Investigations Of Flow Characteristics And Heat Transfer Of Impingement On Curved Surfaces In A Limited Narrow Space

Experiments were carried out to investigate the flow structures and the local heat transfer coefficient of impingement on the inclined concave surface in a limited narrow spaceSmoke wire flow visualization was used to investigate the characteristics of the flow structures of a round jet impinging on the inclined concave surfaces.Reynolds number, the ratio of the jet impingement distance to the diameter of the jet hole H/d and the relative curvature d/D were changed to study the rules of flow structures varying with these parameters.The experimental results of impingement on the inclined surface at narrow space show that the central angle of the impingment fluid separated from the target surface becomes larger with Reynolds number increasing.Because of the influence of inclined impingement,it can be easy to form swirl structure at the left of the obstruct region and cannot form an obvious,unitary big vortex. There exists a proper range range of d/D, which results in a maximum central angle for impingement fluid separated from the target surfaces.And the central angle of the impingment fluid separated from the target surface becomes larger with H/d increasing.The experimental results of impingement on the inclined surface at limited space show that the central angle of the impingment fluid separated from the target surface becomes larger with Reynolds numbe increasing.Both at the left and the right of the stagnation region it can form swirl structure and induced vortex. And the central angle of the impingment fluid separated from the target surface becomes larger with H/d increasing, while the induced vortex become smaller. Because of the influence of inclined impingement, it can be easy to bring swirl structure at the left of the obstruct region.Based on the flow visualization, further experiments were applied to investigate the local heat transfer coefficient Nu of the impingement on the concave surface in limited space.In the experiments, local Nu along the axis and radial direction increases with Rej increasing. The maximum local Nu is achieved in the case of H/d equals 0.8 along the radial direction. Local Nu along the axis and radial direction reduce, when the inclined angle changes from 6o to 18o .