Investigating crossflow interactions in multi-perforation cooling systems: Experimental and numerical insights

This study investigates the effects of employing a multi-perforation cooling system on crossflow interactions, utilizing both numerical simulations and experimental methods. A 30° inclined multi-perforation cooling system is applied on a heated flat plate as part of the experimental setup. Large Eddy Simulation (LES) is utilized for Computational Fluid Dynamics (CFD) calculations to analyze the impact of multi-perforation on heat transfer dynamics. Validation is conducted by comparing the results with experimental investigations. The study encompasses both aerodynamic and thermal considerations, employing Particle Image Velocimetry (PIV) and infrared techniques for analysis, while wall heat flux is measured using electrical discharge. Experimental data on film cooling are collected through these methods, focusing on the impact of blowing ratio (M) and the number of open jet rows (R). The LES-based CFD simulations accurately predict the trajectory of the cooling film. Notably, the influence of flow through the multi-perforation on the primary flow is observable across both configurations of open jet rows (4R and 8R near the wall). The outcomes substantiate the formation of a cooling film emanating from the jet's fourth row (4R configuration), thereby validating the LES simulations. Visualization of wall temperatures illustrates the formation of a cooling film, discernible through the visible heat distribution from row 4R. However, discrepancies arise in predicting the adiabatic cooling efficiency towards the exit of the 4R region and the commencement of the 8R region, potentially attributed to the alterations induced by the additional multi-perforated injection. The novelty and the main objective of this study is to evaluate the impact of the variation of geometric parameters between the jets and the main flow on the dispersion of the jets themselves. A novel function, tailored to the temperature evolution of the cooling gas, is employed for data analysis. Two geometry configurations, featuring varying open hole areas, are evaluated. The film-cooled heat transfer coefficient, depicted by the Nusselt number, and the adiabatic film cooling efficiency results, serve to appraise the film cooling efficacy of the configurations.