•X-ray CT indicates variations of 20% in the L/D ratio and 4% in the nozzle area relative to design dimensions.•X-ray radiography reveals plume density variations of up to 17% about the mean.•The ...plumes exit the holes at up to 5 degrees smaller than the hole drill angle.•The plumes converge with increasing distance from the nozzle.•The plumes also converge with time, which may promote spray collapse.
Gasoline direct injection (GDI) sprays are complex multiphase flows. When compared to multi-hole diesel sprays, the plumes are closely spaced, and the sprays are more likely to interact. The effects of multi-jet interaction on entrainment and spray targeting can be influenced by small variations in the mass fluxes from the holes, which in turn depend on transients in the needle movement and small-scale details of the internal geometry. In this paper, we present a comprehensive overview of a multi-institutional effort to experimentally characterize the internal geometry and near-nozzle flow of the Engine Combustion Network (ECN) Spray G gasoline injector. In order to develop a complete picture of the near-nozzle flow, a standardized setup was shared between facilities. A wide range of techniques were employed, including both X-ray and visible-light diagnostics. The novel aspects of this work include both new experimental measurements, and a comparison of the results across different techniques and facilities. The breadth and depth of the data reveal phenomena which were not apparent from analysis of the individual data sets. We show that plume-to-plume variations in the mass fluxes from the holes can cause large-scale asymmetries in the entrainment field and spray structure. Both internal flow transients and small-scale geometric features can have an effect on the external flow. The sharp turning angle of the flow into the holes also causes an inward vectoring of the plumes relative to the hole drill angle, which increases with time due to entrainment of gas into a low-pressure region between the plumes. These factors increase the likelihood of spray collapse with longer injection durations.
On January 4 2020, the World Health Organization (WHO) reported the emergence of a cluster of pneumonia cases in Wuhan, China due to a new coronavirus, the SARS-CoV-2. A few weeks later, hospitals ...had to put in place a series of drastic measures to deal with the massive influx of suspected COVID-19 (COronaroVIrus Disease) patients while securing regular patient care, in particular in the intensive care units (ICU). Since March 12th, 77 of the 685 COVID-19 patients admitted to our hospital required hospitalization in the ICU. What are the roles and the added-value of the critical care pharmacist during this period? His missions have evolved although they have remained focused on providing health services for the patients. Indeed, integrated into a steering committee created to organize the crisis in the intensive care units, the role of the clinical pharmacist was focused on the organization and coordination between ICU and the pharmacy, the implementation of actions to secure practices, to train new professionals and the adaptation of therapeutic strategies. He participated to literature monitoring and increased his involvement in the clinical research team. He provided a link between the ICU and the pharmacy thanks to his knowledges of practices and needs.
This study aims at evaluating fluconazole exposure in critically ill patients and identifying variables associated with the latter.
This was a 2-year (2018-2019) retrospective multicenter cohort ...study. Adult patients > 18 years-old with at least one fluconazole concentration measurement during their ICU stay were included.
Twenty patients were included. Only 11 patients had a fluconazole trough concentration (Cmin) within the target range (≥15 mg/L). According to bivariable analysis, SOFA score, GGT, fluconazole clearance, Ke, and Vd, were independently associated with a decrease in fluconazole Cmin. The median loading dose required to achieve the Cmin target appeared to be greater in patients with higher SOFA or GGT level and in patients undergoing renal replacement therapy.
This study supports recommendation for routine fluconazole therapeutic drug monitoring in ICU patients so as to avoid underexposure, especially if SOFA score is ≥ 7 and/or GGT is ≥ 100 U/L.
Solid rocket propellant combustion is hindered by agglomeration of aluminum particles on its burning surface and determining the particle size has been a problem for half a century. The actual size ...of the agglomerates at motor pressures is unknown due to the opacity of the combustion plume, particularly at the elevated pressures seen in operational rocket motors. Sampling techniques can provide data at elevated pressure but may be biased due to the sampling method and do not provide information on the dynamics of agglomerate formation. This study uses time-resolved synchrotron x-ray imaging (with both absorption and phase contrast) to view aluminum agglomerate formation in situ at relevant rocket pressures. We have for the first time observed agglomerate formation at motor-relevant pressures in real time with unprecedented fidelity, providing critical data for understanding the combustion of aluminized solid rocket propellants.
