Product category:
Powder, droplet and particle characterisation
News Release from: Oxford Lasers | Subject: VisiSizer
Edited by the Processingtalk Editorial
Team on 24 November 2004
Towards cleaner, more powerful, auto
engines
To make cleaner, more powerful auto engines, a deeper understanding of fuel injection, mixing and combustion process is required: the VisiSizer is enabling fuel droplet size and velocity measurement
In the drive to make cleaner, more powerful auto engines, a deeper understanding of the fuel injection, mixing and combustion process is required For the next generation of engines - Gasoline Direct Injection (GDI) technology is being seriously investigated by most automotive manufacturers since it is generally accepted that both European and US government regulations concerning emissions are becoming more stringent
This article was originally published on Processingtalk on 16 Nov 2004 at 8.00am (UK)
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Droplet sizing systems measure heat transfer
Oxford Lasers VisiSizer enables Penn State University researchers to measure water droplet population size and velocity distributions simultaneously, to study loss of coolant incidents
Reduction in environmental pesticide contamination
Oxford Lasers VisiSizer systems are being used to characterise the size spectrum of sprays produced by new nozzle designs for pesticide sprays, to reduce the spray drift and consequent pollution
Producing a uniform fuel spray of small droplets is essential to the efficiency of GDI engines following the discovery that large droplets of fuel do not burn completely.
Being able to visualise and study fuel sprays produced in the combustion process is essential in order to find out exactly how small the droplets are for each different type of GDI nozzle.
Oxford Lasers has been working in the field of combustion imaging for many years and their latest range of VisiSizer particle and droplet in-flight sizing systems are ideal for the job.
Further reading
Automatic paint spray characterisation systems
The Oxford Lasers VisiSizer cost effective optical spray characterisation systems have the ability to measure down to 1 micron with high data rates, high resolution images and real time data analysis
Low cost precision pinholes and flow control units
Oxford Lasers is now supplying cost effective, precision pinholes and flow control devices direct from its micro-machining facility in polymers, ceramics, metals and semiconductors
How does it work?.
A very short flash of light from a laser is used to illuminate a diffusing target behind the subject spray.
A digital camera with a long-distance microscope lens captures images of the spray, which are frozen by using a very short pulse of the laser.
Oxford Lasers VisiSizer software then analyses the images to find drop/particle/bubble sizes, using known calibration data for the lens being used.
The software can correct for out-of-focus droplets (which appear larger than they really are), it then sorts the droplet images and measures all shapes and sizes with equal precision.
By using two laser flashes in quick succession, and measuring the movement of the droplets between exposures, it is also possible to measure droplet velocity.
This allows velocity versus size distributions to be produced, and conversions of spatial distributions (which are biased to droplet size classes with low velocity) to temporal distributions (no velocity bias).
When compared with other sizing techniques, Oxford Lasers VisiSizer has several benefits, including: the observation and sizing of non-spherical droplets, the visualisation of processes rather than just size data, and the elimination of velocity bias.
Key VisiSizer advantages are as follows.
* non-intrusive droplet, solid powder and bubble sizing.
* in-flight measurements.
* image based - can visualise process and measure shape.
* size down to 1 micron, no upper limit.
* measure size and velocity with the same system.
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