The film cooling performance of the louver scheme was presented and compared with other traditional and advanced published film hole geometries. The film cooling performance of the louver scheme was investigated for blowing ratios ranging from 0.5 to 1.5 and for a density ratio of 0.94. The results showed that the louver scheme has a superior centerline and lateral film cooling effectiveness. Also, its film cooling effectiveness is enhanced with increasing blowing ratio. The louver scheme centerline and lateral average heat transfer coefficients were lower over the downstream surface than those obtained with the circular hole but very close to those of the shaped hole. Moreover, the louver scheme heat transfer ratio is not significantly affected by the blowing ratio. The louver scheme Frossling number increases with increasing blowing ratio until it reaches a peak point then starts decreasing with any further increase in blowing ratio. It is constant along the downstream jet holes of the louver. The net heat flux reduction was presented to illustrate the overall film cooling performance by combining the film cooling effectiveness and heat transfer coefficient ratio. The dimensionless reference temperature, theta = 1.5, was used to calculate the NHFR. The louver scheme provided a high film cooling effectiveness with relatively low heat transfer coefficient ratio therefore it yielded the highest NHFR in the streamwise and lateral average directions compared to circular and fan shaped holes. In conclusion, the louver scheme could increase the airfoil's life time and allow an increase in the gas turbine inlet temperature, hence improving the overall gas turbine efficiency. The present study was focused on investigating the film cooling performance of the louver scheme. However, the proposed scheme was designed to include an impingement effect which could significantly influence the conjugate heat transfer (CHT). Therefore, further experimental and numerical work is required to investigate both the conjugate effect and the film cooling effect over an airfoil.
An experimental investigation of film cooling performance of louver scheme
Experimentelle Untersuchung der Filmkühlleistung von Lüftungsschlitzen
International Journal of Heat and Mass Transfer ; 54 , 7/8 ; 1387-1399
2011
13 Seiten, 12 Bilder, 1 Tabelle, 33 Quellen
Article (Journal)
English
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