bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Grid Resolution on Predicted Spray Variability Using Multiple Large-Eddy Spray Simulations
Authors: Van Dam Noah , Som Sibendu , Swantek Andrew B. , Powell Christopher F. 
Published: December 2016

Shot-to-shot spray variability is recognized as an important contributor to cycle-to-cycle variations in direct-injection engines. Large-eddy Simulations (LES) have been used to resolve more of the gas-phase turbulent fluctuations in Computational Fluid Dynamics (CFD) simulations, but the sources of shot-to-shot spray variability are not directly modeled in the Lagrangian parcel approach used most often for engine fuel spray simulations. Instead, the variability comes from variations in the spray boundary conditions. Currently, the most common way to introduce shot-to-shot variability in Lagrangian spray simulations is to vary the random seed used in the spray models for each spray realization. This approach was used to compare against recent near-nozzle (up to ≈9 mm downstream) projected mass density (PMD) measurements of a single-hole diesel injector. The injector has a nominal nozzle diameter of 110 μm, though analysis of experimental data indicates the actual diameter is approximately 118 μm. The measurements were acquired under non-vaporizing conditions using fast radiography with high-intensity X-rays available at the Advanced Photon Source at Argonne National Laboratory.
Spray simulations used the Dynamic Structure LES turbulence model along with a Lagrangian parcel approach with the blob injection model and modified KH-RT break-up model. 10 spray realizations were simulated each at three different minimum cell sizes, 62.5 μm, 93.75 μm and 125 μm. This is much finer mesh resolution than is typically performed for Lagrangian spray calculations and allows the simulations to capture more of the gas-phase turbulent fluctuations that develop from the different random seeds. The effect of the grid resolution on the predicted shot-to-shot variability was investigated. Larger minimum cell sizes increased the predicted variability in projected mass density slightly. This difference in predicted variability was less apparent in global spray quantities such as penetration length.
Initial turbulence kinetic energy (TKE) variations have also been proposed as a method to introduce shot-to-shot variations in spray simulations. 10 further simulations were run where the initial turbulence intensity was varied randomly between 0.1 and 1 m2/s2. The resulting spray variability was similar, but slightly lower than that introduced by varying the random seed.
Numerical Investigation of Two-Stage Turbocharging Systems Performance
Authors: Avola Calogero , Copeland Colin , Burke Richard , Brace Chris 
Published: December 2016

In regulated two-stage sequential turbocharging systems, a smaller, high pressure (HP), and a larger, low pressure (LP), turbocharger are sequentially positioned to recover the energy available in the exhaust gases and deliver acceptable level of boost to the intake of an internal combustion engine. Due to the different sizes of the turbochargers, by-pass valves are placed in the system to control operations.
Due to the turbocharging system layout, it is clear that the air pressurized by the LP compressor enters non-uniformly the HP compressor. This is caused by the rotating radial compressor and the interconnecting bends which cause swirl and velocity to scatter, respectively. Furthermore, the heat transfer in the two turbochargers may have an effect on the apparent efficiencies. For these reasons, the standard mapping approach for turbochargers is not able to take into account the effect of non-uniform flow and heat transfer.
In this paper, a novel approach for mapping the two-stage turbocharging system is proposed and performed into a mono-dimensional simulation code. Although, flow non-uniformity and turbochargers heat transfer effects on the performance of the turbocharging system are not considered, at this present time, the study centralizes on the investigation and the validation of the mapping approach. In fact, a two-stage sequential turbocharging system has been considered for the study and a simulation code to investigate the mapping technique has been implemented.
Tailoring Charge Reactivity Using In-Cylinder Generated Reformate for Gasoline Compression Ignition Strategies
Authors: Ekoto Isaac W. , Wolk Benjamin M. , Northrop William F. , Hansen Nils , Moshammer Kai 
Published: December 2016

