並列タイトル等A Requirement Consideration of Future Arc-heated Wind Tunnels for TPS Evaluation
一般注記Two major arc heated wind tunnels in JAXA both have contributed to projects of reentry missions for years, though their capabilities may not meet requirements of future missions, which include sample return from even further astronomical objects, or vehicles equipped with larger size of Thermal Protection System (TPS). Figured out is the crucial flow parameters in the arc heated wind tunnel testing with which proper evaluations for the TPS materials can be made under expected flow conditions for future missions. Reproducing both the heating rate and the surface pressure has been required in most situations where not only the pyrolysis or fusion but also oxidization is to consider. Accordingly, too low wind tunnel total enthalpy compared with the flight would cause very small size of testing specimen to achieve the heating rate with the specific pressure. Provided that ϕ40 mm in diameter is m+AF3inimum allowable size for evaluating TPS material characteristics, our preliminary analysis suggests that the total enthalpy of our future arc heated wind tunnel should cover as high as 60 MJ/kg considering to deal with the case of the reentering velocity of 15 km/s. Decreasing the fraction of oxygen in the working gas however allows higher impact pressure to achieve the required stagnation heating rate with the partial pressure of oxygen unchanged. In fact, the wind tunnel total enthalpy of 40 MJ/kg is found enough to reproduce reentering environments even at speeds of 15 km/s using 80% nitrogen diluted air as working gas. It is further shown that not only the heat flux or the oxygen partial pressure at the surface but diffusion of oxygen and of C3 by sublimation through the boundary layer can also be reproduced under lower total enthalpies than the flight conditions. By means of the strategy, depicted are requirements for the future arc-heated wind tunnel in JAXA which is well capable of evaluating TPS materials for future sample-return missions, after predicting representative flight environments. For missions with lower reentering speed but with larger and complicated TPS system, however, system evaluation would be sometimes required where partial prototype models are exposed to flight 'equivalent' thermal environment, though either of our current arc-heated wind tunnels in JAXA is not capable of testing specimen larger than ϕ50 mm in diameter. Defining representative flight environments of expecting large-size reentering missions from the low earth orbit and from lunar return orbit, additive requirements for the future arc-heated wind tunnel in JAXA for such missions are described supposing minimum size of specimen to be ϕ150 mm∼ ϕ200 mm. A comprehensive solution satisfying the requirements is then proposed, where total input power is roughly estimated as 17 MW supposing energy transfer efficiency as 25 % in high enthalpy operations of 40 MJ/kg with mass flow rate of 120 g/s.
形態: カラー図版あり
Physical characteristics: Original contains color illustrations
資料番号: AA2230007000
レポート番号: JAXA-RR-22-003
連携機関・データベース国立情報学研究所 : 学術機関リポジトリデータベース（IRDB）（機関リポジトリ）
提供元機関・データベース宇宙航空研究開発機構 : 宇宙航空研究開発機構リポジトリ