bluuebunny/crossref_metadata_2025 huggingface dataset:
Porosity Driven Approaches to Model Fouling Effects on Flow Field
Authors: Casari Nicola , Suman Alessio , Pinelli Michele
Published: November 2019

Air contamination by solid particles represents a real hazard for compressors for both heavy-duty and aero-propulsion gas turbines. Particles impacting the inner surfaces of the machine can stick to such surfaces or erode them. The presence of deposits entails the reduction in performance of the machinery. As the severity of the problem increases, the performance reduction can become so big to demand engine shut-down and off-line washing. Numerical modeling is one of the techniques employed for tackling the fouling problem. In this work, an innovative procedure is proposed in order to evaluate the losses and the variation in the fluid flow due to the deposits. Specifically, as the deposit grows, it is assumed it forms a porous medium attached to the wall. The porosity of this zone (related to the packing of the particles and to the amount of particles that sticks in to a zone) is responsible for the deposition-induced losses. Different approaches to compute such losses are proposed and discussed. By using this methodology, the two main effects of fouling (variation in roughness and in shape of the airfoil) can be easily included in a comprehensive analysis of the variation of the performance of the compressor over time. Furthermore, this approach overcomes the difficulties that may arise by using a mesh morphing technique. The computational grid is not modified and thus its quality is retained, without remeshing requirements, even for large deposits.
Lean Fully Premixed Injection for Commercial Jet Engines: An Initial Design Study
Authors: Palies Paul , Acharya Ragini , Hoffie Andreas , Thomas Matthew
Published: November 2019

This article presents the results of an initial design study for a lean fully premixed (LFP) injector for commercial jet engine. The operating point considered is that of an high overall pressure ratio, small core engine at take-off condition. To perform this feasibility study, multiple relevant constraints are taken into account. The three-unit fully premixed injector has been designed by utilizing numerical simulations. The first unit of the injector is intended to perform complete fuel vaporization through heat transfer from the compressed air to the liquid fuel via a compact onboard heat exchanger. The second unit is designed to ensure premixing of the fully evaporated fuel and the air. Finally, the third unit ensures additional premixing and stability of the premixed swirling flame. The autoignition challenge associated with the design of the LFP injector is discussed in this article. The computational modeling approach that was used to design the units of the LFP injector is presented.
Experimentally Measured Effectiveness of Different Shroud Swirl Brake Profiles in a Centrifugal Compressor
Authors: Wilkes Jason , Smith Natalie , Venkataraman Balaji , Vagani Marco , Goucher Sara
Published: November 2019

As centrifugal compressors are pushed to operate at higher pressures and higher power levels, destabilizing gas forces often increase the challenge of designing a stable rotordynamic system. While technical innovations like damper seals, swirl brakes, and damper bearings that help stabilize compressors are numerous, predicting the impact that these improvements will have on a specific system is somewhat of an art form. To this end, researchers are constantly improving the depth of knowledge on these features so that the impact of these improvements is well defined. In the current work, the authors experimentally measured the impact of different swirl brake/vane concepts on the flow characteristics of a centrifugal compressor shroud cavity. The eye seal configuration studied here is a tooth on rotor labyrinth eye seal.

The different shroud swirl vane geometries considered consist of various castellated features, each having the intent to reduce swirl velocity in the shroud cavity prior to entering the seal. The purpose of the testing was to determine whether a significant reduction in swirl velocity entering or exiting the seal could be measured with the different anti-swirl vane profiles over a conventional shroud cavity that was tested with the same setup. The metrics that determine the effectiveness of the swirl brake were based on upstream and downstream measurements of swirl velocity using pitot-probes at different depths in the shroud cavity, and measurements of seal exit angle and velocity using a traversing cobra-probe.

The test data presented herein show definitively that the different swirl brake designs, including a slotted seal, a long vane, and a short vane, have a major impact on swirl velocities relative to the conventional shroud design. The most effective at reducing swirl entering/leaving the seal is the slotted seal, while the concepts employing shroud vanes were more effective at reducing swirl in the shroud cavity.
Development and Analysis of an Integrated Mild/Partial Gasification Combined (IMPGC) Cycle: Part 1 — Development of a Baseline IMPGC System
Authors: Wang Ting , Long Henry A.
Published: November 2019

