Performance and durability improvement in compressor structure design

An integral assembly that may improve control over thermal and mechanical behaviors of assembly structures during various transient operation conditions is disclosed. The integral assembly comprises a continuous ring disposed coaxial with, and orthogonal to a central axis, the continuous ring comprising a plurality of surfaces, the plurality of surfaces having a continuous outer surface and a continuous inner surface; the plurality of surfaces being characterized by a continuous cross section having a first cross sectional dimension longitudinally disposed parallel to the central axis; the plurality of surfaces comprising a bell mouth surface in physical communication with a compressor shroud surface; the compressor shroud surface being in physical communication with a diffuser surface; and the diffuser surface being in physical communication with the bell mouth surface. The integral assembly comprising a compressor shroud is also provided. An auxiliary power unit including the integral assembly, and a method of making the integral assembly are also disclosed.