Academic literature on the topic 'Alfven numbers low stratification'
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Journal articles on the topic "Alfven numbers low stratification"
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Kimura, Y., and J. R. Herring. "Diffusion in stably stratified turbulence." Journal of Fluid Mechanics 328 (December 10, 1996): 253–69. http://dx.doi.org/10.1017/s0022112096008713.
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We examine results of direct numerical simulations (DNS) of homogeneous turbulence in the presence of stable stratification. We focus on the effects of stratification on eddy diffusion, and the distribution of pairs of particles released in the flow. DNS results are presented over a range of stratification, and at Reynolds numbers compatible with aliased free spectral results for a resolution of 128 mesh points. We compare results for particle dispersion to simple analytic theories such as that proposed by Csanady (1964) and Pearson et al. (1983) by adapting the basic Langevin model to decaying turbulence at low Reynolds numbers. Stable stratification is found to arrest both single particle displacements and pair separation in the direction of stratification, but it leaves these quantities nearly unaltered in the transverse direction. With respect to the dynamics of stratified flows, we find that regions of strong viscous dissipation are intermittently spaced, and are associated with large horizontal vorticity, consistent with recent experimental results by Fincham et al. (1994).
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Castell, A., M. Medrano, C. Solé, and L. F. Cabeza. "Dimensionless numbers used to characterize stratification in water tanks for discharging at low flow rates." Renewable Energy 35, no. 10 (October 2010): 2192–99. http://dx.doi.org/10.1016/j.renene.2010.03.020.
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BALMFORTH, NEIL J., and YUAN-NAN YOUNG. "Stratified Kolmogorov flow." Journal of Fluid Mechanics 450 (January 9, 2002): 131–67. http://dx.doi.org/10.1017/s0022111002006371.
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In this study we investigate the Kolmogorov flow (a shear flow with a sinusoidal velocity profile) in a weakly stratified, two-dimensional fluid. We derive amplitude equations for this system in the neighbourhood of the initial bifurcation to instability for both low and high Péclet numbers (strong and weak thermal diffusion, respectively). We solve amplitude equations numerically and find that, for low Péclet number, the stratification halts the cascade of energy from small to large scales at an intermediate wavenumber. For high Péclet number, we discover diffusively spreading, thermal boundary layers in which the stratification temporarily impedes, but does not saturate, the growth of the instability; the instability eventually mixes the temperature inside the boundary layers, so releasing itself from the stabilizing stratification there, and thereby grows more quickly. We solve the governing fluid equations numerically to compare with the asymptotic results, and to extend the exploration well beyond onset. We find that the arrest of the inverse cascade by stratification is a robust feature of the system, occurring at higher Reynolds, Richards and Péclet numbers – the flow patterns are invariably smaller than the domain size. At higher Péclet number, though the system creates slender regions in which the temperature gradient is concentrated within a more homogeneous background, there are no signs of the horizontally mixed layers separated by diffusive interfaces familiar from doubly diffusive systems.
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DIXIT, HARISH N., and RAMA GOVINDARAJAN. "Vortex-induced instabilities and accelerated collapse due to inertial effects of density stratification." Journal of Fluid Mechanics 646 (February 9, 2010): 415–39. http://dx.doi.org/10.1017/s0022112009992515.
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A vortex placed at a density interface winds it into an ever-tighter spiral. We show that this results in a combination of a centrifugal Rayleigh–Taylor (CRT) instability and a spiral Kelvin–Helmholtz (SKH) type of instability. The SKH instability arises because the density interface is not exactly circular, and dominates at large times. Our analytical study of an inviscid idealized problem illustrates the origin and nature of the instabilities. In particular, the SKH is shown to grow slightly faster than exponentially. The predicted form lends itself for checking by a large computation. From a viscous stability analysis using a finite-cored vortex, it is found that the dominant azimuthal wavenumber is smaller for lower Reynolds number. At higher Reynolds numbers, disturbances subject to the combined CRT and SKH instabilities grow rapidly, on the inertial time scale, while the flow stabilizes at low Reynolds numbers. Our direct numerical simulations are in good agreement with these studies in the initial stages, after which nonlinearities take over. At Atwood numbers of 0.1 or more, and a Reynolds number of 6000 or greater, both stability analysis and simulations show a rapid destabilization. The result is an erosion of the core, and breakdown into a turbulence-like state. In studies at low Atwood numbers, the effect of density on the inertial terms is often ignored, and the density field behaves like a passive scalar in the absence of gravity. The present study shows that such treatment is unjustified in the vicinity of a vortex, even for small changes in density when the density stratification is across a thin layer. The study would have relevance to any high-Péclet-number flow where a vortex is in the vicinity of a density-stratified interface.
