Conjugate Heat Transfer Analysis of a Blade Leading Edge Cooling Configuration Using Double Swirl Chambers

<jats:p>The efforts to improve the process efficiency of modern gas turbines usually lead to competing objectives for the design of the cooling system as turbine inlet temperatures are continuously increased. Typically, the designer of modern cooling systems is confronted with the requirement to achieve a wall temperature below the maximum allowable wall temperature which is fixed by the material and life span requirements. Simultaneously, a homogenous temperature distribution is desired in order to reduce thermal stresses due to temperature gradients. To maximize cycle efficiency, all this should be achieved by minimizing the necessary cooling air consumption. The Double Swirl Chamber (DSC) cooling technology is a promising configuration to satisfy these design requirements combined. The DSC cooling technology is an advanced kind of internal cooling passage which is created by the merging of two standard single swirl chambers. In the DSC cooling configuration, two anti-rotating large scale swirls are generated which enhance the mixing of the cooling air. This leads subsequently to an increased internal heat exchange. Additionally, the recurring reattachment of the swirl flows at the center of the chamber leads to a linear impingement effect due to local velocity elevations which makes the DSC configuration very suitable for an effective and uniform cooling of thermally high loaded blade leading edges as turbine inlet temperatures are further increased. Thus, the DSC cooling technology has great potential to lengthen the life span of gas turbine blading. In the present work, two DSC configurations are compared numerically to the state-of-the-art leading edge impingement cooling technology with a conjugate heat transfer approach of a simplified blade leading edge geometry. The two investigated DSC are similar, but with the second one being slightly modified in its geometry in order to ease the manufacturing process. With the same numerical setup in terms of applied boundary conditions and under consideration of Reynolds similarity, the DSC configurations show a local temperature reduction of 1.0–1.3% of the turbine inlet temperature in comparison to the impingement cooling case. The total pressure drop in the DSC configurations is in the same range as in the impingement cooling configuration and even slightly decreased by 0.15–0.20%. The heat transfer is 12–16.2% higher in the DSC configurations, which shows the potential for improving the internal cooling performance of a system by the application of the DSC cooling technology in real engine conditions.</jats:p>