Exhaust system and gas turbine

An exhaust system comprising:

• a casing having an annular shape;
• an outer diffuser having an annular shape and supported on a radially inner side of the casing;
• an inner diffuser having an annular shape and disposed on a radially inner side of the outer diffuser to form an exhaust gas flow passage between the inner diffuser and the outer diffuser;
• a strut cover having a cylindrical shape, and the strut cover being coupled at a first end in a longitudinal direction to the outer diffuser and coupled at a second end to the inner diffuser;
• a cooling air introduction portion provided in the casing, further on an upstream side or a downstream side of the exhaust gas flow passage than the strut cover;
• a partition member having an annular shape so as to cover a radially outer side of the outer diffuser and supported by the casing, the partition member being non-perforated and disposed annularly in the axial direction and having a free first axial end such that a space is formed between the free first axial end and a rear end of the outer diffuser, and having a fixed second axial end fixed to the casing;
• and
• a cooling air flow passage provided between the radially outer side of the outer diffuser and the partition member and formed so as to guide cooling air, introduced from the cooling air introduction portion, from the space at the free first axial end of the partition member toward the fixed second axial end of the partition member and to a strut cover flow passage inside the strut cover.