Month in the Patent Office

The inner wall 10 of a gas‐turbine diffuser is formed with two rows of circumferential slots 40, 42 whereby, due to the increasing static pressure in the downstream direction, gas will flow into the downstream slots 42 and out of the upstream slots 40 to set up a circulation which will energize the boundary layer to increase its flow in the same direction as the gas stream. The rows of slots are staggered circumferentially but do not overlap axially. In an alternative arrangement the slots are formed in the outer wall of the diffuser, an external U‐shaped member surrounding the slots to provide an annular circulation chamber.