This study presents a comprehensive analysis of heat transfer enhancement, flow resistance, and thermal performance in rectangular channels equipped with three baffle configurations: conventional transverse baffles (TBs), in-line downward-facing notched baffles (IDF-NBs), and staggered downward-facing notched baffles (SDF-NBs). The influence of the pitch-to-baffle height ratio (P/e), ranging from 2.0 to 10, was examined across Reynolds numbers from 6000 to 24,000. Results indicate that a P/e ratio of 6.0 consistently yielded the highest Nusselt numbers across all configurations. While the TB configuration produced significant heat transfer at P/e= 6.0, it experienced a substantial friction penalty, with its best thermal enhancement factor (TEF = 1.168) observed at P/e = 8.0. The IDF-NB configuration achieved optimal performance at P/e = 6.0 with a TEF of 1.257, offering a better balance between heat transfer and flow resistance. The SDF-NB arrangement outperformed all other cases, delivering the highest Nusselt number (Nu = 116.9), TEF (1.362), and improved flow reattachment, primarily due to enhanced mixing from the staggered layout. These findings demonstrate that the staggered notched baffle configuration at P/e = 6.0 offers the most effective thermal performance enhancement among the configurations studied.

This study investigates heat transfer enhancement in the cooling channels of gas turbine blade turbulators using modified transverse baffles with isosceles triangular sawtooth perforations. The proposed baffle design aims to improve convective heat transfer by promoting flow mixing and disrupting the thermal boundary layer. Experiments were conducted in a rectangular channel with an aspect ratio of 3.75 under constant heat flux conditions using air (Pr = 0.7) as the working fluid. The effects of Reynolds number (Re = 6000–24,000), sawtooth width ratio (a/W = 0.0, 0.0625, 0.125, 0.25, and 0.5), and sawtooth height ratio (b/e = 0.0, 0.25, 0.5, 0.75, and 1.0) were systematically investigated. The blockage ratio (e/H) and pitch ratio (P/H) were maintained at 0.3 and 1.5, respectively. Heat transfer characteristics were evaluated using the thermochromic liquid crystal (TLC) technique, while thermal–hydraulic performance was assessed in terms of the Nusselt number (Nu), friction factor (f), and thermal performance factor (TPF). The results demonstrate that introducing sawtooth perforations significantly enhances heat transfer compared with a smooth channel, yielding Nusselt number ratios (Nu/Nu_s) between 1.6 and 2.6. The highest heat transfer enhancement was achieved at a/W = 0.0625 and b/e = 0.25, where the relatively small sawtooth openings generated stronger jet impingement, enhanced flow mixing, and more effective disruption of the thermal boundary layer. However, these geometric modifications also increased the pressure loss due to intensified flow blockage and recirculation, resulting in friction factor ratios (f/f_s) ranging from 8.9 to 14.9. The maximum pressure-drop penalty occurred at b/e = 0.25 because the smaller openings produced stronger turbulence and increased flow resistance. Despite the increased friction loss, the optimum configuration (a/W = 0.0625 and b/e = 0.25) achieved the highest thermal performance factor of 1.2 at Re = 6000.