A flow system for use in a gas turbine engine includes a diffuser case strut defining a first opening at a first radial end, a second opening at a second radial end, and a strut passage radially therethrough between the first and second openings. A first chamber wall and a second chamber wall define a first mixing chamber disposed radially inward of the diffuser case strut in fluid communication with the strut passage. A third chamber wall extends between the second flowpath wall and the second chamber wall to define a second mixing chamber disposed between the diffuser case strut and the first mixing chamber. The second flowpath wall and the second chamber wall are shaped to form a venturi in the second mixing chamber.