NEWSWAVE - HSVA

NEWSWAVE 

T HE H AMBURG S HIP M ODEL B ASIN N EWSLETTER 2006/2 

Dear Reader, 

I would like to welcome 

you to the latest 

edition of NEWSWAVE. 

Today the integrated procedure which 

combines numerical predictions with model 

experiments represents a vast improvement 

in design efficiency compared with the old 

days. Present service procedures of model 

basins include a combination of an initial 

set of calculations which are complemented 

by a focussed set of experiments. 

Nevertheless, often very quick answers are 

required. Therefore HSVA has introduced 

“Quick Check”, an assessment service for 

new designs based on comparison with 

HSVA data bases. This allows for rapid 

checks of principal design parameters to be 

made at a very early project stage, and can 

give guidance to the customer for further 

optimisation. “Quick Check” is another step 

forward in our effort to continuously 

improve services in response to our industry’s 

needs. 

During the last two months we have 

invested in our large towing tank, mainly in 

the towing carriage which has been totally 

overhauled, upgraded and modernised. 

The SMM in Hamburg is approaching in 

September, and I hope we will have a 

chance to meet you during this unique 

event for our industry. The team of HSVA 

welcomes you to visit us at our stand 

no. 220 in hall 12 where we are prepared 

to answer any question you may have. 

Juergen Friesch 

Managing Director 

“QUICK CHECK” 

MAIN DIMENSIONS AND OPTIMISATION 

by Uwe Hollenbach 

This new service, introduced as “Quick Check” 

of individual main dimensions of a customers project vessel, 

is based on a comparison of main parameters of a 

project vessel with the HSVA database in order to estimate 

the necessity to perform certain calculations or 

model tests for this specific project. 

The most effective measure to minimise the vessels resistance is to 

choose suitable main dimensions in the first place, after which the 

optimisation of the form should be considered. The “QUICK CHECK” 

of main dimensions based on HSVA’s database gives an indication whether 

a certain project is within typical limits, or if main dimensions are outside 

of the typical range and that some extra effort might be necessary for 

optimisation of the design. 

Figure 1 for example illustrates that the selected mid ship section coefficient 

of a project (red circle) is much lower than the average and that 

special attention has to be paid to possible effects resulting therefrom. 

Fig. 1 Quick Check of main dimensions Cm= f(Cb)

For the optimisation process two 

different strategies can be observed 

today. On the one hand most of the 

shipyards follow the strategy of increasing 

the block coefficient without 

increasing the resistance. On the other 

hand ship owners and a few shipyards 

investigate variants with lower block 

coefficient and therefore lower resistance, 

especially for vessels in a seaway. 

Having in mind the actual fuel prices 

which have almost doubled during the 

last years, this strategy may be more 

successful to cover future demands of 

ship owners and operators. 

The “QUICK CHECK” of the 

speed/power characteristics based on 

HSVA’s database can serve as input for 

a cash flow analysis comparing different 

design variants featuring different main 

parameters. The results of this analysis 

can be the basis on which decision makers 

can consider which variant shall be 

chosen for optimisation of the overall 

economy of a certain design. 

SERVICE SPEED 

AND SEA MARGIN 

This “QUICK CHECK” includes advise 

regarding a maximum economical 

speed for the customers vessel which 

should not be exceeded in service in 

order to avoid an excessive fuel consumption. 

This will help designers at 

shipyards and in design offices as well 

as decision makers at shipping companies 

when selecting main dimensions in 

an early stage of project development. 

Figure 2 illustrates that the economic 

speed of a project vessel (red line) 

can be expected to be in the range of 

FN between 0.225 and 0.255. The 

upper value can be achieved with well 

optimised lines. 

For service speed a sea margin of 

15% is often applied to the power, 

independent of the type and size of the 

vessel and any environmental and operational 

requirements. Having in mind 

the increasing fuel prices this simple 

procedure can no longer be recommended. 

