Experimental Evaluation of Elastic Ring Squeeze Film Dampers for Small Gas Turbine Engine

Squeeze film dampers play a vital role in absorbing vibration energy in a rotor bearing system. The damper under study has an elastic ring with pedestals between bearing and stator dividing oil cavity into small oil pockets. This arrangement is different from conventional squeeze film damper where a single annular oil film is formed. This provides the required support stiffness as well as damping to the rotor. These types of dampers are called elastic ring squeeze film dampers (ERSFD) which are mainly used in high-speed small gas turbine engines by virtue of its compact design. There are very few literatures available to evaluate the damping offered by these SFDs. The main objective of this work is to determine the damping offered by ERSFD experimentally. For this study the rotor is designed to simulate the dynamics of a typical gas turbine engine. The rotor has to cross two rigid critical speeds within 18,000 rpm. The rotor response is measured under undamped (UND-without oil supply) and damped (D-with oil supply) conditions to evaluate the damper performance. The performance data is generated at three different oil temperatures (40, 70 and 100 ℃) under unbalanced load ranging from 2 to 8 g at 58.5 mm radius (UBR). This experimentation and performance analysis shows enhanced damping at critical speeds leading to the reduction in rotor vibrations after introducing ERSFD. The experimental data is further processed to calculate the amount of damping offered by ERSFD using rotor dynamic relations.