MHD flow in a prototypical manifold of DCLL blankets (KIT Scientific Reports ; 7673)

Critical issues for the feasibility of dual coolant lead lithium blankets are large pressure drop and flow imbalance in parallel ducts due to 3D induced electric currents and 3D magnetohydrodynamic (MHD) phenomena that occur in liquid metal manifolds. In the present work we simulate MHD flows in a manifold where the liquid metal is distributed from a single duct into three parallel channels. The aim is identifying sources of flow imbalance, predicting velocity and pressure distribution

Geometric Optimization of Electrically Coupled Liquid Metal Manifolds for WCLL Blankets

A number of previous theoretical and experimental studies for helium-cooled or water-cooled lead lithium (WCLL) blankets show that the major fraction of magnetohydrodynamic (MHD) pressure drop in the breeder flow originates from manifolds that distribute and collect the liquid metal into and from the breeder units (BUs). Moreover, those studies revealed that without a proper design of the manifolds, the flow partitioning among breeder units would be strongly nonuniform along the poloidal direction. In the present work, MHD flows in electrically coupled liquid metal manifolds are studied by using an efficient hybrid model that has been developed for prediction of MHD pressure drop in such geometries and for determining flow distribution in BUs. The tool combines global mass conservation and pressure drop correlations with detailed 3-D simulations. From the experience gained when applying the model to the geometry of a test blanket module (TBM), it is concluded that the design of the manifolds requires optimization for achieving a balanced flow partitioning among BUs. In the second step, the hybrid model is applied to determine the optimum position of the baffle plates that separate the feeding and collecting ducts in manifolds in order to guarantee comparable flow rates in all BUs

MHD Flow in Curved Pipes Under a Nonuniform Magnetic Field

In fusion reactors, a very hot deuterium–tritium plasma is confined in a toroidal volume by means of a strong magnetic field. In the blanket structure that surrounds the fusion plasma, high-energy neutrons, produced in the D-T fusion reaction, are absorbed by the lithium-containing liquid metal releasing their kinetic energy in the form of volumetric thermal load and breeding the fuel component tritium. The liquid metal flows from the blanket toward external ancillary systems for purification and tritium extraction. When the electrically conducting fluid moves in the strong plasma-confining magnetic field, induced electric currents generate electromagnetic Lorentz forces, which modify velocity distribution and increase pressure losses compared with hydrodynamic flows. These magnetohydrodynamic (MHD) effects have to be investigated to determine their impact on blanket performance. A number of studies on pressure -driven and buoyant MHD flows in geometries related to blanket modules are available, while only few works consider MHD flows in pipelines connecting blanket and ancillary systems. In the present study, we investigate numerically liquid metal MHD flows in the pipes, which cross the shield that protects the superconducting magnets from neutron radiation-induced damages. The geometry features two bends in series that turn the flow from the radial direction perpendicular to the magnetic field into a direction parallel to it and then back to a perpendicular orientation. The correct radial distribution of the magnetic field, as expected along the pipe axis, is taken into account. The flow experiences strong 3-D effects caused by Lorentz forces due to large-scale current loops driven by axial potential differences along the bend axis. In spite of very strong local MHD effects on velocity and pressure distribution, the overall pressure drop does not increase significantly compared with the one in a fully developed flow in a straight pipe of same length

Direct and adjoint global stability analysis of turbulent transonic flows over a NACA0012 profile

In this work, various turbulent solutions of the two-dimensional (2D) and three-dimensional compressible Reynolds averaged Navier?Stokes equations are analyzed using global stability theory. This analysis is motivated by the onset of flow unsteadiness (Hopf bifurcation) for transonic buffet conditions where moderately high Reynolds numbers and compressible effects must be considered. The buffet phenomenon involves a complex interaction between the separated flow and a shock wave. The efficient numerical methodology presented in this paper predicts the critical parameters, namely, the angle of attack and Mach and Reynolds numbers beyond which the onset of flow unsteadiness appears. The geometry, a NACA0012 profile, and flow parameters selected reproduce situations of practical interest for aeronautical applications. The numerical computation is performed in three steps. First, a steady baseflow solution is obtained; second, the Jacobian matrix for the RANS equations based on a finite volume discretization is computed; and finally, the generalized eigenvalue problem is derived when the baseflow is linearly perturbed. The methodology is validated predicting the 2D Hopf bifurcation for a circular cylinder under laminar flow condition. This benchmark shows good agreement with the previous published computations and experimental data. In the transonic buffet case, the baseflow is computed using the Spalart?Allmaras turbulence model and represents a mean flow where the high frequency content and length scales of the order of the shear-layer thickness have been averaged. The lower frequency content is assumed to be decoupled from the high frequencies, thus allowing a stability analysis to be performed on the low frequency range. In addition, results of the corresponding adjoint problem and the sensitivity map are provided for the first time for the buffet problem. Finally, an extruded three-dimensional geometry of the NACA0012 airfoil, where all velocity components are considered, was also analyzed as a Triglobal stability case, and the outcoming results were compared to the previous 2D limited model, confirming that the buffet onset is well detected

