National Aerospace Laboratory Kakuda Research Center
National Aerospace Laboratory Kakuda Research Center
National Aerospace Laboratory Kakuda Research Center
National Aerospace Laboratory Kakuda Research Center
National Aerospace Laboratory Kakuda Research Center
National Aerospace Laboratory Kakuda Research Center
National Aerospace Laboratory Kakuda Research Center
National Aerospace Laboratory Aeroengine Division
National Space Development Agency of Japan
Mitsubishi Heavy Industries Ltd
Ceramic thermal barrier coating systems will be of growing importance for the reusable high performance Orbiting Maneuvering Engine (OME). These coatings have been previously studied for many years aiming to improve the resistance to extreme conditions of high temperatures and oxidizing atmosphere at the inner walls of the combustion chamber. 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, as shown in the test results of the thermal fatigue properties of Functionally Graded Materials (FGM) specimens, 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 FGM. In this test series, High Altitude Performance Tests (HAPT) of a regeneratively cooled 1,200 N thrust engine composed of ZrO2/Ni FGM chambers were conducted with Nitrogen Tetroxide/Monomethyl Hydrazine (NTO/MMH) bipropellant. To enhance the engine performance, the high performance unlike quadlet element injector was employed. The film cooling fraction was reduced to zero percent of the total fuel flow rate to obtain high performance. The combustion chamber used in HAPT was composed of perfect ZrO2/Ni FGM, i.e., the chamber inner wall was made of ZrO2-8 percent Y2O3 (8YSZ: 100 vol percent), the cooling wall side was made of pure Ni and intermediate materials were ZrO2/Ni FGM. The method of applying perfect FGM is to spray 8YSZ mixed with NiCoCrAlY onto a mandrel and electro-form onto the sprayed 8YSZ (24.5 vol percent)/NiCoCrAlY (75.5 vol percent) FGM layer. It is believed that this reversed process of composing perfect FGM will provide an improved ceramic-metal bond between the sprayed FGM layer and electro-formed FGM layer. This series of tests was initiated at Kakuda Research Center (KRC) to evaluate the real engine performance and to study the effect of FGM coatings on thrust chamber life. A total of 50 firing tests including sea level tests were performed to evaluate the engine performance in terms of vacuum specific impulse (I(sub spv)), and also to obtain chamber thermal data. The high performance of the engine, i.e., I(sub spv) = 318 s at P(sub c) = 1.4 MPa, was verified. This paper also presents the preliminary design concept of FGM, used for the thrust chamber, which prolongs thrust chamber life.
ZrO2/Ni系完全傾斜機能型燃焼器の高空性能試験
naltr0001327.pdf
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