Flat-Plate Film Cooling With Steam Injection Through One Row and Two Rows of Inclined Holes

Experiments have been performed to investigate the film-cooling characteristics with steam injection through one row (7 tubes) and two rows (13 tubes) of holes, inclined at an angle of 35 deg, over a flat plate. The spacing between the holes as well as the distance between the rows is 2 1/2 hole diameters. Data have been obtained for both steam and air film-cooling effectiveness at different axial and lateral locations downstream of the injection holes. The blowing rate M varied from 0.2 to 1.5. In the case of one-row injection, the results show that the film-cooling effectiveness with steam injection is about 50 to 100 percent higher than that with air injection at downstream locations, depending upon the blowing rate; however, the increase in film-cooling effectiveness is reduced near the injection hole region at high blowing rates. In the case of two-row injection, the laterally averaged film cooling effectiveness η can be correlated with the two-dimensional film-cooling parameter ξ. The η with steam injection is about 80 to 100 percent higher than that with air injection at low blowing rates and/or at downstream locations (ξ ≥ 15). However, the increase in η with steam injection is reduced near the injection hole region and/or at high blowing rates (ξ ≤ 15).