Abstract: A high efficiency environmental control system uses air exhausted from a pressurized cabin to cool compressed air entering the cabin. Air exhausted from the cabin may flow directly from the cabin through a heat exchanger which cools the compressed air entering the cabin. Alternatively, air exiting the cabin may flow through a turbine which expands and cools the air prior to passing through the heat exchanger. The turbine may be used to drive a compressor to provide the compressed air to the cabin. Supplemental power to drive the compressor may be provided by a second turbine driven by bleed air from one or more turbine engines, or by an electric motor. Bleed air may also be mixed with air from the compressor to provide fresh air to the cabin. To further increase efficiency and meet the cooling requirements of the cabin on the ground and at altitude, switch dampers may be employed to selectably vary the flow path of air supplied to the cabin.

Abstract: An apparatus for generating an air stream that is substantially-columnated about a given axis includes a converging-diverging nozzle, a manifold in fluid communication with the nozzle, and a compressor supplying a quantity of compressed air to the manifold to induce a first air flow through the nozzle. The first air flow is characterized by sonic flow at the nozzle throat and supersonic flow at the nozzle exit. The supersonic first air flow exiting the nozzle is directed into one end of an elongate tube. The thus-directed first air flow induces a second flow of ambient air into the one end of the tube. The first air flow mixes with the second air flow within the tube and exits as an air stream that is substantially columnated about the axis of the tube.