Effect of Blowing Ratio on the Film Cooling Effectiveness on a Flat Plate With Various Blockage Ratios
Conference Paper
Overview
Research
Identity
View All
Overview
abstract
AbstractEffusion cooling has emerged as an advanced cooling technique for applications that function at high temperatures, especially in gas turbines. Although this technology has shown higher cooling effectiveness compared to traditional cooling schemes, it is not yet considered a sustainable application for turbine stators and rotors due to manufacturing and structural challenges. The emergence of 3D printing techniques, especially additive manufacturing, is making significant strides in this direction. One such modification is the use of partition walls, barriers that are placed between the cooling holes, which were proposed to enhance the mechanical strength of the cooled components. This study aims to identify the effect of blowing ratio on the film cooling effectiveness over partitioned walls with various blockage ratios.To understand this effect, flat plates with full effusion or partial effusion were additively manufactured. For the partial effusion configurations, blockage ratios of 20%, 40%, and 60% were studied. In a flat plate wind tunnel, the mainstream velocity was maintained at 21.6 m/s, and tests were conducted on all plates based on coolant blowing ratios of 0.1, 0.25, and 0.7 at a fixed density ratio (DR = 1.0). Pressure-sensitive paint (PSP) was used to measure the film cooling effectiveness on each plate. The results showed that raising the blowing ratio increased the coolant flow and cooling effectiveness. However, there was a practical limit to that increase since high blowing ratios resulted in significant coolant detachment, pressure decreases and flow instability. That practical limit for the baseline flat plate was at a blowing ratio of 0.25. At low blockage ratios, the cooling effectiveness varied minimally. The reduction became more significant at blockage ratios of 40%, especially for low blowing ratios, until reaching its minimum at a blockage ratio of 60%.
