Effect of the multiple rows of pin-fins on the cooling performance of cutback trailing-edge

• Published in: International journal of heat and mass transfer 2021-05, Vol.170, p.120992, Article 120992
• Main Authors: Ye, Lin, Liu, Cun-liang, Zhang, Fan, Li, Ji-chen, Zhou, Tian-liang
• Format: Article
• Language: English
• Subjects: Cooling; Cooling effects; Crystal structure; Downstream effects; Experimental measurement; Film cooling; Heat flux; Heat transfer; Heat transfer coefficients; Heat transfer enhancement; Pin fins; Pressure-sensitive paints; Trailing edges; Trailing-edge cutback surface
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2021.120992

•A novel turbulated cutback structure comprising a combination of pin-fins and cutback surface is proposed.•Detailed data of η is obtained using PSP experiment, and Nu is acquired by transient thermochromic LC measurement.•The elliptical pin-fins, which are advantageous on the high η values, can be selected at low M values.•The case with the round pin-fins is applied at large M values due to high heat transfer enhancement. Based on heat transfer analyses of trailing-edge cutback configuration, a novel turbulated cutback structure comprising a combination of pin-fins and cutback surface is proposed in this paper to enhance the film cooling effects of trailing-edge cutback cooling. Experimental investigations on the effects of the pin-fin cross-sectional geometry (round, elliptical, and teardrop-shaped) on the trailing-edge cooling performance at varying blowing ratios (M) ranging from 0.25 to 2.00 are conducted. Detailed data of the adiabatic film effectiveness η is obtained using pressure-sensitive paint experiments, and the heat transfer coefficient is acquired by transient thermochromic liquid-crystal measurements. Then, the overall cooling performance of the turbulated cutback structure is evaluated and compared using the net heat flux reduction (NHFR). The experimental results show that the addition of pin-fins has an adverse effect on the film coverage on the expanded cutback surface, but only in the case at low M. The η distributions in the far-downstream region have a slight effect for the cases with different pin-fins. At M = 0.50, the area-averaged η values in the cases with elliptical and teardrop-shaped pin-fins are closer to those in the baseline case. As M increased, there is a monotonic increase in the heat transfer coefficient in each of the three cases with pin-fins. The case with pin-fins exhibits a high heat transfer rate that is significantly higher than that of the smooth baseline case, especially 13.3–26.0% higher than the smooth case in the M range of 1.00 to 1.50. The pin-fin shape exerted no significant impact on the surface heat transfer level at low M values. The case with round pin-fins gradually shows advantages at large M, and there is no significant difference in the area-averaged heat transfer between the cases with elliptical and teardrop-shaped pin-fins. Compared with the primeval cutback trailing-edge, the NHFR of the cases with pin-fins can significantly improve as M increased. At low M values, no significant difference i