Abstract: A compressor assembly for a gas turbine engine is provided. The compressor assembly includes a rotating impeller including an inlet, an outlet, and a body extending therebetween. The compressor assembly further includes a non-rotating impeller shroud. The body and the shroud define an impeller chamber including a radially inner surface and a radially outer surface. The radially inner surface includes an arcuate flow surface. The flow surface includes a first portion and a second portion extending downstream from the first portion. The impeller chamber includes a variable area wherein a first cross-sectional area is defined between the radially outer surface and the first portion, and a second cross-sectional area is defined downstream from the first cross-sectional area. The first cross-sectional area is greater than the second cross-sectional area. A method of operating the compressor assembly is also included.