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Dandekar, Rajat, Vaseem A. Shaik, and Arezoo M. Ardekani. "Swimming sheet in a density-stratified fluid." Journal of Fluid Mechanics 874 (July 4, 2019): 210–34. http://dx.doi.org/10.1017/jfm.2019.445.
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In this work, we theoretically investigate the swimming velocity of a Taylor swimming sheet immersed in a linearly density-stratified fluid. We use a regular perturbation expansion approach to estimate the swimming velocity up to second order in wave amplitude. We divide our analysis into two regimes of low ($\ll O(1)$) and finite Reynolds numbers. We use our solution to understand the effect of stratification on the swimming behaviour of organisms. We find that stratification significantly influences motility characteristics of the swimmer such as the swimming speed, hydrodynamic power expenditure, swimming efficiency and the induced mixing, quantified by mixing efficiency and diapycnal eddy diffusivity. We explore this dependence in detail for both low and finite Reynolds number and elucidate the fundamental insights obtained. We expect our work to shed some light on the importance of stratification in the locomotion of organisms living in density-stratified aquatic environments.
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Ezhova, Ekaterina, Claudia Cenedese, and Luca Brandt. "Interaction between a Vertical Turbulent Jet and a Thermocline." Journal of Physical Oceanography 46, no. 11 (November 2016): 3415–37. http://dx.doi.org/10.1175/jpo-d-16-0035.1.
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AbstractThe behavior of an axisymmetric vertical turbulent jet in an unconfined stratified environment is studied by means of well-resolved, large-eddy simulations. The stratification is two uniform layers separated by a thermocline. This study considers two cases: when the thermocline thickness is small and on the order of the jet diameter at the thermocline entrance. The Froude number of the jet at the thermocline varies from 0.6 to 1.9, corresponding to the class of weak fountains. The mean jet penetration, stratified turbulent entrainment, jet oscillations, and the generation of internal waves are examined. The mean jet penetration is predicted well by a simple model based on the conservation of the source energy in the thermocline. The entrainment coefficient for the thin thermocline is consistent with the theoretical model for a two-layer stratification with a sharp interface, while for the thick thermocline entrainment is larger at low Froude numbers. The data reveal the presence of a secondary horizontal flow in the upper part of the thick thermocline, resulting in the entrainment of fluid from the thermocline rather than from the upper stratification layer. The spectra of the jet oscillations in the thermocline display two peaks, at the same frequencies for both stratifications at fixed Froude number. For the thick thermocline, internal waves are generated only at the lower frequency, since the higher peak exceeds the maximal buoyancy frequency. For the thin thermocline, conversely, the spectra of the internal waves show the two peaks at low Froude numbers, whereas only one peak at the lower frequency is observed at higher Froude numbers.
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Gupta, Supriya, Phillip M. Ligrani, and J. Calvin Giddings. "Characteristics of flow instabilities from unstable stratification of density in channel shear layers at low Reynolds numbers." International Journal of Heat and Mass Transfer 42, no. 6 (March 1999): 1023–36. http://dx.doi.org/10.1016/s0017-9310(98)00169-0.
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Spurgin, J. M., and S. E. Allen. "Flow dynamics around downwelling submarine canyons." Ocean Science 10, no. 5 (October 14, 2014): 799–819. http://dx.doi.org/10.5194/os-10-799-2014.
