A ring segment for a gas turbine, a method to operate a gas turbine and computer-implemented method to design and/or manufacture said ring segments

A computer-implemented method for designing and/or manufacturing a ring segment for a gas turbine,

• wherein the ring segment comprises a base body having a first surface subjectable to a working medium of the gas turbine and a second surface, which is opposite of the first surface and on which fastening elements are located at different axial positions,
• wherein multiple ring segments, when assembled in a gas turbine, form a portion of an annular outer flow path boundary of a working medium of the gas turbine, the portion of the annular outer flow path boundary surrounding a row of airfoil tips of rotor blades and forming radial gaps therebetween,
• the method comprising the steps of:
• determining or providing a first surface embodied completely as a nominal area for cold operation state of the gas turbine by considering its axial position in the flow path, radial distances of the first surface to a rotational axis of the gas turbine and/or an opening angle of the outer annular flow path boundary,
• determining or providing an operational temperature distribution of the ring segment for hot operation state, of the gas turbine,
• determining a hot operation contour of the first surface by considering a thermal growth of the ring segment, and,
• modifying the first surface in cold operation state away from a complete nominal area to a first surface comprising a troughed center area to reduce an average radial gap, compared to an average radial gap based on the hot operation contour of the first surface.