bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Investigation of Combustion Properties of a Gasoline Primary Reference Fuel Surrogate Blended With Butanol
Authors: Richter Sandra , Braun-Unkhoff Marina , Herzler Jürgen , Methling Torsten , Naumann Clemens , Riedel Uwe 
Published: November 2019

Abstract
Currently, many research studies are exploring opportunities for the use of novel fuels and of their blends with conventional, i.e. petroleum-based fuels. To pave the way for their acceptance and implementation in the existing energy market, a comprehensive knowledge about their combustion properties is inevitable, among others. Within this context, alcohols, with butanol in particular, are considered as attractive candidates for the needed de-fossilization of the energy sector.
In this work, we report on the oxidation of mixtures of n-heptane/i-octane (PRF90, primary reference fuel, a gasoline surrogate) and addition of n-butanol, 20% and 40%, respectively, in a combined experimental and modeling effort. The focus was set on two fundamental combustion properties: (i) Ignition delay times measured in a shock tube, at ambient and elevated pressures, for stoichiometric mixtures, and (ii) Laminar burning velocities, at ambient and elevated pressures. Moreover, two detailed chemical kinetic reaction mechanisms, with an in-house model among them, have been used for investigating and analyzing the combustion of these mixtures.
In general, the experimental data agree well with the model predictions of the in-house reaction model, for the temperatures, pressures, and fuel-air ratios studied. Room for improvements is seen for PRF90. The results achieved were also compared to those of n-butanol reported recently; the findings demonstrated clearly the effect of the n-butanol sub model on binary fuel-air mixtures consisting of PRF and n-butanol. From the present work it can be concluded that the addition of n-butanol to gasoline appears to be an attractive alternative fuel for most types of heat engines.
Effects of Velocity Ratio on Trends in Film-Cooling Adiabatic Effectiveness and Turbulence
Authors: Stratton Zachary T. , Shih Tom I.-P. 
Published: November 2019

Abstract
For film-cooling of a flat plate with cooling jets issuing from round holes, turbulent mixing has been shown to scale with the velocity ratio (VR). In this paper, large-eddy simulations (LES) were performed to investigate the effect of varying blowing ratio (BR = 0.5 – 1.3), density ratio (DR = 1.1 – 2.1), and momentum-flux ratio (MR = 0.2–0.8) on adiabatic effectiveness and turbulence, while keeping the VR fixed at 0.46 and 0.63. Simulations based on Reynolds-Averaged Navier-Stokes (RANS) equations with the realizable k-ϵ and shear-stress transport k-ω models were also performed. The LES results show that separation and spreading of the film-cooling jet increase as BR, DR, and MR increase while VR remains constant. For a given VR, the LES predicts an absolute difference between the minimum adiabatic effectiveness of the lowest and highest MRs to be 2 to 5 times greater than those predicted by RANS. This is because RANS with either model cannot respond appropriately to changes in MR. However, RANS can correctly predict that adiabatic effectiveness decreases as VR increases. The LES results show the turbulent kinetic energy and Reynolds stresses near the film-cooling hole to change considerably with MRs at a constant VR, while turbulent heat flux changes negligibly. This suggests that while improved turbulence models for heat flux can improve RANS prediction of spreading, capturing trends, however, requires improved modeling of the Reynolds stresses.
An Assessment of the Implicit Non-Iterative PISO Solution Procedure for the Prediction of Combustor Performance
Authors: Karalus Megan , Krishnamoorthy Niveditha , Reynolds Bob , Mallouppas George 
Published: November 2019

Abstract
Large Eddy Simulation (LES) of gas turbine combustors has gained traction as a key tool in the design process. Accurate prediction of the multiphysics of reacting flows — evaporating fuel spray, turbulent mixing, turbulent chemistry interaction, radiation, and conjugate heat transfer to name a few — is key to the accurate prediction of combustor performance. The overall solution time for a standard LES simulation on an industrial system can be burdensome because of the small time and length scales required to capture the aforementioned multiphysics to an acceptable level. Any performance improvements are therefore welcomed. In this paper, we compare the implicit non-iterative PISO solution procedure with the implicit iterative SIMPLE method for the Large Eddy Simulation of a Honeywell combustor using the commercial software, Simcenter STAR-CCM+ v13.04. Time averaged simulation results are validated against rig data. Results show that the PISO solution method provides results which are similar to those found using the SIMPLE method, and accurate when compared to rig data, but at up to a 3.4X speed-up for this liquid fueled gas turbine combustor.
Flow Induced Dynamics of Plate Seals
Authors: Trivedi Deepak , Kerr Bernardo 
Published: November 2019

