Computational optimization of a subsonic compressible gas Venturi's ejector

The paper deals with a 3-D numerical simulation and validation against industrial measurements of turbulent frozen reacting flow in a subsonic compressible gas Venturi’s ejector used as “fluid dynamic engine” for external flue gas recirculation in a state-of-the-art “annular shaft” lime kiln. Higher stagnation thermodynamics parameters of the ejector hot gas primary stream permit the avoidance of the condensing temperature window of compounds such as K2O and Na2O, and KCl and NaCl that produce sticky builds-up on the ejector’s internal wall. An improved gas dynamics effectiveness allows the maximization of the amount of secondary flue gas stream using much less primary stream mass flow rate. The commercial FluentTM UNS/5 software was used to predict all flow behaviour characteristics inside the original and new Venturi’s ejectors. A reasonable agreement has been found between the computed and experimental flow rate figures of the secondary flue gas stream of the actual functional kiln

Multibody analysis and soft tissue strength refute supersonic dinosaur tail

Sauropod dinosaurs are well known for their massive sizes and long necks and tails. Among sauropods, flagellicaudatan dinosaurs are characterized by extreme tail elongation, which has led to hypotheses regarding tail function, often compared to a whip. Here, we analyse the dynamics of motion of a 3D model of an apatosaurine flagellicaudatan tail using multibody simulation and quantify the stress-bearing capabilities of the associated soft tissues. Such an elongated and slender structure would allow achieving tip velocities in the order of 30 m/s, or 100 km/h, far slower than the speed of sound, due to the combined effect of friction of the musculature and articulations, as well as aerodynamic drag. The material properties of the skin, tendons, and ligaments also support such evidence, proving that in life, the tail would not have withstood the stresses imposed by travelling at the speed of sound, irrespective of the conjectural 'popper', a hypothetical soft tissue structure analogue to the terminal portion of a bullwhip able to surpass the speed of sound

Modelling of internal nozzle flow in high pressure water mist injector for fire suppression applications

The internal flow in a water mist injector for fire suppression applications is investigated, implementing 3D Large Eddy Simulations based on the Volume-of-Fluid methodology. The flow is assumed to be incompressible under isothermal non-reacting conditions. The effect of internal nozzle geometry on the injector behaviour is investigated, for different operating conditions, by modifying the inclined swirling channels. The injector behaviour is mapped varying the injection pressure for each nozzle geometry. Detailed in-nozzle flow analysis is performed

Numerical simulations of internal flow in an aircraft engine pressure swirl atomizer

he internal flow and the liquid structure at the nozzle exit are investigated in a typical pressure swirl atomizer for aeroengine applications under an isothermal nonreacting environment using a two-phase flow modeling according to the volume-of-fluid numerical methodology. A parametrical analysis is performed to investigate the effect of operating conditions on the injector performances and the characteristics of the liquid jet exiting the nozzle. The liquid film thickness at the nozzle exit and the injector discharge coefficient predicted by the simulations are compared against commonly used correlations available in the literature. The influence of the turbulence model on the injector performances is also analyzed using three different models: the renormalization group k-e model, the Reynolds stress model, and the large-eddy simulation model

Modeling hemodynamics in intracranial aneurysms: Comparing accuracy of CFD solvers based on finite element and finite volume schemes

Image-based computational fluid dynamics (CFD) has shown potential to aid in the clinical management of intracranial aneurysms, but its adoption in the clinical practice has been missing, partially because of lack of accuracy assessment and sensitivity analysis. To numerically solve the flow-governing equations, CFD solvers generally rely on 2 spatial discretization schemes: finite volume (FV) and finite element (FE). Since increasingly accurate numerical solutions are obtained by different means, accuracies and computational costs of FV and FE formulations cannot be compared directly. To this end, in this study, we benchmark 2 representative CFD solvers in simulating flow in a patient-specific intracranial aneurysm model: (1) ANSYS Fluent, a commercial FV-based solver, and (2) VMTKLab multidGetto, a discontinuous Galerkin (dG) FE-based solver. The FV solver's accuracy is improved by increasing the spatial mesh resolution (134k, 1.1m, 8.6m, and 68.5m tetrahedral element meshes). The dGFE solver accuracy is increased by increasing the degree of polynomials (first, second, third, and fourth degree) on the base 134k tetrahedral element mesh. Solutions from best FV and dGFE approximations are used as baseline for error quantification. On average, velocity errors for second-best approximations are approximately 1 cm/s for a [0,125] cm/s velocity magnitude field. Results show that high-order dGFE provides better accuracy per degree of freedom but worse accuracy per Jacobian nonzero entry as compared with FV. Cross-comparison of velocity errors demonstrates asymptotic convergence of both solvers to the same numerical solution. Nevertheless, the discrepancy between underresolved velocity fields suggests that mesh independence is reached following different paths

