Browsing by Author "Elwekeel, Fifi N. M"

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Effect of mist cooling technique on exergy and energy analysis of steam injected gas turbine cycle
(PERGAMON-ELSEVIER SCIENCE LTD, 04/05/2016) Abdala, Antar M. M.; Elwekeel, Fifi N. M
The common cogeneration application is steam injected gas turbine. By using cogeneration, it can be obtained with the greatest benefit from fuel energy. In steam injected gas turbine the heat of exhaust gases is used to produce the steam, and this steam injects to combustion chamber. In the present work, the generated steam not only will be directed to the combustion chamber but also will be used to cool the blade turbine by using a closed loop. In this study, the effect of addition mist to steam as coolant fluid was investigated. The energy and exergy analyses for steam injected gas turbine cycle with a closed loop cooling technique by using steam and steam/mist were investigated. The investigation was made at varied values of steam coolant temperature, mist fraction, mist temperature, pressure ratio, turbine inlet temperature and blade temperature. These parameters affected network, plant efficiency, energy ratio, fuel conversion ratio and exergy efficiency. The results show that the efficiency can reach 47.2% at low coolant temperature with a mist fraction of 2%. The coolant heat gain is enhanced at lower mist temperature, so the blade surface temperature can be improved with mist addition to steam. At a mist fraction of 2% exergy efficiency is decreased by 0.03% than that for exergy efficiency of steam only. (C) 2015 Elsevier Ltd. All rights reserved.
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.
An influence of novel upstream steps on film cooling performance
(PERGAMON-ELSEVIER SCIENCE LTD, 2016-02) Elwekeel, Fifi N. M; Abdala, Antar M. M
In this study, computational simulations were made using ANSYS CFX to predict the improvements in film cooling performance by using novel upstream steps. These steps are curved shapes instead of the normal shapes. The film cooling effectiveness (eta), the heat transfer coefficient (h) and the net heat flux reduction (NHFR) over flat plate were investigated and compared with experiments. The width of the curved steps was changed from (W) to (W/8). Blowing ratios in the range (0.5, 1, 1.5 and 2) were investigated. Results show that the curved step with less width (W/8) gives higher laterally film cooling effectiveness, lower heat transfer coefficient and higher NHFR comparing with normal step, rectangular and circular film holes without step at all blowing ratios. Interpretation of the low and high heat transfer coefficient regions for curved step (W/8) depending on the flow structures was explained in detail. (C) 2015 Elsevier Ltd. All rights reserved.