Session: 21-06: Labyrinth and Damper Seals

Paper Number: 122313

122313 - Experimental and Analytical Investigation of Labyrinth Seal Packing Ring Behavior in Contact With a Whirling Rotor 

 Labyrinth seal packing ring behavior in case of contacting with a whirling rotor which simulates the expected rotor vibration in an actual steam turbine was investigated experimentally and analytically. The labyrinth seal packing ring used in this study was designed to be supported to a casing with weak coil springs. The force of the coil springs is set to be slightly larger than the packing ring weight so that it escapes in the radial direction in case of contacting with a rotor and the temperature rise of the rotor could be prevented.

 The experimental investigation with a seal test rig which consists of a rotor, a labyrinth seal packing ring and a casing was carried out. The tests were conducted with two different types of split structures of the packing ring. The first one is the 2-split structure, and the second one is the 3-split structure, in a lower half of the packing ring, respectively. In the 2-split structure, contact position of the rotor and the packing ring coincides with the split position of the packing ring in the directly below position. In the 3-split structure, the contact position is the circumferential center of the packing ring segment located in the below position. The casing with the packing ring installed was moved upward with a stepper motor and forcibly brought it into contact with the whirling rotor. The radial displacement of the packing rings was measured with displacement sensors attached to the casing and its amplitude and dominant frequency were evaluated. The temperature of the rotor was also measured by thermocouples embedded near its surface. The 3-split structure resulted in a lower vibration frequency and a higher amplitude. The temperature rise of the rotor was smaller for the 3-split structure than the 2-split structure.

 Analytical investigation using motion equations of a rigid body was carried out to understand the packing ring behavior in case of contacting with a whirling rotor. The characteristics of vibration of packing rings and the difference of behavior between the 2-split structure and the 3-split structure were explained by the solutions obtained from the equations. The difference of temperature rise of a rotor between the 2-split structure and the 3-split structure were also explained by simple evaluation of heat generation using the solutions of the equations.

Presenting Author: Tomohiko Tsukuda Toshiba Energy Systems & Solutions Corporation

Presenting Author Biography: Tomohiko Tsukuda is a specialist of Turbine Technology Group of Toshiba Energy Systems & Solutions Corporation. He joined the company in 2006 and has been involved in steam turbine development since then, up to the present. His work focuses specifically on fluid mechanics and structural mechanics for the enhancement of steam turbine performance and reliability. He had an experience of studying abroad as a visiting researcher at the University of Virginia in the United States for a year and a half.

Authors:

Tomohiko Tsukuda Toshiba Energy Systems & Solutions Corporation
Yoshifumi Iwasaki Toshiba Energy Systems & Solutions Corporation
Shogo Iwai Toshiba Energy Systems & Solutions Corporation
Tsuguhisa Tashima Toshiba Energy Systems & Solutions Corporation