PRODUCTS AND SERVICES
high-speed cameras
and fluid dynamics
In fluid dynamics applications, high-speed imaging provides
an indispensable tool to measure and visualize the complex
movement of liquids, gases and plasmas in motion
The movement of liquids and gases is
generally referred to as flow, a concept
that describes how fluids behave and
how they interact with their surrounding
environment. A flow can be either steady or
unsteady, laminar or turbulent.
Laminar flows are smoother, while
turbulent flows are more unstable. The study
of liquid flow is called hydrodynamics. While
liquids are comprised of a variety of
substances including oils and chemicals, the
most common liquid is water. Most
applications for hydrodynamics involve
managing the flow of these types of liquids.
The flow of gas, commonly referred to as
aerostatics, has many similarities to the flow
of liquid, however it is important to note that
there are also some differences. First, gas is
compressible, and liquids are generally
considered incompressible. Second, gas
flows are only slightly affected by gravity.
The most common gas is air. Wind can
cause air to move around various structures,
and it can also be forced to move with the
use of fans or pumps.
Photron high-speed cameras have been
designed to meet the requirements of a
specialized imaging technique employed in
fluid dynamics known as Particle Image
Velocimetry (PIV). With PIV, a fluid is seeded
with tracer particles that are visualized, and
automatically tracked using sophisticated
image analysis techniques to identify the
speed and direction of a given flow.
Some key factors to consider when
purchasing a high-speed camera for PIV
applications are frame rate, synchronization
accuracy, pixel resolution and pixel size.
The frame rate requirements of flow
visualization and measurement are highly
variable. While some applications require
only very low frame rates because movement
within the field of view is slow, others require
extremely high frames – up to 100,000fps
(frames per second) or more – to ensure that
a sufficient number of images are captured
to effectively analyze the event.
In PIV applications the field of view is
typically illuminated with a pulsed laser or
pulsed LED. The ability to precisely
synchronize the start of a high-speed
camera’s video frame or the start of an
individual exposure with an illumination
source is critical. Also required is the ability
to adjust and delay the timing of
synchronization signals and trigger signals.
MARCH 2020 \\ AEROSPACETESTINGINTERNATIONAL.94 COM
The resolution and pixel size requirements
of flow visualization and measurement can
vary widely from one PIV application to the
next. The field of view might be small enough
and seed particles large enough that a onemegapixel
(i.e. 1024 x 1024 pixel) resolution
and a 20 micron pixel size can capture
enough detail within the recorded images.
However, if the field of view is large and the
seed particles are very small, a 2 megapixel
or higher resolution and a 10 micron pixel
size might be required.
Fluid dynamics applications in aerospace
testing environments can be very
challenging for high-speed camera suppliers.
To guarantee the successful implementation
of high-speed cameras within such
environments it is important to select an
experienced supplier who can provide a
broad range of highly reliable cameras along
with exceptional customer support. Photron
is one of the most trusted high-speed
camera suppliers in the world. Photron’s
FASTCAM Series consists of a wide range of
cameras that have been designed to function
effectively within the aerospace industry. \\
FREE READER INQUIRY SERVICE
PHOTRON USA
For more about this advertiser, visit www.magupdate.co.uk/pati
1 // PIV of air flow over
wing tip
2 // PIV of helicopter
blade with tracer particles
3 // FASTCAM Nova
high-speed PIV camera
option
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2
3
/pati
/www.aerospacetestinginternational.com
