Effects of dusting film cooling placement and configuration on surface heat transfer characteristics of a transonic turbine squealer blade tip

Abstract

Investigated are the effects of dusting hole film cooling placement and configuration on the surface heat transfer characteristics of a transonic turbine squealer blade tip. Three different blade tip arrangements are investigated, which are denoted C1, C2, and C3. Data are provided which include spatially-resolved and line-averaged distributions of heat transfer coefficient ratio and adiabatic film cooling effectiveness. The University of Alabama in Huntsville SS/TS/WT (supersonic/transonic/wind tunnel) blow down facility is employed with a transonic test section containing a five blade linear cascade for the investigation. Spatially-resolved surface heat transfer characteristics are measured using time- and spatially-resolved infrared thermography, in conjunction with an impulse response transient measurement procedure. Film coolant is supplied with a carbon dioxide injection system. Results indicate that heat transfer coefficient and adiabatic film cooling effectiveness distributions vary significantly as dusting hole placement and configuration are altered. For example, heat transfer coefficients for the C1 and C2 blade configurations are substantially lower, compared to baseline values with no film cooling, within the squealer recess region downstream of the dusting holes. Smaller heat transfer coefficient deviations, relative to baseline values, are present when the C3 configuration is employed. In general, distributions and magnitudes of local adiabatic film cooling effectiveness indicate that all three dusting hole configurations provide reasonably good film coverage within portions of squealer recess regions. For downstream portions of the blades, the C1 and C3 configurations both provide good surface protection which are indicated by film cooling effectiveness values, whereas coverage provided by the C2 arrangement ends abruptly at the location of a structural rib which is located within the squealer recess region.