Pipe flow resistance characteristics of test system for low-thrust NTO/MMH rocket engines with high chamber pressure

To research the pipe flow resistance characteristics of the low-thrust NTO/MMH (nitrogen tetroxide/methyl hydrazine) rocket engine with high chamber pressure, comparative analysis of pipe flow resistances on the theoretical analysis, cold-flow tests and firing tests were conducted. According to the calculation methods of flow energy loss, the theoretical analysis models of NTO/MMH pipe flow resistance were established. After alcohol-cold-flow tests and low-thrust NTO/MMH rocket engine's firing tests with high chamber pressure, the pipe flow resistance characteristics fitting formulas based on test results were obtained with the least-square method. Compared with the cold-flow test results, when mass flow rates of alcohol were 0.10~0.40 kg/s, 0.09~0.36 kg/s respectively, the average errors of theoretical flow resistances of NTO/MMH pipes were 5.42% and 3.67%. With the results of firing tests, when mass flow rates of NTO/MMH were 0.39~0.47 kg/s, 0.26~0.31 kg/s respectively, the average errors of theoretical flow resistances of NTO/MMH pipes were 2.44% and 2.47%, and those based on cold-flow tests of NTO/MMH pipes were 5.74% and 3.46%, but when mass flow rates of NTO were 0.47~0.51 kg/s (without 0.47 kg/s), the average errors of theoretical flow resistence and cold-flow tests increased to 16.56% and 9.73%. These NTO/MMH flow resistance characteristics acquired from firing tests could be applied in the firing test, providing a necessary support in design of the rocket engine test system in the future.