Around 50% of the world’s electrical power supply comes from the Rankine cycle, and the majority of existing Rankine cycle plants are driven by coal. Given how politically unattractive coal is as an energy resource in spite of its high energy content, it becomes necessary to find a way to utilize coal in a cleaner and more efficient manner. Designed as a potential retrofit option for existing Rankine cycle plants, the Integrated Mild/Partial Gasification Combined (IMPGC) Cycle is an attractive concept in cycle design that can greatly increase the efficiency of coal-based power plants, particularly for retrofitting an old Rankine cycle plant. Compared to the Integrated Gasification Combined Cycle (IGCC), IMPGC uses mild gasification to purposefully leave most of the volatile matters within the feedstock intact (hence, yielding more chemical energy) compared to full gasification and uses partial gasification to leave some of the remaining char un-gasified compared to complete gasification. The larger hydrocarbons left over from the mild gasification process grant the resulting syngas a higher volumetric heating value, leading to a more efficient overall cycle performance. This is made possible due to the invention of a warm gas cleanup process invented by Research Triangle Institute (RTI), called the High Temperature Desulfurization Process (HTDP), which was recently commercialized. The leftover char can then be burned in a conventional boiler to boost the steam output of the bottom cycle, further increasing the efficiency of the plant, capable of achieving a thermal efficiency of 47.9% (LHV). The first part of this paper will analyze the individual concepts used to create the baseline IMPGC model, including the mild and partial gasification processes themselves, the warm gas cleanup system, and the integration of the boiler with the heat recovery steam generator (HRSG). Part 2 will then compare this baseline case with four other common types of power plants, including subcritical and ultra-supercritical Rankine cycles, IGCC, and natural gas.
The Influence of Ambient Pressure on the Measured Load Capacity of Bump-Foil and Spiral-Groove Gas Thrust Bearings at Ambient Pressures up to 69 Bar on a Novel High-Pressure Gas Bearing Test Rig
Authors: Wilkes Jason , Cater Ryan , Swanson Erik , Passmore Kevin , Brady Jerry
Published: November 2019

This paper will show the influence of ambient pressure on the thrust capacity of bump-foil and spiral-groove gas thrust bearings. The bearings were operating in nitrogen at various pressures up to 69 bar, and were tested to failure. Failure was detected at various pressures by incrementally increasing the thrust load applied to the thrust bearing until the bearing was no longer thermally stable, or until contact was observed by a temperature spike measured by thermocouples within the bearing.

These tests were performed on a novel thrust bearing test rig that was developed to allow thrust testing at pressures up to 207 bar cavity pressure at 260°C while rotating at speeds up to 120,000 rpm. The test rig floats on hydrostatic air bearings to allow for the direct measurement of applied thrust load through linkages that connect the stationary thrust loader to the rotor housing. Test results on a 65 mm (2.56 in) bump-foil thrust bearing at 100 krpm show a marked increase in load capacity with gas density, which has not previously been shown experimentally. Results also show that the load capacity of a similarly sized spiral-groove thrust bearing are relatively insensitive to pressure, and supported an order-of-magnitude less load than that observed for the bump-foil thrust bearing. These results are compared with analytical predictions, which agree reasonably with the experimental results. Predicted power loss is also presented for the bump-foil bearing; however, measured power loss was substantially higher.
Fine Particulate Deposition in an Effusion Plate Geometry
Authors: Varney B. , Barker B. , Bons J. P. , Wolff T. , Gnanaselvam P.
Published: November 2019

Fine particulate deposition testing was conducted with an effusion plate film cooling geometry representative of a gas turbine combustor liner. Preheated coolant air with airborne particulate (0–10 μm Arizona Road Dust) was fed into an effusion plate test fixture with the flow parallel to the target plate. The test fixture was located in an electric kiln that establishes the elevated plate temperature, similar to a gas turbine combustor. Experiments were conducted at constant pressure ratio (1.03) across the effusion plate which consists of an array of approximately 100 effusion holes. Test variables include hole diameter, length/diameter ratio, inclination angle and compound angle. In addition, coolant temperature and plate temperature were varied independently to determine their influence on in-hole deposition. All tests were continued until the effusion holes had blocked to produce a 25% reduction in mass flow rate while maintaining constant pressure ratio. The blockage was found to be more sensitive to flow temperature than to plate temperature over the range studied. Blockage was insensitive to effusion hole diameter from 0.5 to 0.75 mm, but increased dramatically for hole diameter below 0.5mm. Blockage shows a moderate increase with hole length/diameter ratio. The strongest dependency was found with the inclination angle; roughly an order of magnitude increase in deposition rate was documented when increasing from a 30° to 150°. A compound angle of 45° caused a negligible change in blockage, while a compound angle of 90° increased blockage for low inclination angles while decreasing it for high inclination angles. For the flow angle dependency, interpretation is provided by means of CFD simulations of the particulate delivery and initial deposition location prediction using the OSU Deposition Model.
Radial Variation in Distortion Transfer and Generation in a Highly Loaded Fan Stage From Near-Stall to Choke
Authors: Soderquist Daniel R. , Orme Andrew D. , Gorrell Steven E. , List Michael G.
Published: November 2019

Understanding distortion transfer and generation through fan and compressor blade rows is able to assist in blade design and performance prediction. Using full annulus URANS simulations, the effects of distortion as it passes through the rotor of a transonic fan at five radial locations (10%, 30%, 50%, 70%, and 90% span) are analyzed. The inlet distortion profile is a 90-degree sector with a 15% total pressure deficit. Fourier distortion descriptors are used in this study to quantitatively describe distortion transfer and generation. Results are presented and compared for three operating points (near-stall, design, and choke). These results are used to explain the relationship between inlet total pressure distortion, pressure-induced swirl, total pressure distortion transfer, total temperature distortion generation, and circumferential rotor power variation. It is shown that very large changes in pressure-induced swirl and distortion transfer and generation occur between near-stall and design, but only small changes are seen between design and choke. The greatest changes are shown to be near the tip. Local power variations are shown to correlate with total pressure distortion transfer and total temperature distortion generation.
Compact Heat Exchanger Semi-Circular Header Burst Pressure and Strain Validation
Authors: Lance Blake W. , Carlson Matthew D.
Published: November 2019

Compact heat exchangers for supercritical CO2 (sCO2) service are often designed with external, semi-circular headers. Their design is governed by the ASME Boiler & Pressure Vessel Code (BPVC) whose equations were typically derived by following Castigliano’s Theorems. However, there are no known validation experiments to support their claims of pressure rating or burst pressure predictions nor is there much information about how and where failures occur.