Instead, the speed/power 

prognosis of a project vessel should 

2 NEWSWAVE 2006/2 

Fig. 2 Quick Check of the economic speed 

take into account the actual environmental 

conditions expected during 

normal operation. 

The “QUICK CHECK” of additional 

power demand which can be expected 

for actual environmental conditions 

(wind, sea state, restricted water) will 

give an indication if a charter contract 

based on 15% sea margin as service 

allowance will fall short, either in 

respect to the guaranteed speed or in 

respect to the guaranteed fuel consumption. 

PROPELLER DESIGN 

AND PRESSURE PULSES 

The “QUICK CHECK” of the propeller 

parameters, the tip speed, the power 

density and the pressure pulses to be 

expected for the actual design give an 

indication if the selected propeller in 

combination with the selected main 

parameters of the hull may face problems 

with respect to efficiency and cavitation 

induced pressure pulses. 

In this case the designer should consider 

not only using potential flow 

codes for optimising the hull, but also 

using more advanced numerical CFD 

tools for calculating the wake field and 

the expected pressure pulses for the 

actual design well in advance of model 

tests. Furthermore this check is helpful 

to decide upon the necessity of cavitation 

tests with the design propeller. 

INTERACTION OF SHIP 

AND PROPELLER 

Few shipyards spend time and money 

to improve the interaction between the 

ship, the propeller and the rudder. 

When the results of resistance and self 

propulsion tests are satisfactory (i.e. the 

target speed has been reached), the 

customer is often not willing to improve 

a wake field of average quality by further 

modifications to the aft body of the 

vessel. It is sometimes overseen that a 

wake field of good quality not only 

helps to reduce the pressure pulses of 

the propeller, thus minimising the danger 

of propeller induced vibrations in 

the structure, it is also the basis for 

reducing frictional losses of the propeller 

by allowing selection of the lowest 

area ratio Ae/Ao possible. 

The “QUICK CHECK” of the quality 

of the wake field based on HSVA’s database 

will give an indication whether 

further improvements of the wake field 

can be expected.

MANOEUVRING 

CHARACTERISTICS 

Generally, the higher the block coefficient, 

the lower the length-breath ratio 

and the higher the speed in relation to 

the block coefficient, the higher is the 

risk to fail some of the IMO criteria for 

manoeuvrability. The “QUICK CHECK” 

comparison of the project vessels main 

parameters with the HSVA database will 

give an indication what manoeuvring 

characteristics may be expected, and if 

measures have to be taken to meet the 

IMO manoeuvring recommendations 

and to improve the yaw stability of the 

project vessel. 

The following Figure 3 shows the 

estimated and exact figures for the 

1st overshoot angle during 10°/10° 

zig-zag manoeuvre in our database and 

the expected figures (red line) for a project 

vessel. 

Model tests with different hull form 

variants of a full block vessel have 

shown that a variant with a lower resistance 

is more exposed to the risk being 

unstable in yaw for a larger range of 

rudder angles and that for this variant 

the IMO criteria for the overshoot 

angles at 10°/10° and 20°/20° zigzag 

manoeuvres will be exceeded. For hull 

forms which have demonstrated a supe- 

rior speed / power characteristic during 

calm water tests we therefore recommend 

to consider either additional 

numerical investigations and/or 

manoeuvring tests to check compliance 

with IMO criteria. 

SEA-KEEPING 

CHARACTERISTICS 

Fig. 3 Quick Check of the manoeuvring characteristics 

Ships main dimensions and the hull 

form are largely determined by other 

design factors than ships motions in 

waves. After the main dimensions and 

hull form are fixed, there is not much to 

be done to reduce ship motions or the 

related derived responses. 

The “QUICK CHECK” of the most 

important motion components heave, 

pitch and roll can give an indication in 

an early stage of the design, when the 

main dimensions are selected. The 

uncoupled, undamped natural periods 

can be estimated on the basis of a few 

main dimensions like length, breadth, 

water plane area coefficient and metacentric 

height and are compared with 

the wave encounter periods to be 

expected for a ship in the operational 

sea area. As a standard, wave 

encounter periods of the Baltic Sea, the 

North Sea, the Bay of Biscay, the 

Mediterranean Sea and the North 

Atlantic are checked, but this can be 

extended to suit the customer needs. 

