Rotordynamic characteristics of High-Pressure Turbopump for 9.5ton thrust liquid propellant rocket engine

摘要

In this paper, we investigate rotordynamic stability of an LOX (oxidizer) and LCH4 (fuel) turbopump system for 9.5ton thrust liquid propellant rocket engine. Critical speed analysis and unbalance response analysis were conducted by use of finite element method. The finite element model consists of shaft with fifty-six elements, nine rigid disks and four ball bearings. An elastic damping ring was installed for the turbopump system to have sufficient safety margin. Campbell diagram in case no elastic damping ring showed the first critical speed of 44,000rpm and rather marginal safety of 12% from its operating speed of 50,000rpm. The use of elastic damping ring decreased the first critical speed from 44,000rpm to 15,769rpm, which led to the increased margin from 12% to 68%. From unbalance response analysis, the vibration amplitude due to unbalanced mass was within the permissible limits of ISO-1940 Balancing Quality. Finally, after proper balance during the manufacture of turbopump system, test results of the turbopump system confirmed that there was no particular vibration problem.