SBIR Phase II: Design-Based Developments for Pump Cavitation Control

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This Small Business Innovation Research Phase II project is to provide the means to reliably calculate turbopump stiffness and damping matrices based on dynamic force measurements collected using a magnetic bearing rig. During Phase I exploratory development of a high suction specific speed (NSS) = 65,000 rocket engine turbopump pump stage was carried out and laid the foundation for this project. A complementary Phase I project for NASA focused on an NSS = 85,000 stage. Earlier Air Force funding concentrated on demonstrating magnetic bearings as a useful lab instrument. More recent breakthroughs include a novel fix for auto-oscillation and establishing the structure of an innovative dynamic force matrix measurement methodology. The primary challenge in this work is to isolate those forces on the rotor (with and without cavitation) due to the interaction of the impeller with the stator using innovative test and signal processing techniques. By testing a series of impellers, a database of rotordynamic coefficients will be established based on component dynamic force data. An additional objective is to evaluate the capability of CFD for replicating those physical force measurements. The goal is to create scientifically based design methods for lighter high-performance turbopumps. Smaller, lighter, and higher speed rocket engine turbopumps are required to meet lower space launch cost requirements. Successful accomplishment of this fundamentally based approach for measuring component specific rotor dynamic forces and a method for using experimental results on a broader basis in the design process can lead to a breakthrough technology. It will enable turbopump designers to overcome current thresholds due to hydraulic induced rotor dynamic instabilities. In addition to reducing equipment size and cost, reliability will improve. The technology is also applicable to industrial turbomachinery including industrial pumps, aircraft engine fuel pumps, and compressors.