Turbine shroud segment and its manufacture

A turbine shroud segment for a gas turbine engine that has a supply of cooling air, the turbine shroud segment comprising:

• a segment casing that has a radially outer surface and a radially inner surface;
• the segment casing houses a main plenum, a first layer of impingement chambers, a second layer of impingement chambers, and a plurality of effusion passages;
• the first layer of impingement chambers fluidly communicates with the main plenum via transfer passages that are formed in the segment casing;
• the second layer of impingement chambers fluidly communicates with the first layer of impingement chambers via impingement passages that are formed in the segment casing;
• and
• the effusion passages run between impingement chamber core surface, which is a radially inner surface of an impingement chamber, and the radially inner surface of the segment casing;
• wherein in use the main plenum receives cooling air from the supply of cooling air, the cooling air passes through the transfer passages to the first layer of impingement chambers, then through the impingement passages into the second layer of impingement chambers, and then through the effusion passages that open onto the radially inner surface of the segment casing;
• wherein the segment casing has a cooling system inlet that is formed in a side of the segment casing to provide access to a particle separator that is configured to guide lower mass particles suspended in cooling air into the main plenum via a primary passage and guide higher mass particles suspended in cooling air into and along a dust passage in the segment casing that exits the segment casing via a dust outlet;
• and
• wherein the particle separator is swan-necked.