bluuebunny/crossref_metadata_2025 huggingface dataset:
The Impact of Friction in Lube Oil Feed Grooves on Power Loss in High-Speed Journal Bearings
Authors: Vetter Daniel , Hagemann Thomas , Schwarze Hubert
Published: August 2024

The contribution of internal friction in the boundary layer flow of lube oil feed grooves to the power loss of high-speed journal bearings is a function of the rotor speed and the flow regime in which the bearing operates. The literature shows that the portion of power loss in the groove region can exceed 30% of the overall power loss. This paper investigates the impact of gas phases in the feed groove region on the reduction of the internal friction in the lubricant. For this purpose, existing measurement data for two fixed-pad bearings with different bore geometries is evaluated for different lubrication conditions including flooded lubrication of all grooves and a deactivation of the oil supply in one groove. The latter configuration involves a significant reduction of measured power loss with increasing bearing unit load. Comparisons with thermo-elasto-hydrodynamic (TEHD) calculations indicate that the partial filling of deactivated lube oil feed grooves leads to a significant reduction of frictional power loss. Different approaches for the theoretical approximation of the impact of the gas phase in the groove region are investigated and validated with the test data to provide improved understanding of friction in high-speed bearings.
Combustor Traverse Optimization to Lower High-Pressure Turbine Rotor Temperatures
Authors: Carta Mario , Ghisu Tiziano , Shahpar Shahrokh
Published: August 2024

As turbine entry temperatures of modern jet engines continue to increase, additional thermal stresses are introduced on the high-pressure turbine rotors, which are already burdened by substantial levels of centrifugal and gas loads. Usually, for modern turbofan engines, the temperature distribution upstream of the high-pressure stator is characterized by a series of high-temperature regions, determined by the circumferential arrangement of the combustor burners. The position of these high-temperature regions, both radially and circumferentially in relation to the high-pressure stator arrangement, can have a strong impact on their subsequent migration through the high-pressure stage. Therefore, for a given amount of thermal power entering the turbine, a significant reduction in maximum rotor temperatures can be achieved by adjusting the inlet temperature distribution. This paper is aimed at mitigating the maximum surface temperatures on a high-pressure turbine rotor from a modern commercial turbofan engine, by conducting a parametric analysis and optimization of the inlet temperature field. The parameters considered for this study are the circumferential position of the high-temperature spots, and the overall bias of the temperature distribution in the radial direction. High-fidelity unsteady (phase-lag) and conjugate heat transfer simulations are performed to evaluate the effects of inlet clocking and radial bias on rotor metal temperatures.
The EPA Proposed Greenhouse Gas Standards: A Gas Turbine Fleet Impact Analysis
Authors: Perullo Christopher , Harper James , Caravaggio Michael , Noble David , Emerson Benjamin , Lieuwen Tim
Published: August 2024

The EPA previously proposed new CO2 standards for both new and existing stationary combustion turbines under Section 111 of the Clean Air Act. At the time of writing, these standards would have had a have significant implications on the operation, capacity factor, reliability, availability, and performance of the gas turbine fleet within the U.S. power grid. The standards would impact the costs of operating the fleet which will impact fleet owners and operators and the public. The proposed standards limit CO2 emissions from new and existing sources and are justified with associated Best System of Emission Reductions (BSER) using Hydrogen-blended fuels or Carbon Capture and Storage. The paper shows that the BSER used to justify the proposed limits are insufficient (i.e., levels of Hydrogen and CCS required for rule compliance are beyond what is stated as BSER justification). Analysis is presented to consider the impact of the rules on the existing gas turbine fleet as operated including assessments of the amount of hydrogen required, number of plants that would be impacted, and projections of the required renewable generation required to replace non-compliant or curtailed gas turbines. The authors also discuss potential unintended incentivized actions based on the rules, such as early retirement of critical generation capacity, and minimizing plant capacity factors at the expense of total CO2 emissions. The methodology to assess the economy-wide impact of technology depends on the analysis’s assumptions. Therefore, this analysis does not predict specific outcomes but offers insights into potential impacts under certain assumed conditions.
Advanced Design of a Transition Duct for Supersonic Inlet Turbines in Rotating Detonation Engines
Authors: Mushtaq Noraiz , Pini Matteo , Gaetani Paolo
Published: August 2024

A supersonic inlet turbine can extract substantial energy from the highly fluctuating and transonic flow delivered by a rotating detonation combustor (RDC). However, a transition duct is necessary to achieve the supersonic inlet conditions required by the turbine. In this work, the supersonic transition duct is designed with the method of characteristics (MOC). A generalized implementation of the MOC is proposed for the generation of annular ducts with asymmetric and rotated hub and shroud walls. The model is extended to deal with ideal and non-ideal flows, namely flows characterized by non-ideal thermodynamic effects, and its accuracy has been verified through comparison with results obtained with computational fluid dynamic (CFD) simulations. In addition, boundary layer flow equations are combined with the MOC to predict viscous losses on the endwalls and to adjust duct geometry by accounting for the boundary layer thickness. Furthermore, it is essential to predict the effects of the large unsteadiness generated by the detonation combustor for an efficient operation of the turbine. The maximum incidence angle at the turbine inlet is predicted with a one-dimensional annular duct model. Supersonic duct flow behavior to unsteady inlet conditions is characterized through two-dimensional inviscid axisymmetric unsteady CFD simulations. The accuracy of the reduced order models is finally verified with a three-dimensional unsteady viscous simulation assuming inlet flow conditions representative of RDC operation.
Numerical Simulation and Prediction Using Neural Network for Internal Flow Field and Outlet Distortion Contour of S-Shape Inlet Ducts
Authors: Wang ShiXuan , Zhang Min , Du Juan , Ba Dun , Nie ChaoQun , Wang YangYang
Published: August 2024