In cases, where the natural and the 

wave encounter periods are nearly the 

same, violent resonant ship motions 

may occur. For these cases it is good 

practice to perform sea-keeping calculations 

in an early stage of the design 

or, in a later stage, to perform sea-keeping 

model tests. In addition to the ship 

motions and loads, various associated 

dynamic effects or derived responses 

can be used in comparison of different 

designs. 

OPERATION IN ICE 

Due to the increasing amount of crude 

oil exported from Russia a quickly growing 

fleet of tankers is employed in seasonally 

ice-infested waters like the 

Baltic Sea, the Southern Barents Sea 

(Petchora), and the waters around 

Sakhalin (Far East). For a number of 

tanker projects the transit performance 

in brash ice channels has been proven 

by model tests. The power derived from 

the model test was in no case higher 

than the power calculated by the FSIR 

formulas. In some cases the tanker 

models were transiting through the 

brash ice channel with only 70% of the 

power calculated by the FSIR formulas. 

A “QUICK CHECK” of the required 

engine output based on previous model 

tests performed at HSVA will give advice 

if there is a possibility for upgrading the 

ice class of a project, without increasing 

the installed engine power. 

CONCLUSION 

The “QUICK CHECK” of a customer’s 

project vessel gives designers at shipyards 

and decision makers in shipping 

companies advice if there is potential 

for optimisation in an early design stage 

when main dimensions are selected and 

the feasibility of a project is investigated. 

And what is also important - the 

“QUICK CHECK” will take no more time 

than is necessary to read this article. 

2006/2 


3

CALCULATION OF 

HYDRODYNAMIC BODY 

FORCE COEFFICIENTS FOR 

TThe motion of a ship can be predicted if the hydrodynamic forces on the 

hull, rudder and propeller are known. The forces are a function of ship 

velocity and acceleration (higher order time-derivatives can usually be 

neglected). With a polynomial approach like: 

the time dependent forces can be calculated. The unknown coefficients are determined 

either by model-testing or calculations. A sufficiently accurate set of these 

coefficients is vital for a reliable prediction of the manoeuvring capabilities and 

thus for the design of the manoeuvring devices like rudder and thrusters in an early 

state of the design process. 

Since 1 st January 2005 the European Integrated Project (IP) VIRTUE, 

“The Virtual Tank Utility in Europe” works on advanced numerical simulation tools. 

“The Numerical Manoeuvring Tank”, being one of the 4 different CFD development 

fields in the project, focuses on numerical manoeuvring predictions. Within this 

work package a major task is a substantial improvement in accuracy, efficiency and 

consistency of computations for simple modes of motion like steady drift and rotation. 

Fig. 1 Forces and Moments on 

the “Hamburg Test Case” 

at 1.05 m/s model speed 


News from the VIRTUE labs 

MANOEUVRING PREDICTIONS 

by Marco Schneider 

X=Xu u+X 2 u u u2 u+Xu u+Xu 2u 2 +Xυ 2υ 2 +Xr 2r 2 • • 

• • 

+... 

Fig. 2 Forces and Moments on 

the “Hamburg Test Case” 

at 1.89 m/s model speed 

Wake field of the 

“Hamburg Test Case” 

at 30° drift angle 

Comprehensive investigations on 

numerical discretisation, turbulence 

modelling, free surface flow and scale 

effects are performed that yield recommendations 

for practical applications. 

Based on these developments HSVA 

sets out to deliver CFD based manoeuvring 

coefficients. 

Figure1 shows the comparison of 

the calculated non-dimensional forces 

and moments at different drift angles 

and velocities of the “Hamburg Test 

Case” with experiments. The calculations 

were performed with the 

Reynolds-Averaged Navier-Stokes 

Equations (RANSE) solver Comet. In a 

first approach the deformation of the 

free surface at speed was neglected. 

