Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/43748
Title: Numerical and experimental investigation on the effect of swirl brakes on the labyrinth seals
Authors: Sun, D
Wang, S
Fei, CW
Ai, YT
Wang, KM
Keywords: CFD
Experimental identification
Labyrinth seal
Rotordynamic characteristic
Static characteristic
Swirl brake
Issue Date: 2016
Publisher: American Society of Mechanical Engineers (ASME)
Source: Journal of engineering for gas turbines and power, 2016, v. 138, no. 3, 032507 How to cite?
Journal: Journal of engineering for gas turbines and power 
Abstract: Swirl brake influences the static and rotordynamic characteristics of labyrinth seal which are important in the prediction of turbomachine stability. To study the influence of the swirl brakes on improving seal stability, the effects of swirl brakes on the static and rotordynamic characteristics of labyrinth seals were investigated by the combination of numerical simulation and experiment. First, it was performed to the effects of swirl brake on the static flow characteristics of labyrinth seal with swirl ratio and pressure distribution based on computational fluid dynamics (CFD). And then a comparison between leakage predicted by the CFD model and measurement was presented to verify the accuracy of the simulation. Moreover, an experiment was implemented to analyze the rotordynamic characteristics of labyrinth seal using an improved impedance method based on an unbalanced synchronous excitation method on a rotor test rig. The influences of swirl brake density, length, inlet/outlet pressure ratio, and rotating speed were measured and discussed, respectively. The CFD numerical results show that the swirl brake effectively reduces the seal swirl ratio (∼60-75% less), circumferential pressure difference (∼25-85% less) so that the seal destabilizing forces decrease. With the increasing of the swirl vanes density and length, the seal leakage drops (∼8-20% less). The experimental rotordynamic characteristics results show that it is more obvious to reduce the crosscouple stiffness (∼50-300% less) and increase the direct damping (∼50-60% larger) with the increasing in the number and length of the swirl vanes, and thus the swirl brake improves the seal rotordynamic stability. The efforts of this paper provide a useful insight to clearly understand the effects of swirl brakes on the labyrinth seal static and rotordynamic characteristics, which is beneficial to improve the design of annular seals.
URI: http://hdl.handle.net/10397/43748
ISSN: 0742-4795
DOI: 10.1115/1.4031562
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