熱応力緩和型ＺｒＯ２／Ｎｉ系傾斜機能材料の再生冷却燃焼器への適用に関する研究 （その２） 完全ＦＧＭ型再生冷却エンジンの高空性能試験

Abstract

Ceramic thermal barrier coating systems will be of growing importance for the reusable high performance engine. These are very attractive ways to achieve a high performance engine because of their potential for reducing the film-cooling requirements in the rocket chamber. However, due to the large difference in thermal coefficient of expansion between the coating materials and the metal wall and the low ductility of the ceramic coating, cracks occur in the ceramic coating layer or spalling occurs during repeated thermal cycles. One method of improving adhesion of the coating to the metal wall is to apply functionally graded materials (FGM). In this test series, high altitude performance tests (HAPT) of a regeneratively cooled 1, 200N thrust engine composed of ZrO2-8%Y2O3(PSZ)/NiCr FGM chamber were conducted with nitrogen tetroxide/monomethyl hydrazine (NTO/MMH) bipropellant. To enhance the engine performance, we employed the high performance unlike quadlet element injector. The film cooling fraction was reduced to 0% of the total fuel flow rate to obtain high performance. The combustion chamber used in HAPT was composed of perfect PSZ/NiCr FGM, i. e., the chamber inner wall was made of PSZ, the cooling wall side was made of NiCr and intermediate materials were PSZ/NiCr FGM. A total of 50 firing tests including high altitude performance tests and sea level tests were performed to evaluate the engine performance in terms of vacuum specific impulse (ISPV), and also to obtain chamber thermal data. The high performance of the engine, i. e., ISPV=318s at PC=1.4MPa, was verified.