A double body model that uses a 

symmetry plane located at the undisturbed 

free surface has been employed. 

At lower ship speeds the double body 

model gives good agreements between 

experiment and simulation for the X 

and Y forces and the N moment. At 

higher speed the hydrostatic pressure 

generated by the bow wave (shown in 

Figure3) has a significant influence on 

the forces and thus cannot be neglected 

any more. Here the volume of fluid 

(VOF) free-surface model implemented 

in Comet was used to predict the forces 

and moments more accurately (shown 

in Figure2) at the cost of a significant 

increase of the computation time.

Further investigations on turbulence 

modelling and scale effects and the 

investigation of unsteady ship motions 

are scheduled. The promising results 

achieved so far will soon allow to integrate 

numerical manoeuvring computations 

into the portfolio of HSVA’s CFD 

services. 

MINIMISE OPERATING COSTS BY TRIM VARIATION TESTS 

RoRo-Vessel Heavy-Lift-Vessel 

Full Scantling Draught 18 kn 21 kn 23 kn 15 kn 17 kn 18 kn 

Trimming by head 97% 98% 95% 106% 105% 105% 

Trimming to the stern 105% 102% 99% 105% 97% 95% 

Design Draught 18 kn 21 kn 23 kn 15 kn 17 kn 18 kn 



Ballast Draught 18 kn 22 kn 24 kn 15 kn 17 kn 18 kn 



Table 1 – Results of Trim Variation Tests for two Newbuildings 

Fig. 3 

Bow wave in the 

experiment 

by Uwe Hollenbach 

In the past three years costs for fuel oil have almost doubled. 

To face this problem more and more ship owners order numerical calculations, or take the 

opportunity to use an existing ship model of their newbuildings for additional model tests. 

The aim of these tests and calculations is to provide decision support to 

their nautical officers on board their ships to minimise operating costs. 

In addition to manoeuvring tests to 

check the fulfilment of IMO 

manoeuvring criteria, sea-keeping 

tests to determine the speed loss for 

contracted environmental conditions, 

tests and numerical investigations to 

determine the squat effect and to find 

out the economical speed in shallow 

water, some ship owners order trim variation 

tests for their actual newbuildings 

in order to quantify the effect of trim 

on the power demand and the fuel oil 

consumption. 

Most recently such tests have been 

ordered for newbuildings of a RoRoand 

a Heavy-Lift-Vessel. When compared 

to the even keel condition, 

remarkable differences in power 

demand have been found for calm 

water conditions on various draughts 

and different ship speeds. Some results 

are given below, with the even keel condition 

as reference (100%). 

While for the RoRo-Vessel the 

largest power saving (-11%) has been 

found when the vessel is trimmed by 

the head, the largest power saving 

(-9%) of the Heavy-Lift-Vessel has been 

found when trimming by the stern. The 

largest differences in power demand 

between the best and the most 

unfavourable trim condition are more 

than 20% for the RoRo-Vessel and 

about 15% for the Heavy-Lift-Vessel. 

It should be mentioned that the 

differences in the power demand may 

be lower for other size and type of 

ships. 

2006/2 NEWSWAVE 

5


RESEARCH PROJECT “SINSEE” 

SUCCESSFULLY FINISHED 

by Walter L. Kuehnlein 

Final results of the German research project “SinSee” were presented 

at a colloquium held at HSVA on June 22nd. Within the framework of 

“SinSee”, HSVA cooperated with four partners 

(FSG, TUB, TUHH, and OceanWaves) on the 

evaluation of safety issues of vessels in severe seas. 

Topics like numerical analysis and 

simulation, validation by means of 

model test investigations, full scale 

measurements and evaluation of capsizing 

risks were covered within this project. 

Available means for investigating the 

sea-keeping performance of vessels are 

model tests and/or numerical simulations. 