S-shape inlet (or S-intake) has been widely employed to satisfy the demand of stealth and compactness for modern aircraft. However, the large curvature of the S-intakes triggers boundary layer separation, generating severe flow separation that further lead to total pressure and swirl distortion at the S-intake outlet. The flow distortion can significantly deteriorate the efficiency of downstream compressor. Therefore, studying the internal flow dynamics within the S-intake and the distortion at the S-intake’s exit is an important work. Due to this, this paper investigated a S-intake in the open literature. First, the S-intake is parameterized. Then, a design of experiment study based on numerical simulations is conducted. The influences of key geometric parameters on the performance of the intake are analyzed. Using those numerical simulation data, back propagation (BP) neural networks are trained. They are intended to realize a quick evaluation of the total pressure recovery coefficient and total pressure distortion index (DC120) of the outlet for the S-intakes with varying geometric parameters under difference flight Mach number conditions. Also, other neural networks are established for predicting total pressure and velocity fields on the S-intake outlet section. Results demonstrate that the BP neural network has an impressive accuracy in predicting the total-pressure recovery coefficient, with a mean square error of approximately 0.049%. However, the predictive capability for the DC120 model is relatively modest, with a mean square error of approximately 7%. In addition, the average predicting error in flow field on the S-intake outlet is about 3.9 % when compacted to numerical simulation results.
Impact of Manufacturing Variability From Different Compressor Stages on Aerodynamic Uncertainty: An Interchangeability Study
Authors: Li Mingzhi , Yu Xianjun , Meng Dejun , An Guangfeng , Liu Baojie
Published: August 2024

Aerodynamic uncertainties in compressors introduced by manufacturing variability have garnered increasing attention in recent years. Accurately assessing the impact of manufacturing variations on newly designed blades is essential for facilitating robust design. However, the assessment of performance uncertainty of designed blades is significantly influenced by the method employed to introduce geometric uncertainty. This paper investigates the appropriate approach for superimposing manufacturing variations onto new blade profiles to obtain accurate insights into aerodynamic uncertainties. The first part of the paper thoroughly analyzes manufacturing variations in over 1400 newly manufactured rotor blades from different compressor stages, which were measured using a coordinate measurement machine. The statistical characteristics of geometric variations in distinct directions are captured. In the second part, by calculating the aerodynamic performance of numerous compressor blade profiles with manufacturing variability, we investigate the interchangeability of manufacturing variations from different compressor stages for accurately assessing the aerodynamic uncertainties of new designs. The results demonstrate that manufacturing variations among different stages exhibit some similar geometric characteristics and are easily interchangeable when evaluating mean performance. When assessing the standard deviation of aerodynamic performance, the statistical results corresponding to the manufacturing variations from different stages exhibit a consistent trend, with some discrepancies emerging under different operating conditions.
CFD Study for Mitigation of H2 Explosion Inside Gas Turbine Enclosure
Authors: De Leo Elena , Quartieri Eugenio , Minotti Stefano , Rossin Stefano
Published: August 2024

There are several potential sources of risk in the design of a gas turbine burning 100% hydrogen.

Risks arise from the criticality of hydrogen characteristics: low ignition energy, wide flammability range, high burning velocity. During the design process, it is required to focus on safety aspects. All credible hazard scenarios in terms of occurrence probability shall be considered to avoid undesired catastrophic consequences. Looking to auxiliary systems, the main source of hazard can be considered the fuel gas supply system that is installed close to the gas turbine inside an enclosed space.

Although fuel gas line is properly designed to avoid the possibility of hydrogen leaks inside the enclosure, the occurrence probability of a sudden leakage of tubing rupture is not impossible.

The potential consequence of such remote event, combined with the higher flammability range of hydrogen, could lead to an undesired delayed ignition. Depending on several factors such as dispersed flammable mass and presence of obstacles in confined volume, an explosion could follow the ignition.

