COMPUTATIONAL STUDY OF FLOW AND HEAT TRANSFER WITH ANTI CROSS- FLOWS (ACF) JET IMPINGEMENT COOLING FOR DIFFERENT HEIGHTS OF CORRUGATE Radheesh Dhanasegaran Chalmers University of Technology Gothenburg, Sweden Ssheshan Pugazhendhi Indian Institute of Technology Madras (IITM) Chennai, TamilNadu, India ABSTRACT In the present study, a flow visualization and heat transfer investigation is carried out computationally on a flat plate with 10x1 array of impinging jets from a corrugated plate. This corrugated structure is an Anti-Cross Flow (ACF) technique which is proved to nullify the negative effects of cross-flow thus enhancing the overall cooling performance. Governing equations are solved using k-ω Shear Stress Transport (SST) turbulence model in commercial code FLUENT. The parameter variation considered for the present study are (i) three different heights of ACF corrugate (C/D=1, 2 & 3) and (ii) two different jet-to-target plate spacing (H/D=1 & 2). The dependence of ACF structure performance on the corrugate height (C/D) and the flow structure has been discussed in detail, therefore choosing an optimum corrugate height and visualizing the three- dimensional flow phenomena are the main objectives of the present study. The three-dimensional flow separation and heat transfer characteristics are explained with the help of skin friction lines, upwash fountains, wall eddies, counter-rotating vortex pair (CRVP), and plots of Nusselt number. It is found that the heat transfer performance is high at larger corrugate heights for both the jet-to-plate spacing. Moreover, the deterioration of the skin friction pattern corresponding to the far downstream impingement zones is greatly reduced with ACF structure, retaining more uniform heat transfer pattern even at low H/D values where the crossflow effects are more dominant in case of the conventional cooling structure. In comparison of the overall heat transfer performance the difference between C/D=3 & C/D=2 for H/D=2 is significantly less, thus making the later as the optimal configuration in terms of reduced channel height. Keywords: Cross flow, Flow Visualization, Jet Impingement, Heat Transfer NOMENCLATURE Alphabets Abbreviations Subscripts C-Corrugate Height, [m] ACF-Anti-Cross Flows x-span-wise direction D-Impingement Hole Diameter, [m] AL-Attachment line y-normal direction H-Jet-to-target plate spacing, [m] CRVP-Counter Rotating Vortex Pair z-streamwise direction P-Hole Spacing, [m] NA-Nodal point of Attachment NS-Nodal point of Separation Nu-Nusselt number SP-Saddle point INTRODUCTION The necessity of increased turbine inlet temperatures in the modern air breathing engines substantiates the design of efficient cooling systems for these components. Hot spot formations due to the hot temperature mainstream lead to thermal failure of the blade materials. A combination of different cooling methodologies such as film cooling for the external surface and impingement cooling for the internal surface are generally used especially in the first stages of turbines (NGV & HPT). The later method is mostly found in the regions where localized heat transfer is necessary and that cannot be protected by the film cooling holes. In impingement cooling, crossflow from the upstream jets is one of the major factor that may affect the heat transfer performance. This crossflow is sometimes useful in providing localized heat Proceedings of the ASME 2017 Heat Transfer Summer Conference HT2017 July 9-12, 2017, Bellevue, Washington, USA HT2017-4783 1 Copyright © 2017 ASME