Both model tests and numerical motion 

simulations are often used post-accidental 

in order to investigate the causes. Standard 

seakeeping tests (tank or numerical) are 

available for investigating several phenomena 

such as slamming, green water, capsizing, 

etc. but are only occasionally used – 

mainly for rather unusual designs, or in 

cases where sea keeping characteristics are 

more vital than for standard vessels. 

Within the research project “SinSee”, 

HSVA developed the following concept of 

computer controlled capsizing tests in 

order to ensure that the processes of large 

rolling and capsizing take into account the 

following wave characteristics: 

➢ Extreme wave height and wave steepness, 

➢ Wave grouping, and 

➢ Propagation velocity and direction. 

Unfavourable phase relationships between 

wave components as well as wave / structure 

interactions may lead to dangerous situations 

such as: 

➢ Loss of stability at the wave crest, 

➢ Resonant excitation, especially 

parametric rolling, and 

➢ Broaching due to a loss of course 

stability. 

The analysis of this complex, non-linear 

behaviour puts high demands on the 

capsizing test set-up and procedure: 

➢ Exact correlation of cause (wave 

excitation) and reaction (ship motion), 

➢ Reproducibility, high accuracy of 

measurement and control units, 

and 

➢ Deterministic performance of test 

events. 

These demands require a highly sophisticated 

testing procedure. Figure 1 

shows a schematic test configuration for 

computer controlled seakeeping tests. 

Three main system components have to 

be coordinated: 

➢ Wave maker, 

➢ Towing carriage (including the transverse 

carriage), and 

➢ Ship model. 

In head seas, the ship is positioned at 

the end of the tank opposite to the 

wave maker. In seas from astern, the 

ship model has to wait close to the wave 

maker until a defined sequence of the 

wave train has passed. 

The ship model is controlled by the 

master computer which via telemetry 

commands a z-manoeuvre at constant 

course angle and model velocity. These 

test parameters as well as the model 

sea parameters are chosen according to 

the metacentric height GM of the 

model, the expected rolling mode and 

occurrence of resonance. Both the towing 

carriage and the transverse horizontal 

carriage are computer controlled.

During the entire test run, the ship 

model stays within the view field of the 

optical system’s line cameras, and ship 

motions in six degrees of freedom are 

registered precisely. Additionally, the 

wave train is measured at several fixed 

positions along the wave tank. 

Thus the tests are performed and 

monitored in a manner which allows a 

reproducible correlation of wave excitation 

and ship motion. Figure 2 illustrates 

some sequences of a capsizing 

test in HSVA’s model basin. 

WAVE GENERATION 

Fig. 1 Schematic Test Configuration for Computer 

Controlled Seakeeping Tests 

The experimental investigation of 

extreme behaviour such as excessive 

rolling and capsizing also requires an 

appropriate approach for generating 

the harsh wave environment: 

➢ Definition of the target wave train, 

➢ Transformation of the target wave 

train to the position of the wave 

maker, 

➢ Calculation of the wave maker 

control signals, and 

➢ Performance of the model test. 

DETERMINISTIC WAVE TRAINS 

Applying the non-linear approach all 

kinds of waves can be tailored for each 

individual test scenario and generated 

in the model tank: 

➢ Wave packets, 

➢ Extreme waves such as 

”Three Sisters”, 

➢ Storm seas, 

➢ Random seas with embedded high 

wave sequences, 

➢ Regular waves with embedded high 

wave groups, and 

➢ Realization of natural wave 

scenarios. 

CALCULATION OF WAVE TRAINS 

IN THE MOVING REFERENCE 

FRAME OF CRUISING SHIPS 

For the deterministic analysis of motions 

and forces of ships, the wave excitation 

denotes the beginning of a complex causereaction 

chain. This requires knowledge of 

the wave evolution in time and space in 

order to correlate wave excitation with the 

structural response. Especially when the 

ship is sailing at non-constant speed it is 

not a state of the art task to determine the 

wave excitation with respect to a moving 

reference point as wave probes can be 

installed at defined positions, but usually 

not at the position of the model (due to 

relative motions and disturbances). 

As all model tests are fully reproducible, 

even a statistical analysis of extreme 

behaviour like capsizing events is conceivable. 

