Impingement sleeve and methods for designing and forming impingement sleeve

A method for designing an impingement sleeve, the method comprising:

• determining a desired operational value for a transition piece;
• inputting a combustor characteristic into a processor;
• and
• utilizing the combustor characteristic in the processor to determine a cooling hole pattern for the impingement sleeve, the cooling hole pattern comprising a plurality of cooling holes, at least a portion of the plurality of cooling holes being generally longitudinally asymmetric, the cooling hole pattern providing the desired operational value.

An impingement sleeve for a combustor, comprising:

• a body configured to at least partially surround a transition piece of the combustor;
• and
• a plurality of cooling holes defined in the body, the plurality of cooling holes having a cooling hole pattern configured to provide a desired operational value for the transition piece,
• wherein at least a portion of the plurality of cooling holes are generally longitudinally asymmetric.