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Abstract. Flow dynamics around a downwelling submarine canyon were analysed with the Massachusetts Institute of Technology general circulation model. Blanes Canyon (northwestern Mediterranean) was used for topographic and initial forcing conditions. Fourteen scenarios were modelled with varying forcing conditions. Rossby and Burger numbers were used to determine the significance of Coriolis acceleration and stratification (respectively) and their impacts on flow dynamics. A new non-dimensional parameter (χ) was introduced to determine the significance of vertical variations in stratification. Some simulations do see brief periods of upwards displacement of water during the 10-day model period; however, the presence of the submarine canyon is found to enhance downwards advection of density in all model scenarios. High Burger numbers lead to negative vorticity and a trapped anticyclonic eddy within the canyon, as well as an increased density anomaly. Low Burger numbers lead to positive vorticity, cyclonic circulation, and weaker density anomalies. Vertical variations in stratification affect zonal jet placement. Under the same forcing conditions, the zonal jet is pushed offshore in more uniformly stratified domains. The offshore jet location generates upwards density advection away from the canyon, while onshore jets generate downwards density advection everywhere within the model domain. Increasing Rossby values across the canyon axis, as well as decreasing Burger values, increase negative vertical flux at shelf break depth (150 m). Increasing Rossby numbers lead to stronger downwards advection of a passive tracer (nitrate), as well as stronger vorticity within the canyon. Results from previous studies are explained within this new dynamic framework.
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MacKinnon, J. A., and M. C. Gregg. "Spring Mixing: Turbulence and Internal Waves during Restratification on the New England Shelf." Journal of Physical Oceanography 35, no. 12 (December 1, 2005): 2425–43. http://dx.doi.org/10.1175/jpo2821.1.
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Abstract Integrated observations are presented of water property evolution and turbulent microstructure during the spring restratification period of April and May 1997 on the New England continental shelf. Turbulence is shown to be related to surface mixed layer entrainment and shear from low-mode near-inertial internal waves. The largest turbulent diapycnal diffusivity and associated buoyancy fluxes were found at the bottom of an actively entraining and highly variable wind-driven surface mixed layer. Away from surface and bottom boundary layers, turbulence was systematically correlated with internal wave shear, though the nature of that relationship underwent a regime shift as the stratification strengthened. During the first week, while stratification was weak, the largest turbulent dissipation away from boundaries was coincident with shear from mode-1 near-inertial waves generated by passing storms. Wave-induced Richardson numbers well below 0.25 and density overturning scales of several meters were observed. Turbulent dissipation rates in the region of peak shear were consistent in magnitude with several dimensional scalings. The associated average diapycnal diffusivity exceeded 10−3 m2 s−1. As stratification tripled, Richardson numbers from low-mode internal waves were no longer critical, though turbulence was still consistently elevated in patches of wave shear. Kinematically, dissipation during this period was consistent with the turbulence parameterization proposed by MacKinnon and Gregg, based on a reinterpretation of wave–wave interaction theory. The observed growth of temperature gradients was, in turn, consistent with a simple one-dimensional model that vertically distributed surface heat fluxes commensurate with calculated turbulent diffusivities.
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Spurgin, J. M., and S. E. Allen. "Flow dynamics around downwelling submarine canyons." Ocean Science Discussions 11, no. 3 (May 23, 2014): 1301–56. http://dx.doi.org/10.5194/osd-11-1301-2014.
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Abstract. Flow dynamics around a downwelling submarine canyon were analysed with the Massachusetts Institute of Technology general circulation model. Blanes Canyon (Northwest Mediterranean) was used for topographic and initial forcing conditions. Fourteen scenarios were modelled with varying forcing conditions. Rossby number and Burger number were used to determine the significance of Coriolis acceleration and stratification (respectively) and their impacts on flow dynamics. A new non-dimensional parameter (χ) was introduced to determine the significance of vertical variations in stratification. Some simulations do see brief periods of upwards displacement of water during the 10 day model period, however, the presence of the submarine canyon is found to enhance downwards advection of density in all model scenarios. High Burger numbers lead to negative vorticity and a trapped anticyclonic eddy within the canyon, as well as an increased density anomaly. Low Burger numbers lead to positive vorticity, cyclonic circulation and weaker density anomalies. Vertical variations in stratification affect zonal jet placement. Under the same forcing conditions, the zonal jet is pushed offshore in more uniformly stratified domains. Offshore jet location generates upwards density advection away from the canyon, while onshore jets generate downwards density advection everywhere within the model domain. Increasing Rossby values across the canyon axis, as well as decreasing Burger values, increase negative vertical flux at shelf break depth (150 m). Increasing Rossby numbers lead to stronger downwards advection of a passive tracer (nitrate) as well as stronger vorticity within the canyon. Results from previous studies were explained within this new dynamic framework.
