Effect of Radial Growth on Rotordynamic Characteristics of Labyrinth Seal-Rotor System
Publication: Journal of Aerospace Engineering
Volume 32, Issue 4
Abstract
Modern turbomachinery is progressing with regard to its compact geometry structure, superior thermodynamic efficiency, and high power density. The rotating speed, operating temperature, and pressure ratio of the turbine are significantly increased with this development. As a result, the centrifugal load and thermal load should be treated more seriously with these latest developments. To this end, the leakage model and fluid force model of the labyrinth seal and the dynamic model of the rotor system are established to take into account the centrifugal growth and the thermal growth. The effective seal clearance, axial flow velocity, and working fluid-exciting force are updated in each calculation step with the varying rotational speed or operating temperature. Using a three-dimensional (3D) contour map, spectrum cascade, and bifurcation diagram, the influences of the radial growth on the leakage performance and the dynamic characteristics of the rotor system are analyzed at steady state. The results show that the leakage flow rate and discharge coefficient are greatly reduced by the radial growth, which implies an improved sealing effect. The dynamic responses of the rotor system remain nearly unchanged when accounting for centrifugal growth only. Excluding the impact of the thermal growth, the system stability is slightly enhanced with the operating temperature. However, the system stability appears to be much more sensitive to temperature when thermal growth is included in the dynamic model.
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Acknowledgments
This work has been supported by the National Natural Science Foundation of China (Grant No. 11672083).
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Journal of Aerospace Engineering
Volume 32 • Issue 4 • July 2019
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©2019 American Society of Civil Engineers.
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Received: Oct 26, 2017
Accepted: Nov 9, 2018
Published online: Apr 29, 2019
Published in print: Jul 1, 2019
Discussion open until: Sep 29, 2019
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