Browsing by Author "Huang, Diangui"

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    Film cooling effectiveness and flow structures for novel upstream steps
    (PERGAMON-ELSEVIER SCIENCE LTD, 2016) Abdala, Antar M. M; Elwekeel, Fifi N. M; Huang, Diangui
    In this study, computational simulations were made using ANSYS CFX to predict the improvements in film cooling performance by using novel upstream steps. There are twenty-one novel steps consisting of three groups are tested. The first group consists of a rectangular step with different tilt angles. The second group consists of a normal rectangular step with and without segmentation. The third group consists of curved steps with and without segmentation. Optimizing the curved steps dimensions is performed. The film cooling effectiveness (1) of twenty-one novel steps were investigated and compared with experiment. Velocity profiles, pressure coefficient profiles and turbulent kinetic energy contours were discussed. Blowing ratios in the range (0.5, 1, 1.5 and 2) were investigated. Results indicate that the best novel step is the curved step with width (W/8) and the average values of film cooling effectiveness is increased to 138.8% compared with the experiment. (C) 2015 Elsevier Ltd. All rights reserved.
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    Upstream and Downstream Step Curvature Effects on Film Cooling Effectiveness and Flow Structures
    (SPRINGER, 2015) Elwekeel, Fifi N. M.; Abdala, Antar M. M.; Huang, Diangui
    In this study, computational simulations were made using ANSYS CFX to predict the influence of upstream and downstream step curvature radii on the film cooling effectiveness. Five upstream steps and four downstream steps with different curvature radii were studied. The curvature radii of these steps of R = 1.64D, 2D, 3D, 4D, and 5D were used. The film cooling effectiveness (eta) of these steps was investigated and compared with experiment. The near-field flow phenomena such as the pressure coefficient and the jet trajectories were discussed. Results indicate that the step position in the upstream of a film hole has a higher effect on the film cooling effectiveness compared with the downstream position. The film cooling effectiveness increases in the case of the upstream curved steps at lower radii due to entrapping more coolant in the region upstream of a hole. The results show that the pressure difference has an important effect to draw the coolant in the upstream region of a film hole compared with the case without step.