The stability of rigid rotor mounted in multilobe bearings, those are 2-lobe, 3-lobe, 4-lobe bearing, is experimentally studied for which the preload factor and load angle ratio are symmetrcally varied, also theoretically and experimentally studied according to radial clearance variations in circular bearings.
For the multilobe bearings two variations are presented, where offset factor is held constant at 0.5. First, two values of preload factor are presented : 1/3, 1/2. Second, the preload factor is held at 1/3 and three values of load angle ratio are presented : 0, 1/4, 1/2.
Also the circular bearings, three values of clearance are presented : 50 ㎛, 70 ㎛, 97 ㎛.
The absolute air supply pressure is applied from 2kgf/㎠ to 6kgf/㎠ .
Results indicate that, for a particular value of preload factor exists for which the rotor system will have maximum whirl instability threshold speed. Also, for a particular value of load angle ratio, the same conclusion is reached.
Results also indicate that, for the circular bearings, as decreasing clearance, increasing whirl instability threshold speed but decreasing frequency ratio and whirl ratio.
Finally, increasing the supply pressure, whirl instability threshold speed, critical speed, frequency ratio and whirl ratio are all increased regardless of bearing types.