In order to assess the impact of this scenario, a numerical simulation campaign for a LT16 100% H2 gas turbine enclosure was carried out with commercial code FLACS, which is a tool able to simulate a complex phenomenon like an explosion. Different gas dispersion and delayed ignition cases were analyzed to predict the consequences in terms of overpressure inside the enclosure without carrying out complex experimental tests. The present work also investigated the use of relief panels as a mitigation method to reduce the overpressure inside the enclosure. The position, shape and venting area of the panels were evaluated in terms of their effectiveness.
CFD Speedline Simulations of High-Work Radial Compressor Stages
Authors: Hansen Thorsten , Munktell Erik , Scheuerer Georg , Zhuang Qingyuan , Zwiener Kim
Published: August 2024

Consistent simulations of compressor speedlines from choke to surge are challenging for CFD codes. Changing the outlet boundary condition along the speedline is often necessary to obtain physically plausible and numerically robust results. The root of the problem is the compressor characteristic: Close to choke, a mass flow rate as outlet boundary condition can produce ambiguous values and close to surge, a pressure boundary condition can yield multi-valued results. The paper discusses an outlet boundary condition based on a reduced outlet mass flow rate to overcome this problem. The boundary condition behaves like a pressure boundary condition close to choking and like a boundary condition for the mass flow rate close to surge, allowing for consistent simulations of whole speedlines. The paper explains the mechanics and advantages of this boundary condition in detail.

The authors applied outlet boundary conditions for static pressure, mass flow rate, and reduced mass flow rate to the High-Efficiency Centrifugal Compressor (HECC) experimentally investigated at the NASA Glenn Research Centre. The HECC has an impeller with 15 blade-splitter pairs, a diffusor with 20 blade-splitter pairs and 60 exit guide vanes. It is representative of the final stage of a compressor for rotorcraft applications. The HECC is a challenging test case for every CFD method because of its small diameter, the total pressure ratio of 4.7, the high work factor of 0.81, and the complex shock structures in the flow close to the choke condition.

In the paper’s results section, the authors discuss the pros and cons of static pressure, mass flow rate and reduced mass flow rate as boundary conditions regarding numerical accuracy and robustness. The simulations are conducted on a sequence of three homogeneously refined meshes with an effective refinement factor of 1.6 between the meshes. For three-dimensional problems, an effective refinement factor of 1.6 increases the number of cells by four. The solutions on the three meshes serve to quantify the numerical accuracy using Richardson extrapolation.

The mathematical model for the simulations consists of the steady-state averaged conservation equations for mass, momentum, and total enthalpy, complemented by two-equation eddy-viscosity turbulence models, namely the SST and BSL two-equation eddy-viscosity models and an eddy-diffusivity model for the turbulent heat fluxes. The rotor-stator interaction is modelled with a steady-state mixing plane algorithm using single-blade passages.
The Effect of Additive ‘Depositional’ Reprofiling of Compressor Blade Leading Edges on Engine Performance
Authors: Mullaney Drew , Jones Merren , Bojdo Nicholas , Covey-Crump Stephen , Pawley Alison
Published: August 2024

A common problem for gas turbine engines after ingesting atmospheric dust is compressor fouling, where small particles adhere to component surfaces. By sampling components from both a test engine and a service engine, deposits that are hard and sintered were observed to have formed on the leading edges of compressor blades and stators reprofiling their leading-edge geometry. Sectioning of the components showed that the deposits consist of layers of different chemical compositions and that new minerals have crystallized within the deposits. The change in geometry caused by the deposits suggests that they negatively affect the operating incidence range, surface pressure distribution and profile losses from the design intent of the original component, changing the compressor working line and reducing surge margin, efficiency and pressure ratio.
Study on an Automatic FMECA Analysis for Gas Turbine Systems Using Model-Based Systems Engineering Method
Authors: Chen Jinwei , Hu Zhenchao , Zhang Huisheng
Published: August 2024

Gas turbine systems operate in high temperature and high pressure conditions, which easily lead to performance degradation or various serious failures. The reliability is one of the most important attributes to monitor the gas turbine safety. Failure Mode, Effects, and Criticality Analysis (FMECA) is a well-known approach to systematically analyze the gas turbine reliability. However, traditional document-centric implementation of FMECA requires manual recording of fault related information. Such implementation approach is prone to human error and tedious. As an evolving approach, Model-based Systems Engineering (MBSE) has been applied in many industries to support system design, analysis and management. In this study, an automatic FMECA analysis approach for gas turbine systems is proposed based on MBSE. The FMECA architecture model is established according to the SysML diagrams of internal block diagram and block definition diagram. The topology between FMECA related concepts is characterized through the constructed architecture model. Then, the Design Structure Matrices is used to realize the risk analysis automatically. A case study of a real gas turbine is conducted to demonstrate the effectiveness of the proposed approach. The case results suggest that proposed approach can significantly enhance the efficiency of FMECA analysis.
A Digital Engineering Analysis of an Additively Manufactured Turbine Vane
Authors: Berdanier Reid A. , Tien Leland , Thole Karen A.
Published: August 2024

Additive manufacturing (AM) has transformed the ability to accelerate gas turbine component research and development at a fraction of the cost and time associated with conventional manufacturing. However, whereas prior works have assessed manufacturing variability in cast turbine airfoils, limited data are available to understand the impact of as-built deviations in AM turbine parts. As metal additive airfoils are becoming more prevalent in research turbine architectures, it is increasingly important to understand the effects of potential hardware deviations specific to additively manufactured parts. With this goal in mind, the current study utilizes a digital engineering approach to evaluate the aerodynamic impact of surface deviations on a high-pressure turbine vane design created for research purposes. RANS-based CFD studies derived from structured light scans of as-built turbine vanes are used to quantify performance relative to design intent geometries. Further computational analyses compare results from individual serialized parts with an average vane doublet geometry serving as a surrogate for the entire wheel. Particular emphasis in the study focuses on external surface defects caused by internal cooling features that are inherent through additive manufacturing and how these features can impact the vane performance. Ultimately, this study identifies specific regions of the vane that are subject to increased sensitivity, which benefits future designers intending to use AM as a tool for turbine research and development.
Complete Dynamics From Ignition to Stabilization of a Lean Hydrogen Flame With Thickened Flame Model
Authors: Amerighi Matteo , Senatori Giada , Yahou Tarik , Schuller Thierry , Dawson James R. , Andreini Antonio
Published: August 2024