ACKNOWLEDGEMENTS 

HSVA is indebted to the German Ministry of 

Education, Research, and Technology, 

BMBF, for funding the project “SinSee” and 

the new successor project “LaSSe”, which 

allows the five partners to continue their 

very successful work on improving the 

safety of modern vessels. 

Fig. 2 

Sequences of a 

Capsizing Model Test 

(model length approx. 6 m) 

2006/2 


7

Fig. 1 Brash ice test 

These power requirements can 

be calculated with the formulae 

given in the regulations or as an 

alternative they can be obtained in ice 

model tests, i.e. the performance of the 

ship is demonstrated in model tests in 

brash ice channels. Figure 1 illustrates a 

typical brash ice model test setup 

The guidelines for the verification of 

the ship’s performance for ice classes 

through model tests have changed in 

December 2005. 

The main changes are: 

➢ Increase of the thickness of the 

brash ice channel 

➢ Increase of the friction coefficient 

between model surface and ice from 

µ = 0.05 to 0.10. 


BRASH ICE MODEL TESTS – 

CONSEQUENCES OF THE 

CHANGES IN THE GUIDELINES 

FROM DECEMBER 2005 

The Finnish – Swedish Ice Classes 1C to 1AS were developed 

in order to provide power requirements 

which ensure a certain ship’s performance in brash ice channels. 

As compared to the old guidelines 

for brash ice model tests, these changes 

result in a higher power requirement. 

Figure 2 illustrates the increase in delivered 

power due to the change in the 

guidelines for ice class 1B and 1A for a 

PANMAX tanker. But also with the new 

guidelines it can be stated that the performance 

of model tests leads to lower 

power requirements compared to that 

required by the given formulae. In some 

cases a reduction of up to 30% of the 

required power can be achieved. 

If the vessel is equipped with a controllable 

pitch propeller the engine 

which has been chosen for good open 

water performance will be able to deliver 

the required power in brash ice channels. 

by Karl-Heinz Rupp 

In the case of a fixed pitch propeller 

the motor limit curve restricts the available 

power in brash ice as the propeller 

loading is significantly higher. Figure 3 

illustrates that in these cases HSVA can 

assist you to find a solution where the 

vessel is able to fulfil the new power 

requirement guidelines without any 

change in the ship design for ice class 1A. 

However, in other cases changes may 

be necessary. But of course especially 

in these cases, HSVA can offer you 

assistance in finding cost efficient 

solutions. 

Fig. 2 

Comparison 

of old and new 

guidelines, 

delivered power 

vs. brash ice 

thickness

The oil produced will be transferred 

via a sub-sea pipeline 

from an ice-resistant fixed 

production platform to the FSO. The oil 

shall be stored in FSO tanks and 

periodically offloaded into shuttle 

tankers moored at the FSO. 

Ice load calculations have been carried 

out previously to estimate the ice 

loads acting on the bow and the stern 

of the FSO when the ice drift direction is 

in-line with the FSO tanker. 

A change in wind direction is associated 

with a change of the ice drift direction 

which introduces a “weather vaning” 

effect and as a consequence the FSO 

tanker starts to rotate around the SPM 

(single point mooring) as shown in 

Figure 1. In this particular case the ice 

will fail along the vertical hull of the FSO 

tanker, resulting in higher ice forces on 

the soft yoke mooring system. It is 

expected that the ice drift change is the 

2006/2 

Fig. 2 

Effect of the change 

in guidelines for a 

fixed pitch propeller in 

the area of the motor 

limit curve. 

OPERATIONS OF A FSO WITH 

A SOFT YOKE MOORING SYSTEM (SYMS) IN SEA ICE 

Bluewater Energy Services B.V. 

has recently performed ice model tests 

at HSVA for a permanently moored “Floating 

Offshore Storage” system (FSO). 

Fig. 1 FSO with SYMS connected 

to a Single Point Mooring Tower (SPM) 

controlling parameter with respect to 

maximum ice forces and the attention is 

focussed on the “weather vaning” effect. 

