Development of a modeling framework of the feeding system for the characterization of POGO oscillations

This thesis has been carried out within the framework of the MIT-UNIPI Project funded by MISTI Global Seed Funds and entitled “Dynamic Characterization of POGO Instabilities in Cavitating Turbopumps”, which provides a collaboration between the Massachusetts Institute of Technology and the University of Pisa, aiming to jointly develop a novel theoretical foundation capable of characterizing the dynamics of POGO oscillations and devising new design guidelines. The first section of this thesis deals with a literature review of the past POGO experiences of NASA human spaceflights and a collection of some procedures used to obtain a prediction of the dynamic performances of space rocket turbopumps. In the second part, a modeling framework defined in the time-domain has been developed to characterize the steady-state and dynamic behavior of each component of a typical feeding system for liquid rocket engines. A typical water loop for experimental characterization of liquid rocket turbopumps has been modeled according to the modeling framework in order to understand the best way to perform forced experiments for the characterization of the transfer matrix of cavitating turbopumps necessary for understanding the POGO instability phenomena that affect rocket launchers