bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Numerical Thermohydrodynamic Study of Fixed Pad Oil Lubricated Thrust Bearings
Authors: Dousti Saeid , Allaire Paul , Cao Jianming , Nichols Bradley , Dimond Timothy 
Published: November 2019

Abstract
Hydrodynamic thrust bearings are vital components of rotating machinery and often undergo high axial loads and temperatures. High loads and the consequent shear heating result in high temperature development and viscosity drop of the lubricant. This phenomenon is captured in the solution of a three dimensional energy equation problem. The inlet flow temperature via a groove mixing model and its interaction with outflow from the previous pad is also included in the analysis. Traditionally, capturing the heat conduction at the lubricant solid interfaces in the energy solution for the fixed pad, lubricant, and rotating disk (runner) have faced significant convergence problems. In this study, an integrated method is proposed to remedy this issue. The effects of various model features on the computed results are investigated.
Numerical Simulation of Surge in a Centrifugal Compressor With Different Operating Condition Using the Plenum Model
Authors: Jia Cheng , Qin Guoliang , Chen Xuefei , Wang Yi 
Published: November 2019

Abstract
Surge happens when the mass flow rate reduces to a certain value in the centrifugal compressor and pipe network system. Surge will cause fatal damage to the centrifugal compressor. So researchers need to capture the surge fluctuation in the compressor and pipe system by methods. These works can research more details of surge. This study takes an attempt to use the CFD method with a plenum model to investigate the surge fluctuation in a centrifugal compressor and pipe system. Using the three dimensional transient numerical simulation, authors obtain the low frequency fluctuation of the mass flow rate and the total pressure at the diffuser outlet over simulation time. The flow field in the impeller and the diffuser passage are also obtained in the simulation. Authors take more detail researches on the surge fluctuation by the flow field result. By changing the plenum volume and the compressor operating point, authors compare and analyze the surge fluctuation under different operating conditions. The changing plenum volume has great influence on the mass flowrate fluctuation and the total pressure fluctuation. Only rotating stall will occur when connecting a smaller capacity pipe network. But the rotating stall will lead to the surge of the system when connecting a larger capacity pipe network. The decreasing mass flow rate has little influence on the fluctuation frequency but the fluctuation amplitude increases. It is verified that the surge in the compressor system is much more serious when connecting a larger capacity pipe system or decreasing the centrifugal compressor operating mass flowrate.
Porosity Driven Approaches to Model Fouling Effects on Flow Field
Authors: Casari Nicola , Suman Alessio , Pinelli Michele 
Published: November 2019

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.