Counter-rotating compressor case and assembly method for tip turbine engine

Abstract

A tip turbine engine () provides an axial compressor () having a compressor case () from which extend radially inwardly a plurality of outer compressor airfoils (). The compressor case () is directly driven by the rotation of the turbine () and fan (), while at least one gear () couples the rotation of the turbine () and fan () to an axial compressor rotor () having a plurality of inner compressor airfoils (). In this manner, the axial compressor rotor () is driven in a direction opposite the direction of the outer compressor airfoils (), thereby increasing the compression provided by the compressor without increasing the number of airfoils. The outer compressor airfoils () are formed on a plurality of outer airfoil assemblies () each having an arcuate substrate () from which the outer compressor airfoils () extend. Each of the outer compressor airfoil assemblies () includes more than one axially-spaced stage of outer compressor airfoils (). For assembly, the outer compressor airfoil assemblies () are moved toward the axial compressor rotor () and then inserted into the compressor case ().