cd adapco inz Andrzej Rachwalik

63 Pages·2013·3.56 MB·English

Politechnika Gdańska
WYDZIAŁ OCEANOTECHNIKI
I OKRĘTOWNICTWA

Thesis:

Parametric B-Wagenigen screw model.
Verify compliance CFD computation with
hydrodynamics plots.

Performed : Andrzej Rachwalik

Gdańsk 18.02.2013
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I want to thanks for:

Cd-Adapco for sparing STAR-CCM+ software.
Especially Ralph Habig for be my software guide

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Gdansk University of Technology

Faculty of Ocean Engineering and Ship Technology

B.Sc. course in Ocean Engineering

Specialization: Shipbuilding Technology
Title: Parametric B-Wageningen screw model. Verify compliance CFD
computation with hydrodynamics plots.

Author: Andrzej Rachwalik
Album No: 128305
Supervisor: dr hab. inż. Cezary Żrodowski

Abstract:
B-Wageningen screw series is one of the oldest propellers. Due to its simplicity is one of the most
frequently used. With several polynomials describing it we could create new marine propeller. If
someone fell into in the twenty-first century to use the latest technology and software cad / cam we
can create a parametric 3D geometric model of the screw. Then we performed CFD studies and see
how it behaves in a stream of water, and find the right parameters for a given screw ship contracted
speed. In work I will try to improve that CFD calculation it’s equal to B-Wageningen hydrodynamics
series graph.

Keywords: B-Wageningen propeller, cfd propeller calculation

Gdansk, 18 February 2013

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1. Introduction .............................................................................................................................5
1.1. Target of work. ................................................................................................................5
1.2. Argument. .........................................................................................................................5
1.3. Methodology. ...................................................................................................................5
2. Description of a B-Wageningen series. ............................................................................6
2.1. History, propeller description and how does it work. ............................................6
2.2. Description of the geometry of B-Wageningen screw........................................... 11
2.3. Description of the properties of B-Wageningen screw. ........................................ 18
3. CFD simulation. .................................................................................................................... 21
4. Description of the process of creating parametric model 3D. ..................................... 21
4.1. Describing of model 3D ............................................................................................... 22
5. Describing CFD simulation. ............................................................................................ 30
6. Analysis of the results. ....................................................................................................... 57
7. Analysis of the results. ....................................................................................................... 62
8. Bibliography .......................................................................................................................... 63

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1. Introduction

1.1. Target of work.
Evaluation of the usefulness of CFD analysis by comparing the simulation results with the
propeller model results. For this I choose B-Wageningen screw series, because it is very
good knowed. So we can verify CFD results with plots from books. Finding information on
the geometric description of individual profiles is not a problem. The geometry of these
propeller is described accurately. The parameterization is very simple.

1.2. Argument.
CFD simulation, the current level of software development, allow for reliable opinion
marine propeller characteristic.

1.3. Methodology.
Verification of the CFD simulation results is done by comparing the dimensionless
characteristics of the propeller simulation results with model research. To do it, we make
a series of simulations for one screw to prevent accidental compatibility we do several
variants of B-Wagenigen screw. For this purpose it was made parametric screw geometry
model, allowing for rapid generation variant geometry. In this way we obtain random
diameter propeller from smallest for fishship to biggest like large ships. The model was
made in Siemens NX 8.0 and CFD simulations in the STAR-CCM+ from Cd-Adapco.

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2. Description of a B-Wageningen series.