Ice model tests have been carried 

out in HSVA’s Large Ice Tank simulating 

level ice conditions. The SYMS-FSO 

tanker model was tested in different 

scenarios, i.e. straight astern and ahead 

penetration into level ice, turning astern 

and ahead in level ice for different ice 

by Karl-Ulrich Evers 

drift changes and turning 90 degree 

ahead in level ice. 

From the ice model tests the maximum 

ice loads acting on the SYMS-FSO 

tanker system were derived. The model 

test results validate the ice forces calculated 

for the bow and the stern sections 

of the FSO. In terms of improvement of 

the SYMS design, these kind of ice 

model tests are of high value. 


9

ACTUAL RESEARCH ACTIVITIES 

ON PROPELLER AND RUDDER CAVITATION 

HHigh-Speed-Video recordings 

during the systematic model 

tests revealed that the propeller 

tip vortex bursting can be divided 

into two different types. First there is 

the vortex bursting due to hydrodynamic 

instability which can be found 

on marine propellers as well as in the 

field of aerodynamics. The second type 

is also called bursting of a propeller tip 

vortex, where its calm structure is 

“destroyed” by the rolled-up sheet cavity 

and looks like a bursting vortex. Both 

patterns are observed on marine propellers 

(see Figures 1 and 2) but they 

have different governing mechanisms. 

The bursting due to hydrodynamic 

instability can be related to the radial 

gradients of the tangential and axial 

velocities (Vt, Vx) inside the vortex. 

Under consideration of the Ludwieg’s 

stability criterion for vortical flows, the 

danger of vortex bursting was determined 

by applying the Betz vortex 

model outside the viscously dominated 

vortex core. Figures 3 and 4 show the 


by Thomas Luecke 

At the end of last year HSVA successfully completed the BMBF research project PROTIP. 

The purpose of this project was to investigate the basic parameters influencing propeller tip vortex 

bursting. High speed video recordings were made during model tests with a periodically moving 

hydrofoil and a model propeller. These pictures gave insight into the 

temporal vortex behavior during the bursting process. 

Fig. 1 Bursting trailing vortex (type 1) 

Fig. 2 Bursting vortex due to rolled 

up sheet cavity (type 2) 

Fig. 3 Non bursting vortex Fig. 4 bursting vortex 

predicted radial velocity distributions 

(blue: Vx/U red: Vt/U) and the stability 

criterion (blue dots) within a vortex 

without and with bursting respectively. 

It has been found that the vortex 

bursting due to the roll-up of sheet cavitation 

is driven by the boundary layer 

on the propeller blade with high vorticity 

created at the leading edge or at its 

further developed edge vortex. RANS 

calculations were made for the investigated 

propeller in different wake fields 

in order to correlate their results with 

the observations made in the cavitation 

tunnel. The results show a good correlation 

between the predicted edge vortex 

(Figure 6) and the observed vortex 

bursting. The result calculated for the 

propeller in the smooth wake showed 

no vortex trace (Figure 5). This corresponded 

well with the calm vortex 

behavior observed. 

This challenging research topic will 

be further investigated in the future in 

order to extend our consultancy capabilities.

Fig. 5 Non bursting vortex, smooth wake Fig. 6 Bursting vortex, sharp wake 

HSVA’s interest is also focused on 

rudder cavitation. This topic is investigated 

in the research project RUKAV. Its 

aim is to investigate the scale effects of 

erosive cavitation on semi spade rudders, 

which are often faced with severe 

erosion problems around the pintle 

area, see Figure 7. The erosive cavitation 

phenomenon will be investigated 

by model tests in the HYKAT facility on 

a rudder placed behind a ship as well as 

on a partial rudder model of much larger 

scale (about 3:1!). High-Speed-Video and 

Particle-Image-Velocimetry recordings 

During June HSVA’s large towing 

tank has been closed 

down due to a major upgrade 

of the main carriage. The energy supply, 

the electric drive motors and the entire 

control and monitoring equipment of 

the main towing carriage and of the 

manoeuvring carriage CPMC (computerized 

planar motion carriage) have 

been renewed. 

vortex trace 

will resolve the cavitation pattern and 

the related flow field around the pintle. 

