Research Article Influence of Narrow Rectangular Channel (AR = 1 : 4) on Heat Transfer and Friction for V- and W-Shaped Ribs in Turbine Blade Applications Karthik Krishnaswamy , 1 Suresh Sivan , 1 and Hafiz Muhammad Ali 2 1 Mechanical Engineering, National Institute of Technology, Tiruchirappalli 620015, India 2 Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia Correspondence should be addressed to Suresh Sivan; ssuresh@nitt.edu Received 13 January 2021; Revised 8 May 2021; Accepted 17 May 2021; Published 25 May 2021 Academic Editor: Gianluca Coccia Copyright © 2021 Karthik Krishnaswamy et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Effective cooling of blades with a nominal pressure drop is essential for performance augmentation and thermal management of gas turbines. Hence, present work is aimed at determining the heat transfer enhancement and friction for W- and V-shaped ribs inside a rectangular cooling channel having hydraulic diameter (D h ) of 0.048 m and aspect ratio (AR) 1 : 4. Ribs are fixed facing downstream with angle of attack (α) 45 ° on opposite walls. Pitch (P) between two successive ribs is 25 mm for both cases. Continuous V- and W-shaped ribs with height to channel hydraulic diameter ratio (e/D h ) 0.052 and 0.0416 and pitch to height ratio (P/e) 10 and 12.5, respectively, have been examined for Reynolds number (Re) range 20000-80000. Heat transfer augmentation achieved at Re 80000 is 1.94 and 1.8 times higher than Re 20000 for V- and W-shaped ribs, respectively. Streamwise and spanwise variations in local Nusselt number ratio are highest for V-shaped ribs, which are estimated to be 31% and 12%. For W-shaped ribs, variations are 17.5% and 3.5%. Nusselt number (Nu) is highest along span length 0.5w for V- shaped ribs due to dominance of apex induced secondary flow. For W-shaped ribs, Nusselt number along the span lengths is found to be nearly same view uniformity in secondary flow. Maximum enhancement (Nu/Nu o ) estimated for both the rib shapes is 3.9 at Re 20000. Due to increased rib height, friction losses for V-shaped ribs are higher than W-shaped ribs. Maximum friction loss increment is estimated to be 85% for V-shaped ribs and 42% for W-shaped ribs between Re 20000 and 40000. For both rib shapes, impact of ribs is found to be greatest at Re 40000. Thermohydraulic performance (THP) for W- shaped ribs is superior to V-shaped ribs. Best THP achieved for W- and V-shaped ribs are 3.7 and 3.4 at Re 20000. 1. Introduction Gas turbine engines propel aircraft, ships, and automobiles. In addition, they are also extensively used for power genera- tion. The efficiency and output of these engines are depen- dent upon the Turbine Inlet Temperature (TIT). Increase in TIT will result in increased power output. The present generation turbines are already operating closer to melting point, and therefore, any further increase in TIT is possible only through efficient thermal management. The cooling of inner and outer blade surfaces is done by withdrawing a small quantity of compressed air. Withdrawal of air impacts the output and efficiency. Hence, the aim of various cooling tech- niques is to attain more heat transfer with marginal drop in pressure, thereby reducing the coolant consumption. Rib cooling is one amongst the cooling techniques used for heat removal from midsection of turbine blade. For years, many researchers have examined the thermohydraulic perfor- mance generated due to ribs in turbine blade cooling chan- nels which are generally rectangular, trapezoidal, and square in cross section. Studies have established that various geometrical parameters like channel cross section, rib height, coolant angle of attack, pitch between the ribs, rib profile, and number of walls with ribs influence the friction and heat Hindawi International Journal of Photoenergy Volume 2021, Article ID 5581081, 13 pages https://doi.org/10.1155/2021/5581081