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Expecting that the laser propulsion is one of the most interesting next-generation space propulsion systems, it is important to analyze the mechanism of LSD (Laser-Supported Detonation) waves caused by laser absorption. The performance of laser propulsion is determined mainly by the laser absorption efficiency. We find that four physico-chemical processes take place in a LSD wave: (i) Laser energy is absorbed by free electrons through inverse bremsstrahlung. (ii) This energy is distributed to heavy particles (atoms and ions) through elastic and (iii) inelastic collisions, (iv) although it is partly lost as radiation emission by bremsstrahlung. We simulate this LSD wave, using 1-D and axi-symmetric 3-D models, and considering CO2 and CO lasers. Then we clarify the mechanism of LSD wave. Rapid radiation and ionization processes impose stiffness problems to the numerical analysis.

Interesting physics and chemistry can happen in LSD wave, including a number of unknown phenomena. As it is impossible to take into account all the phenomena occurring in the process of laser-absorption heating, a numerical simulation needs appropriate assumptions. In this simulation four chemical reactions (elastic collision, inelastic collision, bremsstrahlung and inverse bremsstrahlung) are considered for simplicity. It is also assumed that the laser light is focused spherically and all the physical quantities are solved by one-dimensional spherical coordinate. The propellant gas used here is Argon, while the source laser is CO2 (wave length λ = 10.6μm). The problem is described by the two governing equations; the laser intensity equation and Euler equation. Once LSD wave is formed, large discontinuity appears at the shock front, so that several devices are required in order to delete the stiffness. The temperature of electron is separated from that of heavy-particle.

A transversely injected jet into a hypersonic flow is simulated numerically in order to study the flow field of the injection jet in the hypersonic atmosphere, its heat flux on the body surface and the moments working on the body. The flowfields is governed by the two-dimentional Reynolds averaged full Navier-Stokes equations with an algebraic eddy viscosity model developed by Baldwin-Lomax. The governing equations are solved using the Harten-Yee type TVD and central difference schemes to the convex and viscous terms, respectively. The real gas effect is considered in the numerical analysis. The jets injected across the main flows of Mach 10 and 15 are compared.

An impingement of axisymmetric supersonic jet on the ground is simulated numerically to evaluate the jet flow configuration on the ground, which inclines from 0 to 45 degrees, with a real gas assumption for two-dimensional simulations and with an ideal gas assumption for three-dimensional simulations. A solid particle-suspended two-phase jet impinging on the ground is also solved using the Euler equations for the solid particle-phase with a real gas assumption. An explicit TVD-Upwind scheme is used for the gas-phase and an explicit Flux Vector Splitting Upwind scheme for the solid-phase. Numerical results of a vertically impinging jet to the ground show that a plate shock forms just above the ground for the cases of the single-phase and two-phase jet. Then the jet flow is curved along the ground after hitting the ground to form the so-called wall jet, which is expanded and recompressed alternately along the ground. The solid particles hit and stay on the ground in the present system.