Green run test assessment of the high-altitude simulation test facility for liquid attitude and orbit control engines

This study aims to validate the operational capabilities of a newly developed high-altitude simulation test facility (HASTF), designed for 5000 N-class liquid bipropellant NTO/MMH attitude and orbit control engines. To reduce safety risks and testing costs, as well as to enhance test reliability, we selected a low-thrust 50 N engine, which represents down to 1% of the maximum thrust level, to conduct the Green Run Test (GRT) of the HASTF. The GRT validation followed a phased, step-by-step approach to ensure comprehensive and manageable assessment. This approach consisted of three tests, with each test building upon the previous one as a prerequisite for the next. The test results demonstrated successful engine ignition and stable combustion during Test 1, the achievement of ≤2 Pa vacuum chamber pressure to simulate bipropellant triple-phase point ignition at an altitude of 76 km during Test 2, and the achievement of ≤220 Pa vacuum chamber pressure to simulate full flow short-duration steady-state operation above 42 km during Test 3. The results of the GRT, covering 35 key parameters for the HASTF, demonstrate that the approach successfully validates 89.7% of the critical parameters required to assess the performance of the HASTF. This not only strengthens our confidence in using this HASTF for higher thrust engine testing but also highlights the GRT approach's ability to evaluate the validation degree of similar test facilities, confirming its broad applicability for future testing scenarios.