Since particulate emissions control technologies are dependent on filtration technologies, development of porous materials with optimized pore structures is crucial to improve filtration efficiency ...and pressure drop across filters. Despite increasing attention to 3D measurements of porous materials, there are few reports of pore structure investigations of diesel/gasoline particulate filters (D/GPFs) using 3D visualization techniques. In this work, GPF 3D pore structures were examined using X-ray tomography (XRT) to identify the impacts of catalyst coating or ash loading. Voxel resolution of 2.93 µm made it impossible to distinguish coating or ash materials from the cordierite substrate or to recognize smaller pores than the voxel resolution. However, pores up to 200 µm, which are responsible for the most pore volume, were successfully analyzed. Coating and ash loading resulted in lowering average pore diameter, total porosity, and open porosity, as the peak density of pore diameter at 60 µm decreased, while pores below 20 µm increased. Also, the visualized closed pores, which were homogeneously distributed throughout the bare filter, tended to get larger from inlet to outlet sides and more likely to be on the surface inlet due to coating and ash loading, indicating gas pathways originally existing in open pores were blocked due to coating and ash loading, leading to increased pressure drop. The ash impact was found to be more noticeable on mid and back positions than on front position. In addition, the investigation of areal porosity along the direction of gas flow suggested that while ash penetration could reach the outlet side as noted from increased closed pore population, most ash particles would be contained up to 150 µm. The 2D crosscut microscopic analysis that requires destructive procedures with the limited examination area could provide underestimation of ash penetration, whereas the 3D XRT analysis seems to provide more accurate information of pore structure changes due to ash loading at different locations.
The multiphase flow inside a diesel injection nozzle is imaged using synchrotron X-rays from the Advanced Photon Source at Argonne National Laboratory. Through acquisitions performed at several ...viewing angles and subsequent tomographic reconstruction, in-situ 3D visualization is achieved for the first time inside a steel injector at engine-like operating conditions. The morphology of the internal flow reveals strong flow separation and vapor-filled cavities (cavitation), the degree of which correlates with the nozzle's asymmetric inlet corner profile. Micron-scale surface features, which are artifacts of manufacturing, are shown to influence the morphology of the resulting liquid-gas interface. The data obtained at 0.1 ms time resolution exposes transient flow features and the flow development timescales are shown to be correlated with in-situ imaging of the fuel injector's hydraulically-actuated valve (needle). As more than 98.5% of the X-ray photon flux is attenuated within the steel injector body itself, we are posed with a unique challenge for imaging the flow within. Time-resolved imaging under these low-light conditions is achieved by exploiting both the refractive and absorptive properties of X-ray photons. The data-processing strategy converted these images with a signal-to-noise ratio of ~ 10 into a meaningful dataset for understanding internal flow and cavitation in a nozzle of diameter 200 μm enclosed within 1-2 millimeters of steel.
We present laboratory experiments in which both a buoyancy and mechanical forcing are imposed on the surface of a rectangular tank filled with freshwater. The buoyancy forcing is generated by a ...saltwater source at the surface that drives a sinking half-line plume along one endwall, and the mechanical forcing is generated by a continuous flow of freshwater across the surface of the tank. A steady-state circulation is achieved when the advection of salt by the plume is matched by the diffusion of salt through the upper boundary. The surface stress drives flow in the same direction as the plume, resulting in a convective cell whose depth is determined by the interplay of the two forcings. When the surface stress is relatively weak, the steady-state flow is described by a high-Rayleigh number ‘recycling box’ model for horizontal convection (Hughes et al. in J Fluid Mech 581:251–276,
2007
). Once the stress is strong enough to overturn the stratified waters, a region of localized mixing develops. The immediate consequence of this regional turbulence is a net input of stabilizing buoyancy in the form of fresher water into the plume, which renders it too weak to penetrate to the bottom boundary. In general, the plume is unable to recover a full-depth circulation within the experiment time frame. The resulting flow can be described by the recycling box model with a spatially varying turbulent diffusivity parameterized by the characteristics of the turbulent eddy that develops in the mixing region. This work applies experimental techniques to show that, with adequate mechanical forcing, a buoyancy-driven circulation will develop localized mixing that significantly alters the overall structure and density distribution of the circulation for relatively long timescales. The experimental results corroborate the recycling box model as a valid descriptor of the flow structure in such systems.
The feasibility of liquid temperature measurements using X-ray scattering is investigated for liquids with varying properties (water, ethanol, and n-dodecane) on beamline 7-BM at the Advanced Photon ...Source at Argonne National Laboratory. The temperature is inferred through the change in the scattering pattern from the liquid as a function of temperature using partial least squares regression. An accuracy of ∼98% or higher was achieved enabling measurements for a wide range of applications.
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