Development of a Propeller Afterbody Analysis with Contracting Slipstream

A developmental study was performed of an analytical method to predict the aerodynamic behavior of propeller afterbodies in a contracting slipstream. An existing axisymmetric body panel code was used as the basis. The slipstream was modeled by a finite set of vortex rings lying on a deformable tube boundary. Relations were formulated giving the ring strength in terms of the propeller operating conditions.

An experimental program was conducted to investigate the accuracy of the method. The static pressure distribution of an axisymmetric afterbody was measured in the presence of a propeller slipstream. The results showed good agreement at high advance ratios, but increased in error as the advance ratio was reduced. The error was traced to losses in slipstream total pressure adjacent to the afterbody due to stall of the inboard section of the test propeller.