For a particular printing ink and drop-on-demand piezoelectric inkjet printhead, piezoelectric voltage and temperature of the ink were varied to change the inkjet performance, and the jetting velocity of the inkjet was analyzed under various conditions. The ink was cooled by using a Peltier module, which was attached to the nozzle plate as a heat sink. The inkjet drops were captured by the shadowgraphic method using a high-speed camera. The positions and velocities of these drops were then estimated after image processing. The drop state was distinguished by dimensionless numbers, such as the Weber and Z numbers, to decide whether it was stable for ejection and printing. Increasing the piezoelectric voltage increased the ejection velocity but with an associated generation of satellite drops. Cooling the ink increased the viscosity, which in turn decreased the drop velocity while diminishing the satellite drops. Therefore, it was shown that the cooled ink enabled stabilized inkjet ejection.

This study analyzes the turbomachinery flow of a gas turbine using OpenFOAM, an open-source CFD code. While foam-extend, a version of OpenFOAM, includes tools for turbomachinery analysis, some of its codes are incomplete, resulting in incorrect results. Consequently, this study required the investigation and correction of the solvers and libraries. Specifically, foam-extend-4.1 and a compressible multi-reference-frame solver were utilized. Two primary errors related to temperature calculation were identified. The first error involved temperature discontinuity at the interface between the stator and rotor domain when using the mixingPlane. The second error was related to temperature rising at the wall. To address the temperature discontinuity problem, the rothalpy jump equation in the enthalpyJump code was modified from a scalar product to an inner product of vectors. To resolve the high-temperature problem at the wall, modifications were made to the energy equation code in iEqn.H. A rothalpy separation was introduced, and the rothalpy equation was adjusted to mimic the enthalpy equation. The results obtained with the corrected codes were consistent with those from the commercial code, demonstrating the effectiveness of the modifications.

An analytical study was conducted on the intake design of a supersonic micro gas turbine engine. The Pitot inlet, known for its simple shape and suitability for low supersonic speeds, was selected as the type of supersonic intake. Various parameters of the inlet geometry depend on the size of the micro gas turbine engine, air flow rate, and internal flow separation; these factors were taken into account during design process. The feasible size was determined by comparing analysis results based on the inlet throat radius. Additionally, analyses were performed considering the thickness of the inlet lip and the angle of attack. The result confirmed that using a thin inlet lip allows a shock wave to attach to the inlet, enabling a wide range of angle of attack operation for a large inlet area. 초 록 초음속 마이크로 가스터빈엔진의 흡입구 설계를 위한 해석적 연구를 수행하였다. 초음속 흡입구의 종류로는 형상이 간단하고 낮은 초음속 구간에도 적용이 가능한 Pitot 흡입구를 선정하였다. 흡입구 형상 설계의 여러 파 라미터들은