Model on Gas Turbine Geometries and Conditions
Authors: Klein Sikke , Sarakatsanis Christos 
Published: October 2022

Abstract
Hydrogen is considered as a promising zero carbon battery fuel to deliver balancing power for the future electricity system with an increasing share of variable renewable power generation. Flame flashback is one of the main challenges for the application of hydrogen in gas turbines. Lean premixed hydrogen combustion is more prone to flashback than natural gas combustion due to higher flame speed and Lewis number effect.
The TU Delft developed a boundary layer flashback model based on a previous work by TU Munich. The TU Delft model includes amongst others the effect of the laminar flame speed, boundary layer profile, Lewis number and adverse pressure gradient of the mean flow. The model was successfully validated on academic experiments from TU Munich.
In the present paper the turbulent flame speed closure in the TU Delft flashback model is updated for gas turbine like conditions using experimental data from the University of California, Irvine (UCI). This updated model is validated against data from the Paul Scherrer Institute (PSI) and back tested on the original academic experiments from TU Munich.
The updated TU Delft boundary layer flashback model and the flashback model from the Paul Scherrer Institute (PSI) have been applied to a scaled version of the Flamesheet™ combustor. The outcome of the PSI flashback model correlates very well with test results from the TU Delft laboratory, the TU Delft flashback model only with the original flame speed correlation.
Estimation of Autoignition Propensity in Aeroderivative Gas Turbine Premixers Using Incompletely Stirred Reactor Network Modelling
Authors: Gkantonas Savvas , Jella Sandeep , Iavarone Salvatore , Versailles Philippe , Mastorakos Epaminondas , Bourque Gilles 
Published: October 2022

Abstract
The study of autoignition propensity in premixers for gas turbines is critical for their safe operation and design. Although premixers can be analysed using reacting Computational Fluid Dynamics (CFD) coupled with detailed autoignition chemical kinetics, it is essential to also develop methods with lower computational cost to be able to explore more geometries and operating conditions during the design process. This paper presents such an approach based on Incompletely Stirred Reactor Network (ISRN) modelling. This method uses a CFD solution of a non-reacting flow and subsequently estimates the spatial evolution of reacting scalars such as autoignition precursors and temperature conditioned on the mixture fraction, which are used to quantify autoignition propensity. The approach is intended as a “postprocessing” step, enabling the use of very complex chemical mechanisms and the study of many operating conditions. For a representative premixer of an aeroderivative gas turbine, results show that autoignition propensity can be reproduced with ISRN at highly reactive operating conditions featuring multi-stage autoignition of a dual fuel mixture. The ISRN computations are consequently analysed to explore the evolution of reacting scalars and propose some autoignition metrics that combine mixing and chemical reaction to assist the design of premixers.
Non-Linear Numerical Simulation of Pre-Loaded Turbine Blades With Frictional Shroud Contact Under Dynamic Conditions
Authors: de Filippis Hugo , Thouverez Fabrice , Blanc Laurent , Girard Patrick , Chevillot Fabrice 
Published: October 2022

Abstract
In a process of permanent innovation and increase of turbojet efficiency, the low pressure turbine is designed to run at higher rotational speed in future engines. Such an evolution requires a precise evaluation of their effects on dynamic behavior of the turbine. Low-pressure turbine blades in aeronautical industry are generally composed of a shroud, whose main purpose is to keep the tightness of the primal air stream, but it produces in consequence a mechanical damping into the dynamic response of the full blade turbine assembly through frictional contacts. Depending on the industrial design choices, the geometry of these blades can induce a pre-torsion effect which will straighten the shrouds during the assembly process, in this way they are brought into contact and the blades are pre-loaded. Predicting the dynamic behavior of such structure and calculating forced responses is a major challenge considering the complexity involved. The numerical model used in this article is based on the geometry of a test bench which was designed to reproduce the pre-torsion assembly loading on the blades through a geometrical interpenetration, and to evaluate the dynamics of the contact between the shrouds. It includes only three blades with a simplified geometry but represents the main dynamic characteristics of a real turbine. A static analysis on a commercial FE software of the test bench blades assembly has been carried out to evaluate the contact area on the shrouds, and determine the deformation related to the pre-torsion loading. Modal analyses were also realized to determine the natural frequencies of the structure and the modal shapes according to the imposed contact status. Then a reduced order model of the structure is generated, and is used into a specific numerical code. A procedure is implemented to handle the interpenetration generated by the pre-torsion of the blades, which is the key part of the static loading of the structure. In order to solve this non-linear dynamic problem in the frequency domain, based on the static loading results, the Harmonic Balance Method (HBM) is coupled to the Dynamic Lagrangian Frequency Time (DLFT) method or a classic penalty method to evaluate the non-linear contact forces. Numerical results around the first and third bending modes of the structure are computed and a parametric study is presented, pointing out the impact of the static normal load distribution depending of the method used, the friction coefficient between, the excitation force level, etc. The precision of the nodal coupling scheme used to manage the contact between the shrouds meshes for the numerical simulation is also evaluated by changing the meshing, in order to quantify such hypothesis.
Experimental Investigation of Twin Scroll Turbocharger Performance Under Pulsating Conditions
Authors: Brodbeck Philipp , Guse Eduard 
Published: October 2022