Dissertations / Theses on the topic "Alfven numbers low stratification"
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Kobera, Marek. "Qualitative properties of radiation magnetohydrodynamics." Doctoral thesis, 2016. http://www.nusl.cz/ntk/nusl-352088.
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We consider a simplified model based on the Navier-Stokes-Fourier system coupled to a transport equation and the Maxwell system, proposed to describe radiative flows in stars. We establish global- in-time existence for the associated initial-boundary value problem in the framework of weak solutions. Next, we study a hydrodynamical model describing the motion of internal stellar layers based on compressible Navier-Stokes-Fourier-Poisson system. We suppose that the medium is electrically charged, we include energy exchanges through radiative transfer and we assume that the system is steadily rotating. We analyze the singular limit of this system when the Mach number, the Alfven number, the Peclet number and the Froude number go to zero in a certain way and prove convergence to a 3D incompressible MHD system with a stationary linear transport equation for transport of radiation intensity. Finally, we show that the energy equation reduces to a steady equation for the temperature corrector.
Book chapters on the topic "Alfven numbers low stratification"
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FRANK, KALTER, and NADIA GRANATO. "Educational Hurdles on the Way to Structural Assimilation in Germany." In Unequal Chances. British Academy, 2007. http://dx.doi.org/10.5871/bacad/9780197263860.003.0007.
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There are five major groups of classic ‘labour migrants’ in Germany: Greeks, Italians, (ex-)Yugoslavs, Turks, and Iberians, with the Turks being the largest single group. Today, there are significant numbers of second-generation men and women from these origins in the German labour market. More recently, they have been joined by a more diverse group of migrants from Western Europe, Eastern Europe, the (middle) East, and Africa. In the first generation, the labour-migrant groups had relatively low levels of education, leading to marked ethnic stratification within the labour market. This stratification continues in the second generation although on a reduced scale. While the second generation has acquired higher levels of education than the first, they still lag some way (the Turks especially so) behind native Germans in their education. Ethnic penalties in the labour market itself are also much reduced in the second generation, although significant penalties remain for Turks. However, most of the continuing ethnic stratification is due to processes that operate prior to entry into the labour market.
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Aruch, Daniel, and Ronald Hoffman. "Thrombocytosis and essential thrombocythaemia." In Oxford Textbook of Medicine, edited by Chris Hatton and Deborah Hay, 5239–47. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780198746690.003.0518.
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The term thrombocytosis refers to a platelet count elevated above 450 × 109/litre, which can be (1) primary—including essential thrombocythaemia, chronic myeloid leukaemia, polycythaemia vera, and myelodysplastic syndromes; or (2) secondary—including iron deficiency, infection, blood loss, and malignancy. Essential thrombocythaemia: aetiology—the JAK2 V617F missense mutation typical of polycythaemia vera is found in about 50% of cases. In addition, 10% of patients have a mutation in the thrombopoietin receptor gene, MPL, and 30% have a mutation in calreticulin (CALR). Approximately 10% of patients have none of these mutations and are referred to as ‘triple negative’ essential thrombocythaemia. Diagnosis requires all of the following four major criteria: (1) platelet count greater than 450 × 109/litre; (2) bone marrow biopsy showing proliferation mainly of the megakaryocyte lineage with increased numbers of enlarged, mature megakaryocytes with hyperlobulated nuclei without a significant increase or left shift in neutrophil granulopoiesis or erythropoiesis and very rarely minor (grade 1) increase in reticulin fibres; (3) failure to meet the criteria for other myeloproliferative neoplasms; and (4) presence of JAK2, CALR, or MPL mutations. Alternatively, diagnosis can be met when the first three major criteria are present and the one minor criterion, namely the presence of another clonal marker or absence of evidence for reactive thrombocytosis. Treatment requires risk stratification based on the age of the patient and any prior history of thrombosis, with treatment being reserved for those at a high risk of developing complications and not introduced simply on the basis of platelet counts alone unless there is extreme thrombocytosis (>1500 × 109/litre). Therapies include low-dose aspirin and cytoreduction.
