Kiyomichi Ishida

Spectroscopic Flow Evaluation in Inductively Coupled Plasma Wind Tunnel

Radiation spectroscopy of high-enthalpy flows in a 110-kW-class inductively coupled plasma wind tunnel is conducted to improve the accuracy of the radiation code and to measure the flow properties in the test section of the wind tunnel in detail. Imaging spectroscopy is done to obtain radial profiles of emission spectra at a single moment, from which the radial distribution of the emission intensity is determined by the inverse Abel conversion. The molecular temperature and the chemical species concentration are determined by the spectrum fitting method through the use of the radiation code, SPRADIAN2. To accomplish better agreement between the numerical predictions and experiments, the theoretical model and the spectroscopic data for the radiation code are replaced with more accurate data to reflect the recent experimental and theoretical results. As a result, the radial distributions of the temperature, the concentration of the impurities as well as the major chemical components, and the flow enthalpy are accurately determined for nitrogen and air flows in the test section of the wind tunnel.

Laser induced fluorescence of nitric oxide and atomic oxygen in an arc heated wind tunnel

Laser induced fluorescence diagnosis system for NO and O detection has been introduced in the 750kW arc heated wind tunnel in JAXA. Parameters in the measurement have been optimized and operational wind tunnel conditions for the LIF measurement has been determined. Nitric oxide fluorescence was observed at a total enthalpy no greater than 10 MJ/kg. Whereas atomic oxygen fluorescence was observed at a total enthalpy less than 20 MJ/kg in this wind tunnel. It was observed that the center of excited wavelength is shifted in the shock layer. The Doppler shift due to the free stream velocity has a same order effect on excitation wavelength. The translational temperature was reduced from the measurement using spectral broadening of atomic oxygen excitation spectrum.

110 kW New High Enthalpy Wind Tunnel heated by Inductively-Coupled-Plasma

New inductively coupled plasma-heated wind tunnel was completed and some performance evaluations have been conducted to simulate atmospheric reentry environment and to study catalytic effect and so on. Maximum power of this wind tunnel is 110 kW, and maximum total enthalpy is presently about 20 MJ/kg. The electronic excitation temperature was evaluated in the torch, and it was about 10000 K. This result was compared with real gas CFD analysis coupled with electromagnetic field. At the test section, maximum heat flux was about 1 MW/m 2 , and the obtained temperature of C/C-SiC samples was about 1500 degree C, which was same condition of actual flight. This new wind tunnel can operate more numbers of runs to obtain experimental data effectively than the existing arc-heated wind tunnel because of easiness of maintenance. This wind tunnel still has some problems, which are instability of the flow at low mass flow rate and effect of rotational flow. The modification of gas supply system might be needed as one of the idea to solve this problem.

Evaluation of Surface Catalytic Effect on TPS in 110kW ICP-heated wind tunnel

New 110kW inductively coupled plasma (ICP)-heated wind tunnel in JAXA-ISTA was constructed and some performance evaluations have been conducted to simulate atmospheric reentry environment. Using this wind tunnel, initial heating tests for catalytic effect research were carried out, and new materials were tested to evaluate its characteristics including catalysis, emissivity, and so on. SiC coating samples showed comparatively low temperature, but high catalytic coating showed higher temperature. The difference was about 100 ~ 200 C, and it corresponded to 0.3 ~ 0.4MW/m 2 of heat flux. The difference of heat flux due to effect of catalytic effect was reasonable to compare with former CFD results for arc-heated wind tunnel tests. Ultra high temperature ceramic (UHTC) material was also tested, and its characteristics changed from low catalytic region to high catalytic region as the temperature increased. It was caused by changing catalytic effect and emmisivity due to oxidization.

CFD Evaluation of Pressure Effects on Surface Catalysis of SiO 2 -Based TPS

Effects of pressure on the surface catalysis of SiO2-based materials are investigated. The stagnation aerodynamic heat is measured in JAXA 750kW arc-heated wind tunnel under several flow conditions with the various pressure levels. Results are evaluated by comparing with CFD results with a reaction model describing heterogeneous finite rate catalysis. Four kinds of the testing conditions are chosen. Operating parameters for the arc-heated wind tunnel are adjusted to get each stagnation pressures ranging from 1.67 to 4.04 kPa. Agreements between CFD and experimental results are good for all four heating conditions within the error of less than 10%. Two kinds of definitions of catalytic efficiencies according to the difference of NO formation on the surface are estimated. For both ones, the influence of partial pressure of dissociating gases on the surface catalysis is clearly recognized. From this study, it is concluded that the dominant mechanism of recombination process should be the Langmuir- Hinshelwood type.

Diagnostic Experiments in an Arc-Heated Channel Nozzle Flow

The 750kW arc-heated (or arc-jet) wind tunnel is equipped with a channel nozzle to evaluate flat plate TPS materials. TPS materials tests for HOPE-X design data have been made with this channel nozzle, but the flow characteristics of the high enthalpy flow generated in the nozzle have not been well investigated. So, flow diagnostics experiments have been planned. Experimental items included in the plan are emission spectroscopy, mass spectrometry, heat flux measurements, and thermometry and direct surface observations of the test materials. A new calibration module was designed to install instrumentation necessary for the measurements of these items in the channel nozzle test section. Conception of the experiments, design details of the module, and main experimental results are presented.