Abstract
The pulsating nature of automotive internal combustion engines (ICE) is one of the main challenges in the modeling of turbochargers in process simulation. Radial compressors and turbines are characterized by maps containing parameters such as wheel speed, mass flow rate, temperatures and pressure ratios. Those parameters are obtained by standardized test bench measurements, which require stationary flow conditions. In this paper an advanced experimental setup is introduced to investigate the turbine behavior under pulsating conditions. Pressure, temperature, mass flow and turbine torque are measured with an equivalent to a resolution of 0.1 degrees camshaft rotation to obtain working cycle resolved parameters. This way, the turbine performance can be evaluated under pulsating conditions.
Turbine Vane Passage Cooling Experiments With a Close-Coupled Combustor-Turbine Interface Geometry Part 1: Describing the Flow
Authors: Nawathe Kedar P. , Nath Aaditya R. , Kim Yong W. , Simon Terrence W. 
Published: October 2022

Abstract
Due to the proximity of the first stage gas turbine vanes to the combustor, coolant introduced to the combustor walls interacts with the endwall film coolant and changes the vane passage flow physics. Recent results show that combustor coolant contributes significantly to cooling the endwall and vane surfaces. In this paper, the traditional combustor-turbine interface was modified to improve overall cooling performance. The performance of this new injection cooling scheme on passage fluid dynamics and surface cooling is assessed. The first of this two-part paper reports detailed experimental tests that document secondary flows and coolant transport throughout the vane passage for four combustor coolant flowrates. The experimental facility imitates combustor coolant injection and engine-level turbulence and has a modified transition duct design, called the ‘close-coupled combustor-turbine interface.’ The ‘impingement vortex’ seen in previous studies with combustor cooling appears as the dominant secondary flow. It is observed in the present study over a wide range of flowrates, confirming its tie to the combustor coolant flowrate and not the combustor-turbine interface geometry. It was found, however, that the location and size of the impingement vortex are affected by coolant flowrate. The second of this two-part paper discusses the impact of the observed secondary flows on cooling vane passage surfaces.
Design of an Axial Flow Fan for a Unique Cooling Application
Authors: Boshoff Francois D. , van der Spuy Sybrand J. , Pretorius Johannes P. , Meyer Christiaan J. 
Published: October 2022

Abstract
A rotor-only axial flow fan is designed for use in a concentrated solar power application. The plant uses a supercritical carbon dioxide Brayton Cycle for power generation and an air-cooled heat exchanger (ACHE) for cooling.
Fan specifications are derived by considering the geometry and air flow rate requirements for the ACHE, using simple, circular finned tube bundles. The specifications lead to a fan design with a relatively large hub-to-tip ratio of 0.5102.
The fan’s performance is estimated numerically using a periodic three-dimensional model (P3DM) in both an annular computational domain and a computational domain representing a simplified ISO 5801 type A fan test facility. A 1:4.78 scale model of the fan was manufactured and tested in an ISO 5801 Type A fan test facility.
Numerical fan performance results for the annular domain show good agreement with those predicted by the design procedure, for both the cases with no tip gap and the design tip gap size present. It also demonstrates the effect of the tip gap on the overall fan performance. Numerical results for the simplified ISO 5801 type A fan test facility indicates that fan performance is significantly worse than in the annular domain, due to the hub size of the fan being considered in this domain.
The experimental results for the manufactured fan demonstrates the accuracy of the numerical methods used and provide the fan performance characteristics over a wide range of flowrates.
On the Use of Kinetic-Energy Balance for the Feature-Based Mesh Adaptation Applied to Large-Eddy Simulation in Complex Geometries
Authors: Grenouilloux Adrien , Balarac Guillaume , Leparoux Julien , Moureau Vincent , Lartigue Ghislain , Bénard Pierre , Mercier Renaud , Ferrey Paul 
Published: October 2022

Abstract
Static and dynamic feature-based mesh adaptation have gained momentum during the last decade as they allow to refine areas to capture specific flow features. These methods do not always guaranty that the budget of the kinetic energy of the mean field is mesh independent as it could be expected. In the present paper, a framework which uses the assessment of the kinetic energy budget to refine or coarsen the mesh resolution locally is presented in the framework of Large-Eddy Simulation (LES). The whole methodology is applied to two industrial configurations, namely the isothermal PRECCINSTA burner and a row of three jets impinging on a surface at Re = 23000 and a nozzle to plate distance of H/D = 5. Flow field quantities, including mean velocity and RMS or Nusselt number on the final grids are in good agreement with experimental data.
Unsteady Rotor-Stator Interaction in a Four-Stage Axial Turbine: An Experimental Investigation
Authors: von Gosen Florian , Winhart Benjamin , di Mare Francesca 
Published: October 2022

