A Mass Addition Approach to the Bypass Turbomachine Through Flow Inverse Design Problem

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.