In recent years, attention has been paid to hydrogen thanks to its carbon-free nature and its interesting characteristics as an energy vector. Despite the large number of numerical analyses regarding hydrocarbon combustion in all the steady and unsteady processes, few papers that cover all those aspects are available in the literature for hydrogen flames. Therefore, a numerical methodology to explore the complete ignition sequence from the spark release to the flame stabilization is validated on a single-sector hydrogen burner. In this context, a preliminary DNS investigation of laminar spherical expanding flames is performed using different diffusive transport models to isolate their impact.

The present work, carried out within the European project HESTIA, investigates the atmospheric test rig installed at the Norwegian University of Science and Technology operating with a lean, perfectly premixed, hydrogen-air flame stabilized on a conical bluffbody. Four simulations are performed adopting the Thickened Flame Model with an energy deposition strategy to assess the impact of preferential and thermal diffusion, as well as grid resolution, on flame dynamics.

3D flame structure visualization coupled with detailed PIV/OH-PLIF measurements allows the investigation of the key mechanisms involved during the ignition. The dynamic response of the flame through axial fluctuations once the ignition transient is concluded, is reconstructed by the numerical strategy employed. Although the overall behavior is almost unchanged by including or not thermal diffusion effects, their local impact on the flame is evident leading to a better agreement with experimental data.
A Bladed Disk Reduction Technique That Captures Variation in Blade Stiffness and Blade Root Joint Contacts
Authors: Krizak Troy , Firrone Christian Maria , Battiato Giuseppe , D’Souza Kiran
Published: August 2024

In practice, a bladed disk will always have variations, known as mistuning, which is a focus of a significant amount of research within the turbomachinery industry. When mistuning is present, the forced response of the system often shows localized amplification of the blade deflection amplitudes when compared to a tuned system. In order to quickly perform a significant number of simulations containing mistuning, reduced order models (ROMs) have been developed where the mistuning can be introduced efficiently in the reduced space. Previously, mistuning had been introduced to bladed disks in the form of natural frequency shifts in the blades, and separately from contact uncertainties in the blade root joint and also separately from the various forms of small and large geometric mistuning. This work introduces a method to efficiently model multiple types of mistuning sources so that any interactions that may result can be studied. This work focuses on cases with stiffness and contact mistuning which are due to design tolerances, manufacturing processes, assembly procedures, material variability, and wear. The technique in this work utilizes the Craig-Bampton component mode synthesis that is applied to the uncoupled blade and disk sector. Small stiffness mistuning is applied by directly adjusting the modulus of elasticity within the uncoupled blade portion of the ROM. The degrees of freedom at the contacts are reduced using a modal basis based on the Gram-Schmidt Interface technique. A numerical validation of the developed methods is performed for cases including small and large stiffness mistuning and contact mistuning using a finite element model of a simplified rotor.
Heat Transfer Coefficients in a Three-Passage Ribbed Channel Using a Transient Liquid Crystal Technique
Authors: Wright Lesley M. , Shiau Chao-Cheng , Han Je-Chin , Krewinkel Robert
Published: August 2024

One-dimensional (1D) transient heat conduction in a semi-infinite solid material with a convection boundary condition has been widely used for determining the surface convection heat transfer coefficient distributions. In this work, the full heat transfer characteristic maps of a turbine blade with a realistic, three-passage, ribbed channel are examined using the 1D transient heat conduction model with narrow-band liquid crystals. The tests were conducted at two different engine representative flow conditions. The time map for the blade’s internal surfaces to reach a target temperature was obtained from the liquid crystal using the maximum green intensity approach. The conventional hue value approach was also applied to obtain the surface time map for data comparison. Since the test channel is of high blockage, delayed flow history was observed and a time correction was needed to address the asynchronous behavior between the flow and heat transfer. In addition, the difficulty of accurately capturing the bulk mean flow temperature within the three-passage channel leads to additional uncertainty for heat transfer coefficient calculations. The effects of delayed flow, time correction, and using different reference fluid temperatures on the Nusselt number calculations are demonstrated and analyzed. Using the current blade as an example, this study compares two different temperature interpretation approaches (maximum green intensity and hue value). In addition, other factors that affect the measurement of detailed heat transfer coefficient distributions using 1D transient conduction model are presented and discussed.
Emissions and Flame Stability Assessment of Hydrogen Addition and Air Dilution in a Micro Gas Turbine Combustor Using 0D/1D Modeling by Chemical Reactor Network
Authors: Yousefzad Farrokhi Farshid , Piscopo Alessandro , Pappa Alessio , Parente Alessandro , De Paepe Ward
Published: August 2024

Hydrogen emerges as a promising fuel for clean and sustainable electricity production when utilized in micro gas turbines (mGTs). However, some challenges linked to hydrogen usage must be overcome as its high reactivity can lead to increased NOx emissions and flame instabilities. Literature suggests that combustion air humidification and/or exhaust gas recirculation (EGR) may be methods to reduce this reactivity. However, these measures are limited due to the small operating range of the mGT combustor.

