In the gas turbine, the clearance between the blade tip of the rotor and the inside of the stationary casing varies depending on the rotation of the rotor and the heat output of the combustor. Accordingly, the assembly clearance is determined, and the leakage of the gas occurs because of the gap during operation, affecting the efficiency of the system. Thus, designers use a variety of techniques to optimize this clearance, a typical method that reduces the relative variation of the clearance using heating and cooling mechanisms. In this study, we developed a method to control the blade tip clearance through the axial movement of the inclined blade without using heating and cooling mechanisms. Recently, we designed an advanced blade tip clearance control system that can control multi-step, not on-off control, to apply to large gas turbines developed by Doosan. The designed system is hydraulic and can be used with a maximum thrust of 100 tons, and the desired displacement can be moved in multiple stages as required. We have completed the reliability verification of the entire lifecycle level and applied it to the newly developed gas turbine.

The liner of CNG pressure vessel was manufactured using a deep drawing and ironing (D.D.I.) process with a single punch. Tip clearance between billet and die suggested in the actual field has been widely used to reduce forming load and to improve die life. However, the analysis and design of tip clearance is necessary for the third stage of forming defect. In this study, the tip clearance of the third stage was determined to limit the ratio of reduction of cross-sectional area based on theoretical analysis. The proposed tip clearance was verified via finite element analysis. In addition, the simulation technique was established by comparing the forming load based on theoretical calculation with the load determined via FEM.