Based on these test results a correlation 

between model and full scale will 

be derived which will facilitate the 

detection of erosive cavitation patterns 

during cavitation tests at normal model 

scales. Special cavitation models for 

CFD-codes will be developed in order to 

predict the cavitation behavior and its 

erosive character through calculations. 

A presentation of the results will follow 

in the future at this place. 

Fig. 7 Erosion at the lower pintle 

MODERNISATION OF THE MAIN CARRIAGE FINISHED 

The modernisation aimed at: 

1. Increasing the maximum speed from 

8 m/s to 10 m/s. 

2. Increasing the measurement time 

by higher acceleration performance. 

3. Improving the measurement 

tolerances for rigid coupled models. 

4. Introducing a free programmable 

control system: 

– to automate tests and 

– to increase the flexibility 

5. Reducing the vibration of the 

carriage. 

6. Minimizing deviations from the 

selected carriage speed. 

7. Improving the reliability and 

maintainability of the carriage. 

by Uwe Hollenbach & Jürgen Friesch 

The entire work has been done right in 

time and the tank is back in operation 

since the beginning of July and nearly 

all requirements have been fulfilled in 

the short time. Reference tests with 

models of different ship types (Tankers, 

Container Vessels and Fast Ships) have 

shown good reproducibility compared 

with tests performed prior to the modernisation. 

This ensures the consistency 

with all our former data. 

2006/2 


11

notes 

5 th HSVA -Customer Seminar 2006 on 

“CFD in Ship Design” 

25 October 2006 

The 5 th Customer Seminar on “CFD in Ship Design” will inform our customers about 

the present range of developments and how these will translate into current and 

future CFD services available at HSVA. 

Key personnel involved in in-house CFD work, together with invited speakers 

from industry and academia will present latest research results obtained in such 

European projects as Leading Edge, EFFORT and VIRTUE, as well as a range of 

advanced design applications. 

The seminar will be held at: 

Hamburgische Schiffbau-Versuchsanstalt GmbH 

Bramfelder Str. 164 

D-22305 Hamburg 

Date: 25 October 2006, Start: 10.00 hrs 

Fees: Seminar incl. Proceedings ? 100.- 

For reservations please contact Ms. A. Breitfeld e-mail: breitfeld@hsva.de 

Shipbuilding • Machinery & 

Marine Technology 

26 – 29 September 2006 

Visit us at SMM 2006: Hall 12, Stand 220 

Ensure your presence at this unique event for our industry. 

MEMBER OF STAFF 

JOHANNES PIEPER 

Johannes Pieper joined our staff in 

May 2006 and will be the 

successor of Karl-Heinz Koop who 

will retire at the end of 2006. 

Mr. Pieper works as a project manager 

in the propeller and cavitation 

department. 

He is responsible for cavitation 

tests for new projects in the HYKAT 

tunnel, in particular propeller and 

rudder cavitation tests for all kinds 

of vessels. 

He studied naval architecture at 

the University of Applied Science in 

Kiel. His master thesis dealt with 

the design of a sailing yacht model 

for a twist-flow wind tunnel. 

Following graduation he worked for 

the Yacht Research Unit in Kiel 

before joining HSVA. 

Johannes Pieper is married and 

lives in Kiel. In his spare time he 

enjoys sailing the Kiel Bay, travelling 

and spending time with his 

friends. 

THE HAMBURG SHIP MODEL BASIN ❙ Bramfelder Straße 164 ❙ D-22305 Hamburg 

Phone + 49 – 40 – 69 203 – 0 ❙ Fax + 49 – 40 – 69 203 345 ❙ E-mail info@hsva.de ❙ Internet http://www.hsva.de

NEWSWAVE - HSVA

Create successful ePaper yourself

Delete template?

Save as template?