Study of Manufacturing Processes for Liquid Rocket Turbopump Impellers: Test and Analysis

Abstract: In the context of the cooperative development of the L75 Liquid Rocket Engine (with 75 kN of thrust) and in the frame of a global enlargement of competence in the field of turbomachines for liquid rocket propulsion systems, Institute of Space Propulsion of the German Aerospace Center (DLR; in German, Deutsches Zentrum für Luft- und Raumfahrt), in Lampoldshausen, and the Brazilian Institute of Aeronautics and Space (IAE; in Portuguese, Instituto de Aeronáutica e Espaço) have managed to produce its first flight ready components for pumps in liquid rocket propulsion systems. Among these components was a series of prototyped shrouded impellers for the oxidizer pumps manufactured in different materials and by different fabrication processes executed by four independent Brazilian and German workshops. Non-destructive and destructive testing methods have been applied for impellers materials validation, and for manufacturing processes verification. A special attention was given to the spin tests results and analysis, which included verification at maximum operational speed and burst testing, in order to determine the failure speed. Each tested impeller reached the required specification for the application in the L75 turbopump. Spin test logic and test results are discussed later on. Therefore, the scope of the present study is to investigate several traditional and cutting-edge processes applied for shrouded turbopump impellers manufacturing. A verification and validation of these processes will also be discussed.

摘要：在L75液体火箭发动机（推力75千牛）协同研发的背景下，以及拓展液体火箭推进系统涡轮机械（turbomachines）领域技术能力的整体框架内，位于德国兰普尔德豪森的德国宇航中心（German Aerospace Center，缩写DLR；德语原称Deutsches Zentrum für Luft- und Raumfahrt）空间推进研究所，与巴西航空航天研究所（Instituto de Aeronáutica e Espaço，缩写IAE）成功制备了首批适用于液体火箭推进系统泵类的飞行级组件。
其中包括一批用于氧化剂泵（oxidizer pumps）的带罩叶轮（shrouded impellers）原型件，这些原型件采用不同材料制造，并由巴西与德国的四家独立制造车间通过多种加工工艺完成制备。研究团队采用无损检测（non-destructive testing）与有损检测（destructive testing）方法，对叶轮材料进行验证并复核制造工艺。
研究重点聚焦于旋转试验（spin test）的结果与分析，其中涵盖最大运行速度下的性能验证及爆破试验（burst test），以确定叶轮的失效转速。所有受试叶轮均满足L75涡轮泵（turbopump）应用的规定技术指标。后续将对旋转试验的逻辑与结果展开详细讨论。
本研究的核心范围为探究适用于涡轮泵带罩叶轮制造的多种传统与前沿工艺，并对上述工艺的验证与确认流程进行探讨。