Abstract: Film cooling apparatus adapted to be connected into a conduit carrying a hot exhaust gas. The apparatus comprises single walled contoured duct means connectible to said conduit and a center-body aerodynamically shaped and supported within said duct means so as to form therewith an annular channel of zero pressure gradient. Slot means are provided in the single walled contoured duct means and in the center-body to enable a flow of cooling air over exterior surfaces thereof to maintain said surfaces at an acceptably low temperature. A network of ducting carries the cooling air to the contoured duct means and interior of the center-body. The duct means and center-body are preferably of circular cross-section taken orthogonally of the overall flow direction. The center-body is an axisymmetric bulb having annular slots for directing the cooling air over the exterior of said bulb.