Application of Two-Photon Absorption Laser-Induced Fluorescence to Atomic Species in the JAXA 750 kW Arc-Heated Wind Tunnel

Abstract

Two-photon absorption laser induced fluorescence (TALIF) is applied to atomic oxygen and nitrogen generated in the JAXA 750 kW arc-heated wind tunnel in order to obtain velocity, translational temperature and atomic number density distributions. Free stream velocity is estimated by Doppler shift and the translational temperature distributions are deduced from spectral broadening. The absolute center excitation wavelength and laser line width are estimated with the TALIF profiles from a static reference cell which is called as a flow reactor. In this flow reactor, atomic species are generated by microwave discharge. The spatial distributions of atomic number density are deduced from the integrated TALIF profiles. The absolute atomic number densities inside the flow reactor are estimated with a titration method. From the mass fraction estimation, it is found that the number densities of atomic oxygen are overestimated owing to the saturation effect. When oxygen is assumed to be totally dissociated, the fractional enthalpies are estimated.

Estimation of the Highest Surface Temperature for CFRP Ablator by Raman Analysis

“…It is well known that a phenolic-based carbon fiber-reinforced phenolic resin composite, referred to as phenolic CFRP herein, has excellent heat resistance and insulation, and is currently used such as a rocket nozzle material of solid rocket and a thermal protection material for re-entry spacecraft. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] It is generally difficult to measure the in-situ temperature of this material in a real application, such as reentry capsules, from the ground. The unknown temperature of the material in such cases may lead to an inefficient design feedback due to the lack of validity of the simulation model relative to the actual usages.…”