Conference papers on the topic "Alfven numbers low stratification"
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Abe, Satoshi, Etienne Studer, Masahiro Ishigaki, Yasuteru Sibamoto, and Taisuke Yonomoto. "Applicability of Dynamic Modeling for Turbulent Schmidt and Prandtl Numbers on Density Stratification Breakup in Several Flow Conditions." In 2020 International Conference on Nuclear Engineering collocated with the ASME 2020 Power Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/icone2020-16837.
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Abstract Many experiments on density stratification breakup in several flow conditions have been performed with the large- and small-scale experimental facilities to understand the mechanism underlying hydrogen behavior in a nuclear containment vessel during a severe accident. To improve the predictability of the RANS (Reynolds-averaged Navier Stokes) approach, we implemented the dynamic modeling for turbulent Schmidt Sct and Prandtl Prt numbers. In this paper, the capability of the RANS analysis with dynamic Sct modeling is assessed with several experimental data obtained by using the MISTRA (Commissariat à l’énergie atomique et aux énergies alternatives, CEA, France), CIGMA and VIMES (Japan Atomic Energy Agency, Japan). For the quantitative assessment, the completion time of the stratification breakup, defined as when helium concentration in the upper region decreases to the same value in the lower region, is focused. The comparison study shows the good performance of the dynamic modeling for Sct and Prt. Besides, in the case with the low jet Froude number, the CFD accuracy declines significantly, because the jet upward bending is over-estimated.
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Derksen, Jos. "Turbulent Mixing With Density Differences." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-21002.
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Homogenization of initially segregated and stably stratified systems consisting of two miscible liquids with different density and the same kinematic viscosity in an agitated tank was studied computationally. Reynolds numbers were in the range of 3,000 to 12,000 so that it was possible to solve the flow equations without explicitly modeling turbulence. The Richardson number that characterizes buoyancy was varied between 0 and 1. The stratification clearly lengthens the homogenization process. Two flow regimes could be identified. At low Richardson numbers large, three-dimensional flow structures dominate mixing, as is the case in non-buoyant systems. At high Richardson numbers the interface between the two liquids largely stays intact. It rises due to turbulent erosion, gradually drawing down and mixing up the lighter liquid.
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Oh, David, and Jean-Sébastien Plante. "A Hydrogen-Fueled, Direct-Injected, Two-Stroke, Small-Displacement Engine for Recreational Marine Applications With High Efficiency and Low Emissions." In ASME 2012 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icef2012-92047.
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A hydrogen-fueled two-stroke prototype demonstrator based on a 9.9 horsepower (7.4 kW) production gasoline marine outboard is presented, which, while matching the original engine’s rated power output on hydrogen, achieves a best-point gross indicated thermal efficiency (ITE) of 42.4% at the ICOMIA Mode 4 operating point corresponding to 80% and 71.6% of rated engine speed and torque, respectively. Brake thermal efficiency (BTE) at rated power is 32.3%. Preliminary exhaust gas measurements suggest that the engine could also meet the most stringent CARB 5-Star marine spark-ignition emission standards limiting HC+NOx emissions to 2.5 g/kWh without any after-treatment. Later fuel injection is found to improve thermal efficiency at the expense of increased NOx emissions and, at the extreme, increased cyclic variation. The mechanism for these observations is reasoned to be increasing charge stratification with the later timings. All these are realized in a cost-effective concept around a proven two-stroke base engine and a low-pressure, direct-injected gaseous hydrogen (LPDI GH2) system, which employs no additional fuel pump and is adapted uniquely from volume production components. This work outlines the pathway — including investigations of several fuel delivery strategies with limited success — leading to the current status including design; modeling with GT-POWER; delivery of lube oil; lubrication issues using hydrogen; and calibration sweeps. Experimental results comprising steady-state dynamometer performance, cylinder pressure traces, NOx emission measurements, as well as heat release analyses, support the reported numbers and the key finding that late fuel injection timing and charge stratification drive the high efficiencies and the NOx trade-off; this is discussed and forms the basis for future work.
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Bayareh, M., S. Dabiri, and A. M. Ardekani. "Interaction Between a Pair of Drops Ascending in a Linearly Stratified Fluid." In ASME 2013 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fedsm2013-16046.
