Turbine bypass working fluid admission

An air cycle machine for conditioning air for supply to an enclosure, comprising:

• shaft means disposed for rotation about a longitudinally extending axis;
• bearing means for supporting said shaft means for rotation about said axis;
• a turbine wheel mounted to a first end portion of said shaft means for rotation therewith, said turbine wheel operative to expand the conditioning air passing therethrough thereby cooling the expanded conditioning air and extracting energy therefrom for driving said shaft means in rotation about said axis, said turbine wheel having a fixed stator and an outlet for directing the cooled expanded conditioning air discharging from said turbine wheel along said axis;
• and
• a bypass flow nozzle disposed coaxially about said axis and extending coaxially along said axis, said bypass flow nozzle having a nozzle inlet including a central region for receiving the cooled expanded conditioning air passing from said turbine wheel outlet and an outer annular region extending circumferentially about said central region for receiving a flow of relatively warm air having bypassed said turbine, whereby said received bypass air flow passes through said outer annular region as an outer annular flow stream passing substantially parallel to and about the cooled expanded conditioning air passing through said central region, and a nozzle outlet for directing the received turbine exhaust flow and the received turbine bypass flow therethrough.