Calculations
Thin mechanized step screen
Input data
Flow
Width (b)
Trashrack width (W)
Distance between trashracks (d)
Downflow level (y)
Inclination (º)
β - Kirschmer
Output data
Upflow level
Upflow velocity
Energy
Velocity between bars
Head loss
Upflow level at 50%
Upflow velocity at 50%
Velocity between bars at 50%
Upflow energy at 50%
Head loss at 50%
Description
The thin mechanized step screen is designed for debris removal in hydraulic flows, using calculation methods based on variables like flow rate and specific channel geometries.
Downflow calculation:
| Parameter | Standard Units | Description |
|---|---|---|
| Flow | m³/s | Volume of water passing through the section |
| Width (b) | m | Channel width |
| Trashrack width (W) | m | Thickness of the trashrack bar |
| Distance between trashracks (d) | m | Spacing between the bars |
| Downflow level (y) | m | Water level at the downstream side |
| Inclination (º) | º | Angle of the bars relative to the flow |
| β - Kirschmer | - | Kirschmer coefficient for calculation |
Calculated results:
| Parameter | Standard Units | Description |
|---|---|---|
| Upflow level (ym) | m | Water level at the upstream side |
| Upflow velocity (Um) | m/s | Velocity of flow at the upstream side |
| Energy (Em) | J | Energy associated with the upstream flow |
| Velocity between bars (Ubb) | m/s | Flow velocity between the trashrack bars |
| Head loss (Hl) | m | Pressure drop or head loss |
| Upflow level at 50% (ym50) | m | Upstream level calculated with 50% of the flow |
| Upflow velocity at 50% (Um50) | m/s | Upstream velocity at 50% of the flow |
| Velocity between bars at 50% (Ubb50) | m/s | Velocity between bars with 50% of the flow |
| Upflow energy at 50% (Em50) | J | Energy with 50% of the flow |
| Head loss at 50% (Hl50) | m | Head loss with 50% of the flow |
| Flow output (Qout) | m³/s | Volume of water exiting the system |
References
- WEF, ASCE, EWRI (2010). Design of municipal wastewater treatment plants. Volume 2: liquid treatment processes. New York, McGraw Hill.