Increased capacity fan demonstrator for a Volvo RM12 upgrade

摘要

For the purpose of a potential upgrade of thrust for the Volvo RM12 engine a new fan is designed that allows for a 6% increase in mass flow and in pressure ratio. Design constraints include that the existing interfaces to the aircraft and fan/compressor interface should be maintained. All 3 rotors in the fan design are of BLISK type. In rotor 1 this calls for particular attention to the stiffness and frequencies of the blade, as it replaces a blade using a part span shroud. The requirements and constraints leads to the challenging task of increasing the power of an existing, highly loaded design, without an increase in outer dimension of the fan. It calls for some special design solutions and measures, such as increasing the length effectively used for the blades and vanes. The outlet guide vane is therefore aerodynamically integrated with the mid-frame in a closely coupled configuration in order to avoid a detrimental OGV-Strut interaction. A non-uniform OGV design is used masking the upstream variation of pressure from the 3rd rotor blade and vane. Using 3D design techniques a design is made that satisfies performance requirements inside the geometric constraints. Much of the original fan hardware can by this design be re-used, which makes the design cost effective.