Fig. 5

Computational Fluid Dynamics Analysis Results: Visualisation of fluid flow velocity (top) and damping coefficient variation (bottom) with time for both constant and variable dampers during rotor rotation. Flow visualisation is shown for four rotor positions (\(\theta\)): \(15^\circ\), \(65^\circ\), \(110^\circ\) and \(165^\circ\). Damping coefficient is shown for constant dampers with clearance \(\Delta r = 0.5, 1, 3, 5\)mm and variable dampers with clearance \(\Delta r = 3 - 0.5\)mm. The rotor-casing clearance was changed during the initial phase of the rotation, varying between \(\beta = 40^\circ\), \(50^\circ\), \(60^\circ\) of the total rotation cycle..