Abstract
This paper presents an experimental investigation of the transient rotor-stator interactions (RSI) in a four-stage axial flow turbine at design as well as off-design conditions. The pressure fluctuations recorded on the surface of a stator vane in stage 3 of the machine are phase-averaged to the rotor position and decomposed into the main contributing periodic components. The origins of the different fluctuations are identified by matching their frequency to the individual blade counts of the different blade rows which, in turn, allows to get insight into their interaction mechanisms and their inter-blade-row propagation mechanisms. Dependent on the operating point, the magnitude, and local distribution of the pressure fluctuation, components change significantly and components originating from different upstream and downstream blade rows become dominant. For operating points close to the design point both directly neighboring blade rows R2 and R3 are the main contributors to the RSI affecting the pressure fluctuations on stator vane 3 at mid span. For the intermediate off-design operating conditions the effect of the downstream blade row R3 diminishes and instead the blade row R1 further upstream beyond the directly neighboring R2 reaches magnitudes similar to that of R2. For strong off-design conditions the influence of the downstream blade row R3 diminishes further and instead of pressure fluctuations corresponding to the blade passing frequency of the immediate upstream blade row R2, a pressure fluctuation corresponding to the difference in blade counts of both upstream blade rows becomes the dominant component.
Power and Hydrogen Co-Production in Flexible “Powdrogen” Plants
Authors: de Cataldo Alessandro , Astolfi Marco , Chiesa Paolo , Campanari Stefano , Martelli Emanuele , Silva Paolo , Bedogni Stefano , Ottolina Luca , Tappani Marco , Romano Matteo C. 
Published: October 2022

Abstract
This study investigates the potential of “Powdrogen” plants for blue hydrogen and decarbonized electric power production, conceived to operate flexibly depending on the electricity price and to increase the capacity factor of the hydrogen production and CO2 separation units. The Hydrogen production is based on fired tubular reforming or auto-thermal reforming technologies with pre-combustion CO2 capture by a MDEA process. The power island is based on a combined cycle with H2-fired gas turbine and a triple pressure reheat heat recovery steam generator (HRSG). The analysis considers three main plant operating modes: hydrogen mode (reformer at full load with hydrogen export and combined cycle off) and power mode (reformer at full load with all hydrogen burned in the combined cycle), plus an intermediate polygeneration mode, producing both hydrogen and electricity. The possibility of integrating the HRSG and the reformer heat recovery process to feed a single steam turbine has been explored to allow keeping the steam turbine hot also in hydrogen operating mode. The economic analysis investigates the competitivity of the plant for different operating hours in hydrogen and power modes. Results suggest that these plants are likely to be a viable way to produce flexibly low-carbon hydrogen and electricity following the market demand.
Casing Treatment: Its Potential and Limitations
Authors: Yoon Sungho , Cargill Patricia 
Published: October 2022

Abstract
Casing treatment is an advanced design feature intended to improve the stability of a compressor. Various investigations have been conducted based on both experimental and numerical studies at least over the last fifty years. In general, it has been demonstrated that a careful design of a casing treatment can substantially improve the stall margin of a tip-limited compressor although this generally comes with an aerodynamic efficiency penalty. This review paper revisits important past studies on casing treatments to clarify findings on the sometimes-conflicting results and understand what lessons are generally applicable to a wider group of machines.
Circumferential grooves over a rotor tip have been in use for some time. Much recent work has focused on axial slots over a rotor tip, because of the significant stall margin improvement and the better efficiency potential of this configuration. This paper includes both configurations, with more emphasis on the latter.
The paper concludes that casing treatment offers powerful benefits to a compressor and deserves continuing research and development. Good benefits result from axial slots which start ahead of the rotor leading edge and cover the front part of the rotor tip and include skew (tangential lean in the direction of rotation). Contributing physical mechanisms include increasing the axial momentum of the casing flow casing and reducing the aerodynamic blockage to improve the casing boundary layer and the tip leakage flow. The role of impacting unsteadiness is yet to be further clarified.
Areas of further research are recommended, both experimental and analytical, including further work to understand and control the loss mechanisms, studying and controlling stage interaction effects in multi-stage compressors, and the simultaneous design optimization of the rotor blade with the casing treatment. Multi-disciplinary issues such as manufacturing cost, weight, length, durability, aeromechanics effects, tolerance to dust and ice, etc. also deserve further attention.