This work includes high pressure bursting of three semi-circular header prototypes for the validation of three aspects: (1) burst pressure predictions from the BPVC, (2) strain predictions from Finite Element Analysis (FEA), and (3) deformation from FEA. The header prototypes were designed with geometry and weld specifications from the BPVC Section VIII Division 1, a design pressure typical of sCO2 service of 3,900 psi (26.9 MPa), and were built with 316 SS. Repeating the test in triplicate allows for greater confidence in the experimental results and enables data averaging. Burst pressure predictions are compared with experimental results for accuracy assessment. The prototypes are analyzed to understand their failure mechanism and locations.

Experimental strain and deformation measurements were obtained optically with Digital Image Correlation (DIC). This technique allows strain to be measured in two dimensions and even allows for deformation measurements, all without contacting the prototype. Eight cameras are used for full coverage of both headers on the prototypes. The rich data from this technique are an excellent validation source for FEA strain and deformation predictions. Experimental data and simulation predictions are compared to assess simulation accuracy.
Modeling Deposit Erosion in Internal Turbine Cooling Geometries
Authors: Libertowski Nathan D. , Geiger Gabriel M. , Bons Jeffrey P.
Published: November 2019

Experiments were performed to study the erosion of deposit structures due to large particle impacts (> 5 μm). Cone shaped dust deposits were created in an oversized (6.35 mm diameter) impingement cooling jet at 811 K with 0–5 μm Arizona Road Dust (ARD). Subsequently, the deposit cones were eroded with larger particle distributions (5–10, 10–20, 20–40, and 40–80 μm ARD) at various velocities and temperatures. It was found that erosion rate increased with increasing particle size and flow velocity and with decreasing temperature. The dependency on size and velocity occurs through the particle’s kinetic energy at impact, while the dependency on temperature is related to the adhesive forces in the deposit structure. Using the experimental data, an empirical erosion model was developed to be added to the OSU deposition model. A computational flow simulation combined with mesh morphing is shown to capture key features of the erosion physics.
Evaluating the Usefulness of RANS in Film Cooling
Authors: Jones Fraser B. , Fox Dale W. , Bogard David G.
Published: November 2019

Film cooling is a very common technique used in cooling turbine engine components, and hence has been studied extensively experimentally and computationally. Computational studies of film cooling range from more simplistic RANS predictions to high fidelity LES predictions. Generally the accuracy of computational predictions of film cooling is evaluated based on the adiabatic effectiveness measured and predicted downstream of the hole. For this study, a RANS computational prediction was used, but the evaluation of the accuracy of the prediction was based on measured thermal and velocity fields within the coolant hole and immediately downstream. We chose a relatively complex film cooling configuration consisting of a row of 7-7-7 shaped holes fed by an internal channel flow with a range of internal crossflow velocities and coolant jet velocities. Previous experimental studies using this configuration showed that at various inlet velocity ratios, the coolant jet becomes biased to one side of the diffusing section of the hole, which degrades performance and can cause ingestion into the hole. For this study we wanted to determine the capability of a RANS computation to correctly predict the flow structures, coolant jet biasing, and film effectiveness for this configuration. Computational results were compared to thermal field measurements made with a micro-thermocouple probe, velocity field measurements made with a PIV, and film effectiveness measurements made with an IR camera. These measurements were made within the coolant hole, at the downstream edge of the hole, and at 5D downstream of the hole. Results from this study show that the RANS computations accurately predicted the bulk flow and thermal fields within and at the downstream edge of the hole, but failed to predict the evolutions of the thermal field, secondary flows, and film effectiveness downstream of the hole.
Thermal Degradation of Biofuels in Contact With Hot Metal Surfaces
Authors: Chagoya Katerina L. , Felix Alan , Torres Fernand E. , Ciaffone Nicholas , Pitts Taylor E. , Curbelo Andres , Tetard Laurene , Kapat Jayanta , Blair Richard G.
Published: November 2019

Biofuels are an important component of a sustainable fuel future. The implementation of such fuels into existing and new engine designs requires an understanding of their interactions with the engine’s components at temperature. The formation of soot deposits on hot metal components, when in contact with fuels at elevated temperatures, can reduce engine performance. We have devised a test rig to measure soot formation from individual biofuel components. Fuel can be sprayed onto metal surfaces up to 750 °C under a controlled atmosphere. Using this rig, we have studied the formation of carbon deposits on steel, nickel, and aluminum metals using the pure small molecule biofuels and fuel mixture simulants. The amount and chemical identity of the deposits formed were studied using Raman spectroscopy. Using this new method for soot quantification, we can more rapidly screen for low soot forming biofuels as promising biofuel candidates grow.
Comparison of Thin Film Heat Flux Gauge Technologies Emphasizing Continuous-Duration Operation
Authors: Siroka Shawn , Berdanier Reid A. , Thole Karen A. , Chana Kam S. , Haldeman Charles W. , Anthony Richard J.
Published: November 2019

