Numerical prediction of imperfections influence on the film cooling effectiveness
Authors/Creators
- 1. Laboratoire de mécanique appliquée, Ecole Préparatoire en Sciences et Techniques
- 2. Laboratoire de mécanique appliquée, Faculté de génie mécanique, USTO
Description
Film cooling is one of the most used techniques for cooling turbine blades. This process is influenced by several geometric and aerodynamic parameters. One such parameter is the geometric shape of the injection holes: their forms and arrangements ... etc. This paper presents the influence of the hole imperfections on the effectiveness of film cooling by means of a computer code ANSYS-CFX. The effect of a jet ejected through a perfect orifice is used as a reference. The effectiveness of film cooling with imperfections in the injection hole is compared to the perfect case. A toric shape acts as a discrete imperfection. The results are presented as two-dimensional graphs and contours. It is found that an imperfection located at the upstream diameter of the cylinder decreases the effectiveness. Under the same conditions and for the same fixed imperfection near the exit of the cylinder the effectiveness improves. For an injection rate of 1.5, the effectiveness becomes better, than the perfect case. Imperfection placed further from the outlet of the cylinder does not have a significant influence on the cooling effectiveness.