Recently, film cooling has been continuously studied to increase the efficiency of gas turbines. A turbine inlet temperature increase occurs as a way to improve the efficiency. However, it is essential to improve the cooling performance of the blade surface because of the melting point of the part. In this paper, a side hole shape wherein a general cylinder hole and two auxiliary holes are combined, is proposed to improve the film cooling efficiency, and the blowing ratio was set to 0.4, 0.8, 1.2, and 2.0. When side hole was applied, the vortex interference at the hole entrance occurred less than that of the cylinder hole. That is, the flow rate of the coolant adsorbed to the surface increased to improve the cooling performance. In conclusion, compared to the cylinder hole, the cooling efficiency of the shape to which the side hole was applied was excellent, and in particular, the average area cooling efficiency with spanwisely designed side holes improved by 83%.

In this study, the design of an axial steam turbine that is installed for a using waste pressure. Airfoils and flow fields are designed based on 1D and 2D meridional plane design techniques. The 3D geometry of the steam turbine is designed considering the 1D and 2D design parameters. The turbine is designed with an average radius of 287 mm and rotates at 8,300 re v/min. The inlet boundary condition of the steam turbine was applied in consideration of the installation condition of the waste pressure turbine. When analyzing the results of the numerical simulation, the performance of the steam turbine is predicted with an output of 3.5 MW and isentropic efficiency of 88.4%. The choked flow in the nozzle throat and the flow separation in the suction side on the blades are predicted numerically, and it is expected to be a study to determine the cause of the reduction in efficiency of the steam turbine.

In this paper, we analyze the cooling performance according to the HVAC types installed in the energy storage system (ESS). Batteries in ESS have the disadvantages of decomposition and catching fire at high temperatures, so it is important to control the temperature. For the purpose of cooling the batteries in ESS, we designed the cooling systems with stand and ceiling type HVAC. Both the cooling systems for ESS are analyzed numerically for the comparison of cooling performance. The heat dissipation of the battery is 1979.3 W/m3 on 1 C-Rate discharge, and the cooling flow rate and temperature are 6.375 kg/s and 17℃, respectively. The maximum temperature of batteries with stand and ceiling type cooling systems are calculated to be 65.85 and 60.5℃, respectively. In conclusion, cooling systems with ceiling type HVAC are more efficient than cooling systems with stand type HVAC.

Research on advanced cooling system design is significant in achieving a high turbine inlet temperature in the gas turbine industry. The higher turbine inlet temperature of the gas turbine increases thermal efficiency. However, it also aggravates the gas turbine deterioration, lifespan, and efficiency. In this study, a numerical model is developed for simulating the cooling performance of the gas turbine vane with the turbine inlet temperature of 1528 K. The impact of the coolant air flow rate and hole-shape were investigated. The expanded hole shape had better cooling performance than the general cylindrical shape, and showed higher cooling efficiency. We suggest that there is a relationship between the shape of the film cooling holes and the cooling air flow rate that achieves the desired cooling effectiveness.

A brushless direct current (BLDC) motor electronically performs rectification without brushes. It therefore does not have the typical mechanical friction contacts between the brushes and commutators. The BLDC motor has the advantages of high speed, low noise, and electronic noise reduction in addition to high durability and reliability. Therefore, it is mainly used in electric vehicles and electric equipment. However, iron loss and copper loss due to long-term use induce temperature increases in the motor, which reduces its performance and life. The temperatures of the stator and permanent magnet are predicted to be 62.3℃ and 32.2℃, respectively. This study shows the enhanced temperature distribution in a 600 W BLDC motor using unsteady and threedimensional (3D) numerical investigations validated with experimental data.