Thin film heat flux gauges (HFGs) have been used for several decades to measure surface temperatures and heat flux in test turbines with the majority being used in facilities that are short-duration. These gauges are typically composed of two resistive temperature devices deposited on opposing sides of a dielectric. However, because these sensors have been traditionally applied for measurements in short-duration, transient-type facilities, the challenges facing adaptation of this technology for a continuous-duration steady facility warrant investigation. Those challenges are highlighted, and solutions are presented throughout the paper. This paper describes the nanofabrication process for heat flux gauges and a new calibration method to address potential deterioration of gauges over long runtimes in continuous-duration facilities. Because a primary uncertainty of these sensors arises from the ambiguity of the thermal properties, special emphasis is placed on the property determination and potential errors due to improper thermal properties. Also, this paper presents a discussion on the use of impulse response theory to process the data showing the feasibility of the method for steady-duration facilities after an initial settling time. The latter portion of the paper focuses on comparing well-established heat flux gauges developed for short-duration turbine test facilities to recently developed gauges fabricated using modern nanofabrication techniques for a continuous turbine test facility. Using a commercially available heat flux gauge, capable of measuring a steady heat flux as a reference, the gauges were compared using the test case of an impinging jet over a range of Reynolds numbers. The comparison between the PSU gauge and the reference device indicated agreement within 14%, and similar results were achieved through comparison with established sensors from partner institutions.
Adjoint-Based Multidisciplinary, Multipoint Optimization of a Radial Turbine Considering Aerodynamic and Structural Performances
Authors: Mueller Lasse , Verstraete Tom , Schwalbach Marc
Published: November 2019

This paper presents a multidisciplinary adjoint-based design optimization of a turbocharger radial turbine for automotive applications. The aim is to improve the total-to-static efficiency of the turbine while keeping mechanical stresses below a predefined limit. The search for the optimal design is accomplished using an efficient Sequential Quadratic Programming algorithm considering additional aerodynamic and manufacturing constraints. The aerodynamic performance of the wheel is evaluated by a Reynolds-Averaged Navier-Stokes solver, whereas the maximum stresses in the material are predicted by a Finite Element Analysis tool. The design gradients required by the optimizer are computed with the adjoint approach which provides sensitivity information largely independent of the number of design variables. The results presented in this paper show the clear need to take into account mechanical stresses during optimization, as they are the most restrictive design limitation. However, the gradient-based optimization algorithm is able to effectively keep the stress levels below the critical value while significantly improving the turbine efficiency in a few design cycles.
Structural Dynamics and Aeroelasticity of Airborne Diesel Engine Turbochargers
Authors: McGowan Ryan C. , Murugan Muthuvel , Szedlmayer Michael T. , Kim Kenneth S. , Kruger Kurt M. , Gondol David J. , Kweon Chol-Bum M. , Clerkin Peter J. , Meininger Rik D. , Gibson Joseph A. , Lindsey Christopher A. , Acker Bernard N. , Musser Marshall R.
Published: November 2019

Compared to turbodiesel technology for ground vehicles, the increasing application of turbochargers in aircraft diesel engines presents a unique set of structural dynamics and aeroelasticity considerations due to their more extreme operating conditions. In particular, blade vibration and flutter are two related but distinct phenomena that impact the design of these turbochargers and reliable operation over their lifetime. Deformation or fatigue due to blade excitation can reduce efficiency or cause components to fail prematurely. The existing literature on turbomachinery covers many research efforts to analyze these phenomena by investigating the physical mechanisms responsible as well as the relationships between the fluid and solid dynamics. This review paper emphasizes those efforts most relevant to airborne diesel turbochargers, including research focusing on altitude effects on centrifugal compressors. Early work in which the dominant parameters for modeling turbocharger behavior were identified is highlighted as are current efforts to develop higher-fidelity models. An overview of existing and proposed techniques for measuring and controlling blade resonance is also given. Finally, an experimental facility for testing of turbochargers is proposed. The facility will include a nonintrusive stress measurement system and enable measurement of blade deflection/vibration together with blade stress, temperature, pressure, and flow rate across a range of simulated altitudes. The goal will be to characterize the blade bending modes, resonances, and critical speeds for various simulated altitude, pressure, temperature, and flow rate conditions so that designs may be devised that could prevent or avoid the associated failure modes in airborne diesel applications.
Confidence Bound Estimation for Mechanism-Based Small Crack Growth Probabilistic Design Life Predictions
Authors: Golden Patrick J. , Jha Sushant K. , Larsen James M.
Published: November 2019

Current design lives for US Air Force turbine engine materials are based on a 1 in 1000 rate of nucleation of an engineering sized crack (B0.1). These lives are determined from models fitted to test coupon fatigue data at many different loading conditions. It has been shown that this methodology can sometimes lead to excess conservatism, and it often does not fully incorporate understanding of the mechanisms that drive crack initiation, growth, and fracture. A mechanism based probabilistic life forecasting methodology has been previously proposed with the objective to improve the prediction of minimum fatigue life or design life through understanding of the type and frequency of the material mechanisms that lead to early or immediate fatigue crack initiation.

