Comparative study on unsteady film cooling characteristics of HP turbine shroud based on the multiple reference frame method and sliding mesh method

CFD simulations were conducted to investigate the changes in the film cooling effectiveness (FCE) and Nusselt number (Nu) of the high-pressure (HP) turbine shroud under blade rotating sweep event at blowing ratios (BR) ranging from 0.5 to 1.5. The turbine shrouds with single-row film holes and multi-rows of impingement/film holes were examined at a high blade rotation rate of 15,000 rpm, respectively. Steady-state compressible RANS equations and multiple reference frame (MRF) methods in combination with the rotational invariance techniques were used. The predicted results by the MRF method were also compared with those from the transient sliding mesh (SM) method. Generally, the results revealed that using both methods, similar local and spanwise time-averaged distributions of FCE and Nu on the turbine shroud were observed for both single and multi-row hole configurations. However, the MRF method tended to significantly underestimate the time-averaged FCE and Nu downstream of film holes, especially at a higher BR (BR ≥ 1.0). Overall, the global time-averaged FCE and Nu obtained by the MRF method differed by less than 9 % from the SM method for the multi-row hole configurations across all BRs. Despite this deviation, the MRF method remains attractive due to its significantly lower computational costs.