In this context, a 20 kWth mGT combustor is investigated under various inlet conditions to assess the effect of EGR towards increased flame stability and emission control when operating under hydrogen-enriched methane firing, using a Chemical Reaction Network (CRN) model. The CRN modeling is a fast and low computational complexity tool to model combustion performance and emissions by representing complex reactive flow fields through idealized reactor models, leading to reduced computational costs. This study examines partial load conditions, fuel compositions, and the effect of combustion air dilution through EGR. The CRN model of the combustion process is designed based on combustion zones extracted from the main flow fields with similar thermo-chemical states from CFD, while emission predictions are experimentally validated for different operating points. Predicted NOx and CO emissions by the proposed CRN model show an acceptable agreement with the experimental data at high power loads. However, its accuracy diminishes for loads below 70% due to the variability in model tuning parameters across different loads, whereas the current model is optimized for 90% load conditions. At full load with the activation of EGR, these emissions are reduced by approximately 20%. CRN results predict that NOx emissions do not increase excessively by hydrogen addition due to the constant power operation of the mGT. Indeed, the higher reactivity of hydrogen leads to a lower fuel flow rate and, thus, leaner operating conditions. On the other hand, CO emissions decrease by 15 to 40% when adding hydrogen from 5 to 50% of the volume fraction to natural gas. Finally, air dilution by EGR positively affects flame temperature and NOx emissions. Tuning CRN models that are not dependent on specific load parameters to get a better agreement with experimental data, as well as EGR/humidified air dilution effects on partial loads and hydrogen added fuels, are subjects to future work.
A Scalable Conjugate Heat Transfer Method Applied to Engine Transients
Authors: Paul Neil H. E. , Atkins Nicholas R. , Brandvik Tobias
Published: August 2024

This paper introduces a scalable implementation of a loosely coupled approach for solving unsteady conjugate heat transfer (CHT) problems. The framework uses segregated solvers; computational fluid dynamics (CFD) to solve the Reynolds-averaged Navier-Stokes (RANS) equations on the fluid side, and an iterative finite element analysis (FEA) method to solve the heat equation on the solid side. Thermal coupling is achieved through an iterative procedure that applies temperature (Dirichlet) boundary conditions on the fluid side, and convective (Robin) boundary conditions on the solid side. It is assumed that the disparity in characteristic timescales between fluid and solid is such that the fluid can be treated as quasi-steady, permitting the use of steady CFD. The loosely coupled approach allows simulations to time-march at time steps suitable for the solid side, offering at least an order of magnitude speed-up compared to a fully coupled approach, which is limited by the stability of the fluid side. For validation purposes, the framework is applied to two test cases: a flat plate and a rotating cavity with radial inflow. The convergence characteristics for a range of relaxation levels are compared. Under certain conditions, as has been reported in the literature, loosely coupled CHT methods can become unstable. We discuss these instability mechanisms, and offer practical guidelines for maintaining stability for complex cases. Computational scalability is demonstrated using a 100+ million cell full-annulus radial inflow cavity model, which is run through an engine representative transient in ∼ 24 hours.
Thermal Load Control in High-Temperature Heat Pumps: A Comparative Study
Authors: Pettinari Matteo , Frate Guido Francesco , Ferrari Lorenzo , Yücel Fatma Cansu , Tran A. Phong , Stathopoulos Panagiotis , Kyprianidis Konstantinos
Published: August 2024

High-temperature heat pumps (HTHPs) are becoming increasingly relevant in the industry as they represent a promising solution for decarbonising industrial heat. These technologies can enable the electrification of industrial processes by exploiting electricity from renewables to provide process heat at temperatures above 250 °C, as in the case of emerging Brayton-based HTHPs.

To succeed in this purpose, HTHPs must also ensure operational flexibility, which entails the ability to operate safely under varying loads and promptly respond to fluctuations in demand, while maintaining high efficiencies. Moreover, the ability to provide large flexible electric loads to transmission system operators, has the potential to unlock innovative business cases and further promote the use of these systems. Common control strategies for achieving this, include employing bypass mechanisms, fluid inventory control, and adjusting turbomachinery rotational speeds. Despite their variety, the simultaneous use of such control strategies is often limited as they may lead to significantly different system behaviours, both in terms of transient and steady performance.

