Numerical Analysis of Hydrodynamic Journal Bearings for Turbine Pump Applications

Performance testing of turbomachinery components is a critical stage in the development and validation of gas turbine engines. Experimental investigations are required to determine the aerodynamic, mechanical, and dynamic characteristics under both design and off-design operating conditions. In addition to evaluating aerodynamic efficiency and performance, these tests are essential for verifying the structural integrity and reliability of rotating components subjected to high velocity and severe loading conditions. To achieve these objectives, a test section was designed, developed, and integrated into an existing high-speed test rig. The test section consisted of the turbine stage under investigation, a journal-bearing, the surrounding casing, and an appropriate support structure. The turbine drive shaft was supported by a pair of hydrodynamic journal bearings specifically selected to withstand high-speed operating conditions.

The primary objective of the present work was to redesign the journal-bearing system in order to improve the overall dynamic behavior and operational reliability. A second objective was to develop a bearing configuration whose preload characteristics remain relatively insensitive to variations in operating conditions such as velocity, temperature, and applied loads. Although extensive research has been conducted on the rotor dynamics of high-speed rotating machinery, including turbopumps, machine tool spindles, and gas turbine engines. Very limited information is available regarding practical design solutions for troubleshooting and stabilizing rotating systems that exhibit severe operational instabilities.

This work presents a comprehensive experimental and numerical investigation of the journal-bearing system used in a high-speed turbine test bench. Dynamic response measurements, vibration analyses, and numerical simulations were performed to identify the sources of instability and evaluate alternative bearing designs. The proposed solutions successfully improved the stability and operability of the rotating system, providing valuable guidelines for the design and optimization of high-speed turbomachinery test facilities.