CFD simulations of a two-phase ejector for transcritical CO2 cycles applied to supermarket refrigeration systems

The use of carbon dioxide (CO2), as a working fluid for large refrigeration systems, has grown tremendously in recent years. Factors such as its low cost, easy accessibility and environmentally friendly characteristics compared to HFCs and HCFCs, has made CO2a viable alternative. To efficiently operate with CO2, the thermodynamic cycle needs high-pressure levels that can easily exceed the critical point due to the low critical temperature. By replacing conventional expansion valves with ejectors, the thermodynamic losses of the high-pressure throttling are mitigated, and the overall system performance is improved. To design and efficiently control the whole cycle, a thorough comprehension of the ejector fluid dynamics is mandatory. In this work, Computational Fluid Dynamics (CFD) is used to thoroughly investigate such a device. The employed CFD solver uses a modified form of the Homogenous Relaxation Model (HRM) to deal with two-phase flows in a non-thermodynamic equilibrium state, per Colarossi et al. (2012). Preliminary numerical results for an ejector in supermarket refrigeration system operating conditions are presented and discussed

New orphan disease therapies from the proteome of industrial plasma processing waste- a treatment for aceruloplasminemia

Abstract Plasma-derived therapeutic proteins are produced through an industrial fractionation process where proteins are purified from individual intermediates, some of which remain unused and are discarded. Relatively few plasma-derived proteins are exploited clinically, with most of available plasma being directed towards the manufacture of immunoglobulin and albumin. Although the plasma proteome provides opportunities to develop novel protein replacement therapies, particularly for rare diseases, the high cost of plasma together with small patient populations impact negatively on the development of plasma-derived orphan drugs. Enabling therapeutics development from unused plasma fractionation intermediates would therefore constitute a substantial innovation. To this objective, we characterized the proteome of unused plasma fractionation intermediates and prioritized proteins for their potential as new candidate therapies for human disease. We selected ceruloplasmin, a plasma ferroxidase, as a potential therapy for aceruloplasminemia, an adult-onset ultra-rare neurological disease caused by iron accumulation as a result of ceruloplasmin mutations. Intraperitoneally administered ceruloplasmin, purified from an unused plasma fractionation intermediate, was able to prevent neurological, hepatic and hematological phenotypes in ceruloplasmin-deficient mice. These data demonstrate the feasibility of transforming industrial waste plasma fraction into a raw material for manufacturing of new candidate proteins for replacement therapies, optimizing plasma use and reducing waste generation

Tocilizumab for patients with COVID-19 pneumonia. The single-arm TOCIVID-19 prospective trial

BackgroundTocilizumab blocks pro-inflammatory activity of interleukin-6 (IL-6), involved in pathogenesis of pneumonia the most frequent cause of death in COVID-19 patients.MethodsA multicenter, single-arm, hypothesis-driven trial was planned, according to a phase 2 design, to study the effect of tocilizumab on lethality rates at 14 and 30 days (co-primary endpoints, a priori expected rates being 20 and 35%, respectively). A further prospective cohort of patients, consecutively enrolled after the first cohort was accomplished, was used as a secondary validation dataset. The two cohorts were evaluated jointly in an exploratory multivariable logistic regression model to assess prognostic variables on survival.ResultsIn the primary intention-to-treat (ITT) phase 2 population, 180/301 (59.8%) subjects received tocilizumab, and 67 deaths were observed overall. Lethality rates were equal to 18.4% (97.5% CI: 13.6-24.0, P=0.52) and 22.4% (97.5% CI: 17.2-28.3, P<0.001) at 14 and 30 days, respectively. Lethality rates were lower in the validation dataset, that included 920 patients. No signal of specific drug toxicity was reported. In the exploratory multivariable logistic regression analysis, older age and lower PaO2/FiO2 ratio negatively affected survival, while the concurrent use of steroids was associated with greater survival. A statistically significant interaction was found between tocilizumab and respiratory support, suggesting that tocilizumab might be more effective in patients not requiring mechanical respiratory support at baseline.ConclusionsTocilizumab reduced lethality rate at 30 days compared with null hypothesis, without significant toxicity. Possibly, this effect could be limited to patients not requiring mechanical respiratory support at baseline.Registration EudraCT (2020-001110-38); clinicaltrials.gov (NCT04317092)