Termodinámica de la atmósfera

Se dice que el planeta Tierra debería llamarse planeta Agua, pues más del 70% de su superficie es acuosa, pero el aire aún ocupa más, y nos es más preciado si cabe a los animales terrestres (si falta el aire, es cuestión de vida o muerte en unos minutos), y particularmente a los ingenieros aeroespaciales. Cuando se diseñan sistemas de soporte de vida (aeroespaciales, submarinos u otros) las prioridades son: aire, agua, y alimento. La termodiná- mica es una de las ciencias básicas para comprender todos estos sistemas y los procesos que en ellos tienen lugar, puesto que es el calentamiento desigual de la superficie planetaria la fuente motriz de toda la maquinaria del tiempo meteorológic

Experimental analysis of the breakage of a liquid bridge under microgravity conditions.

The experimental results obtained of the experiment \STACO" made on board the Spacelab D-2 Mission are analyzed. The conguration consisted of a liquid bridge between two solid supporting disks. An expected breakage occurred during the experiment. The recorded images are analyzed and the measured behaviour compared with the results of three dimensional model

Experimental analysis of the vibration of a liquid bridge under microgravity conditions.

The experimental results obtained of the experiment \LICOR" made on board the Spacelab D-2 Mission are analyzed. The conguration consisted of a liquid bridge where one of the supporting disks was vibrated. The recorded images are analyzed and the measured behaviour compared with the results of one dimensional models. The results of two pressure sensors located in each of the supporting disks are also analyzed

Response of a liquid bridge to an acceleration varying sinusoidally with time

The response of a long cylindrical liquid column subjected to an axial microgravity field has been experimentally studied on a TEXUS sounding rocket flight to check with theoretical predictions. The expected response of the liquid bridge was a quasi-static amphora-type deformation of the cylindrical shape. However, the experimental results showed a more complex behaviour. Nevertheless it has been possible to find out the reasons of this discrepancy except for a mysterious 0.5% uncertainty in the stimuli

IMYEL

Esta obra contiene resultados y estudios llevados a cabo por el alumno, durante el Curso Académico 1974-75, sobre el proyecto teórico de la confección de un Satélite Geoestacionario de Información Meteorológica (IMYEL). Se ha pretendido dar una visión detallada de las posibilidades, y hacer un estudio particular de la solución considerada como nominal o de trabajo, pero es preciso reconocer que no siempre se ha llegado a conseguir este propósito básico, y que el tiempo ha sido el elemento más crítico en este desarrollo. Es por esto, que las diferentes partes del proyecto se han redactado de una forma no homogénea, y asi, ciertos subsistemas particularmente críticos o ligados directamente con la misión del sistema, se han tratado con cierta profusión quedando otros, que por considerarlos como menos difíciles o más familiares no han visto sus características más que sucintamente esbozadas en el curso de este análisis. Se ha hecho hincapié en la justificación de la elección de los sistemas opcionales, dejando un poco en el aire el análisis detallado del sistema nominal elegido, con la idea de dar unas bases, unas ofertas de elección, más amplias, y más interesantes que el simple cálculo numérico de un ejercicio teórico más o menos complicado. El contenido global queda detallado en el índice general de bloques que antecede a cada parte, y que consideramos muy intuitivo y simple, pero para un conocimiento más preciso de los temas aquí tratados, véase el índice detallado que figura al final de la obra. En rasgos generales, se incluye - un estudio de la misión trazada, y los requerimientos que lleva aparejados. - una descripción de los subsistemas que deberá comprender el satélite para satisfacerlos. - una breve descripción de algún punto caracteristico de otros satélites semejantes. - un estudio orbital en el que se incluye un pequeño estudio del vehículo lanzador - una descripción de equipos, correspondiente a un prediseño de conjunto, con unas consideraciones sobre fiabilidad — un análisis más profundo de los subsisteraas integrantes del satélite Se ha creído conveniente, por razones pedagógicas, incluir una breve Memoria Personal como colofón, por razones de esta obra, la cual no tiene otro objetivo que el dar una sincera opinión, muy subjetiva, sobre el trabajo llevado a cabo y las circunstancias que lo enmarcaron

Mechanical behaviour of liquid bridges in microgravity

The mechanical behaviour of liquid bridges is revisited with the emphasis in experimental work under microgravity conditions. A liquid bridge is a liquid mass spanning between two solid supports and held together by surface tension and wetting (i.e. capillary) forces, provided the other mechanical loads (due to gravity, vibration, rotation) are smaller. Apart of its own interest on ground for natural capillary systems, it offers some unique characteristics that makes it interesting for fluid physics research under microgravity. On the one side, the liquid bridge is the simplest mechanical model of the floating zone technique of crystal growth, a key process in material sciences for purification. On the other side, a particular instance of liquid bridges (the cylindrical shape) is one of the simpler free interfaces one can establish in space; the other (simplest) cases, the flat surface and the sphere are much more difficult to handle. Consequently, the liquid bridge configuration has been extensively used to study a number of difficult problems like Marangoni convection among others

Long liquid bridges aboard sounding rockets

Large free liquid volumes, 30 mm in diameter and 80 mm long, anchored to coaxial discs, have been achieved during a sounding-rocket flight. As these flights provide some six minutes of microgravity and the formation of the liquid column takes only a matter of seconds, ample time is left for experimentation. The results of these trials are presented, and the equipment used to obtain them is briefly described

Minimum volume for a liquid bridge between equal disks

The lower stability limit for axisymmetric floating zones at rest between equal coaxial disks has been experimentally verified for several disk-separation/disk-diameter ratios by using the neutral buoyancy technique. Results show a close agre ment with theory in the case of bridge disruption and a wide scatter in the case of bridge etachment

Effects of Axial and Centrifugal Forces on the Stability of Liquid Bridges

The equilibrium and stability equations for liquid bridges are well known, but they are nonlinear and it is difficult to guess real behavior, such as the sensitivity of the shape to axial and rotational forces (measured by Bond and Weber numbers, respectively) or to the geometry of the solid supports that support the bridge. A parametric study by numerical methods of the different effects and the analytical solutions at the bifurcation points in the stability diagrams is presented. The well known shooting method to numerically compute equilibrium shapes of liquid bridges, and their stability limits, is applied to a five parameter case, when different disc sizes (measured by H), bridge lengths (Lr), liquid volumes (Vr), residual axial acceleration (Bo), and solid body centrifugation (We) are contemplated. The bundle of diagrams presented give an idea of the complexities of such a multiparametric analysis and may help in further research to delimitate other forms of instability. The numerical results were used to check the validity of several analytical asymptotic expressions, with perfect agreement over the range of interest (long liquid bridges), but these models only take into consideration the subset (Lr, Vr = 1, H = 0, Bo, We) of the five parameter family. These results will be of great help to plan future space experiments on liquid columns and floating zones in space and in particular will show a method to easily measure very weak residual forces in microgravity platforms

Floating liquid zones

The aim of our experiment on the Spacelab Dl Mission was to study the stability of long liquid columns under microgravity. Nominal configuration was a cylindrical liquid bridge anchored at the edges of two equal solid discs, 35 mm in diameter. Mechanical stimuli were applied through the discs and the liquid outer shape recorded for analysis. Nominal experiment procedures [1] were similar to those proposed for Spacelab-1 (1983), where by wetting problems allowed only partial success [2]. The same Fluid Physics Module, but with corrected end discs and a manually operated syringe for liquid injection, was used