Numerical investigation of the influence of a hole imperfection on film cooling effectiveness

Abstract

PurposeThe purpose of this paper is to report a numerical investigation of jet‐cross‐flow interaction in the presence of imperfection inside the injection hole with application to film cooling of turbine blades.Design/methodology/approachThe work includes the prediction of the thermal and hydrodynamic fields by solving the Reynolds Averaged Navier Stokes and energy equations using the finite volume method with a body‐fitted hexahedral unstructured grid. The turbulence field is resolved by use of the k‐epsilon turbulence model.FindingsThe computational results show a dramatic and rapid decrease of the film cooling effectiveness when the obstruction is superior to 50 per cent. It is found that when the obstruction is close to the exit hole, the thermal protection is significantly reduced.Research limitations/implicationsThe present numerical investigation is simply directed towards a qualitative investigation of hole imperfection effects on film cooling.Practical implicationsThe motivation comes from several industrial applications such as film cooling of gas turbine components and fuel injection. One of the main challenges of using film cooling is the blockage of holes by particles ingested by the engine during landing/take off or due to application of thermal barrier coating or due to combustion particles as well as inaccuracies that result from drilling of holes.Originality/valueThe main goal of the present study is to conduct a numerical parametric investigation rather than reproducing the exact Jovanović's experimentation.