An approach is proposed and demonstrated for the estimation of probabilistic mechanism-based design life prediction confidence bounds. These confidence bounds on the calculated B0.1 or minimum life predictions are dependent on the quality and quantity of the data used in the analysis. The effect of additional data from either small crack growth tests or microstructural characterization or fractography analysis on the extent of the calculated confidence bounds is shown. The analysis presented can ultimately be used to describe a relationship between the required confidence in the design life predictions to the cost of the test program required to collect the necessary data. Comparisons are made between data requirements and the level of confidence in empirical statistical predictions from fatigue test data and the new probabilistic mechanism-based design life predictions for laboratory specimens in a turbine engine material.
3D Heat Transfer Assessment of Full-Scale Inlet Vanes With Surface-Optimized Film Cooling: Part 2 — Conjugate CFD Simulations
Authors: Johnson J. J. , Clark J. P. , Anthony R. A. , Ooten M. K. , Ni R. H. , Humber W. H.
Published: November 2019

An investigation of the experimental heat transfer and cooling effectiveness for a modern fully-cooled high-pressure turbine (HPT) inlet vane is presented. Conjugate Heat Transfer (CHT) Computational Fluid Dynamics (CFD) is conducted to simulate experiments using thin-film heat-flux gauges on full-scale 3D vanes at engine-representative conditions from Part 1 of this paper. Pressure side (PS) film cooling performance is compared for a baseline and optimized configuration, in which the latter was previously developed using genetic algorithm (GA) optimization. The optimized vane was iterated using hundreds of computationally efficient 3D Reynolds Averaged Navier Stokes (RANS) CFD simulations with a transpiration boundary condition to simulate film cooling. This combination of CFD and GAs determined surface-optimized cooling hole orientations and placement. Steady-state flat plate infrared thermography experiments that followed also determined the best cooling hole shapes to use on different sections of the vane pressure side surface. This ultimately generated the cooling design to be fabricated using realistic materials and experimentally tested in Part 1 and simulated using CHT CFD in the current work (Part 2). Here, spanwise and streamwise heat transfer distributions for the baseline and optimized cooling design are validated against experimental data. 3D CHT CFD results are then assessed at the same conditions, providing relevance and credence to the overall cooling design methods. Ultimately, surface-optimized film cooling designs can be used to reduce the adverse effects of sub-optimal heat distribution on critical high temperature engine parts, increasing the life of the part. Alternatively, such a design could lead to increases in engine efficiency since less cooling air is required from the mainstream per part.
Aeromechanic Response of a Coupled Inlet-Fan Boundary Layer Ingesting Distortion-Tolerant Fan
Authors: Heinlein G. S. , Bakhle M. A. , Chen J. P.
Published: November 2019

Boundary layer ingestion has significant potential to reduce fuel burn in aircraft engines. However, designing a fan that can operate in an environment of continuous distortion without aeromechanical failure is a critical challenge. Capturing the requisite aeromechanical flow features in a high-fidelity computational setting is necessary in validating satisfactory designs as well as determining possible regions for overall improvement. In the current work, a three-dimensional, time-accurate, Reynolds-averaged Navier-Stokes computational fluid dynamic code is utilized to study a distortion-tolerant fan coupled to a boundary layer ingesting inlet. The comparison between this coupled inlet-fan and a previous fan-only simulation will provide insight into the changes in aeromechanic response of the fan blades. Additionally, comparisons to previous wind tunnel tests are made to provide validation of inlet distortion as seen by the distortion-tolerant fan. A resonant crossing was also investigated for the 85% speed operational line condition to compare resonant response between the inlet-fan, fan-only, and experiment. A decrease in maximum tip displacement is observed in the forced response of the coupled inlet-fan compared to the fan-only simulation. The predicted maximum tip displacement was still below the upper limit on the range observed in the wind tunnel tests but matched well with the average tip displacement value of 27.6 mils. A single mode was chosen at the 100% speed condition to provide insight into the effects that the inlet duct has on fan stability. Near stall and near choke conditions were also simulated to observe how the changes of progressing along the speed line affects flutter stability prediction. The analysis shows the fan has low levels of aerodynamic damping at all the conditions tested. However, the coupled inlet-fan shows a decrease in the level of aerodynamic damping over what was observed with the fan-only simulation. Some of the blades experienced single cycles of negative aerodamping which indicate a possibility of increased blade vibration amplitude but were followed by positive aerodamping cycles. Work is continuing to understand possible sources to account for the differences observed between the two simulation cases as well as with the experiment.
Turbulent Flame Shape Switching at Conditions Relevant for Gas Turbines
Authors: Langella Ivan , Heinze Johannes , Behrendt Thomas , Voigt Lena , Swaminathan Nedunchezhian , Zedda Marco
Published: November 2019

