Contaminant dust effects on mist cooling in ribbed U-shaped channels of gas turbine blades

Abstract

Mist cooling within turbine blades’ internal channels is a promising alternative to protect the blades from exceeding the temperature limit without additional coolant extraction. However, the presence of dust commonly encountered in harsh environments, such as deserts or sandstorms, can significantly affect cooling performance. This research employed numerical simulation methods and utilized the user defined function to direct the motion of mist/dust particles post-wall impact, to analyze the dust affected unsteady mist cooling effectiveness in a ribbed, U-shaped channel which is arranged within the blade to serve as a cooling passage. Additionally, this study examined the performance of mist cooling and heat transfer non-uniformity under various dust loading environments. The unsteady cooling mechanism of mist was discussed through the analysis of secondary flows induced by the inclined ribs and turning region. Enhanced cooling performance near the leading edge of the U-shaped channel was achieved by the coolant with mist under the action of a couple of vortices rotating in reverse. Moreover, this study revealed that dust particles exchanged heat with droplets and disrupted the flow fields, thereby altering the performance of mist cooling. These findings indicated that dust with smaller size, higher concentration, and greater specific heat significantly suppressed the mist cooling, but larger loading of dust led to an improvement in thermal uniformities within the channel.