In this paper, rotational speed and fluid inventory control are examined from a transient perspective to maintain the desired sink temperature while regulating the thermal load of the system. Results indicate that rotational speed control leads to negligible sink temperature residuals, while fluid inventory control better preserves the HTHP performances for varying temperature glides.
Development of a Dynamic Model of a Two-Shaft Turbine for Control Tuning and Testing
Authors: Ferrari Lorenzo , Bigazzi Tommaso , Di Gioia Gabriele , Bagni Gianni , Giovanardi Lorenzo
Published: August 2024

An accurate prediction of the dynamic performance of gas turbines is still of primary importance in industrial applications, both for control development and diagnostic purposes. In this study, a dynamic model of a two-shaft low-emission gas turbine based on a grey-box approach is proposed. As a first step, a grey-box static model of the turbine was developed in Matlab Simulink based a dataset of multiple simulations of a commercial tool. The results of the grey-box model turned out to be able to predict both machine performance and operating thermodynamic conditions of its components. Starting from these results, a dynamic model was developed of the machine operating in open loop conditions by using time series data from the field. Pattern search and genetic algorithms have been employed to optimize the matching between model and machine outputs. The accuracy and reliability of the dynamic model were tested by using historical data of engine performance. Finally, the model was used in a closed-loop configuration by linking the control software simulator with the system simulator in Simulink, creating a co-simulation between the two environments. This co-simulation allowed for the accurate simulation of the closed-loop system and has proven to be a solid foundation for future developments.
A New Experimental Facility for the Study of Blade Tip Rubs at Engine Relevant Temperatures
Authors: Broski Noah , Keener Christopher , Loizos Theodore , Mathison Randall , D’Souza Kiran , Kasprow Thomas , Wusatowska-Sarnek Agnieszka M.
Published: August 2024

As aircraft engines become more and more efficient, minimizing blade tip clearance in all rotating components of the turbomachinery is critical. This has reduced the distance between the rotating blade tips and the stationary casing to the point that small deviations in manufacturing, uneven thermal expansion, or centrifugal growth can cause the blade to contact the engine’s abradable casing lining. This abradable lining is added to the casing with the foresight that blades are likely to rub against it. In some cases, the clearances are designed so that the blades will cut into this abradable on the first run of the engine. Understanding the interactions between this abradable casing lining and the blades at engine relevant conditions is imperative to the safe and efficient operation of engines. The Ohio State Gas Turbine Laboratory and Pratt & Whitney have developed an in-ground experimental facility for studying the material interactions occurring during blade tip rub events. This facility is designed to allow for variable abradable incursion rates, abradable incursion depths, and blade rotational speed. Additional capabilities of the facility include: the use of an optical temperature sensitive paint system for non-contact sub ambient blade temperature measurements, high speed infrared measurement of blade temperatures, temperature control capabilities for the blades and abradable liner, and blade force measurements on the abradable liner. In this work, a temperature control system for sub and hyper ambient temperatures is presented along with the philosophy and design process for the creation of this system. To aid in designing the temperature control system, a transient heat transfer model was developed and validated in non-rotating experiments. The results of these experiments are discussed and the applicability of these results to the rotating case are examined.
Factors Influencing Hard Running Distances in National Collegiate Athletics Association Division I Women’s Soccer Players
Authors: Sam Isaac A. , Anderson Amanda A. , Johnson Emma L. , Yang Hyung Suk
Published: August 2024

As the total distances covered in soccer games have remained relatively constant, the hard running distances (HRDs) covered by players have shown variations due to the higher physical demands and dynamics of team running performances. Although factors affecting the total distances covered in a match are multifactorial, no study has specifically examined match performance indicators (MPIs) that impact HRD. Consequently, the purpose of this study was to better understand how MPIs (hard running efforts, turnovers, minutes played, duels won, duels lost, and pass completions) are associated with HRD and to investigate how each variable contributes to HRD using multiple regression analysis. The study included a sample of 21 female Division I soccer players aged between 18 and 22 years (mean ± SD = 20 ± 1.32 years), all of whom were outfield players: center backs (n = 5), defensive midfielders (n = 4), outside midfielders (n = 5), center-attacking midfielders (n = 4), and center forwards (n = 3). Overall, all MPIs were positively associated (.639 ≤ r ≤ .992) with HRD, yet hard running efforts showed the strongest relationship with HRDs (r = .992). The regression models indicated that all variables contributed to HRD. In particular, hard running effort had the most significant impact (p < .001), implying its dominant influence on HRD compared with other variables. These findings may play a pivotal role in supporting coaches and trainers to better understand the influence of MPIs on HRD. The models developed could help predict a player’s workload related to HRD.
Millimeter-scale soft capsules for sampling liquids in fluid-filled confined spaces
Authors: Dong Xiaoguang , Xiao Boyang , Vu Hieu , Lin Honglu , Sitti Metin
Published: August 2024

