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：在推力75千牛的L75液体火箭发动机（L75 Liquid Rocket Engine）协同研发背景下，处于拓展液体火箭推进系统涡轮机械领域全球技术能力的框架内，德国航空航天中心（DLR，德语全称Deutsches Zentrum für Luft- und Raumfahrt）兰普特豪森分院空间推进研究所与巴西航空航天研究院（IAE，葡萄牙语全称Instituto de Aeronáutica e Espaço）联合完成了液体火箭推进系统泵用首批飞行合格组件的研制。上述组件包含一批氧化剂泵用带罩原型叶轮，该系列叶轮采用不同材料制造，由四家巴西与德国独立工坊通过差异化制造工艺完成加工。研究团队采用无损检测与有损检测方法对叶轮材料进行验证，并对制造工艺开展核验。本次研究重点关注旋转试验（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破裂试验，以确定叶轮的失效转速。所有受试叶轮均满足L75涡轮泵应用的相关规范要求。后续将对旋转试验逻辑与试验结果展开详细讨论。本研究的核心范畴为探究适用于带罩涡轮泵叶轮的多种传统与前沿制造工艺，并对上述工艺的验证与确认流程展开探讨。