| The type of flow can be defined using the Reynolds number Re. This gives the criterion for laminar and turbulent flow. The Reynolds number Re is influenced by various factors:
- The kinematic viscosity of the compressed air.
- The mean speed of the compressed air.
- The inside diameter of the pipe.
The flow in the pipeline remains laminar until what is known as the critical Reynolds number Re crit is exceeded. It then takes on the condition of unevenness and turbulence.
Note
The high flow speeds that lead to Re crit being exceeded do not normally occur in pneumatic networks. The prevailing flow in pneumatic networks is laminar. Turbulent flow only occurs at points where there are massive flow disturbances.
The speed of flow in compressed air lines must not exceed 20 m/s, since noise and turbulent flow will otherwise occur. |