A numerical investigation is conducted in this work to shed light on the reasons leading to different flame configurations in gas turbine combustion chambers of aeronautical interest. Large eddy simulations (LES) with a flamelet-based combustion closure are employed for this purpose to simulate the DLR-AT Big Optical Single Sector (BOSS) rig fitted with a Rolls-Royce developmental lean burn injector. The reacting flow field downstream this injector is sensitive to the intricate turbulent-combustion interaction and exhibits two different configurations: (i) a penetrating central jet leading to an M-shape lifted flame; or (ii) a diverging jet leading to a V-shaped flame. First, the LES results are validated using available BOSS rig measurements, and comparisons show that the numerical approach used is consistent and works well. The turbulent-combustion interaction model terms and parameters are then varied systematically to assess the flame behavior. The influences observed are discussed in the paper from physical and modelling perspectives to develop physical understanding on the flame behavior in practical combustors for both scientific and design purposes.
Investigation Into Advanced Combustion System Health Monitoring
Authors: Noble David , Angello Leonard , Sheppard Scott , Kee Jared , Emerson Benjamin , Lieuwen Tim
Published: November 2019

Dry, low NOx gas turbines are extremely complex machines that are heavily relied upon in the power industry as baseload, cycling, and/or peaking units. These low-emission gas turbines present potential maintenance and monitoring challenges due to the intrinsically harsh pressure and temperature environments, which make diagnostics and prognostic capabilities extremely difficult. One such challenge involves understanding and interpreting combustion dynamics data. This paper focuses on gas turbine combustion dynamics monitoring (CDM) and describes an algorithm to determine combustor health based upon dynamic pressure. The ongoing CDM and diagnostic work has progressed from taking basic binned FFT data and transforming this data to statistically-based health indicators that can be continuously calculated to determine combustion system anomalies. These anomalies can be detected hours, days, and sometimes even weeks before passive CDM alarm levels are reached, thus, giving additional time to plan for shutdown, inspection, and repair. The paper will discuss real-time observed successes and challenges associated with combustor health monitoring, including sensor health determination and factors associated with the non-linear nature of combustion dynamics. Overall, this work is helping to better alleviate the user’s “black box” perspective of combustion dynamics monitoring systems through automated, real-time interpretation for combustion system health for can annular gas turbines.
Data Assimilation and Optimal Calibration in Nonlinear Models of Flame Dynamics
Authors: Yu Hans , Jaravel Thomas , Ihme Matthias , Juniper Matthew P. , Magri Luca
Published: November 2019

We propose an on-the-fly statistical learning method to take a qualitative reduced-order model of the dynamics of a premixed flame and make it quantitatively accurate. This physics-informed data-driven method is based on the statistically optimal combination of (i) a reduced-order model of the dynamics of a pre-mixed flame with a level-set method, (ii) high-quality data, which can be provided by experiments and/or high-fidelity simulations, and (iii) assimilation of the data into the reduced-order model to improve the prediction of the dynamics of the premixed flame. The reduced-order model learns the state and the parameters of the premixed flame on the fly with the ensemble Kalman filter, which is a Bayesian filter used, for example, in weather forecasting. The proposed method and algorithm are applied to two test cases with relevance to reacting flows and instabilities. First, the capabilities of the framework are demonstrated in a twin experiment, where the assimilated data is produced from the same model as that used in prediction. Second, the assimilated data is extracted from a high-fidelity reacting-flow direct numerical simulation (DNS), which provides the reference solution. The results are analyzed by using Bayesian statistics, which robustly provide the level of confidence in the calculations from the reduced-order model. The versatile method we propose enables the optimal calibration of computationally inexpensive reduced-order models in real time when experimental data becomes available, for example, from gas-turbine sensors.
Influence of Hole Inlet Geometry on the Film Cooling Effectiveness From Shaped Film Cooling Holes
Authors: Watson Travis B. , Vinton Kyle R. , Wright Lesley M. , Crites Daniel C. , Morris Mark C. , Riahi Ardeshir
Published: November 2019

The effect of film cooling hole inlet geometry is experimentally investigated in this study. Detailed film cooling effectiveness distributions are obtained on a flat plate using Pressure Sensitive Paint (PSP). The inlet of a traditional 12°-12°-12°, laidback, fanshaped hole varies from a traditional “round” opening to an oblong, racetrack shaped opening. In this study, a single racetrack inlet with an aspect ratio of 2:1 is compared to the round inlet. For both designs, the holes are inclined at θ = 30° relative to the mainstream. Blowing ratios of 0.5, 1.0, and 1.5 are considered as the coolant–to–mainstream density ratio varies between 1.0 and 4.0. For all cases, the freestream turbulence intensity is maintained at 7.5%. With the introduction of the racetrack shaped inlet, the coolant spreads laterally across the diffuse, laidback fanshaped outlet. The centerline film cooling effectiveness is reduced with the enhanced lateral spread of the coolant. However, the benefit of the shaped inlet is also observed with an increase in the area averaged film cooling effectiveness, compared to the traditional round inlet. Not only does the shaped inlet promote spreading of the coolant, it is also believed the racetrack shape suppresses turbulence within the hole allowing for enhanced film cooling protection near the film cooling holes.
Offering Engineering Students Global Prospective Through Experiential Learning Project in Wind Energy and Sustainability
Authors: El-Gabry Lamyaa , Jaskolski Martina
Published: November 2019

