JFCMV  Vol.4 No.1 , January 2016
Flow Visualization of Multi-Hole Film-Cooling Flow under Varying Freestream Turbulence Levels
Abstract: A flat plate film cooling flow from a multi-exit hole configuration has been numerically simulated using both steady and unsteady Reynolds Averaged Navier Stokes (RANS and URANS) Computational Fluid Dynamics (CFD) formulations. This multi-exit hole concept, the Anti-Vortex Hole (AVH), has been developed and studied by previous research groups and shown to mitigate or counter the vorticity generated by conventional holes resulting in a more attached film cooling layer and higher film cooling effectiveness. The film cooling jets interaction with the free stream flow is a long studied area in gas turbine heat transfer. The present study numerically simulates the jet interaction with the multi-exit hole concept at a high blowing ratio (M = 2.0) and density ratio (DR = 2.0) in order to provide a more detailed, graphical explanation of the improvement in film cooling effectiveness. This paper presents a numerical study of the flow visualization of the interaction of film cooling jets with a subsonic crossflow. The contour plots of adiabatic cooling effectiveness were used to compare the multi-exit hole and conventional single hole configurations. The vortex structures in the flow were analyzed by URANS formulations and the effect of these vortices on the cooling effectiveness was investigated together with the coolant jet lift-off predictions. Quasi-Instantaneous Temperature Isosurface plots are used in the investigations of the effect of turbulence intensity on the cooling effectiveness and coolant jet coverage. The effect of varying turbulence intensity was investigated when analyzing the jets’ interaction with the cross flow and the corresponding temperatures at the wall. The results show that as the turbulence intensity is increased, the cooling flow will stay more attached to the wall and have more pronounced lateral spreading far downstream of the cooling holes.
Cite this paper: Repko, T. , Nix, A. , Uysal, S. and Sisler, A. (2016) Flow Visualization of Multi-Hole Film-Cooling Flow under Varying Freestream Turbulence Levels. Journal of Flow Control, Measurement & Visualization, 4, 13-29. doi: 10.4236/jfcmv.2016.41002.

[1]   Kim, S.I. and Hassan, I. (2010) Unsteady Simulations of a Film Cooling Flow from an Inclined Cylindrical Jet. Journal of Thermophysics and Heat Transfer, 24, 145-155.

[2]   Kalghatigi, P. and Acharya, S. (2014) Modal Analysis of Inclined Film Cooling Jet Flow. ASME Journal of Turbomachinery, 136, 081007-1-081007-11.

[3]   Nemdili, F., Nemdili, S. and Azzi, S. (2013) Numerical Investigation on Film Cooling Effectiveness Using the Anti-Vortex Concept. 21ème CongrèsFrançais de Mécanique.

[4]   Yao, Y., Zhang, J. and Yang, Y. (2012) Numerical Study on Film Cooling Mechanism and Characteristics of Cylindrical Holes with Branched Jet Injections. Propulsion and Power Research, 2, 30-37.

[5]   Repko, T.W., Nix, A.C. and Heidmann, J.D. (2013) A Parametric Numerical Study of the Effects of Freestream Turbulence Intensity and Length Scale on Anti-Vortex Film Cooling Design at High Blowing Ratio. ASME Paper HT2013-17255.

[6]   Heidmann, J.D. and Ekkad, S.V. (2007) A Novel Anti-Vortex Turbine Film Cooling Hole Concept. ASME Paper GT2007-27528.

[7]   Dhungel, A., Lu, Y., Phillips, W., Ekkad, S.V. and Heidmann, J.D. (2007) Film Cooling from a Row of Holes Supplemented with Anti-Vortex Holes. ASME Paper GT2007-27419.

[8]   Heidmann, J.D. (2008) A Numerical Study of Anti-Vortex Film Cooling Designs at High Blowing Ratio. ASME Paper GT2008-50845.

[9]   Hunley, B.K., Nix, A.C. and Heidmann, J.D. (2010) A Preliminary Numerical Study on the Effect of High Freestream Turbulence on Anti-Vortex Film Cooling Design at High Blowing Ratio. ASME Paper GT2010-22077.

[10]   Repko, T.W. (2014) Numerical Investigation of the Influence of Elevated Freestream Turbulence Levels on the Cooling Effectiveness of an Anti-Vortex Hole Geometry. MS Thesis, West Virginia University, Morgantown, West Virginia.

[11]   Bons, J.P., Macarthur, C.D. and Rivir, R. (1996) The Effect of High Freestream Turbulence on Film Cooling Effectiveness. ASME Journal of Turbomachinery, 118, 814-825.

[12]   Saumweber, C., Schultz, A. and Wittig, S. (2002) Free-Stream Turbulence Effects on Film Cooling with Fan Shaped Holes. ASME Paper GT2002-30170.

[13]   Saumweber, C. and Schultz, A. (2012) Free-Stream Effects on the Cooling Performance of Cylindrical and Fan-Shaped Cooling Holes. ASME Journal of Turbomachinery, 127, 061007-1-061007-12.

[14]   Haven, B.A., Yamagata, D.K., Kurosaka, M., Yamawaki, S. and Maya, T. (1997) Anti-Kidney Pair of Vortices in Shaped Holes and Their Influence on Film Cooling Effectiveness. ASME Paper 97-GT-45.

[15]   Walters, D.K. and Leylek, J.H. (2000) A Detailed Analysis of Film Cooling Physics: Part 1-Streamwise Injection with Cylindrical Holes. ASME Journal of Turbomachinery, 122, 102-112.

[16]   Leylek, J.H. and Zerkle, R.D. (1994) Discrete-Jet Film Cooling: A Comparison of Computations Results with Experiments. ASME Journal of Turbomachinery, 116, 358-368.