Effect of Squealer Tip with Deep Scale Depth on the Aero-thermodynamic Characteristics of Tip Leakage Flow

BI Shuai; WANG Longfei; WANG Feilong; WANG Lei; LI Ziqiang

doi:10.1007/s11630-022-1683-4

Journal of Thermal Science >

2022 , Vol. 31 >Issue 5: 1773 - 1789

DOI: https://doi.org/10.1007/s11630-022-1683-4

Aerothermodynamics

Effect of Squealer Tip with Deep Scale Depth on the Aero-thermodynamic Characteristics of Tip Leakage Flow

BI Shuai ,
WANG Longfei ,
WANG Feilong ,
WANG Lei ,
LI Ziqiang

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Jiangsu Province Key Laboratory of Aerospace Power System, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China

Online published: 2023-12-01

Supported by

The authors gratefully acknowledge the financial supports for the project from the National Science and Technology Major Project of China (2017-III-0010-0036), China Postdoctoral Science Foundation (NO.2020TQ0147) and Natural Science Foundation of Jiangsu Province (NO. BK20200454).

Copyright

Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag GmbH Germany, part of Springer Nature 2022

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Abstract

In this paper, the aero-thermal performance of squealer tips with deep-scale depth is numerically investigated in an axial flow turbine, which is compared with the squealer tip with traditional cavity depth. Numerical methods were validated with experimental data. The effect of cavity depth and tip clearance was considered. The numerical results show that for the squealer tip with conventional cavity depth, the size of the reflux vortex enlarges as the cavity depth increases. The velocity and uniformity of high entropy production rate (EPR) inside the cavity reduce obviously with the cavity developing into deep-scale. However, the increase of depth 10% of the blade span (H) leads to enlargement of cavity volume, which increases the total entropy production rate. And the overall dimensionless entropy production rate (DEPR) of gap and cavity obtains a maximum increase of 43.54% in contrast to the case with 1%H depth cavity. As a result, the relative leakage mass flow rate reduces by 20.6% as the cavity depth increases from 1% to 10%. Given the heat transfer, as the cavity significantly increases to 10%H, the enhanced cavity volume results in a more enormous cavity vortex with low velocity covering the floor, which weakens the convective heat transfer intensity and reduces the area of high heat transfer. The normalized average heat transfer coefficient at the cavity bottom reduces by 40.26% compared to the cavity depth of 1%H. In addition, the deep-scale cavity is more effective in inhibiting leakage flow at smaller tip clearance. The reduction amplitude of normalized average heat transfer coefficient at the squealer floor decreases as tip clearance increases, which reduces at most by about 72.6% for the tip clearance of 1%H.

Key words： squealer tip; turbine aerothermodynamics; tip leakage flow; deep-scale depth; heat transfer; numerical methods

Cite this article

BI Shuai , WANG Longfei , WANG Feilong , WANG Lei , LI Ziqiang . Effect of Squealer Tip with Deep Scale Depth on the Aero-thermodynamic Characteristics of Tip Leakage Flow[J]. Journal of Thermal Science, 2022 , 31(5) : 1773 -1789 . DOI: 10.1007/s11630-022-1683-4

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