Sampling liquids in small and confined spaces to retrieve chemicals and microbiomes could enable minimally invasive monitoring human physiological conditions for understanding disease development and allowing early screening. However, existing tools are either invasive or too large for sampling liquids in tortuous and narrow spaces. Here we report a fundamental liquid sampling mechanism that enables millimeter-scale soft capsules for sampling liquids in confined spaces. The miniature capsule is enabled by flexible magnetic valves and superabsorbent polymer, fully wirelessly controlled for on-demand fluid sampling. A group of miniature capsules could navigate in fluid-filled and confined spaces safely using a rolling locomotion. The integration of on-demand triggering, sampling, and sealing mechanism and the agile group locomotion allows us to demonstrate precise control of the soft capsules, navigating and sampling body fluids in a phantom and animal organ ex vivo, guided by ultrasound and x-ray medical imaging. The proposed mechanism and wirelessly controlled devices spur the next-generation technologies for minimally invasive disease diagnosis.
Five centuries of consanguinity, isolation, health, and conflict in Las Gobas: A Northern Medieval Iberian necropolis
Authors: Rodríguez-Varela Ricardo , Yaka Reyhan , Pochon Zoé , Sanchez-Pinto Iban , Solaun José Luis , Naidoo Thijessen , Guinet Benjamin , Pérez-Ramallo Patxi , Lagerholm Vendela Kempe , de Anca Prado Violeta , Valdiosera Cristina , Krzewińska Maja , Herrasti Lourdes , Azkarate Agustín , Götherström Anders
Published: August 2024

Between the 8th and 11th centuries CE, the Iberian Peninsula underwent profound upheaval due to the Umayyad invasion against the Visigoths, resulting in population shifts and lasting demographic impacts. Our understanding of this period is hindered by limited written sources and few archaeogenetic studies. We analyzed 33 individuals from Las Gobas, a necropolis in northern Spain, spanning the 7th to 11th centuries. By combining archaeological and osteological data with kinship, metagenomics, and ancestry analyses, we investigate conflicts, health, and demography of these individuals. We reveal intricate family relationships and genetic continuity within a consanguineous population while also identifying several zoonoses indicative of close interactions with animals. Notably, one individual was infected with a variola virus phylogenetically clustering with the northern European variola complex between ~885 and 1000 CE. Last, we did not detect a significant increase of North African or Middle East ancestries over time since the Islamic conquest of Iberia, possibly because this community remained relatively isolated.
Zidovudine in synergistic combination with nitrofurantoin or omadacycline:
in vitro
and in murine urinary tract or lung infection evaluation against multidrug-resistant
Klebsiella pneumoniae
Authors: Tian Ping , Li Qing-Qing , Guo Ming-Juan , Zhu Yun-Zhu , Zhu Rong-Qing , Guo Ya-Qin , Yang Yi , Liu Yan-Yan , Yu Liang , Li Ya-Sheng , Li Jia-Bin
Published: August 2024

Limited treatment options and multidrug-resistant (MDR)
Klebsiella pneumoniae
present a significant therapeutic challenge, underscoring the need for novel approaches. Drug repurposing is a promising tool for augmenting the activity of many antibiotics. This study aimed to identify novel synergistic drug combinations against
K. pneumoniae
based on drug repurposing. We used the clinically isolated GN 172867 MDR strain of
K. pneumoniae
to determine the reversal resistance activity of zidovudine (AZT). The combined effects of AZT and various antibiotics, including nitrofurantoin (NIT) and omadacycline (OMC), were examined using the checkerboard method, growth curves, and crystal violet assays to assess biofilms. An
in vitro
combination activity testing was carried out in 12 isolates of
K. pneumoniae. In vivo
murine urinary tract and lung infection models were used to evaluate the therapeutic effects of AZT + NIT and AZT + OMC, respectively. The fractional inhibitory concentration index and growth curve demonstrated that AZT synergized with NIT or OMC against
K. pneumoniae
strains. In addition, AZT + NIT inhibited biofilm formation and cleared mature biofilms.
In vivo
, compared with untreated GN 172867-infected mice, AZT + NIT and AZT + OMC treatment decreased colony counts in multiple tissues (
P
< 0.05) and pathological scores in the bladder and kidneys (
P
< 0.05) and increased the survival rate by 60% (
P
< 0.05). This study evaluated the combination of AZT and antibiotics to treat drug-resistant
K. pneumoniae
infections and found novel drug combinations for the treatment of acute urinary tract infections. These findings suggest that AZT may exert significant anti-resistance activity.
Pharmacokinetics and safety of TBAJ-876, a novel antimycobacterial diarylquinoline, in healthy subjects
Authors: Lombardi Antonio , Pappas Fran , Nedelman Jerry , Hickman Dean , Jaw-Tsai Sarah , Olugbosi Morounfolu , Bruinenberg Paul , Beumont Maria , Sun Eugene
Published: August 2024

