Development of Ultra High DN Ceramic Ball Bearing for High Thrust Liquid Rocket Engine Turbopump

The new liquid oxygen-kerosene engine under development in Liquid Propulsion Systems Centre uses deep groove ball bearing with 75 mm bore diameter in its turbopump, which operates at a speed of 21,000 rpm. Since this bearing is working near its limiting speed, alternate design using ceramic balls was considered, for improving its speed capability. The design parameters of this ceramic ball bearing were optimized based on experience gained earlier, in developing cryogenic bearings for rocket engine applications. The bearing prototype was realized and qualification tested in Liquid Nitrogen medium. Tests indicate improved speed capability and lower heat generation up to 25%, when compared to ball bearings made of Stainless Steel 440C balls. This paper presents an overview of the development of a ceramic deep groove ball bearing for operation at 21,000 rpm, its design optimization, tests carried out and performance assessment in comparison to ball bearing made of Stainless Steel 440C balls.