Flow visualisation kit reveals computer heating

The Flow-Tek CCD portable flow visualisation kit has recently been used to analyse the flow of cooling air around a computer.

The Problem
Computers are relied on for many everyday processes, and as a result they need to be highly reliable. Most companies use fans to cool the processors and stop them from overheating, which could cause total failure of the chip and motherboard. As these fans are mechanical they are the component that has the greatest possibility of failure. Computer fans also generate a lot noise which is undesirable for the operator. For these reasons it is beneficial to remove the fan. An improvement of the layout design of the components within the computer that allows natural convection, generated by the heating of the components, will result in the required processor cooling flow. In order to analyse the flow, VisEng's Flow-Tek CCD equipment was used.

Flow Tek CCD - Capabilities and Equipment
The Flow-Tek CCD system has been used in other studies such as flows in automotive liquid coolant systems and injector sprays for wax coatings.
The system comprises a diode laser and camera capturing system.
The camera sensitivity is matched to the wavelength of the laser so a low-power laser can be used.
The relatively simple arrangement of the camera and laser allow seeding particles present within the flow to be illuminated and recorded.

Seeding System
Oil particles were used to seed the flow within the computer.
The particles are generated by pushing air through small holes in tube submerged in vegetable oil.
The oil particles travel, via tube, into a chamber.
The chamber is used so the particles are pulled into the computer by convection rather than forced by the seeding air.

Experimental Set-Up
The computer that was analysed in this experiment is a standard PC tower.
The fan was disconnected so the convection flows could be analysed.
The sides and base of the computer were replaced with Perspex to provide optical access.
The seeding chamber was attached to the front of the computer covering some of the intake holes.
The seeding chamber was filled and then the computer was turned on.
The particles were drawn into the computer by convection currents and illuminated by the laser and recorded by camera system.

Results
In the test setup the processor was mounted vertically into the tower.
Results around the processor were taken using a vertical light sheet, highlighting the vertical flow past the processor, and a horizontal light sheet showing the flow perpendicular to the chip.
The flow perpendicular to the chip was slow, with recirculations forming and shedding in the order of minutes.
The vertical plane in contrast has a much faster flow with recirculation features lasting only seconds.

Conclusions
The Flow-Tek system has shown that the complex flows generated by the heating of the electrical components can be recorded.
Modifications to the layout of computer components can be made and the resulting change in flow quickly recorded.

The equipment can be demonstrated on demand to companies who wish to qualitatively conduct fluid measurements for gases as well as liquids either for visualising cooling flows around computers or numerous other flow visualisation applications.

If you wish to discuss how our technology could benefit your business you can contact us by post, phone or e-mail. Our details are given here:

VisEng Ltd
PO Box 2623
Warwick
CV34 6ZX
United Kingdom

Telephone from the UK:
07773 800769

Telephone from Outside the UK:
+44 7773 800769

Email: info@viseng.com