Numerical flow and experimental heat transfer of S-shaped two-pass square channel with cooling applications to gas turbine blade

• Published in: International journal of heat and mass transfer 2017-05, Vol.108, p.362-373
• Main Authors: Wu, Pey-Shey, Chang, ShyyWoei, Chen, Chuan-Sheng, Weng, Chien-Chou, Jiang, Yu-Ru, Shih, Shih-Hao
• Format: Article
• Language: English
• Subjects: S two-pass channel; Turbine blade cooling
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2016.11.107

•Numerical flow and experimental thermal performances of S-shaped two-passchannel are studied.•Effects of channel geometry on fluid flows, Nu and f properties are examined.•Empirical Nu and f correlations are generated.•Comparative TPF properties are analyzed. This study experimentally detected the endwall Nusselt numbers (Nu) distributions, Fanning friction factors (f) and thermal performance factors (TPF) for a stationary S-shaped two-pass square channel with the associated turbulent flow fields analyzed by ANSYS Fluent code to disclose the flow mechanisms responsive to the measured thermal performances. The full-field Nu distributions over the endwalls of present S-shaped inlet/outlet legs and 180° sharp bend at Reynolds numbers (Re) of 5000, 7500, 10,000, 12,500, 15,000, 20,000 and 30,000 were measured using the steady-state infrared thermography method; while the validated RNG k-ε turbulence model was adopted to reveal the fields of time-mean fluid velocity, turbulent kinetic energy and cross-plane secondary flow. Acting by sectional vortices induced along the inlet/outlet S-pathways and 180° sharp bend, the core-to-wall momentum/heat exchanges are boosted to elevate both Nu and f values. Accompanying with the f augmentations from 10.19–8.27 times of Balssius f∞ levels, the area-averaged Nusselt numbers (Nu‾A) over the entire S-shaped endwall were elevated to 3.21–3.09 times of Dittus-Boelter Nusselt number (Nu∞) values at 5000⩽Re⩽30,000, resulting in the TPF between 1.4 and 1.44. To assist relevant engineering applications, two sets of empirical correlations evaluating the regionally averaged endwall Nusselt numbers and f factors are devised.