Investigations of the leakage characteristic and the sealing effectiveness on turbine bite rim seals

摘要

In order to meet the needs of designing for high performance secondary air system in the turbine, a new turbine bite engineering rim seal of type-A and the related test rig were designed and set up. The numerical investigation and the experimental verification of the leakage characteristic of rim seal were carried out based on k - ω SST turbulence model. The key feature of the engineering rim seal of type-A, a bite type, was extracted, hence the other three kinds of rim seal named type-B, type-C and type-D were proposed. The sealing mechanism of bite rim seal was revealed from two aspects of the leakage characteristic and the seal effectiveness. The results show that: the numerical results of the k -ω SST turbulence model agree well with the experimental ones, and the maximum error is less than 4.2% in the range of this paper. The leakage of turbine bite rim seal of type-C and type-D are less than that of conventional rim seal (type-B). Compared with type-C, the radial inward shoulder structure of type-D reduces the leakage in the cavity, however, it enhances the pumping effect of the rotor. The average sealing efficiency of type-C and type-D are increased by 8.9% and 8.82% compared with that of conventional rim seal of type-B, respectively. The effects of entrainment and diffusion of the vortex in the sealing channel are one of the important reasons for the ingestion. There are two kinds of vortex structure named recirculation zone vortex (RZV) and rotationally induced vortex (RIV). The RZV will be rapidly replaced by the RIV with the rotation speed increasing at a low flow rate of the hot gas. However, the RZV will be relatively stable while the hot gas mass flow rate is increased.