Experimental validation of the operation of tilting-pad journal bearing lubricated by high-test peroxide under excessive vibrations and reduced flow of the lubricant

Abstract

Hydrogen peroxide is commonly used as a low-toxicity liquid rocket propellant (oxidizer). Hydrodynamic bearings lubricated by this propellant may be applicable in rocket engine pumps. In this paper, a hydrodynamic tilting-pad journal bearing lubricated by highly concentrated (87 wt%) hydrogen peroxide was proposed. Furthermore, an experimental validation of the performance of this bearing with pads made of PEEK material (polyetheretherketone) was carried out on the developed high-speed measuring device. To verify the endurance of this bearing, measurements were performed at different peroxide flow rates from 100% to 20% of the nominal flow rate. The tests were also conducted under excessive vibrations induced by the misalignment of the test rotor with the drive connected by a flexible coupling. In addition to vibration measurement, the wear of the bearing sliding surfaces and lubricant temperature variations were evaluated. The measured results were compared with the calculated data. For this purpose, a two-dimensional computational model based on the thermo-elasto-hydrodynamic lubrication theory was presented. To improve the solution convergence, Newton's method is used to calculate the equilibrium tilt of the pads. The involved bearings operated smoothly at the mentioned misalignment even at 20% peroxide flow, only slight foaming occurred at the outlet.