Van Nuffel, D.

Open Marine Archive

Pressure Measurement on the Surface of a Rigid 
Cylindrical Body during Slamming Wave Impact 
Diederik VAN NUFFEL 
Supervisor(s): Ives DE BAERE, Wim VAN PAEPEGEM, Joris DEGRIECK 
I. INTRODUCTION 
Water wave slamming on marine structures 
is a critical sea load which always involves 
very high localized pressure peaks travelling 
very fast over the surface of the structure. To 
prevent naval constructions from failing due 
to wave impact, slamming loads should be 
carefully investigated. Hence, it is necessary 
to estimate these loads. Besides analytical and 
numerical calculations, experimental data is 
of crucial importance. 
II. MEASURING SLAMMING LOADS 
Experimentally, slamming loads can be 
measured by performing pressure recordings 
on the surface of the object during impact. 
Literature [1] showed that precise and correct 
measurements are very difficult to perform, 
especially for slamming events with small 
deadrise angles. Large scatter mostly 
characterizes the measurements. 
III. EXPERIMENTAL STUDY 
To improve the pressure recordings, a 
detailed study is necessary. A rigid cylindrical 
body, characterized by a variable deadrise 
angle (= angle between water surface and 
object surface), was chosen as test object.  
A. Experimental test facilities 
Two test facilities are used to perform 
slamming drop tests: a vertical drop set-up 
and a rotational drop set-up (Figure 1).  
 
D. Van Nuffel is with the Materials Sciences & 
Engineering Department, Ghent University, Ghent, 
Belgium, E-mail: Diederik.VanNuffel@UGent.be 
         
Figure 1. Vertical and rotational drop set-up 
B. Factors affecting the pressure recordings 
(i) Deadrise angle: a very small shift can 
result in large pressure variations. 
(ii) Sensor mounting: flush mounting (= in 
line with object's surface) is essential to 
avoid air bubbles and turbulences. 
(iii) Temperature shock: before impact, the 
sensors should be cooled down to water 
temperature. 
(iv) Water surface profile: reproducibility is 
only guaranteed if successive tests are 
performed with a calm water surface. 
(v) Degree of object's wetness:  successive 
experiments should be performed with 
dry object surfaces. 
(vi) Sampling rate of DAQ-system: > 200 
kHz is required to measure the complete 
pressure peak. 
(vii) Sensor cable length: cables should not 
be long to avoid capacitive signal effects. 
IV. CONCLUSIONS  
Taking into account all mentioned 
parameters, a significant decrease in scatter 
was achieved in the pressure measurements. 
 
[1] Lin, M.-C. and L.-D. Shieh, Flow 
visualization and pressure characteristics of a 
cylinder for water impact. Applied Ocean 
Research, 1997. 19(2): p. 101-112. 


Pressure measurement on the surface of a rigid cylindrical body during slamming wave impact

Van Nuffel, Diederik

Ghent University Academic Bibliography

Pressure Measurement on the Surface of a Rigid Cylindrical Body during Slamming Wave Impact Diederik VAN NUFFEL Supervisor(s): Ives DE BAERE, Wim VAN PAEPEGEM, Joris DEGRIECK I. INTRODUCTION Water wave slamming on marine structures is a critical sea load which always involves very high localized pressure peaks travelling very fast over the surface of the structure. To prevent naval constructions from failing due to wave impact, slamming loads should be carefully investigated. Hence, it is necessary to estimate these loads. Besides analytical and numerical calculations, experimental data is of crucial importance. II. MEASURING SLAMMING LOADS Experimentally, slamming loads can be measured by performing pressure recordings on the surface of the object during impact. Literature [1] showed that precise and correct measurements are very difficult to perform, especially for slamming events with small deadrise angles. Large scatter mostly characterizes the measurements. III. EXPERIMENTAL STUDY To improve the pressure recordings, a detailed study is necessary. A rigid cylindrical body, characterized by a variable deadrise angle (= angle between water surface and object surface), was chosen as test object.  A. Experimental test facilities Two test facilities are used to perform slamming drop tests: a vertical drop set-up and a rotational drop set-up (Figure 1).   D. Van Nuffel is with the Materials Sciences & Engineering Department, Ghent University, Ghent, Belgium, E-mail: Diederik.VanNuffel@UGent.be          Figure 1. Vertical and rotational drop set-up B. Factors affecting the pressure recordings (i) Deadrise angle: a very small shift can result in large pressure variations. (ii) Sensor mounting: flush mounting (= in line with object's surface) is essential to avoid air bubbles and turbulences. (iii) Temperature shock: before impact, the sensors should be cooled down to water temperature. (iv) Water surface profile: reproducibility is only guaranteed if successive tests are performed with a calm water surface. (v) Degree of object's wetness:  successive experiments should be performed with dry object surfaces. (vi) Sampling rate of DAQ-system: > 200 kHz is required to measure the complete pressure peak. (vii) Sensor cable length: cables should not be long to avoid capacitive signal effects. IV. CONCLUSIONS  Taking into account all mentioned parameters, a significant decrease in scatter was achieved in the pressure measurements.  [1] Lin, M.-C. and L.-D. Shieh, Flow visualization and pressure characteristics of a cylinder for water impact. Applied Ocean Research, 1997. 19(2): p. 101-112. 

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https://biblio.ugent.be/publication/1111626/file/1215485

Pressure measurement on the surface of a rigid cylindrical body during slamming wave impact

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