2.1. History, propeller description and how does it work.
Marine propellers are mechanical traction equipment that produce pressure which make
vessel in motion. There are many types of propellers, with different rules of engagement
and various construction. The best known include propellers, paddle wheels. In my
engineering work I will limit myself to the most commonly used propeller. Work propulsor is
rejection by the masses of water surrounding the hull of the rig in the opposite direction to the
movement of the ship. Water propeller reject patches that assume the reaction forces
rejected the masses, giving pressure. Propellers include: fixed pitch propeller, adjustable
pitch propeller , nozzle-screw assemblies, supercavitating screw and tandem screw (two-
stage) concurrent and counter. Also divide them in terms of speed on the shaft at high speed
and low speed (about 120 rpm / s) Integrated Speed is a high-speed motorboat propellers
and large low-speed vessels. Much depends on the number of wings on the screw and there
is another division. Double-wing propellers are fast boats while three to are ships. Another
division of the selection function in terms of the bolt or screw is used as pulling, who has a
small stroke did not disperse the boat, however, gives greater traction or power. Pitch
propellers are set fixed pitch propellers are used in the propulsion of motor reversing, where
the direction and speed of the ship is controlled speed and direction of rotation of the main
drive motor ship. However, the propeller or so. variable pitch is the ability to set the angle of
the blades, so that keeps one direction of rotation and constant speed main engine by
changing the tilt angle of the blades. This allows you to flow forward and backward with
variable speed. If you set the propeller flaps in neutral position that is neutral, does not
produce any propeller thrust forces. Propeller generally horizontal axis, the longitudinal
consist of several (2 to 7) of the wings situated radially in the hub, in equal angular intervals
from each other. Uniform motion while rotating screws and uniform movement of the ship
progressive wing sections describe in the regular screw lines. The detailed work principle of
the screw shown in Figure 1 Wing screws lengthwise two cylindrical surfaces coaxial with the
axis of the rays r and r + dr creates a flap elementary, where water flows at VR for αE attack.
VR speed is the sum of the speed ωr, progressive VA and speed work produced the same
screws UI. At the elementary panel formed elementary resultant force dF, which consists of
elementary lift force dL and dF elemental resistance, which consists of elementary lift force
dL and dD elemental resistance. This force is distributed over the direction of the screw axis
and the direction of the tangent to the circle of radius r gives, respectively pressure
elementary dT and elementary moment dQ = dKr. Total sum of elementary and elementary
kinetic moments taken over the whole screw give respectively the resultant pressure and
resultant bolt load torque drive motor.

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Figure.1: The principle of screw (uniform velocity field) [2]
Helix is a circuit point which moves along the peripheral surface of a circular cylinder in such
a way that there is constant velocity return retaining components: V parallel and normal to
x
the axis V of the cylinder. Helical pitch P is called the stretch between two consecutive
ϴ
points of intersection of the cylinder by either creating a helix. An angle of pitch of the helix
angle Θ is called that the tangent to the helix formed with a plane normal to the axis of the
cylinder. If the ratio of the two components remains constant speed

, helix Has a constant pitch angle.

Figure.2: Constant pitch helix line. [2]

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Propeller blade surface are screw surfaces, wherein at least one of them is abnormal helical
surface. Wing surface facing towards the stern is called the suction side / dorsal surface
facing towards the stern side or bottom press. Edge of the wing bolts designated direction of
rotation is called the leading edge, the edge is a trailing edge opposite. In plan view the
surface normal to the axis of the screw wing is sometimes elliptical outline and knife

Figure.3: Wing contour shapes. [2]
Cylindrical cross-section of the wing surface, the axis coincides with the axis of the screw, is
a profile of the wing, the side push is usually part of the helix with constant pitch.

Figure.4: Cross-wing propeller cylinder coaxial with the axis of the screw [2]

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The most common propulsor is a fixed pitch propeller. It is relatively simple, easy to install on
the hull, is characterized by high efficiency, low weight and relatively low cost. The
disadvantages of a fixed pitch propeller include: inability to use the full power of the drive
motor operating conditions other than those strictly defined, and little flexibility for
maneuvers. In order to eliminate these drawbacks constructed pitch propeller: propeller
blade is adjusted by turning the hub. This screw is structurally more complex, more
vulnerable to damage and requires handling with higher qualifications. It also has a slightly
lower performance than the corresponding fixed pitch propeller. The elimination of these
defects fixed pitch propeller, however, caused the propeller is now quite widely used,
especially on ships that sailed the heavily changing load propulsor such as tugs,
minesweepers.
In the description of the shape profile of the reference string is usually a point lying in the
middle of its length, or at the maximum thickness of the profile. Plane normal to the axis of
the screw routed through the base profile of the reference point is called the plane of the
wing bolt circle, the plane passing through the same point of reference and the screw axis in
the plane of the circle of intersection with the edge of the screw creates a known axis of the
wing, and the intersection of the surface gives the nominal screw forming.

Figure.5: Propeller geometry elements. [2]

Is the pitch of the propeller pitch screw surface or nominal P helical pitch surface tangent to
the PF wing press. Pitch of the propeller may be any within the same or may vary with the
radius. Instead of frequently used stroke stroke ratio which is the ratio of the diameter of the
screw pitch P / D.

The surface area of the nominal helical limited contour of the wings and wing chords basics
section is equal to the surface area AE upright. Straight wing surface is formed by a
combination of a smooth line segments of equal length ends chords plotted on the respective
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radii (Fig. 6), while maintaining the appropriate distance between the leading edge and a line
of maximum thickness.

Figure.6: Straight wing surface. [2]

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