In-cylinder reforming of injected fuel during an auxiliary negative valve overlap (NVO) period can be used to optimize main-cycle combustion phasing for low-load Low-Temperature Gasoline Combustion, where highly dilute mixtures can lead to poor combustion stability. The objective of this work is to examine the effects of reformate composition on main-cycle engine performance for a research gasoline. A custom alternate-fire sequence with nine pre-conditioning cycles was used to generate a common exhaust temperature and composition boundary condition for a cycle-of-interest. Performance metrics such as main-period combustion stability and total cycle efficiency were collected for these custom cycles. The NVO-produced reformate stream was also separately collected using a dump valve apparatus and characterized in detail using both gas chromatography and photoionization mass spectroscopy. To facilitate gas sample analysis, sampling experiments were conducted using a five-component gasoline surrogate (iso-octane, n-heptane, ethanol, 1-hexene, and toluene) that matched the molecular composition, 50% boiling point, and ignition characteristics of the research gasoline.
For the gasoline, it was found that the most advanced NVO start-of-injection (SOI) led to the most advanced main-cycle 10% burn angle. The effect was more pronounced as the fraction of total fuel injected in the NVO period increased. With the most retarded NVO SOI, shorter residence times and piston spray impingement limited the opportunity for injected fuel decomposition. For the gasoline surrogate, the most advanced NVO SOI had reduced reactivity relative to more intermediate NVO SOI, which was attributed to rapid in-cylinder mixing that led to a large amount of fuel quench in the piston crevice. For all NVO periods, combustion phasing advanced as the main-period fueling decreased. Slower kinetics for leaner mixtures were offset by a combination of increased bulk-gas temperature from higher charge specific heat ratios and increased fuel reactivity due to higher charge reformate fractions.
Insulated Catalyst With Heat Storage for Real World Vehicle Emissions Reduction
Authors: Daya Rohil , Singh Maneet Raj , Hoard John , Chanda Sreedhar 
Published: December 2016

In previous publications, the model development and simulation of a vacuum-insulated catalytic converter was presented. GT-Suite model simulations demonstrated the heat retention capacity of the converter, and corresponding emissions reductions. This paper provides an update of the converter model development and analysis of real-world benefits of the converter.
The vehicle-aftertreatment model of the vacuum-insulated converter (VICC) was improved significantly, and detailed explanations of all theoretical modeling considerations are presented. In absence of experimental data, a flow-test experiment was conducted to measure the flow rate in exhaust tailpipe during vehicle soak due to thermosiphon. These results were used as inputs in the GT-Suite model simulations of conventional and hybrid electric vehicles (HEVs). New model simulations demonstrated the ability of the VICC to achieve significant emissions reductions following vehicle soaks of up to 18 hours.
To examine the real-world benefits of the converter, driving data was obtained from the National Renewable Energy Laboratory (NREL), and a MATLAB code was developed to statistically analyze 23,156 drive cycles. The VICC was simulated on standard drive cycles to develop a correlation between melt time of the phase-change material (PCM) and average drive cycle speed and acceleration. This correlation was used to predict the probability that the PCM will melt in a given real-world driving cycle. The MATLAB code was also used to calculate soak time and re-solidification time probability. Finally, FTP emission results were weighted with the soak time probabilities. This analysis showed that in real-world driving conditions, the VICC is expected reduce cold-start CO and HC emissions by 26% and 48% respectively.
Determination of Service Life for Undamaged and Damaged Delayed Coker Drums
Authors: Aumuller John J. , Carucci Vincent A. 
Published: December 2016

A stated goal of governments in addressing climate warming and to transition to a low carbon future by the end of this century is to increase the proportion of energy supplied by alternative sources. For the hydrocarbon processing industry, the question of stranded assets will become significant as these alternative energy sources become more prevalent. Existing equipment will need to operate to the end of its useful life and new equipment may need to be avoided. In particular, coker drums are very expensive investments due to their size, materials and number required in the delayed coker unit of a processing facility. Because of the severe service environment in which coke drums operate, the service life of a drum is not well established.
Long term reliability of coker drums is impacted by thermo-mechanical damage mechanisms associated with self constraint of the drum shell and skirt during the formation of hot and cold temperature spots and patches. By assessing the imposed thermomechanical strains, a more precise determination of drum fatigue may be made, allowing better estimation of service life. This service life may be estimated for newly fabricated drums and those drums with shell damage, such as bulging.
Service life determination is of practical importance for operators since it provides a more realistic estimate of operational life as compared to the normally referenced Code design life. An accurate estimation of drum service life has not been available in the industry to date due to a number of deficiencies and conservatisms in the current calculation practices. Insight into the causal damage mechanism provides opportunities in identifying alternatives in design, material selection, fabrication, inspection, and maintenance for operating this equipment to a practical and optimal target service life.
Thermal Gradient Within DOE 3013 Containers During Storage
Authors: Hensel Steve J. , Lee Si 
Published: December 2016

The Department of Energy (DOE) Model 9975 Package is used to store plutonium bearing materials at the Savannah River Site (SRS). The plutonium is packaged in a 3013 container which consists of a convenience container, an inner welded container, and an outer welded container [1]. All containers are made of stainless steel. A portion of the population of 3013 containers have plutonium oxide with alkaline earth chloride salts. Temperatures and temperature gradients within the 3013 container are useful to evaluate the transport of water vapor and potential corrosion in the inner container, particularly near the weld region. Thermal analyses of plutonium oxide packaged in 3013 containers which are stored in 9975 shipping packages were performed with emphasis on the temperatures and temperature gradients between the plutonium oxide and the inner container weld region. Thermal analyses investigated various plutonium oxide fill levels, heat generation, plutonium oxide thermal conductivity and 9975 package boundary conditions.
Not surprisingly, the results suggest the source heat is mostly dissipated radially outward as opposed to the vertical direction, and the 9975 package is insensitive to an adiabatic top and bottom surface boundary condition versus an adiabatic bottom surface assumption. The temperatures at locations of interest, such as the inner container weld region and the plutonium oxide centerline temperature may be correlated as a linear function of thermal loading and ambient temperature.
Dissimilar Metal Welds: Impact of the Residual Stresses on the Risk of Failure
Authors: Blouin A. , Chapuliot S. , Marie S. 
Published: December 2016

