Various systems and apparatuses are provided for a fluid transfer system for an engine. In one example, a system includes a first turbine having an exit for discharging a main fluid flow and a second turbine having an inlet for receiving at least a portion of the main fluid flow. A main conduit fluidically couples the exit of the first turbine to the inlet of the second turbine. A transition conduit is coupled with the main conduit and includes a volute passageway curving around the main conduit. The volute passageway includes a slot that follows a route around the curving volute passageway and opens into an interior of the main conduit. The slot is defined at least in part by a lip and establishes a path for either a secondary fluid flow to enter the main conduit or a portion of a main fluid flow to exit the main conduit.