616 / 2019-01-20 23:01:48

Numerical investigation of impingement heat transfer on four flat plates with different dimple structure

impingement cooling; dimple structures; conjugate heat transfer; numerical simulation; gas turbine

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Gas turbines are commonly used in aero-propulsion, ship power and industrial power generation. The inlet temperature of modern gas turbines exceeds 2,000 K, which is far beyond the melting point of component materials. Impingement cooling is a method to reduce the temperature of blades, which is of vital importance. To investigate the effect of dimple structure on the flat plate impingement cooling, four plates with different dimple structure have been numerically simulated, in which 3-D steady RANS approach with the k–ω SST turbulence model is used. Effect of liquid-solid conjugate heat transfer is considered in all cases of this paper, while other numerical investigation papers may discuss fluid heat transfer only. Two rows of jet holes are arrayed at the cooling chamber and one row of dimple structures is arrayed at the back of the plate. Four dimple structures differ from each other on shapes of transverse cross section, which include circle, ellipse, triangle and square. Performances of the same dimple structure are also studied at four conditions with different Reynolds number, which include 15,000, 20,000, 25,000, 30,000 and 35,000. The comparative investigations between plate with dimple structures and plate without dimple structures have been carried out to study the effect of dimple structure. The results suggest that the presence of dimple structure enhances turbulence to help heat transfer and dimple structure with transverse cross section of circle performs best in impingement cooling. Corresponding to a certain Reynolds number, four plates with different dimple structure perform differently. Based on the influence of four dimple structures, a new dimple structure is performed to enhance cooling effectiveness.