Abstract: A fan inlet and diffuser apparatus (30) is provided with a lobed mixer (60) for intermixing fan bypass air (25) with a flow of fan discharge air (27). The fan inlet and diffuser apparatus (30) is particularly adapted for use in a inducing a flow of cooling air (21) through an upstream heat exchanger (20) and thence directing a portion (23) of the cooling air passing from the heat exchanger to the inlet side of the fan (14) of an air cycle machine (10), while directing the remaining portion (25) to bypass the fan (14) and pass into the central outlet flow passage (52) flowing over the mixing ejector (60) which imparts a directional swirl to the bypass flow (25) and a counter swirl to the fan discharge flow (27) passing from the fan outlet through the interior of the mixer (60), thereby enhancing the mixing of these two flows within the passage (52).