The phenomenon that was investigated is the Coanda effect and how it can be applied to air jets
when passing different shapes and sizes of obstacles. Coanda effect is the reason for changes of
air direction while it passes through near surfaces and resulting to adhering to them.
When blowing towards a wind meter having an interposing curved obstacle like a bottle, we can
observe that the air jet reaches the wind meter like the obstacle was not in its way.
A free jet of air entrains molecules of air from its immediate surroundings causing an
axisymmetrical tube or sleeve of low pressure around the jet. However, if a solid surface is placed
close and approximately parallel to the jet, then the entrainment of air from between the solid
surface and the jet cause a reduction in air pressure of that side of the jet. The pressure difference
across the jet causes the jet to deviate towards the nearby surface and then to adhere to it.
The parameters investigated were the shape and the size of the obstacle. The objects used were a
wind meter, a hair dryer used as a jet generator, a squared obstacle and cylindrical obstacles of
different radius.
When using the rectangular object, the measurement of the air flow behind the object was 0.
Increased radius of cylindrical objects leads to decreased velocity.
Rectangular surfaces don’t lead to Coanda effect and deceased radius of cylinders form better the
Coanda effect.