Students from Princeton University partnered with students from the American University in Cairo in a three-week intensive hands-on field experience in Egypt. The project was to assemble, install and test a wind mill driven pump used for irrigation and to survey communities across Egypt in the Delta and Red Sea coast to assess water needs in these communities. The course offered a perspective on sustainable development in Egypt followed by water and energy resource challenges in Egypt’s diverse geographic areas. Students assembled a wind pump and installed it at the American University in Cairo for testing prior to installation at El Heiz, a desert oasis community in the Western Desert. The students were selected from diverse backgrounds in Mechanical and Aerospace Engineering, Civil and Environmental Engineering, Computer Engineering, and Operations Research and Financial Engineering and learned the value of having diverse teams address engineering problems in a truly global context. This paper presents the case study including lessons learned in implementation of this experiential learning field project.
Player Session Rating of Perceived Exertion: A More Valid Tool Than Coaches’ Ratings to Monitor Internal Training Load in Elite Youth Female Basketball
Authors: Lupo Corrado , Ungureanu Alexandru Nicolae , Frati Riccardo , Panichi Matteo , Grillo Simone , Brustio Paolo Riccardo
Published: November 2019

Purpose:To monitor elite youth female basketball training to verify whether players’ and coaches’ (3 technical coaches and 1 physical trainer) session rating of perceived exertion (s-RPE) has a relationship with Edwards’ method.Methods:Heart rate of 15 elite youth female basketball players (age 16.7 [0.5] y, height 178 [9] cm, body mass 72 [9] kg, body mass index 22.9 [2.2] kg·m−2) was monitored during 19 team (268 individual) training sessions (102 [15] min). Mixed effect models were applied to evaluate whether s-RPE values were significantly (P ≤ .05) related to Edwards’ data, total session duration, maximal intensity (session duration at 90–100% HRmax), type of training (ie, strength, conditioning, and technique), and whether differences emerged between players’ and coaches’ s-RPE values.Results:The results showed that there is a relationship between s-RPE and Edwards’ methods for the players’ RPE scores (P = .019) but not for those of the trainers. In addition, as expected, both players’ (P = .014) and coaches’ (P = .002) s-RPE scores were influenced by total session duration but not by maximal intensity and type of training. In addition, players’ and coaches’ s-RPE values differed (P < .001)—post hoc differences emerged for conditioning (P = .01) and technique (P < .001) sessions.Conclusions:Elite youth female basketball players are better able to quantify the internal training load of their sessions than their coaches, strengthening the validity of s-RPE as a tool to monitor training in team sports.
Extension as a Backbone Support Organization for Physical Activity Promotion: A Collective Impact Case Study From Rural Kentucky
Authors: McGladrey Margaret , Carman Angela , Nuetzman Christy , Peritore Nicole
Published: November 2019

Background: Rural counties in the United States face daunting structural issues that reduce their populations’ physical activity levels, including geographic isolation as well as deficits in infrastructure, public transportation, health care providers, and funding. Methods: Funding from the Centers for Disease Control and Prevention provided an opportunity to assess how Extension enhanced the collective impact of systems-level physical activity promotion programming through a multisectoral coalition in Clinton County, Kentucky. Results: The Extension-led coalition accomplished the 6 essential functions of a backbone support organization by identifying obesity as a critical local issue (function 1: providing overall strategic direction), developing a multisectoral coalition (function 2: facilitating dialog between partners), compiling data on the county’s physical activity infrastructure (function 3: managing data collection and analysis), creating communication channels (function 4: handling communication), organizing community awareness events (function 5: coordinating community outreach), and securing additional grants (function 6: mobilizing funding). The average rating of Extension’s leadership across multiple dimensions by 3 coalition members in a postproject survey was “excellent” on a 5-point Likert scale. Conclusions: Extension is well positioned through their mission, broad community engagement, data collection, needs assessment, community and academic relationships, and embeddedness in local communities to serve as the backbone support organizations for rural physical activity promotion coalitions.
TFEB drives PGC-1α expression in adipocytes to protect against diet-induced metabolic dysfunction
Authors: Evans Trent D. , Zhang Xiangyu , Jeong Se-Jin , He Anyuan , Song Eric , Bhattacharya Somashubhra , Holloway Karyn B. , Lodhi Irfan J. , Razani Babak
Published: November 2019

TFEB promotes the browning of white adipose tissue through mechanisms unrelated to autophagy.
Extension of the Notch intracellular domain ankyrin repeat stack by NRARP promotes feedback inhibition of Notch signaling
Authors: Jarrett Sanchez M. , Seegar Tom C. M. , Andrews Mark , Adelmant Guillaume , Marto Jarrod A. , Aster Jon C. , Blacklow Stephen C.
Published: November 2019

NRARP interacts directly with the Notch transcriptional activation complex to inhibit signaling.
Biochemical Activity of Vaborbactam
Authors: Tsivkovski Ruslan , Lomovskaya Olga
Published: November 2019

