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Purpose -The 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/approach -The 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. Findings -The 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/implications -The present numerical investigation is simply directed towards a qualitative investigation of hole imperfection effects on film cooling. Practical implications -The 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/value -The main goal of the present study is to conduct a numerical parametric investigation rather than reproducing the exact Jovanović's experimentation.

This paper investigates the performance of the SSG (Speziale, Sarkar, and Gatski) Reynolds Stress Model for the prediction of film cooling at the leading edge of a symmetrical turbine blade model using the CFX 5.7.1 package from ANSYS, Inc. Using a finite-volume method, the performance of the selected turbulence model is compared to that of the standard k−ε model. The test case blade model is symmetric and has one injection row of discrete cylindrical holes on each side near the leading edge. Numerical simulations are conducted for three different blowing ratios; film cooling effectiveness contours on the blade surface and lateral averaged adiabatic film cooling effectiveness are presented and compared with available measurements. The computations with the standard k−ε model reproduce the well-known underpredicted lateral spreading of the jet, and, consequently, lower values of the lateral averaged adiabatic film cooling effectiveness has been obtained. On the other hand, the second order Reynolds Stress Model yields reasonably good agreement with measurement data. In addition to validation data, several longitudinal and transversal contours and vector planes are reproduced and clearly underscore the anisotropic turbulent field occurring in the present shower head film cooling configuration.

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We report three-dimensional simulation results of thermal mixing in square T-junction configuration at high Reynolds number. The square T-junction configuration with different channel sizes was studied experimentally at the Department of Mechanical Engineering of Mie University, Japan. The T-Junction was selected as a benchmark for thermal mixing in the ERCOFTAC Workshop held in EDF Chatou, France, 2011. RANS, URANS and SAS simulations were performed with CFD code using finite volume method The comparison shows excellent agreement between SAS and the data.