Numerical investigations of endwall film cooling design of a turbine vane using four-holes pattern

Jian Liu,Shibin Luo,Bengt Ake Sunden,Jiawen Song,Wenxiong Xi,Mengyao Xu

doi:10.1108/hff-12-2020-0804

Jian Liu, Shibin Luo + Show 4 more

Open Access

https://doi.org/10.1108/hff-12-2020-0804

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Abstract

PurposeEndwall film cooling protects vane endwall by coolant coverage, especially at the leading edge (LE) region and vane-pressure side (PS) junction region. Strong flow impingement and complex vortexaa structures on the vane endwall cause difficulties for coolant flows to cover properly. This work aims at a full-scale arrangement of film cooling holes on the endwall which improves coolant efficiency in the LE region and vane-PS junction region.Design/methodology/approachThe endwall film holes are grouped in four-holes constructal patterns. Three ways of arranging the groups are studied: based on the pressure field, the streamlines or the heat transfer field. The computational analysis is done with the k-ω SST model after validating the turbulence model properly.FindingsBy clustering the film cooling holes in four-holes patterns, the ejection of the coolant flow is stronger. The four-holes constructal patterns also improve the local coolant coverage in the “tough” regions, such as the junction region of the PS and the endwall. The arrangement based on streamlines distribution can effectively improve the coolant coverage and the arrangement based on the heat transfer distribution (HTD) has benefits by reducing high-temperature regions on the endwall.Originality/valueA full-scale endwall film cooling design is presented considering interactions of different film cooling holes. A comprehensive model validation and mesh independence study are provided. The cooling holes pattern on the endwall is designed as four-holes constructal patterns combined with several arrangement choices, i.e. by pressure, by heat transfer and by streamline distributions.

Highlights

Film cooling is a common cooling method for gas turbine blades by ejecting a coolant from discrete holes and protect the solid surfaces
With the film cooling holes designed as a four-holes constructal pattern, the coolant flows are well converged and are not affected by the mainstream in the cluster
Summary and conclusions This work introduces four-holes constructal pattern into the design of the film cooling holes arrangement on the endwall to improve coolant coverage

Summary

Introduction

Film cooling is a common cooling method for gas turbine blades by ejecting a coolant from discrete holes and protect the solid surfaces. The great advantage of film cooling is that the coolant air uses the compressed air from the compressor and reduces the surface temperature effectively though it may affect the aerodynamics. Great efforts have been put into the research works of film cooling in the past few decades (Han and Ekkad, 2001). The research works about film cooling have accumulated a large amount of literature, such as the shape optimization and location arrangement of the cooling holes (Ekkad and Han, 2013). The investigations about film cooling for turbine blades are performed in a regime which tries to approach the reality, such as film cooling on a complex structured surface and the interaction of film cooling holes on a blade surface (Nemdili et al, 2011)

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