Departamento de Bioingeniería e Ingeniería Aeroespacial
http://hdl.handle.net/10016/9269
2019-09-17T10:58:35ZDevelopment and validation of a radial variable geometry turbine model for transient pulsating flow applications
http://hdl.handle.net/10016/28820
Development and validation of a radial variable geometry turbine model for transient pulsating flow applications
Galindo, J.; Tiseira, A.; Fajardo Peña, Pablo; Garcia-Cuevas, L. M.
This paper presents the development and validation of a one-dimensional radial turbine model able to be used in automotive turbocharger simulations. The model has been validated using results from a numerical 3D CFD simulation of stationary and pulsating flow in a variable geometry radial turbine. As the CFD analysis showed, the main non-quasi-steady behavior of the turbine is due to the volute geometry, so special care was taken in order to properly model it while maintaining low computational costs. The flow in the volute has been decomposed in its radial and azimuthal direction. The azimuthal flow corresponds to the flow moving along the volute, while the radial flow is computed by coupling its flow with a stator model. Although the stator caused fewer accumulation effects than the volute, a small accumulation model has been used for it, which also allows to compute the evolution of the flow inside the turbine with lower costs. The flow in the moving rotor can be considered quasi-steady, so a zero-dimensional model for the rotor has been developed. Several losses models where implemented for both the stator and the rotor. The results show good agreement with the CFD computations.
2014-09-01T00:00:00ZElectron cooling and finite potential drop in a magnetized plasma expansion
http://hdl.handle.net/10016/28809
Electron cooling and finite potential drop in a magnetized plasma expansion
Martínez Sánchez, Manuel; Navarro Cavallé, Jaume; Ahedo Galilea, Eduardo Antonio
The steady, collisionless, slender flow of a magnetized plasma into a surrounding vacuum is considered. The ion component is modeled as mono-energetic, while electrons are assumed Maxwellian upstream. The magnetic field has a convergent-divergent geometry, and attention is restricted to its paraxial region, so that 2D and drift effects are ignored. By using the conservation of energy and magnetic moment of particles and the quasi-neutrality condition, the ambipolar electric field and the distribution functions of both species are calculated self-consistently, paying attention to the existence of effective potential barriers associated to magnetic mirroring. The solution is used to find the total potential drop for a set of upstream conditions, plus the axial evolution of various moments of interest (density, temperatures, and heat fluxes). The results illuminate the behavior of magnetic nozzles, plasma jets, and other configurations of interest, showing, in particular, in the divergent plasma the collisionless cooling of electrons, and the generation of collisionless electron heat fluxes.
2015-05-05T00:00:00ZParticle modeling of radial electron dynamics in a controlled discharge of a Hall thruster
http://hdl.handle.net/10016/28757
Particle modeling of radial electron dynamics in a controlled discharge of a Hall thruster
Domínguez Vázquez, Adrián; Ahedo Galilea, Eduardo Antonio; Taccogna, F
An improved radial particle-in-cell model of an annular Hall effect thruster discharge with secondary-electron emission from the walls and a radial magnetic field is presented. New algorithms are implemented: first, to adjust the mean neutral density to the desired mean plasma density; second, to avoid the refreshing of axially accelerated particles; and third, to correctly weigh low-density populations (such as secondary electrons). The high-energy tails of the velocity distribution functions of primary and secondary electrons from each wall are largely depleted, leading to temperature anisotropies for each species. The secondary-electron populations are found to be partially recollected by the walls and partially transferred to the primary population. The replenishment ratio of the primary high-energy tail is determined based on the sheath potential fall. Significant asymmetries at the inner and outer walls are found for the collected currents, the mean impact energy, and the wall and sheath potentials. Radial profiles in the plasma bulk are asymmetric too, due to a combination of the geometric expansion, the magnetic mirror effect, and the centrifugal force (emanating from the E x B drift). The temperature anisotropy and non-uniformity, and the centrifugal force modify the classical Boltzmann relation on electrons along the magnetic lines.
Special issue on plasma-surface Interactions
2018-06-01T00:00:00ZFibroblast activation and abnormal extracellular matrix remodelling as common hallmarks in three cancer-prone genodermatoses
http://hdl.handle.net/10016/28743
Fibroblast activation and abnormal extracellular matrix remodelling as common hallmarks in three cancer-prone genodermatoses
Chacón Solano, Estebán Gonzalo; León Canseco, Carlos; Diaz, F.; Garcia-Garcia, F.; García Díez, Marta; Escámez Toledano, María José; Guerrero Aspizua, Sara; Conti, Claudio Jorge; Mencía Rodríguez, Ángeles; Martínez Santamaría, Lucia; Llames, S.; Pévida, M.; Carbonell-Caballero, J.; Puig-Butille, J.A.; Maseda, R.; Puig, S.; Lucas, R. de; Baselga, E.; Larcher Laguzzi, Fernando; Dopazo, J.; Río Nechaevsky, Marcela del
Background. Recessive dystrophic epidermolysis bullosa (RDEB), Kindler syndrome (KS) and xeroderma pigmentosum complementation group C (XPC) are three cancer-prone genodermatoses whose causal genetic mutations cannot fully explain, on their own, the array of associated phenotypic manifestations. Recent evidence highlights the role of the stromal microenvironment in the pathology of these disorders. Objectives. To investigate, by means of comparative gene expression analysis, the role played by dermal fibroblasts in the pathogenesis of RDEB, KS and XPC. Methods. We conducted RNA-Seq analysis, which included a thorough examination of the differentially expressed genes, a functional enrichment analysis and a description of affected signalling circuits. Transcriptomic data were validated at the protein level in cell cultures, serum samples and skin biopsies. Results. Interdisease comparisons against control fibroblasts revealed a unifying signature of 186 differentially expressed genes and four signalling pathways in the three genodermatoses. Remarkably, some of the uncovered expression changes suggest a synthetic fibroblast phenotype characterized by the aberrant expression of extracellular matrix (ECM) proteins. Western blot and immunofluorescence in situ analyses validated the RNA-Seq data. In addition, enzyme-linked immunosorbent assay revealed increased circulating levels of periostin in patients with RDEB. Conclusions. Our results suggest that the different causal genetic defects converge into common changes in gene expression, possibly due to injury-sensitive events. These, in turn, trigger a cascade of reactions involving abnormal ECM deposition and underexpression of antioxidant enzymes. The elucidated expression signature provides new potential biomarkers and common therapeutic targets in RDEB, XPC and KS.
2019-09-01T00:00:00Z