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In this paper, we provide fully resolved three-dimensional direct numerical simulations of ascending motion of a pair of drops in a linearly stratified fluid using a finite-volume/front-tracking method. We study the density stratification effects on the rise velocity of drops and their stable position for different initial alignments. Due to the formation of a jet in the lee of a single drop rising in a stratified fluid, a decrease in rise velocity (or an increase in drag) is observed compared to the homogeneous case. The hydrodynamic interaction between two drops in a linearly stratified fluid depends on the properties of both fluids and initial orientation of the two drops. For the case of drops rising side by side, the lateral separation of drops is suppressed due to stratification effects. In contrast to homogeneous case, two nearly spherical drops collide with each other at low Froude numbers and oscillate around their neutrally buoyant density level. Two spherical drops rising in tandem in a linearly stratified fluid at finite Reynolds number regime undergo drafting, kissing, and tumbling unlike their counterpart in a homogenous fluid.
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Dempsey, Adam B., Scott Curran, Robert Wagner, William Cannella, and Andrew Ickes. "Gasoline Compression Ignition (GCI) on a Light-Duty Multi-Cylinder Engine Using a Wide Range of Fuel Reactivities and Heavy Fuel Stratification." In ASME 2020 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/icef2020-2929.
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Abstract Many research studies have focused on utilizing gasoline in modern compression ignition engines to reduce emissions and improve efficiency. Collectively, this combustion mode has become known as gasoline compression ignition (GCI). One of the biggest challenges with GCI operation is maintaining control over the combustion process through the fuel injection strategy, such that the engine can be controlled on a cycle-by-cycle basis. Research studies have investigated a wide variety of GCI injection strategies (i.e., fuel stratification levels) to maintain control over the heat release rate while achieving low temperature combustion (LTC). This work shows that at loads relevant to light-duty engines, partial fuel stratification (PFS) with gasoline provides very little controllability over the timing of combustion. On the contrary, heavy fuel stratification (HFS) provides very linear and pronounced control over the timing of combustion. However, the HFS strategy has challenges achieving LTC operation due to the air handling burdens associated with the high EGR rates that are required to reduce NOx emissions to near zero levels. In this work, a wide variety of gasoline fuel reactivities (octane numbers ranging from < 40 to 87) were investigated to understand the engine performance and emissions of HFS-GCI operation on a multi-cylinder light-duty engine. The results indicate that over an EGR sweep at 4 bar BMEP, the gasoline fuels can achieve LTC operation with ultra-low NOx and soot emissions, while conventional diesel combustion (CDC) is unable to simultaneously achieve low NOx and soot. At 10 bar BMEP, all the gasoline fuels were compared to diesel, but using mixing controlled combustion and not LTC.
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Yetisir, M., G. L. Stevens, and S. Robertson. "Management of Component Fatigue in CANDU Stations for Life Extension." In 16th International Conference on Nuclear Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/icone16-48757.
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CANDU® nuclear generating stations and their components were designed for 30 effective full power years (EFPY) of operation. Many CANDU plants are now approaching their design end-of-life and are being considered for extended operation beyond their design life. The Canadian regulator, the Canadian Nuclear Safety Commission (CNSC), has asked utilities to consider component fatigue issues in plant life extension (PLEX) applications. In particular, environmental effects on fatigue is identified as an issue that needs to be addressed, similar to that being addressed for license renewal for U.S. nuclear power plants. To address CNSC concerns, CANDU stations have initiated a program to develop component fatigue management programs for PLEX operation. A pilot study conducted in a typical CANDU plant showed that: • Only 10 to 15% of the numbers of design transients have been used after 25 EFPY of operation. Hence, a significant amount of original design fatigue usage margin remains available for PLEX operation. • Environmental fatigue considerations in heavy water (D2O) were included in the assessment. Only warm-up transients are assessed to have dissolved oxygen concentrations that can result in a significant environmental effect for the ferritic steels used in the CANDU primary and secondary systems. • Due to the low accumulation of transients, and the relative absence of thermal stratification mechanisms, thermal fatigue is not as significant an issue in CANDU plants as in pressurized water reactor (PWR) and boiling water reactor (BWR) plants. This paper summarizes the results of the pilot study conducted for the Canadian CANDU plants.