Numerical investigation on the steady and unsteady flow characteristics of rim seal for the first stage in gas turbine

• We study a more realistic rim seal in the first stage of gas turbine.
• The influence of rim seal structures and rotational speeds have been studied.
• The steady and unsteady flow characteristics of rim seal are discussed in detail.
• The distributions of sealing effectiveness, pressure and minimum sealing flow are presented.

This paper presents a numerical investigation on the steady and unsteady flow characteristics of rim seal for the first stage in gas turbine. The Reynolds-averaged Navier–Stokes equations, coupled with Shear Stress Transport turbulence model, and a scalar equation are solved. In the steady-state conditions, the influences of rim seal structures and rotational speeds on the sealing effectiveness and non-dimensional sealing air mass flow have been numerically investigated. In the unsteady-state conditions, the pressure distribution, pressure-frequency and sealing effectiveness are discussed in detail. The results obtained in this study indicate that the sealing effectiveness increases with the non-dimensional sealing air mass flow. The minimum non-dimensional sealing mass flow for the axial rim seals and radial seals ranges from 9.62×1039.62×103 to 9.63×1039.63×103 and from 5.07×1035.07×103 to 5.75×1035.75×103, respectively. It means that the radial seals perform better than the axial ones in sealing effectiveness. The minimum non-dimensional sealing mass flow increases with the increase of rotational speeds. Compared to Cw,seal=9840Cw,seal=9840, there is an additional pressure frequency of f/fbld=0.125f/fbld=0.125 for the case of Cw,seal=4070Cw,seal=4070. The increase of sealing air is conducive to reducing instability in the rim seal cavity, which has small influences on the circumferential pressure downstream the vane trailing edge. The unsteady-state sealing effectiveness is lower than that calculated in steady state.