design, manufacturing and test of china's largest niobium alloy rocket nozzle
- Paper ID
96404
- DOI
- author
- company
LandSpace Technology Corporation Ltd.
- country
China
- year
2025
- abstract
LandSpace Technology Co., Ltd. successfully flight-proved China's most powerful methane-fueled orbital rocket engine named TianQue-15A (TQ-15A) during ZhuQue-2E (ZQ-2E) launch vehicle's maiden flight in November 2024. TQ-15A is a vacuum-optimized 85tf-level gas-generator cycling engine, reasonably designed to have a single-layer radiation-cooled nozzle for the purpose of achieving vacuum specific impulse as high as possible. Given the cost efficiency and engine operation conditions, niobium alloy is selected to be the most preferable material for the nozzle manufacturing. Performances of the second stage require the nozzle supposed to be at least 1.6m in diameter at the exit. Moreover, the turbine exhaust needs to be injected into the nozzle for the elimination of non-axial thrust disturbance. CFD simulation associated with parametric trade-off study revealed the optimum pressure ratio of turbine exhaust to thrust chamber main flow at their mixing point, which affects the vacuum specific impulse and temperature profile on the nozzle significantly. FEA simulation calculated the modal characteristics and the damping coefficient under vibration conditions, resulting two triangular cross-section reinforce rings to be welded onto the nozzle. Atmospheric laser welding was determined to bond all the niobium alloy pieces avoiding expensive large-scale vacuum electrical beam welding, after sheet metal forming and machining processes. Correspondingly, a highly reliable and elegant Argon atmosphere protection method was developed preventing oxidization by air, which ended up with that the tensile strength and elongation of welds are not less than 95 percent of the raw material performances. A full-scale pathfinder nozzle was manufactured before the flight article, in order to conduct the vibration test, and then shortened for the hot-fire test on the ground. The temperature on the nozzle was optically measured during the ground test, which was well matched with the CFD results. The data review after the first flight indicated that the vacuum specific impulse of the TQ-15A engine achieved and even got beyond 3350m/s with the help of this niobium alloy nozzle.