One important part of the integrity demonstration of large ferritic components is based on the demonstration that they could never undergo brittle fracture. Connections between a ferritic component and an austenitic piping (Dissimilar Metal Weld - DMW) have to respect these rules, in particular the Heat Affected Zone (HAZ) created by the welding process and which encounters a brittle-to-ductile transition.
Within that frame, the case considered in this article is a Ni base alloy narrow gap weld joint between a ferritic pipe (A533 steel) and an austenitic pipe (316L stainless steel). The aim of the present study is to show that in the same loading conditions, the weld joint is less sensitive to the brittle fracture than the surrounding ferritic part of the component. That is to say that the demonstration should be focused on the ferritic base metal which is the weakest material. In addition, residual stresses are also considered and their impact on the fracture resistance is evaluated.
The bases of this study rely on a stress-based criterion developed by Chapuliot et al, using a threshold stress (σth) below which the cleavage cannot occur. This threshold stress can be used to define the brittle crack occurrence probability, which means it is possible to determine the highest loading conditions without any brittle fracture risk.
Experimental and Numerical Analysis of Structures With Bolted Joints Subjected to High Impact Load: Part 2
Authors: Karpanan Kumarswamy , O’Toole Brendan 
Published: December 2016

Military vehicles sustain damaging high impacts and shock loadings due to mine blasts, projectile impacts, and frontal or rear crashes. In all these cases, the vehicle structure and the bolts used in the structure may experience high impact loads. These loads may yield or damage the structure and the bolts. Only a limited amount of published literature describes the proper method for measuring and analyzing transient shock propagation across bolted connections for high-impact loading. Understanding, modeling, and simulating the vehicle response to these impact loadings is critical to designing better vehicle components. This will also help isolate critical components such as electronics and personnel from the shock.
This paper provides a detailed experimental setup and procedure for analyzing high-impact loading on structures with bolted joint connections. An air gun was used to fire an aluminum slug at high velocities on to a bolted structure to induce medium- and high-impact loading. Two structural configurations were evaluated: a hat section bolted to a flat plate, and two hat sections bolted together. Finite element models were created to simulate the damage and shock propagation phenomena during impact. Simulation predictions from detailed 3D solid element models and 2D shell element models were compared to experimental results, including shape deformation and accelerometer data at specific locations. A load cell recording impact force was also used for validation of the simulation. The simplified FE model developed for the bolted joint structure in this report reduced the computational time by one order and can be practically implemented in the full vehicle FE model for crash or blast analysis.
The Case for MACA: The Optimization of Corrosion Allowance
Authors: Taagepera Jaan 
Published: December 2016

Engineers are taught to optimize. In the case of pressure vessel design, one means of optimizing the steel which is used is to increase the rated pressure capacity of the vessel beyond the design needs. This optimized pressure is formally known by the term MAWP or Maximum Allowable Working Pressure. Of historical interest, this concept has existed for over 100 years, with the MAWP formula for cylindrical shells being tracable back to the original edition of the Boiler Code.
However, other variables in vessel design can also be optimized. In addition to pressure, consideration can be given to temperature or corrosion allowance. Increasing the temperature has the effect of reducing the basic allowable tensile stress as well as the allowable compressive stress and flange ratings. In the case of some specialty vessels such as reactors with exothermic reactions adding a few degrees to the design temperature may be very beneficial.
But virtually all vessels degrade in some manner, most often corrosion but sometimes via erosion or other degradation mechanisms. Significant amounts of time and effort are spent with unnecessary shutdowns, repairs, and / or fitness for service (FFS) evaluations all of which might have been avoided or deferred for years had the vessel originally been optimized for corrosion allowance. The term Maximum Allowable Corrosion Allowance or MACA is used to describe this approach.
This paper presents some arguments in favor of optimizing the corrosion allowance of pressure vessels, using a MACA based optimization for the design of new vessels rather than a pressure optimization or MAWP philosophy.
Developments in Structural Integrity Safety Cases for Highest Reliability Components in the UK
Authors: Jelfs T. , Hayashi M. , Toft A. 
Published: December 2016

