《《Section 03 Ideal Propeller Theories》.pdf

Section 3 Theory of Propeller Action  Theory of ideal propulsors - momentum theory for axial flow  Theory of ideal propellers - momentum theory including angular motion  Forces moments acting on propeller blades - based on the idea of blade elements 1 Theory of Ideal Propulsors (The Actuator Theory) Basic assumptions  Water: an ideal and incompressible fluid  Propulsor operating in an unbounded inflow  Propulsor: an actuator disk with no thickness; the water is accelerated only in axial direction when passing through the disk  Velocity and pressure distributions over the disk are uniform 2 V A V A B A C Flow Pattern V V + u V + u A A a 1 A a Control Volume C A 1 B1 V A 1 V A V + u V + u A a Velocity V A A a 1 Pressure p p p 0 p1 1 0 Return  Application of momentum theorem in axial direction