螺旋桨几何参数

Wing section: high efficiency, most often used; cavitation performance not so good in some cases
wing section

Types of blade sections (continued)

Boss cap
Boss/Hub
Tip
Root
Chapter 2 Geometry of Marine Propellers

General terms

5-bladed propeller



Number of blades, Z -bladed propeller Boss/hub: part for fitting the blades & the propeller to the shaft Boss cap: streamlined conical body for fixing the propeller to the shaft Direction of rotation: left- & righthanded Blade tip & root Leading-edge & trailing-edge: L.E. & T.E. Face & back, pressure & suction side
back
t/2 nose t/2 f f1
t1/2 t1/2
camber line or mean line tail
nose-tail line
base line
face
Propeller Drawings

Terms & definitions for blade outlines

Extended outline Extended Area Ratio of blades (EAR, AE/A0)
Chapter 2 Geometry of Marine Propellers

General terms

5-bladed propeller



Number of blades, Z -bladed propeller Boss/hub: part for fitting the blades & the propeller to the shaft Boss cap: streamlined conical body for fixing the propeller to the shaft Direction of rotation: left- & righthanded Blade tip & root Leading-edge & trailing-edge: L.E. & T.E. Face & back, pressure & suction side

Propeller blade section & pitch

The blade section at radius r is defined as the section formed by cutting the blade with a coaxial cylindrical surface of radius r ; This blade section is located on a helix – Section nose & tail on helix – nose-tail pitch Section face on helix – face pitch If P=constant along radius, the propeller is called a constant-pitch propeller ; In most cases P =P (r ), the propeller is called a radially-varying-pitch propeller, and P0.7R or P0.75R is often used as the representative mean pitch of the propeller.
circular cylinder

AB is called the generating line.
A helix is the trajectory of a point on AB, or the intersection of the helicoidal surface and a cylindrical surface coaxial with OO1.
Circular back: better cavitation performance Crescent-shaped: for high speed ships Shuttle-shaped: for frequent astern operations Wedge-shaped: super-cavitating section
Boss cap
Boss/Hub
Back
L.E. T.E. T.E.
Face
L.E.


Tip circle: trace of rotating blade tip when the propeller does not advance D: propeller diameter, diameter of tip circle A0: disk area of propeller, A0=πD2/4 Twin propellers: inward- & outward-turning Tip clearance: shortest distance between tip & stern hull

Helicoidal surface & helix

A helicoidal surface is a surface swept out by a straight line AB, which advances along axis OO1 at a uniform speed, and meanwhile rotates around OO1 with a uniform angular speed.

Projected view (stern view) & outline Projected Area Ratio of blades (PAR, AP/A0) Developed outline Developed Area Ratio of blades (DAR, AD/A0)

Baidu Nhomakorabea

Longitudinally projected view (side view) & outline




The pitch ratio, P/D, is often used, so that

Note that, for the same pitch value, the smaller r is, the larger Φ will be.

Types of blade sections
Definition of Pitch Angle
B1
P Φ 2πr C
B

Propeller blade section & pitch

The blade section at radius r is defined as the section formed by cutting the blade with a coaxial cylindrical surface of radius r ;
circular back crescent-shaped
shuttle-shaped
wedge-shaped (super-cavitating section)

Terms & definitions for blade section

Nose & tail Face & back, pressure side & suction side Nose-tail line & base line Chord, chord length Thickness distribution & maximum thickness ratio Camber distribution & maximum camber ratio



When AB makes a complete revolution to reach its final position A1B1, the distance AA1 or BB1 is called the pitch, denoted by P. When the coaxial cylindrical surface is expanded on a flat surface, the helix will become the straight line BB1, which makes an angle with the horizontal line BC at an angle Φ called the pitch angle and determined by tanΦ = P/ (2πr )