TBAJ-876, a second-generation diarylquinoline with greater antimycobacterial activity and a potentially better safety profile compared with bedaquiline, is under development for the treatment of drug-susceptible and drug-resistant tuberculosis (TB). A phase 1, first-in-human study of TBAJ-876, comprising a single-ascending dose (SAD) part including a food effect cohort, a multiple-ascending dose (MAD) part, and a relative bioavailability part of tablets versus oral suspension, was conducted on 137 healthy adults. A drug–drug interaction study was conducted on 28 healthy adults to evaluate the effects of TBAJ-876 on a cytochrome P450 3A4 substrate (midazolam) and a P-glycoprotein substrate (digoxin). TBAJ-876 was well-tolerated at single doses up to 800 mg and multiple doses up to 200 mg for 14 days. No deaths or serious adverse events occurred. No episodes of clinically significant prolongation of the QTc interval were observed. TBAJ-876 exposures were dose proportional in the SAD and MAD studies. TBAJ-876 exhibited multicompartmental pharmacokinetics (PK) with a long terminal half-life yielding quantifiable concentrations up to the longest follow-up of 10 weeks after a single dose and resulting in accumulation with multiple dosing. In the fed state, TBAJ-876 exposures approximately doubled with the tablet formulation, whereas M3 metabolite exposures decreased by approximately 20%. The relative bioavailability of TBAJ-876 was similar between tablets and the oral suspension at 100-mg doses. With co-administration of TBAJ-876, the AUC
0-inf
of midazolam was unchanged and the C
max
was reduced by 14%; the AUC
0-last
of digoxin was increased by 51%, and the C
max
was increased by 18%. These results support further investigation of TBAJ-876 for the treatment of tuberculosis.
Dose-fractionation studies of a
Plasmodium
phosphatidylinositol 4-kinase inhibitor in a humanized mouse model of malaria
Authors: Gibhard Liezl , Njoroge Mathew , Mulubwa Mwila , Lawrence Nina , Smith Dennis , Duffy James , Le Manach Claire , Brunschwig Christel , Taylor Dale , van der Westhuyzen Renier , Street Leslie J. , Basarab Gregory S. , Chibale Kelly
Published: August 2024

UCT594 is a 2-aminopyrazine carboxylic acid
Plasmodium
phosphatidylinositol 4-kinase inhibitor with potent asexual blood-stage activity, the potential for interrupting transmission, as well as liver-stage activities. Herein, we investigated pharmacokinetic/pharmacodynamic (PK/PD) relationships relative to blood-stage activity toward predicting the human dose. Dose-fractionation studies were conducted in the
Plasmodium falciparum
NSG mouse model to determine the PK/PD indices of UCT594, using the
in vivo
minimum parasiticidal concentration as a threshold. UCT594 demonstrated concentration-dependent killing in the
P. falciparum
-infected NSG mouse model. Using this data and the preclinical pharmacokinetic data led to a low predicted human dose of <50 mg. This makes UCT594 an attractive potential antimalarial drug.
Host cell-specific metabolism of linoleic acid controls
Toxoplasma gondii
growth in cell culture
Authors: Hryckowian Nicole D. , Ramírez-Flores Carlos J. , Zinda Caitlin , Park Sung Chul , Kelty Martin T. , Knoll Laura J.
Published: August 2024

The obligate intracellular parasite
Toxoplasma gondii
can infect and replicate in any warm-blooded cell tested to date, but much of our knowledge about
T. gondii
cell biology comes from just one host cell type: human foreskin fibroblasts (HFFs). To expand our knowledge of host–parasite lipid interactions, we studied
T. gondii
in intestinal epithelial cells, the first site of host–parasite contact following oral infection and the exclusive site of parasite sexual development in feline hosts. We found that highly metabolic Caco-2 cells are permissive to
T. gondii
growth even when treated with high levels of linoleic acid (LA), a polyunsaturated fatty acid (PUFA) that kills parasites in HFFs. Caco-2 cells appear to sequester LA away from the parasite, preventing membrane disruptions and lipotoxicity that characterize LA-induced parasite death in HFFs. Our work is an important step toward understanding host–parasite interactions in feline intestinal epithelial cells, an understudied but important cell type in the
T. gondii
life cycle.
Influenza virus antibodies inhibit antigen-specific
de novo
B cell responses in mice
Authors: Goodwin Eileen , Gibbs James S. , Yewdell Jonathan W. , Eisenlohr Laurence C. , Hensley Scott E.
Published: August 2024

Antibody responses to influenza vaccines tend to be focused on epitopes encountered during prior influenza exposures, with little production of
de novo
responses to novel epitopes. To examine the contribution of circulating antibodies to this phenomenon, we passively transferred a hemagglutinin (HA)-specific monoclonal antibody (mAb) into mice before immunizing with whole inactivated virions. The HA mAb inhibited
de novo
HA-specific antibodies, plasmablasts, germinal center B cells, and memory B cells, while responses to a second antigen in the vaccine, neuraminidase (NA), were uninhibited. The HA mAb potently inhibited
de novo
antibody responses against epitopes near the HA mAb binding site. The HA mAb also promoted IgG1 class switching, an effect that, unlike the inhibition of HA responses, relied on signaling through Fc-gamma receptors. These studies suggest that circulating antibodies inhibit
de novo
B cell responses in an antigen-specific manner, which likely contributes to differences in antibody specificities elicited during primary and secondary influenza virus exposures.

IMPORTANCE

Most humans are exposed to influenza viruses in childhood and then subsequently exposed to antigenically drifted influenza variants later in life. It is unclear if antibodies elicited by earlier influenza virus exposures impact immunity against new influenza virus strains. Here, we used a mouse model to investigate how an anti-hemagglutinin (HA) monoclonal antibody (mAb) affects
de novo
B cell and antibody responses to the protein targeted by the monoclonal antibody (HA) and a second protein not targeted by the monoclonal antibody [neuraminidase (NA)]. Collectively, our studies suggest that circulating anti-influenza virus antibodies can potently modulate the magnitude and specificity of antibody responses elicited by secondary influenza virus exposures.