Investigations on the effect of different influencing factors on film cooling effectiveness under the injection of synthetic coolant

Jianlong Chang,Yang Du,Xinlei Duan,Yutian Pan,Baoquan Guo

doi:10.1038/s41598-021-83080-9

Abstract

By combining the synthetic jet and film cooling, the incident cooling flow is specially treated to find a better film cooling method. Numerical simulations of the synthetic coolant ejected are carried out for analyzing the cooling performance in detail, under different blowing ratios, hole patterns, Strouhal numbers, and various orders of incidence for the two rows of holes. By comparing the flow structures and the cooling effect corresponding to the synthetic coolant and the steady coolant fields, it is found that within the scope of the investigations, the best cooling effect can be obtained under the incident conditions of an elliptical hole with the aspect ratio of 0.618, the blow molding ratio of 2.5, and the Strouhal number St = 0.22. Due to the strong controllability of the synthetic coolant, the synthetic coolant can be controlled through adjusting the frequency of blowing and suction, so as to change the interaction between vortex structures for improving film cooling effect in turn. As a result, the synthetic coolant ejection is more advisable in certain conditions to achieve better outcomes.

Highlights

By combining the synthetic jet and film cooling, the incident cooling flow is specially treated to find a better film cooling method
In order to verify whether the pulsation of the coolant jet can enhance the film cooling effect, Muldoon[14] conducted direct numerical simulation (DNS) on the pulsed film cooling jet
The results showed that at low Strouhal numbers, there was a significant effect for the wake-up time on the instantaneous film cooling effectiveness, but usually the wake timing had little effect on the average time efficiency

Summary

Introduction

By combining the synthetic jet and film cooling, the incident cooling flow is specially treated to find a better film cooling method. By comparing the flow structures and the cooling effect corresponding to the synthetic coolant and the steady coolant fields, it is found that within the scope of the investigations, the best cooling effect can be obtained under the incident conditions of an elliptical hole with the aspect ratio of 0.618, the blow molding ratio of 2.5, and the Strouhal number St = 0.22. In order to verify whether the pulsation of the coolant jet can enhance the film cooling effect, Muldoon[14] conducted direct numerical simulation (DNS) on the pulsed film cooling jet. The results showed that at the same peak blow ratio (M = 1.5), the pulse produced an increase in the overall film cooling efficiency compared to the continuous flow. It should be noted that pulses may be an optional effective way to enhance the cooling effect of the film in many practical configurations

Methods

Results

Conclusion