Variations of cooling performance on turbine vanes due to incipient particle deposition

Abstract

In this paper, to demonstrate the deposition effects on cooling performance, the changing patterns of film cooling due to particle deposition are numerically investigated on a turbine vane that is cooled by an array of film-holes. The uniqueness of this work is addressing the cooling performance at an early deposition stage, in which deposits are relatively slight. The build-ups of the deposits are simulated by moving grid nodes on the wall boundaries. Results show that in addition to particle velocity, the blowing conditions and wall temperatures are two important factors to determine the deposition patterns. Increasing coolant-to-mainstream mass flow ratios and lowering wall temperatures can help inhibit the growth of deposits. In addition, the modifications of the vane profile due to incipient deposition are completely different from those with excessive deposition. Although flow fields are less sensitive to the early-stage deposits in the subsonic vane passage, cooling effectiveness is significantly changed and the changes are linked to the mass flow ratios. Compared to the cooling performance from a non-deposition case, reduced cooling performance due to incipient deposition is found at a low mass flow ratio of 1.09%, while cooling performance is improved at moderate and high mass flow ratios of 1.64% and 2.06%.