Abstract
Plate seals can provide low leakage at rotor-stator interfaces with large pressure drops in turbomachinery within a limited axial span. When designed with a self-correcting hydrostatic feedback mechanism, non-contact operation could be achieved even in the presence of large rotor transients. Flow induced dynamical instability is one of the key design challenges in plate seals for rotor-stator sealing in turbomachinery. The instabilities are caused by potentially multiple flow induced vibration mechanisms operating during different flow regimes. This paper investigates mechanisms of vortex induced flutter in compliant plate seals, which happens when the vortex shedding frequency of the plates comes close to one of the natural frequencies of vibration of the structure. An experimental methodology based on optical flow analysis of high speed videography is proposed to characterize vibrations of the ensemble of plates (“leafpack”.) Experiments show that the compliant plates vibrate in the flow field with amplitude dependent on the pressure drop. Additionally, the vibrations of individual plates are highly coupled to each other, leading to phase-locking or phase-drifting depending on boundary conditions. The leafpack has a characteristic frequency and exhibits traveling wave phenomena under certain conditions of pressurization. Using experimental insights, plate seals are modeled as a ring of a large (∼103) number of locally coupled oscillators, with nonlinear stiffness arising from hydrostatic forces. A two-way coupling exists between the structural and fluid wake dynamics. Using center manifold reduction, the coupled fourth order dynamics of the system is reduced to second order and transform the equations into the normal form for investigating the possibility of mitigating flow induced vibrations through the phenomenon of amplitude death. Conditions under which successful induction of amplitude death could eliminate plate vibration in the mode under consideration is discussed.
Development of Production Eddy Current Inspection Process for Additively Manufactured Industrial Gas Turbine Engine Components
Authors: Kemerling Brandon , Ryan Daniel 
Published: November 2019

Abstract
While metal additive manufacturing (AM) promises substantial efficiency gains to the gas turbine manufacturing sector, uncertainty about the quality of parts produced via AM has been a significant hindrance to widespread implementation. Although high fidelity inspection techniques involving computed tomography (CT) and destructive testing have been effective for low volume development activities, new quality assurance solutions are needed that enable rapid, low-cost inspection of serial production AM components. Solar Turbines Incorporated is actively engaged in the development of inspection processes for high production volume AM part acceptance capability of combustion and turbine hot section components. Eddy current inspection (ECI) was identified as a potential non-destructive evaluation (NDE) solution. Based on the principles of electromagnetism, ECI has been successful on conventional materials for surface and near-surface crack detection. However, limited industry data is available regarding the effectiveness of ECI on AM material. The nature of AM-induced discontinuities, specifically for metal laser powder bed fusion (L-PBF) processing, demands high measurement resolution to detect fine features such as bulk porosity, lack of fusion and interlayer discontinuities. Development activities were thus executed to determine the suitability of ECI for detection of AM discontinuities. NDE training sets were printed with intentional variations in key L-PBF processing parameters to simulate the conditions which produce relevant AM material discontinuities. The training sets were then evaluated with a custom ECI system to determine the inspection capability and sensitivity. Inspections were conducted as a function of multiple input frequencies to determine the optimal tradeoff between measurement resolution and depth of penetration. Additional characterization of the training sets was conducted via metallographic analysis to establish correlations between the ECI results and AM material quality. An optimized multi-frequency inspection setting was identified to provide suitable measurement resolution for near surface AM material inspection. Correlations developed between ECI scan data and materials characterization results have enabled the ability to rapidly discriminate between varying discontinuity levels in AM components. Based on these efforts, ECI is considered a suitable inspection technique for materials produced via the L-PBF AM process.
Supercritical CO2 Tests for Hydrostatic Film Stiffness in Film-Riding Seals
Authors: Trivedi Deepak , Bidkar Rahul A. , Wolfe Christopher E. , Mortzheim Jason 
Published: November 2019

