Lecture 2

There is a setup with one stationary plate and a parallel moving plate. Between the plates is the appropriate fluid. The movement of the second plate requires a Force F and induces shear stress 𝝉 into the fluid:

The dynamic viscosity 𝝁 is

with 𝝉:

The kinematic viscosity 𝝂 is dynamic viscosity over density.

liquid propertier:

• surface tension

• density

• viscosity

non-dimensional numbers:

• Reynolds number:

• Weber number:

• Ohnesorge-Number

• Condensation

• Disintegration

• Tearing

• Bursting

• Dripping (controlled with dropper)

• Droplet-on-Demand generator

• Pressure Atomizer

Droplet diameter depending on needle diameter, surface tension, density:

Variant 1:

Piezoelectric tube widens and narrows, thus squeezing out droplets.

Variant 2:

Piezoeletric buzzer increases and decreases pressure in supply chamber. This sequence leads to drop ejection.

Pressured supply chamber leads to the ejection of a liquid stream. In the orifice a piezoelectric ceramic transmits disturbance to the stream. The droplets are formed in the excitation frequency.

• pressure atomizer

• pressurae swirl atomizer

• twin fluid atmoizer

• ultrasonic atomizer

• electrostatic atomizer