Search results for "FD"

Transient Electrical Behaviour of the TF Superconducting Coils of Divertor Tokamak Test Facility During a Fast Discharge

2022

The paper is focused on the electromagnetic analysis of the Toroidal Field (TF) superconducting coils of the Divertor Tokamak Test facility (DTT) when electrical transients occur in the TF coils system: for example, during the operations of the Fast Discharge Units (FDUs) and considering also, the simultaneous occurrence of a fault condition. During the FDU intervention, a transient voltage excitation lasting few microseconds occurs at the TF coil terminals and it electrically stresses the insulations of TF coils itsef. To investigate the voltage distribution across, inside and between different Double Pancakes (DPs) of each TF coil, a lumped parameters circuital model has been developed an…

Theoretical and Experimental Comparison between the Resistance Components of a fast Catamaran in different Configurations

2009

The investigation performed by the Authors represents the most recent development of a research presented in [1] and [2], in which the geometrical solutions of the hull have been obtained through an optimization process, made by using the CFD numerical methods. The most important result of this optimization was the wave resistance reduction, which arrived up to 20% of the total initial resistance. In this further process the hull catamaran model has been built and tested at the towing tanks of the Universities of Naples and Trieste. The results obtained in the numerical process have been compared with the experimental ones and the reliability of the numerical results will be proved. Then th…

Homeward Bound FDI: Are Migrants a Bridge over Trouble Finance?

2016

Migrants can lower cross-border investment barriers, help investors by providing information about their homeland and reduce transaction costs by sharing expertise on regulations, customs and procedures. In addition to generating these well-known networking effects, migrants can also provide valuable information about local finance, thereby easing the credit constraints foreign investors faced during the 2007 financial crisis. This paper sheds new light on the underlying mechanisms through which migration may affect foreign investment in the migrant's homeland by distinguishing between the effects on FDI's intensive and extensive margins. Gravity estimates for 140 countries for the period 2…

Analysis of steady state thermal-hydraulic behaviour of the DEMO Divertor cassette body cooling circuit

2017

Abstract Within the framework of the Work Package DIV 1 – “Divertor Cassette Design and Integration” of the EUROfusion action, a research campaign has been jointly carried out by ENEA and University of Palermo to investigate the thermal-hydraulic performances of the DEMO divertor cassette cooling system. A comparative evaluation study has been performed considering the two different options under consideration for the divertor cassette body coolant, namely subcooled pressurized water and helium. The research activity has been carried out following a theoretical-computational approach based on the finite volume method and adopting a qualified Computational Fluid-Dynamic (CFD) code. CFD analy…

A geometric approach for predicting vertical stationary profiles of weakly inertial advecting-diffusing particles in closed incompressible flows

2004

Abstract Mixing of weakly inertial particles in closed flows is often addressed by considering individual particles as passive advecting-diffusing tracers, subjected to an additional settling velocity resulting from body forces (e.g. gravity). We show that the qualitative and quantitative features of the vertical particle distribution (i.e. the horizontal cross-sectional averages of particle concentration) can be predicted from the structure of the flow resulting from the superposition of the stirring field and the settling velocity. The prediction is based upon the observation that the resulting flow can be divided into two nonoverlapping regions, namely trajectories that are confined with…

Low-Prandtl Number Natural Convection in Volumetrically Heated Rectangular Enclosures - III. Shallow Cavity, AR=0.25

2001

Abstract Natural convection in a volumetrically heated rectangular enclosure filled with a low-Prandtl number (Pr=0.0321) fluid was studied by direct numerical two-dimensional simulation. The enclosure had isothermal side walls and adiabatic top/bottom walls. The aspect ratio was 4 and the Grashof number Gr, based on conductive maximum temperature and cavity width, ranged from 3.79 × 104 to 1.26 × 109. According to the value of Gr, different flow regimes were obtained: steady-state, periodic, and chaotic. The first instability of the steady-state solution occurred at Gr≈3×105; the resulting time-periodic flow field consisted of a central rising plume and of convection rolls, periodically ge…

MHD free convection in a liquid-metal filled cubic enclosure. II. Internal heating

2002

The buoyancy-driven magnetohydrodynamic flow in a liquid-metal filled cubic enclosure was investigated by three-dimensional numerical simulation. The enclosure was differentially heated at two opposite vertical walls, all other walls being adiabatic, and a uniform magnetic field was applied orthogonal to the temperature gradient and to the gravity vector. The Rayleigh number was 105 and the Prandtl number was 0.0321 (characteristic of Pb–17Li at 573 K). The Hartmann number was made to vary between 102 and 103 and the electrical conductance of the walls between 0 and ∞. The continuity, momentum and enthalpy transport equations, in conjunction with a Poisson equation for the electric potentia…

Investigation of Flow and Heat Transfer in Corrugated-Undulated Plate Heat Exchangers

2000

An experimental and numerical investigation of heat transfer and fluid flow was conducted for corrugated-undulated plate heat exchanger configurations under transitional and weakly turbulent conditions. For a given geometry of the corrugated plates the geometrical characteristics of the undulated plates, the angle formed by the latter with the main flow direction, and the Reynolds number were made to vary. Distributions of the local heat transfer coefficient were obtained by using liquid-crystal thermography, and surface-averaged values were computed; friction coefficients were measured by wall pressure tappings. Overall heat transfer and pressure drop correlations were derived. Three-dimen…

MHD free convection in a liquid-metal filled cubic enclosure. I. Differential heating

2002

On natural convection in a single and two zone rectangular enclosure

1992

Abstract Convective heat transfer was investigated numerically for rectangular enclosures both undivided and divided in two zones by a vertical partition, and having opposite isothermal walls at different temperatures. The aspect ratio was varied from 0.1 to 16 and the Rayleigh number from 3.5 ∗ 10 3 to ∗ 10 7 (non-partitioned enclosures) and from 1.0 ∗ 10 5 to 1.6 ∗ 10 8 (partitioned enclosures). The thickness and conductivity of the partition were varied. The end wall thermal boundary conditions were adiabatic or LTP (Linear Temperature Profile). The continuity, momentum and energy equations for a 2-D laminar steady flow were solved under the Boussinesq approximation by using a finite-dif…