An experimental study was performed to investigate the effects of the arrangement of fan-shaped film cooling holes and density ratio (DR) on heat transfer coefficient augmentation. Both single- and multi-row fan-shaped film cooling holes were considered. For the multi-row fan-shaped holes, the heat transfer coefficient was measured at DRs of 1 and 2, and both staggered and inline arrangements of holes were considered. For the single-row fan-shaped holes, DR = 1.0, 1.5, 2.0, and 2.5 and M = 1.0 and 2.0 conditions were tested. The mainstream velocity was 20 m/s, and the turbulence intensity and boundary layer thickness were 3.6% and 6 mm, respectively. The heat transfer coefficient was measured using the one-dimensional transient infrared thermography method. The results show that an increased heat transfer coefficient augmentation is observed between film cooling holes for the case with a smaller hole pitch and higher blowing ratio. For the given fan-shaped hole parameters, the effects of the row-to-row distance and hole arrangement are not significant. In addition, as the velocity difference between the mainstream and coolant increases, the heat transfer coefficient ratio increases.

The objective of this study is to implement a more realistic integrated analysis model for micro gas turbines by incorporating secondary flow and combustion efficiency into the existing model, which includes main engine components such as the compressor and turbine, and to validate this model by comparing it with test results. The study was based on the JetCat P300-RX, which has a maximum thrust level of 300 N. Simulations were performed using ANSYS CFX, employing the κ-ω SST turbulence model and a mixing plane interface between individual components. The eddy dissipation model (EDM), with a combustion efficiency of 90%, was used as the combustion model. A user subroutine was also applied for the power matching of the compressor and turbine to calculate the fuel flow rate in each iteration. For secondary flow, it was assumed that 3% of the total air flow rate would flow through the secondary path and be applied to the compressor and turbine. Simulations were conducted over a range of 30,000 to 104,000 RPM, with ground conditions evaluated, including altitude-simulated conditions. To validate the analysis model, engine performance metrics such as pressure ratio, air flow rate, fuel flow rate, and exhaust gas temperature (EGT) were compared with test results. The results demonstrated that errors were less than 5% for most engine performance metrics, except for EGT and fuel flow. The discrepancy in EGT was attributed to differences in the sensing methods, while the variation in fuel flow was found to be due to the lubrication system and losses due to the secondary air flow. Consequently, this study confirmed that the integrated simulation model accurately predicts engine performance. The results indicate that the integrated simulation model provides a more realistic prediction of overall engine performance compared to previous studies. Therefore, it can evaluate detailed thermo-fluid properties without the need for component performance maps, enhancing performance evaluation and analysis.

This study presents the arrangement design of the cooling hole and the application of a fan-shaped hole to improve the cooling performance of the high-pressure turbine. To this end, the first stage nozzle vane of the energy efficient engine (E3) was selected as the base model, and for efficient design, the source term method, called the injection region, was applied for producing the effect of the cooling flow when the RANS analysis was performed. At this time, because the cooling flow rate also changed when the location of the cooling hole changed, a neural network model was constructed to predict the cooling flow rate for the location of the cooling hole. Design optimization was performed to improve the film cooling effectiveness and the temperature uniformity on the vane surface using the streamwise location of the cooling hole as a design variable, and then the cooling performance was investigated by applying several fan-shaped holes instead of cylinder holes on the pressure side. As a result, the final design was obtained, which improved the film cooling effectiveness by 4.1%p and temperature uniformity by 0.7% compared with the base model.