SOLUTION SHEET

Submersible Stereo PIV System

For efficient flow-field measurements in submersed applications

Measurements around a ship model in a towing tank.

Streamlined Submersible PIV system for measurements in towing tanks andother underwater applications
Our well-proven and continuously refined solution for underwater Particle Imaging Velocimetry(PIV) enables efficient flow-field measurements in towing tanks and other applications. The
solution is used world-wide for research on hydrodynamic applications such as ship hulls,
propellers and offshore constructions.
With a flexible design the system can be reconfigured on-site to enable different measurement
setups. The standard two camera StereoPIV (3C2D) system provides measurements of the threevelocity components (3C) in a plane (2D). The plane is defined by the overlapping Field-of-View of
the two camera/lens modules and a thick laser light sheet.
The system comes with a modular watertight and streamlined probe for minimum flow disturbance. The system is optimized for easy mounting and dismounting, fast calibration and efficientuse of the towing tank time.
In combination with traverse and a rigid fixture of the probe, the system can be moved while
maintaining alignment and calibration. The entire system - traverse, calibration, automatic
measurements and analysis- is operated from dedicated software – DynamicStudio.

Key benefits•

All integrated submersible solution•

3 velocity component measurements•

Remote controlled laser and cameras•

Streamline shaped to minimize flow disturbance•

Traverse mechanism and rigid mechanics minimizing structural vibrations•

Optimized for space and weight restrictions in towing tank carriages•

Delivered with a trolley for transport and easy storageThe fully integrated Submersible Stereo PIV System
The Submersible Stereo PIV System is optimized for experimental investigations ofship hulls, propellers, offshore constructions and other floating structures performed
in towing tanks, wave tanks, and other facilities. The system is customized to meetthe needs of the facility and optimized for space and weight restrictions of the towing
tank carriages.
The system is a unique product with laser, cameras and support combined into
one unit. The system comes with a modular watertight and streamlined probe forminimum flow disturbance. The well-integrated solution assures easy setup and highquality measurements.
The main PIV components are the cameras (camera and mirror modules), the pulsed
laser (the light source) and the optics to create a light sheet (light-sheet module). The
system is controlled by the DynamicStudio software package. The software is used
for setup, control, measurement and analysis. No additional controllers are required.

Illustration of the cameras field-of-view in the asymmetrical camera configuration. A
dedicated calibration target is used for the camera calibration.

Standard configurations
Dantec Dynamics offers a complete solution for 3 velocity components (3C)
measurements in a 2D plane. The cylindrical modular probe consists of two camera
modules, two mirror modules and one light-sheet module. To ensure ease of
mounting/dismounting with correct orientation, the modules are equipped withguide pins for perfect alignment. The settings of the motorized cameras and the laser
are remote controlled.
The camera modules carry the camera, motorized Scheimpflug mounts and thecamera lens. The lens is mounted on a compact motorized system, which allows
remote controlled focusing and aperture (F-number) adjustment.
The mirror modules, attached to the front of the cameras, enable the cameras to lookat the same area on the light sheet. The mirror modules are closed with a window
towards the outside water, but are not watertight. By allowing water to fill the mirror
compartments, the influence of refraction at the window is minimized. The mirrors
are easy to clean or replace if necessary.
The light-sheet module contains light sheet forming optics to deliver an illuminatedsection matching the FoV (Field of View) of the cameras.
Configuration 1 - AsymmetricalThis configuration minimizes the influence of the PIV probe to the flow at themeasurement section (light sheet, overlapping FoV) and is ideal for measuring
behind a propeller. The viewing angle of the camera close to the light sheet
is 22 deg. relative to the light sheet plane. The viewing angle of the camera
placed in the back of the probe is 52 deg. relative to the light sheet plane. The
mirrors are adjustable for optimizing the field of view.
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Asymmetrical configuration.
The light sheet (green) and theoutlined FoVs from both cameras(white).

Configuration 2 - SymmetricalWith this arrangement, the viewing angles relative to the light sheet plane,
are the same for both cameras. The FoVs have the same size of and are easily
overlapped. This configuration is suitable if the influence of the PIV probe
on the flow at the measurement section (light sheet, overlapping FoV) isnegligible. The distance from the probe axis to the center of the imaging area
is approx. 1100 mm.

PIV components
Cameras and lenses
The cameras and lenses are selected to optimize the magnification and fieldof-view (FoV) to fit the scope of the measurements. The cameras are positioned
at an angle to the light-sheet, Scheimpflug mounts are used to keep theilluminated FoV in focus.

Symmetrical configuration.
The light sheet (green) and theoverlapping FoVs from both
cameras (white).

Illumination sources
A high energy dual cavity pulsed laser combined with light sheet optics
matching the cameras’ FoV and the seeding’s light scattering properties isincluded in the system.
Synchronizer
The Synchronizer ensures that all devices perform their individual tasks at theexact right time. The Synchronizer has numerous outputs and inputs for timingof the PIV acquisition as well as the simultaneous acquisition from sensors,
control/timing of external devices such as encoders in the measurement
application.
The Synchronizer is integrated into the DynamicStudio imaging software
platform for easy setup and configuration. All PIV devices are auto-detected,
which ensures that the user will not have to enter any specific properties forthe system. The connectivity diagram in the software shows how to connect
the synchronization cables.
Data Analysis
To calculate the velocity fields from acquired raw images and analyze theresults, the DynamicStudio Base package, and add-ons for 2D-2C and 2D-3C
analysis are used. Dedicated analysis routines allow for quick user-defined data
analysis and visualization of results. Acquisition and analysis are performed in
the same software, no need to move data around. The software is very easy touse and includes extensive data exchange features e.g. to MATLAB. For further
details, please consult separate data sheet on the “DynamicStudio Software”
on our website.
Wake behind a twin-propellerhull. Courtesy of MARIN.

Traversing
An automated traverse system can be provided as an option. The traversing
mechanism is controlled from the software so that fully automatedexperiments are possible. This can be used to map the flow field at different
sections around a ship model. The software can construct a complete time
averaged 3D-3C flow field by combining 2D-3C data from each measurement
section to achieve volume mapping of the flow.

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Seeding
The flow needs to be seeded with highly reflective particles e.g. coatedplastic spheres. The range of the particle dimensions is typically 20 -200
µm. Polyamide powder with a density of 1,030 kg/m3 and an average
diameter of 20-100 μm can be used. The seeding mixture is injected into
the flow with the help of local injection rakes.

Symmetrical configuration. The light sheet (green) and the overlapping FoVs
from both cameras (white).

Technical specifications of standard design
Specifications for the modular submersible probe with laser and cameras
are shown below. Custom modifications to the specifications are available
upon request. The standard design allows both Symmetrical andAsymmetrical configurations.
The commissioning process includes mounting, test measurements withthe customer and training in the use of the equipment.
Specifications
Probe Length			

2.1 m *

Total Weight			

130 kg *Depth of use			

Up to 1 m *Towing Velocity 			Up to 5 m/s **Measurement Distance		

Up to 1.5 m

Field of View							Up to 200 x 200 mm2 (asymmetrical)
Up to 300 x 300 mm2 (symmetrical)* Other specifications upon request** Dependent on carriage construction stability and depth of use.

Order information
Please contact your Dantec Dynamics representative for a detailed
discussion of your application.

Data Sheet 0567_v1. Subject to change without notice. Copyright © 2019.
Dantec Dynamics. All Rights Reserved. www.dantecdynamics.com