Gross failure of certain components in nuclear power plant has the potential to lead to intolerable radiological consequences. For these components, UK regulatory expectations require that the probability of gross failure must be shown to be so low that it can be discounted, i.e. that it is incredible. For prospective vendors of nuclear power plant in the UK, with established designs, the demonstration of “incredibility of failure” can be an onerous requirement carrying a high burden of proof. Requesting parties may need to commit to supplementary manufacturing inspection, augmented material testing requirements, enhanced defect tolerance assessment, enhanced material specifications or even changes to design and manufacturing processes.
A key part of this demonstration is the presentation of the structural integrity safety case argument. UK practice is to develop a safety case that incorporates the notion of ‘conceptual defence-in-depth’ to demonstrate the highest structural reliability. In support of recent Generic Design Assessment (GDA) submissions, significant experience has been gained in the development of so called “incredibility of failure” arguments. This paper presents an overview of some of the lessons learned relating to the identification of the highest reliability components, the development of the structural integrity safety arguments in the context of current GDA projects, and considers how the UK Technical Advisory Group on Structural Integrity (TAGSI) recommendations continue to be applied almost 15 years after their work was first published. The paper also reports the approach adopted by Horizon Nuclear Power and their partners to develop the structural integrity safety case in support of the GDA process to build the UK’s first commercial Boiling Water Reactor design.
Comparison Between Different Calculation Methods for Determining Bolting Up Moments
Authors: Mutz Alexander , Schaaf Manfred 
Published: December 2016

There are several different standards for flange calculation used in the European and so in the Suisse context. The European Standard EN 1591-1 that is used for the calculation of bolted flanged joints and EN 13555 in which the determination of the required gasket characteristics are defined were reissued in 2013 and in 2014, respectively.
The ASME BPVC, Section III, Appendix 11 regulates the flange calculation for class 2 and 3 components in Suisse nuclear power plants it is also used for class 1 flange connections. A standard for the determination of the required gasket characteristics is not well established which leads to a lack of clarity. As a hint, different m and y values for different kind of gaskets are invented in ASME BPVC Section III. As cited in the Note of table XI-3221.1-1 the values m and y are not mandatory. In Switzerland, mainly the ASME BPVC should be used for the calculation of flange connections. The aim of the ASME Code is more or less not the tightness of the flanges but the integrity. Therefore, stresses are derived for dimensioning the flanges. Following loads are not considered neither for calculation of stresses nor for calculation of tightness. Considering the experience with flanges in general it could be asked, if it is more useful to look at the tightness than at the stresses.
The codes KTA 3201.2 and KTA 3211.2 regulate the calculation of flange connections in German nuclear power plants. Stresses in floating type and in metal-to-metal contact type of flange connections and the tightness are calculated for the different load cases.
In this paper, the differences in the calculations are shown between KTA 3211.2, ASME BPVC, Section III, Appendix 11, EN 1591-1 and Finite element calculations. In all load cases leakage shouldn’t occur. Therefore, internal pressure and temperature in test and operational conditions after bolting-up are also considered for the stress calculation if it is possible in the calculation algorithm.
Overview of EAF Screening Results on the 900 MWe NPP French Fleet
Authors: Métais Thomas , Robert Nicolas , Genette Pierre , Etchegaray Nicolas 
Published: December 2016

In the wake of numerous experimental tests carried out in air and also in a PWR environment, both abroad and in France, an update of the current thermal fatigue codification is underway in France. Proposals are currently being integrated in the RCC-M code [1].
In parallel, it is necessary to evaluate the impact of codification evolution on the RCS components. In the USA, such evaluations have already been implemented for license renewal to operate power plants beyond their initial 40 years of operation. In order to reduce the scope of the calculations to perform, a preliminary screening was carried out on the various areas of the primary system components: this screening is detailed in an EPRI report [2]. The output of this screening process is a list of locations that are most prone to EAF degradation process and it is on these zones only that detailed EAF calculations are carried out.
In France, a similar approach was defined in the perspective of the fourth ten-year visit of the 900 MWe plants (VD4 900 MWe) so as to map out all the locations that are most impacted by EAF and hence concentrate the calculation effort on these specific areas for the VD4 900 MWe.
In that respect, a specific methodology to evaluate the factor to account for environmental effects or Fen [3] based on correlations [4] for hot and cold shocks was established. These correlations use data that is readily accessible in transient description documents and stress reports such as temperature change, heat transfer coefficients, ramp duration and geometry. The need for these correlations is specific to the French context due to a need for a preliminary and yet precise idea of the overall impact of the modifications brought to the RCC-M code in fatigue before the VD4 900 MWe.
This paper presents the results of the screening method that was applied to the whole RCS of the 900 MWe NPP fleet.