An augmentor apparatus for a gas turbine engine comprising: an augmentor outer casing having an inlet for receiving core engine discharge gases and an outlet for discharging augmentor air flow; an annular augmentor liner disposed radially within said augmentor outer casing and having a radially outer surface separated from a radially inner surface of said augmentor outer casing by a predetermined radial spacing to form a generally annular augmentor liner cooling flow path; and a generally annular augmentor flow splitter duct disposed radially between said radially inner surface of said augmentor outer casing and said radially outer surface of said annular augmentor liner, extending axially aftward from an axially forward flow inlet end of said augmentor outer casing and defining a splitter flow path extending axially through a screech suppression zone between said radially outer surface of said annular augmentor liner and a radially inner surface of said annular augmentor flow splitter duct, and a radially outer annular flow path between a radially outer surface of the flow splitter duct and the radially inner surface of the augmentor outer casing, wherein the splitter flow path and the radially outer flow path are open at their respective upstream ends and the radially outer flow path is in fluid communication with a downstream region of the liner cooling flow path, characterized in that at least one of a first and a second air flow blocker dam (530, 532) is provided and is disposed axially downstream of the annular augmentor flow splitter duct and extends radially, whereby a radial spacing is formed between the at least one flow blocker dam and a radial counterpart structure, thereby providing a fluid communication between the splitter flow path and a downstream region of the liner cooling flow path. an augmentor outer casing having an inlet for receiving core engine discharge gases and an outlet for discharging augmentor air flow; an annular augmentor liner disposed radially within said augmentor outer casing and having a radially outer surface separated from a radially inner surface of said augmentor outer casing by a predetermined radial spacing to form a generally annular augmentor liner cooling flow path; and a generally annular augmentor flow splitter duct disposed radially between said radially inner surface of said augmentor outer casing and said radially outer surface of said annular augmentor liner, extending axially aftward from an axially forward flow inlet end of said augmentor outer casing and defining a splitter flow path extending axially through a screech suppression zone between said radially outer surface of said annular augmentor liner and a radially inner surface of said annular augmentor flow splitter duct, and a radially outer annular flow path between a radially outer surface of the flow splitter duct and the radially inner surface of the augmentor outer casing, wherein the splitter flow path and the radially outer flow path are open at their respective upstream ends and the radially outer flow path is in fluid communication with a downstream region of the liner cooling flow path, characterized in that at least one of a first and a second air flow blocker dam (530, 532) is provided and is disposed axially downstream of the annular augmentor flow splitter duct and extends radially, whereby a radial spacing is formed between the at least one flow blocker dam and a radial counterpart structure, thereby providing a fluid communication between the splitter flow path and a downstream region of the liner cooling flow path.