Abstract
Fluid film stiffness is a key design parameter for film-riding seals — a large positive film stiffness ensures stable seal operation with the seal faithfully tracking the rotor in the presence of varying inertial and friction loads. A hydrostatic supercritical CO2 (sCO2) film-riding seal relies on feed ports pressurized with sCO2 to generate film stiffness needed for reliable seal operation. The high-pressure supercritical CO2 expands to lower pressures through the seal bearing face, and during this expansion, undergoes large temperature changes along with a phase change to gaseous state and possibly liquid state. These large temperature changes and phase changes are important design considerations specific to sCO2 as the working fluid. From this perspective, film-stiffness test data with sCO2 as the working fluid is valuable for both understanding the physics as well as for validating the predictions of computational fluid dynamics (CFD) models of sCO2 expansion across a seal bearing face. In prior work, we described a non-rotating stiffness test rig for characterizing fluid film stiffness and presented air-based test data with the rig. In this paper, we present sCO2-based data obtained by connecting this previously described stiffness rig to a newly commissioned sCO2 flow loop (flow rate about 0.1 kg/s, pressures up to 16.5 MPa, temperatures up to 464 K). The test data presented in this paper include seal bearing pressures and fluid/metal temperatures for varying film thickness, seal bearing face tilt and inlet/supply pressures. The test data show significant temperature reduction as the supercritical flow expands across the seal bearing face. The measured bearing pressure was compared with the predictions of a 3D CFD model with real gas CO2 properties, with about 4% error between the measurements and the predictions. The sCO2-based test data in this work and the air-based test data from prior work are used to calculate fluid film stiffness over a range of film thicknesses. It is seen that the sCO2-based data and air-based data tend to collapse on a normalized stiffness curve, which is characteristic of the bearing geometry. Moreover, it is seen that the hydrostatic seal film stiffness generally scales with the supply pressure and can be adjusted to high stiffness values typically expected in hydrodynamic film-riding seals.
Investigation of Mixed Micro-Compressor Casing Treatment Using Non-Matching Mesh Interface
Authors: Patel Purvic , Zha Gecheng 
Published: November 2019

Abstract
In this paper, a non conservative interpolation boundary condition, for the non-matching mesh blocks, was developed and validated for the micro compressor casing treatment. The conservative variables were interpolated in the halo layers of non-matching mesh interface using Finite Element Method (FEM) type linear interpolation shape functions, instead of using overset grids. Using this new boundary condition, the effect of casing treatment on stall margin and compressor performance is investigated for a mixed flow type micro-compressor. The computed compressor performance map for the casing treatment case is compared with the experimental results and shows good agreement except in the region close to stall. With the application of the casing treatment, improvement in the stall margin is observed without the loss of efficiency over the operating range.
An Instrumented High-Speed Rotor With Embedded Telemetry for the Continuous Spatial Pressure Profile Measurement in Gas Lubricated Bearings: A Proof of Concept
Authors: Shalash K. , Schiffmann J. 
Published: November 2019

Abstract
Gas lubricated bearings are capable of supporting high speed rotors with satisfactory load capacities. Pressure is one of the constitutional quantities governing the flow field in gas lubricated bearings. Knowledge of the pressure is of principal importance in the fundamental understanding of such bearings and for the calibration of reduced order models. These measurements can be done from the bearing side using pressure taps in the bushings, however, the measurement points will yield a spatially sampled profile consisting of discrete points relative to the bearing bushing. This measurement technique is simple, yet, several details cannot be captured. In order to acquire a continuous scan of the pressure field inside the bearing, it is necessary to measure from the rotor side. Such onboard measurement technique is challenging due to constraints in volume, G-force, and data and power transmission through the rotor. This paper presents an instrumented measurement rotor with embedded pressure probes and a wireless telemetry, which is capable of the continuous pressure field measurement inside a high-speed externally pressurized gas journal bearing. The bearing under investigation has a diameter of 40mm, L/D = 1, and was tested up to 37.5 krpm. The bearing is of the annular type, with 2×18 Ø0.1mm restrictor orifices. Measurements at discrete points using pressure taps inside the test bearing were also performed for the sake of comparison. The measurements from both sides (bushing and rotor) were in good agreement at quasi-static conditions. At higher operational speeds, it was necessary to perform an in-situ system identification and calibration for the embedded pressure probes using the bearing side measurements as a reference. The in-situ system identification technique was successful to reconstruct the attenuated pressure signals for a wide range of supply pressures and rotor speeds. The instrumented rotor was proven qualified to perform time-resolved pressure measurements within the gas film of journal bearings up to 37.5 krpm.
The Effect of Vanes and Blades on Ingress in Gas Turbines
Authors: Hualca Fabian P. T. , Horwood Josh T. M. , Sangan Carl M. , Lock Gary D. , Scobie James A. 
Published: November 2019

Abstract
This paper presents experimental and computational results using a 1.5-stage test rig designed to investigate the effects of ingress through a double radial overlap rim-seal. The effect of the vanes and blades on ingress was investigated by a series of carefully-controlled experiments: firstly, the position of the vane relative to the rim seal was varied; secondly, the effect of the rotor blades was isolated using a disc with and without blades.
Measurements of steady pressure in the annulus show a strong influence of the vane position. The relationship between sealing effectiveness and purge flow-rate exhibited a pronounced inflexion for intermediate levels of purge; the inflexion did not occur for experiments with a bladeless rotor. Shifting the vane closer to the rim-seal, and therefore the blade, caused a local increase in ingress in the inflexion region; again this effect was not observed for the bladeless experiments.
Unsteady pressure measurements at the periphery of the wheel-space revealed the existence of large-scale pressure structures (or instabilities) which depended weakly on the vane position and sealing flow rate. These were measured with and without the blades on the rotor disc. In all cases these structures rotated close to the disc speed.
On the Development of a Pressure Actuated Leaf Seal for Turbomachinery Applications
Authors: Pedraza-Valle Ernesto , Papageorgiou Georgios , Bowsher Aaron , Crudgington Peter F. , Sangan Carl M. , Keogh Patrick S. , Scobie James A. 
Published: November 2019

