The absolute radiation measurements obtained in the electric arc-driven shock-tube facility at NASA Ames Research Center were analyzed to test the collisional-radiative model developed at École Cen...

Studies of the ultraviolet and visible emission from an atmospheric pressure air plasma and its interaction with two carbon-based ablative materials were performed in an inductively coupled plasma torch. These experiments were conducted at a plate power of 40 kW, which produced an air plasma in local thermodynamic equilibrium with a maximum temperature of approximately 6200 K, corresponding to a specific enthalpy of 16.4 MJ/kg. Three techniques were developed to measure the ablator surface temperature. Recession rates and product species profiles were measured for two different materials (ASTERM™ and carbon-bonded carbon fiber) at a plasma velocity of approximately 20 m/s. Measured surface temperatures were in the range of 2100 to 2300 K, and corresponding hot-wall heat fluxes were approximately 1.4 MW/m2. Spatially resolved profiles of the main species detected in the boundary layer were recorded, and they showed evidence of strong coupling between the ablated material and the freestream.

Experimental pitot pressure measurements in impulse facilities have typically had large-scale harmonic fluctuations associated with them. A combined experimental and numerical approach is used to investigate if a Helmholtz resonance is created from the shrouding that protects the pressure sensor from particle impact, rather than from disturbances being present in the freestream. To verify this experimentally, hydraulic oil was used to change the sound speed in the cavity. Numerical calculations of the pitot probe were used to show that both the steady and the expected transient inflow cause a Helmholtz resonance of similar period. However, a 5% isothermal level of freestream noise was required to match the experimental fluctuation levels. Viscous effects were also shown to be significant during the initial transient response of the pressure measurement. A new pitot probe design was successfully tested and shown to be able to reduce the magnitude and period of the fluctuations

This paper concerns the 3D simulation of corona discharge using high performance computing (HPC) managed with the message passing interface (MPI) library. In the field of finite volume methods applied on non-adaptive mesh grids and in the case of a specific 3D dynamic benchmark test devoted to streamer studies, the great efficiency of the iterative R&B SOR and BiCGSTAB methods versus the direct MUMPS method was clearly demonstrated in solving the Poisson equation using HPC resources. The optimization of the parallelization and the resulting scalability was undertaken as a function of the HPC architecture for a number of mesh cells ranging from 8 to 512 million and a number of cores ranging from 20 to 1600. The R&B SOR method remains at least about four times faster than the BiCGSTAB method and requires significantly less memory for all tested situations. The R&B SOR method was then implemented in a 3D MPI parallelized code that solves the classical first order model of an atmospheric pressure corona discharge in air. The 3D code capabilities were tested by following the development of one, two and four coplanar streamers generated by initial plasma spots for 6 ns. The preliminary results obtained allowed us to follow in detail the formation of the tree structure of a corona discharge and the effects of the mutual interactions between the streamers in terms of streamer velocity, trajectory and diameter. The computing time for 64 million of mesh cells distributed over 1000 cores using the MPI procedures is about 30 min ns ⁻¹ , regardless of the number of streamers.

Cyclic tetrapeptides are a class of natural products that have been shown to have broad ranging biological activities and good pharmacokinetic properties. In order to synthesise these highly strained compounds a ring contraction strategy had previously been reported. This strategy was further optimised and a suite of techniques, including the Edman degradation and mass spectrometry/mass spectrometry, were developed to enable characterisation of cyclic tetrapeptide isomers. An NMR solution structure of a cyclic tetrapeptide was also generated. To illustrate the success of this strategy a library of cyclic tetrapeptides was synthesised.