Abstract
The sealing between rotating components and stator components has become one of the main issues to be studied in the compressor. The mixing of stator root leakage flow and the mainstream can seriously affect the performance of the compressor. This article does a series of work on numerical calculation of plane diffuser cascade with the stator cavity and three-stage labyrinth seal. It also analyzes the details of the flow structure on upstream cavity. In this paper, the 3D streamlines distribution of the cascade corner region is studied, respectively for the no leakage case and the mixing mechanism of the secondary flow and mainstream with leakage. On this basis, the upstream cavity configuration is optimized and some results are obtained as fellows. The mainstream in the blade leading edge into the upstream cavity comes into being the secondary flow, which similar to leakage flow. It can affect the highest 80% leaves of the high range. Leakage flow is mainly influence on the performance of the blade root flow field and weakly of next to casing area. Compared to no leakage case, angular separation position ahead of time and range increased when there is leakage. Thus, added rib on both sides of the vessel wall can reduce the total pressure loss of the S3 section, and the relative position of ribbed effect significantly. The research shows that first layer of rib is better when set on the hub wall surface, the total pressure loss coefficient decreased by 3.49%.
Highlights
Clearance leakage flow is one of the mainstream characteristics in aero engine compressor, and stator root leakage plays a significant role in this process
This paper numerically calculates the static stator model of the compressor to analyze the secondary flow structure and leakage flow structure formed by the mainstream in the upstream cavity
The upstream cavity configuration was optimized, and the following conclusions were drawn: When the main stream flows through the upstream cavity, part of the fluid enters to upstream cavity at the leading edge of the blade, and blended with the leakage flow and eventually merged into the mainstream
Summary
Clearance leakage flow is one of the mainstream characteristics in aero engine compressor, and stator root leakage plays a significant role in this process. Wellborn studied the blade root leakage flow and its effect on the compressor performance, results show that about 0.5% of the leakage can be caused the rotor efficiency and total pressure loss of about 1.5% and 1% respectively [5,6,7]. Popovic changed the upstream cavity of a high-pressure turbine stator into an overlapping seal structure to simulate the influence on the leakage flow, and the results show that vessel geometry size smaller change can cause mainstream pressure loss bigger fluctuation [9]. Researchers mostly deal with the leakage flow of the stator blade root directly by setting the gap with the hub, and the focus is mainly on the complex vortex structure and less on the influence of the real stator structure. The computational domain has a total chord length of 4 times along the flow direction, including 1 times for the inlet chord length and 2 times for the exit chord length, and the computational domain length along the frontal line is a grid spacing
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