Forced convection boiling near inception in zero-gravity

Forced-convection boiling at low heat flux and flow velocities in zero gravity for slightly subcooled distilled wate

Body rotation effects on melting ablation

Rotation effects on melting ablation on reentry of axisymmetric bodie

Burning of solids in oxygen-rich environments in normal and reduced gravity

An experimental program was conducted to investigate the combustion characteristics of solids burning in a weightless environment. The combustion characteristics of thin cellulose acetate material were obtained from specimens burned in supercritical as well as in low pressure oxygen atmospheres. Flame spread rates were measured and found to depend on material thickness and pressure in both normal gravity (1-g) and reduced gravity (0-g). A gravity effect on the burning process was also observed; the ratio of 1-g to 0-g flame spread rate becomes larger with increasing material thickness. Qualitative results on the combustion characteristics of metal screens (stainless steel, Inconel, copper, and aluminum) burning in supercritical oxygen and normal gravity are also presented. Stainless steel (300 sq mesh) was successfully ignited in reduced gravity; no apparent difference in the flame spread pattern was observed between 1-g and 0-g

Gravitational Instabilities In A Protoplanetary Disk Including The Effects Of Magnetic-Fields

We investigate the gravitational instability of a thin, Keplerian protoplanetary disk including the effects of a largely azimuthal magnetic field. The model follows that of our previous work (Noh, Vishniac, & Cochran 1991) except for the inclusion of a magnetic field. The disk is assumed to consist of neutral and ionized gas and neutral dust which are coupled by gravity and friction. The growth rates and eigenfunctions are calculated numerically using nonaxisymmetric linear perturbation methods. The results show that the growth rate has a maximum at some intermediate azimuthal number m, but for each value of m it is reduced relative to the unmagnetized case. The effects of the magnetic field appear more strongly on small scales. As the strength of the equilibrium magnetic field increases the growth rates decrease, and the maximum instability occurs at a lower value of m due to the increasing magnetic pressure. The response of each component to the magnetic field is discussed using the behavior of the eigenfunctions in the radial direction. With the inclusion of the magnetic field, the effects of the ionization fraction and friction on the growth rates also appear to be important for high m modes. Increasing the ionization fraction or the friction suppresses instability, but only slightly changes the maximally unstable azimuthal scales. The enhanced growth rates due to a dust component for which thermal pressure is negligible are somewhat reduced by the inclusion of a magnetic field. The effects of different boundary conditions (reflecting and transmitting) on the growth rates are also shown.NASA NAGW 2418Astronom

Forced-convection peak heat flux on cylindrical heaters in water and refrigerant 113

An investigation was conducted of the peak heat flux on cylindrical heaters in a fluid flowing perpendicular to the major axis of the heater. The test fluids were water and Refrigerant 113. Heaters of 0.049 to 0.181 cm diameter were tested over a fluid velocity range of 10.1 to 81.1 cm/sec. The experimental results were observed to fall within two regions based on the vapor removal geometry: jets or sheets. Mathematical models for each region successfully correlated the data for both fluids

Effects of gravity on laminar gas jet diffusion flames

Zero gravity effects on laminar gas jet diffusion flame

“The Man That I Praise”: Generational Transformation of the Postcolonial Masculine Ideal in Cathleen ni Houlihan, At the Hawk’s Well, and On Baile’s Strand

Many of the plays of W.B. Yeats and Lady Gregory that were presented in the early years of the Abbey Theatre were allegorical works which promoted the cause of Irish nationalism. This impulse existed as a part of a larger political and literary movement to reject British rule and the idea of British exceptionalism in Ireland at the beginning of the 20th century, and it is one which aligns directly with Franz Fanon’s theory of decolonization. Within the plays Cathleen ni Houlihan, At the Hawk’s Well, and On Baile’s Strand this nationalist impulse is exemplified by young masculine characters who stand in stark contrast to the older generation of male characters in the play. Using Franz Fanon’s theory in conversation with Judith Butler’s theory of gender performativity, I argue that these plays constitute an attempt to redefine the masculine ideal in Ireland through depictions of a generational divide. I further argue that this is the result of anxieties around the process of decolonization, and that they constitute an attempt to shape the masculine ideal towards behavior that would facilitate violent armed resistance. This work exemplifies how the process of decolonization can and has influenced the performance of masculinity, and how it runs the risk of perpetuating patriarchal norms in the postcolonial society

Effects of pressure, oxygen concentration, and forced convection on flame spread rate of Plexiglas, Nylon and Teflon

Experiments were conducted in which the burning of cylindrical materials in a flowing oxidant stream was studied. Plexiglas, Nylon, and Teflon fuel specimens were oriented such that the flames spread along the surface in a direction opposed to flowing gas. Correlations of flame spread rate were obtained that were power law relations in terms of pressure, oxygen concentration, and gas velocity

Failure mechanisms of graphene under tension

Recent experiments established pure graphene as the strongest material known to mankind, further invigorating the question of how graphene fails. Using density functional theory, we reveal the mechanisms of mechanical failure of pure graphene under a generic state of tension. One failure mechanism is a novel soft-mode phonon instability of the $K_1$-mode, whereby the graphene sheet undergoes a phase transition and is driven towards isolated benzene rings resulting in a reduction of strength. The other is the usual elastic instability corresponding to a maximum in the stress-strain curve. Our results indicate that finite wave vector soft modes can be the key factor in limiting the strength of monolayer materials