In the design of a low bypass ratio fan stage

this paper links the through flow inverse problem of the fan rotor

the core channel fan stator and the bypass channel fan stator together

as an organic whole

with the splitter aerodynamic design problem.It forms thus a unified through flow inverse problem for two channel turbomachines.After an overall quasi radial equilibrium is iteratively achieved among four parts-the streamlines of the core channel fan stator

the bypass channel fan stator

the splitter and the position of the splitter

the blading processes for one fan blade

two fan vanes and one splitter are performed.This method designs in one pass a fan stage and a splitter with a precise value of bypass ratio.Its primary and key approach scheme is the introduction of a mass addition half way through the through flow streamline development.This scheme can serve as a new feature which can be inserted into existing through flow programs.When subtracting mass flow after adding a mass flow

alternatively

this scheme can also be used to treat the problem of inverse design of fan/compressor rotor blades with part span shrouds.