Controlling cooling flow in a cooled turbine vane or blade using an impingement tube

A method of manufacturing an airfoil for a gas turbine, the method comprising

• providing an outer shell comprising an inner volume,
• arranging an inner shell within the inner volume of the outer shell,
• wherein the inner shell comprises an inner nose section and an inner tail section,
• wherein a high pressure side of the inner shell is formed along a first surface section between the inner nose section and the inner tail section,
• wherein a low pressure side of the inner shell is formed along a second surface section which is located opposite to the first surface section between the inner nose section and the inner tail section,
• wherein the inner shell is spaced apart from the outer shell such that
• a first cooling channel is formed along the high pressure side between the inner nose section and the inner tail section, and
• a second cooling channel is formed along the low pressure side between the inner nose section and the inner tail section,
• wherein the first cooling channel and the second cooling channel merge into a common cooling channel at the inner tail section,
• arranging a first tail fin between the first cooling channel and the common cooling channel and defining a first fluid passage configured to control a first mass flow rate of a cooling fluid flowing through the first cooling channel, and arranging a second tail fin between the second cooling channel and the common cooling channel and defining a second fluid passage configured to control, a second mass flow rate of a cooling fluid flowing through the second cooling channel,
• wherein the first fluid passage and the second fluid passage comprise different flow areas during at least some operating conditions,
• wherein the first tail fin is configured to deform in response to a pressure increase, thereby increasing a flow area of the first fluid passage, and
• wherein the second tail fin is configured to deform in response to the pressure increase, thereby increasing a flow area of the second fluid passage.