Beryllium-10 production in gaseous protoplanetary disks and implications for the astrophysical setting of refractory inclusions

Calcium-aluminum-rich inclusions (CAIs), the oldest known solids of the solar system, show evidence for the past presence of short-lived radionuclide beryllium-10, which was likely produced by spallation during protosolar flares. While such 10Be production has hitherto been modeled at the inner edge of the protoplanetary disk, I calculate here that spallation at the disk surface may reproduce the measured 10Be/9Be ratios at larger heliocentric distances. Beryllium-10 production in the gas prior to CAI formation would dominate that in the solid. Interestingly, provided the Sun’s proton to X-ray output ratio does not decrease strongly, 10Be/9Be at the CAI condensation front would increase with time, explaining the reduced values in a (presumably early) generation of CAIs with nucleosynthetic anomalies. CAIs thus need not have formed very close to the Sun and may have condensed at 0.1–1 AU where sufficiently high temperatures originally prevailed.

Numerical Sensitivity Studies on Nucleation of Droplets in Steam Turbine

This work presents the results of canonical test cases that highlight the importance of nucleation bulk surface tension factor (NBTF) on CFD predictions for condensing flows in steam turbines. Numerical simulations are carried out on nozzle and cascade geometries to explore modeling effects on the condensation of water vapor. The recent Euler-Euler approach [10] for modeling homogeneous condensation provides better results than the equilibrium assumption. Modeling of the nucleation rate plays a significant role in the non-equilibrium approach and it depends on the free surface energy of each droplet. NBTF is introduced in the classical homogeneous condensation nucleation rate expression to control the intensity of the homogeneous condensation event [3, 10]. It is observed that the NBTF controls the location of the condensation front, degree of super cooling, wetness fraction and droplet size. In addition, no unique value of NBTF is found in the range of simulations to match the experimental observations. Finally, by increasing the value of NBTF from 0.7 to 1.0 for a particular nozzle case, the location of condensation front is shown to be delayed by 60 mm and super cooling increased by 20%. This in turn will affect quantities such as the flow angle, pressure at the blade row exit and the thermodynamic loss which are relevant for the turbine designer.

Numerical Modeling of Steam Injection Into Saturated Porous Media

The Steam Enhanced Extraction (SEE) process is being considered for removal of volatile organic contaminants contained in the fractured basalt rocks which lie above the Snake River aquifer at the Idaho National Engineering and Environmental Laboratory (INEEL). In this work the computer code M2NOTS (Multiphase Multi-component Non-isothermal Organic Transport Simulator) was used to simulate an experiment which tracked the movement of a steam condensation front through glass blocks separated by glass beads. The experiment was designed to represent steam injection into highly fractured basalt. For grid spacing equal to the block size heat transfer from the fractures to the blocks was severely under predicted, resulting in an over prediction of the condensation front velocity. A method was developed to accurately simulate the propagation of a steam condensation front through a fractured porous media using grid spacing equal to the block dimension. The method accounts for non-equilibrium conduction within a grid node, allowing the grid spacing to be increased well beyond the local equilibrium restriction. Simulation results compare well with the experimental results, validating the non-equilibrium model, and also indicating that M2NOTs can be effectively used to model the steam enhanced extraction process in fractured porous media.

Surface Laser Plasma in Laser Treatment of Materials in High Pressure Gases

Using holographic interferometry the surface laser plasma generation in high pressure gases has been investigated. Additional information about the generation of surface cover laser plasma, optical breakdown in the presence of aerosol particles and condensation front forming in high pressure gases is given.