Numerical investigation on the labyrinth seal design for a low flow coefficient centrifugal compressor

The leakage flow across the shroud of a centrifugal compressor impeller has an important effect on the compressor's performance, in particular, in the low flow coefficient compressor. This paper presents the three-dimensional CFD simulations and the Radial Basis Function (RBF) model to investigate the aerodynamic performance of the labyrinth seal as well as the low flow coefficient centrifugal impeller. The CFD simulations are performed on the computational domain consisting of the labyrinth seal and the impeller. The relationship between the leakage loss coefficient and the isentropic efficiency is indicated. With the application of the RBF model, the global sensitivity analysis to the seal geometric design parameters is carried out, and the geometry of the labyrinth seal is optimized. The leakage of the optimized labyrinth seal is reduced remarkably and the impeller's isentropic efficiency improved by 2% in a wide operating range.