Search

Laser energy deposition in quiescent air has been studied experimentally and numerically. The study is focused on the gasdynamic effects of the laser energy spot on the flow structure. A Gaussian profile for initial temperature distribution is proposed to model the energy spot assuming the density is initially uniform. A filtered Rayleigh scattering technique has been used for obtaining the experimental results. These consisted of flow visualization of the blast wave, and simultaneous pressure, temperature, and velocity measurements. Good agreement has been achieved between numerical and experimental results for shock radius vs time. The comparison of computed and experimental density, pressure, temperature, and velocity outside the laser spot show good agreement as well.

A supersonic flat-plate boundary layer at a Reynolds number of 2 x [10.sup.4] based on the inflow boundary layer thickness is investigated at different Mach numbers (34 =2.88 and 4) using the monotonically integrated large-eddy simulation (MILES) technique. The inherent numerical dissipation is taken as an implicit subgrid scales (SGS) model to close the Favre-filtered compressible Navier-Stokes (NS) equations. A finite volume method with second-order accuracy in time and space is implemented for the solution of the Navier-Stokes equations on an unstructured grid of tetrahedra. The heat transfer coefficient is predicted by simulating both adiabatic and isothermal cases. The mean flowfield and turbulent stresses are in good agreement with experiment. The relationship between the predicted skin friction coefficient and heat transfer coefficient is in close agreement with the Reynolds analogy factor. The variation of turbulent Prandtl number cross the boundary layer falls within the experimental envelope. These are the first LES predictions of adiabatic and isothermal supersonic flat plate boundary layers using the MILES technique. [DOI: 10.1115/1.1516578]

Research describes the synthesis of the phosphonate-functionalized phosphine triphenylphosphine triphosphonate (TPPTP) by reducing red phosphorus with lithium metal in liquid ammonia to generate phosphide anion to derive the tertiary phosphine, which upon acid hydrolysis yields TPPTP.