Abstract
In gas turbines, seals that reduce the leakage between high and low pressure regions are critical for improved performance. Damaging rubs between the rotating and non-rotating parts of turbomachinery shaft seals occur due to thermal and assembly misalignments, and rotordynamic vibration during engine start-up and shut-down transients. These rubs lead to increased seal leakage and hence to reduced overall turbine efficiency and life span. The Film Riding Pressure Actuated Leaf Seal (FRPALS) is a non-contacting compliant seal under development to adapt to varying clearances without rubbing, while maintaining low leakage.
This paper presents the measurements of the FRPALS in a test rig specifically designed to test novel shaft seals for turbomachinery. The rig features a 254 mm diameter rotor with a maximum surface speed of 200 m/s. Pressure drops of up to 3.5 bar can be achieved. The results of initial testing at zero rotational speed are presented for the FRPALS in a reverse orientation. The opening and closing translations of the leaves have been measured using eddy current displacement probes targeting the movable parts of the seal. The seal clearance has been shown to remain constant for a range of applied pressure drops, which indicates the stable operation of the seal, though resulting in contact with the rotor at 1.5 bar. Mass flow leakage measurements have also demonstrated the sealing performance of the FRPALS. They show the potential of the seal to film ride subject to design modifications to maintain a more uniform film thickness. The steady-state Reynolds equation for lubrication has been used to predict the pressure along the seal clearance. The predictions have been compared with pressure measurements from a transducer located in the clearance fluid thin film.
Shielded Swirl Versus Piccolo Tube Inlet Thermal Anti-Icing System
Authors: Anderson Morris 
Published: November 2019

Abstract
This study presents a CFD comparison of a piccolo tube inlet anti-icing system with benchmark flight test data and a shielded swirl design.
Aircraft engine inlets must prevent ice accretion that could cause damage or inhibit safe operation. A common way to meet this requirement is to heat the inlet with hot air distributed with a piccolo tube or a swirl anti-icing system. Piccolo tube systems generally use less engine bleed air but are more complex and heavier than swirl systems.
The CFD model for this study includes all the inlet key characteristics such as piccolo tube holes, material properties, and thickness. The model is evaluated in a two-step process. Water collection rates for flight in icing conditions are calculated. These results are then mapped onto a conjugate heat transfer film runback model. The CFD results include surface temperatures and the amount of liquid film runback that flows off the heated surface.
Benchmark test data is presented illustrating good inlet surface temperature agreement with the piccolo tube CFD model for flight in both dry air and icing conditions.
This CFD modeling approach is also applied to a unique shielded swirl anti-icing system. The results of this study confirm that a shielded swirl anti-icing system can be designed to provide the same level of anti-icing protection that is achieved with a piccolo tube configuration without overheating the inlet or requiring more engine bleed flow.
Effects of Dust Composition on Particle Deposition in an Effusion Cooling Geometry
Authors: Crowe Evan D. , Bons Jeffrey P. 
Published: November 2019

Abstract
In this study the effects of dust composition on particle deposition in an effusion cooling geometry were investigated through a series of experiments. Single mineral dusts made from five different minerals, Quartz, Dolomite, Albite, Salt, and Gypsum, were milled to similar size distributions (approx. 0–10μm diameter). These dusts were then used in particle deposition tests on a flat plate effusion hole test article which was heated in a kiln to 1116K and supplied with coolant flow heated to 950K. Percent mass flow reduction per gram and deposit morphology were recorded for each test. Results for the different minerals varied greatly ranging from 7.8% to 160% reduction in mass flow per gram injected, with the albite dust producing the greatest blockage. The different dusts also produced varying shapes of deposits. These five dusts were then combined to form a dust blend with the same mass fractions found in AFRL02, a commercially available test dust, and additional tests were conducted using this dust. Results from the tests using the OSU mixed AFRL02 were compared with an estimated blockage per gram found by taking a weighted average of the blockage per gram for each single mineral dust on a percent volume basis. When tested, the mixed AFRL02 produced a lower blockage per gram than the estimate, indicating that an estimate based on volume fraction alone is not sufficient to predict the deposition of dusts composed of a mixture of minerals.