Global Stability Analysis of a Compressible Turbulent Flow around a High-Lift Configuration

The purpose of this work is to analyze a complex high lift configuration for which significant regions of separated flow are present. Current state of the art methods have some diffculty to predict the origin and the progression of this separated flow when increasing the angle of attack. The mechanisms responsible for the maximum lift limit on multi-element wing con?gurations are not clear; this stability analysis could help to understand the physics behind the phenomenon and to find a relation between the flow separation and the instability onset. The methodology presented herein consists in the computation of a steady base flow solution based on a finite volume discretization and a proposal of the solution for a generalized eigenvalue problem corresponding to the perturbed and linearized problem. The eigenvalue problem has been solved with the Arnoldi iterative method, one of the Krylov subspace projection methods. The described methodology was applied to the NACA0012 test case in subsonic and in transonic conditions and, finally, for the first time to the authors knowledge, on an industrial multi-component geometry, such as the A310 airfoil, in order to identify low frequency instabilities related to the separation. One important conclusion is that for all the analyzed geometries, one unstable mode related to flow separation appears for an angle of attack greater than the one correspondent to the maximum lift coe?cient condition. Finally, an adjoint study was carried out in order to evaluate the receptivity and the structural sensitivity of the geometries, giving an indication of the domain region that could be modified resulting in the biggest change of the flowfield

Magnetoconvection in HCLL Blankets (KIT Scientific Reports ; 7672)

The present numerical study aims at clarifying the influence of electromagnetic and thermal coupling of neighboring fluid domains on magneto-convective flows in geometries relevant for the helium cooled fusion blanket concept

Induction of Protective Genes Leads to Islet Survival and Function

Islet transplantation is the most valid approach to the treatment of type 1 diabetes. However, the function of transplanted islets is often compromised since a large number of β cells undergo apoptosis induced by stress and the immune rejection response elicited by the recipient after transplantation. Conventional treatment for islet transplantation is to administer immunosuppressive drugs to the recipient to suppress the immune rejection response mounted against transplanted islets. Induction of protective genes in the recipient (e.g., heme oxygenase-1 (HO-1), A20/tumor necrosis factor alpha inducible protein3 (tnfaip3), biliverdin reductase (BVR), Bcl2, and others) or administration of one or more of the products of HO-1 to the donor, the islets themselves, and/or the recipient offers an alternative or synergistic approach to improve islet graft survival and function. In this perspective, we summarize studies describing the protective effects of these genes on islet survival and function in rodent allogeneic and xenogeneic transplantation models and the prevention of onset of diabetes, with emphasis on HO-1, A20, and BVR. Such approaches are also appealing to islet autotransplantation in patients with chronic pancreatitis after total pancreatectomy, a procedure that currently only leads to 1/3 of transplanted patients being diabetes-free

Vegan foods: Mimic meat products in the Italian market

The current concern about meat consumption tackles many aspects: health, social life, food behaviours, animal welfare, natural resources exploitation. People are more sensitive about these topics and they are shifting individual food habits in favour of a more plant-based diet. Surveys provide a concise view of the increasing percentage of both vegetarians and vegans. The aim of the present research was to develop adequate recipes to prepare food products that mimic the shape and the texture of traditional würstel and Mortadella, focusing on the Italian market. The challenge faced was multiple: firstly, to maintain the similar characteristics of the traditional foods; secondly, to accomplish the consumer's requests; thirdly, to enlarge the market share of the food industries. The results obtained demonstrated that “mimic- würstel” and “mimic-mortadella” were created with vegan allowed ingredients and proteins of vegetal origin. In the case of “mimic-mortadella” the addition of tofu cubes tried to recreate the visual effect of fat globules

In vitro effects of cocaine on tunneling nanotube formation and extracellular vesicle release in glioblastoma cell cultures

The effects of cocaine (150 nM, 300 nM, and 150 μM) on human glioblastoma cell cultures were studied on tunneling nanotube formation (1-h cocaine treatment) and extracellular vesicle release (1-, 3-, and 8-h cocaine treatment). Cocaine significantly increased the number of tunneling nanotubes only at the lowest concentration used. The release of extracellular vesicles (mainly exosomes) into the medium was stimulated by cocaine at each concentration used with a maximum effect at the highest concentration tested (150 μM). Moreover, cocaine (150 nM) significantly increased the number of vesicles with 61-80 nm diameter while at concentrations of 300 nM and 150 μM, and the smaller vesicles (30-40 nm diameter) were significantly increased with a reduction of the larger vesicles (41-60 nm diameter). A time dependence in the release of extracellular vesicles was observed. In view of the proposed role of these novel intercellular communication modes in the glial-neuronal plasticity, it seems possible that they can participate in the processes leading to cocaine addiction. The molecular target/s involved in these cocaine effects could be specific molecular components of plasma membrane lipid rafts and/or cocaine-induced modifications in cytoplasmic lipid composition