The most common mechanism of resistance to β-lactams antibiotics in Gram-negative bacteria is production of β-lactamase enzymes capable of cleaving the β-lactam ring. Inhibition of β-lactamase activity with small-molecule drugs is a proven strategy to restore the potency of many β-lactam antibiotics.
Diverse and Flexible Transmission of
fosA3
Associated with Heterogeneous Multidrug Resistance Regions in Salmonella enterica Serovar Typhimurium and Indiana Isolates
Authors: Fang Liang-Xing , Jiang Qi , Deng Guo-Hui , He Bing , Sun Ruan-Yang , Zhang Jin-Fei , Cen Dao-Ji , Miao Yuan-Yuan , Wang Dong , Guo Wen-Ying , Sun Jian , Liu Ya-Hong , Liao Xiao-Ping
Published: November 2019

We identified
fosA3
at a rate of 2.6% in 310
Salmonella
isolates from food animals in Guangdong province, China. The
fosA3
gene was genetically linked to diverse antibiotic resistance genes (ARGs), including
mcr-1
,
bla
CTX-M-14/55
,
oqxAB
, and
rmtB
. These gene combinations were embedded in heterogeneous
fosA3
-containing multidrug resistance regions on the transferable ST3-IncHI2 and F33:A−:B− plasmids and the chromosome.
The Future of Environmental DNA in Forensic Science
Authors: Allwood Julia S. , Fierer Noah , Dunn Robert R.
Published: November 2019

DNA sequencing technologies continue to improve, and there has been a corresponding expansion of DNA-based applications in the forensic sciences. DNA recovered from dust and environmental debris can be used to identify the organisms associated with these sample types, including bacteria, plants, fungi, and insects. Such results can then be leveraged to discern sample origin or geolocation and investigate individual identification.
Manure Application Did Not Enrich Antibiotic Resistance Genes in Root Endophytic Bacterial Microbiota of Cherry Radish Plants
Authors: Zhang Yu-Jing , Hu Hang-Wei , Chen Qing-Lin , Yan Hui , Wang Jun-Tao , Chen Deli , He Ji-Zheng
Published: November 2019

Our study provides important evidence that manure application increased the occurrence of ARGs in the rhizosphere and phyllosphere of cherry radish, compared with that in the endophytic bacterial microbiota of root, which is the edible part of cherry radish. Our findings suggest that although manure amendment is a significant route of ARGs entering agricultural soils, these manure-derived ARGs may be at low risk of migrating into the endophytes of root vegetables.
Mutations in Hypervariable Domain of Venezuelan Equine Encephalitis Virus nsP3 Protein Differentially Affect Viral Replication
Authors: Meshram Chetan D. , Phillips Aaron T. , Lukash Tetyana , Shiliaev Nikita , Frolova Elena I. , Frolov Ilya
Published: November 2019

The replication of alphaviruses is determined by specific sets of cellular proteins, which mediate the assembly of viral replication complexes. Some of these critical host factors interact with the hypervariable domain (HVD) of alphavirus nsP3. In this study, we have explored binding sites of host proteins, which are specific partners of nsP3 HVD of Venezuelan equine encephalitis virus. We also define the roles of these interactions in viral replication both
in vitro
and
in vivo
. A mechanistic understanding of the binding of CD2AP, SH3KBP1, and FXR protein family members to VEEV HVD uncovers important aspects of alphavirus evolution and determines new targets for the development of alphavirus-specific drugs and directions for viral attenuation and vaccine development.
Complete Genome Sequence of Staphylococcus arlettae Strain P2, Isolated from a Laboratory Environment
Authors: Yu Hiroki , Taniguchi Makoto , Uesaka Kazuma , Wiseschart Apirak , Pootanakit Kusol , Nishitani Yudai , Murakami Yota , Ishimori Koichiro , Miyazaki Kentaro , Kitahara Kei
Published: November 2019

Staphylococcus arlettae
is one coagulase-negative species in the bacterial genus
Staphylococcus
. Here, we describe the closed complete genome sequence of
S. arlettae
strain P2, which was obtained using a hybrid approach combining Oxford Nanopore long-read and Illumina MiSeq short-read sequencing data.
Draft Genome Sequence of the Aquatic Fungus
Margaritispora aquatica
Strain NNIBRFG339
Authors: Goh Jaeduk , Mun Hye Yeon , Park Young-Hwan , Park Sangkyu , Oh Yoosun , Chung Namil
Published: November 2019

Margaritispora aquatica
is an aquatic fungal species found in leaf litter. Here, we report the 42.5-Mb draft genome sequence of
M. aquatica
strain NNIBRFG339, which comprises 61 scaffolds and has an overall G+C content of 45.77% and an
N
50
value of 1.856 Mb.
Improved Draft Genome Sequence of
Microbacterium
sp. Strain LKL04, a Bacterial Endophyte Associated with Switchgrass Plants
Authors: Sahib Mohammad Radhi , Yang Piao , Bokros Norbert , Shapiro Nicole , Woyke Tanja , Kyrpides Nikos C. , Xia Ye , DeBolt Seth
Published: November 2019

We report here the genome assembly and analysis of
Microbacterium
strain sp. LKL04, a Gram-positive bacterial endophyte isolated from switchgrass plants (
Panicum virgatum
) grown on a reclaimed coal-mining site. The 2.9-Mbp genome of this bacterium was assembled into a single contig encoding 2,806 protein coding genes.