A Preliminary Design Tool for Shrouded-Fans

"Shrouded-fans are an integral part of the U.S. Army's transportation systems. TheRAH-66's fan-tail, Sikorsky's Cypher and Micro-Craft's UAV are testimonials to theirincreasing importance. Shrouded-fans are efficient, but aerodynamically very complex,particularly in non-axial flight conditions such as conversion modes. The viscouscharacteristics of the flow through the shrouded-fan play an imortant role in thethree dimensional moments and forces generated in non-axial flight conditons.This proposal offers to develop an efficient, robust and fast preliminary designtool capable of analyzing the performance and flowfield of shrouded-fans in axialand non-axial flight conditions.The principle parts of the tool are:1. A viscous solver for shroud conforming grids2. An efficient rotor model3. An integral body conforming grid generatorIn Phase I, viscous flow through a shrouded-fan in non-axial flight conditions,but with fixed shroud orientation, will be computed as proof-of-concept of anefficient design tool. In Phase II, continuous rotation of the shroud about itsown axis, such as in conversion modes from hover to forward flight, will beundertaken. The software developed under this initiative will find wide usage in the DODrotorcraft organizations, rotorcraft industry and NASA. This proposal offers acomputational tool that will lay the foundations for true transient wakecalculation of a shrouded-fan in axial and non-axial flight conditions.S