Open Orifice (V-Notch) Calculator

Inputs

Customer Information

Customer Name:

Work Order Number:

Engine Make:

Engine Model:

Engine Power:

Engine Speed:

Operating Conditions

Unit System:

V-Notch Type:

Use Normal for most scenarios. Use Special for specialized diffuser rings such as for MLB diffuser rings.

Desired Chamber Gauge Pressure (Pa):

(Gauge pressure inside chamber at maximum RPM)

Volumetric Flow Rate at Max RPM (m³/s):

(Seawater flow rate at maximum engine RPM as specified by the manufacturer)

Backpressure & Idle Conditions

Volumetric Flow Rate at Idle RPM (m³/s):

(Seawater flow rate into the chamber when engine is idling)

Exhaust Backpressure at Idle RPM:

(Use the actual exhaust backpressure at idle RPM. If not known, an estimated value will be calculated.)

Exhaust Backpressure Units:

Note: Effective differential pressure = Chamber gauge pressure - Exhaust backpressure

Outputs

Customer Information
Customer	N/A
Work Order #	N/A
Date	--/--/----

Engine Specs
Make	N/A
Model	N/A
Power	N/A
Speed	N/A

Engineering Inputs
Desired Chamber Gauge Pressure	0
Volumetric Flow Rate at Max RPM	0

Description	Result
Required Number of Open V-Notches	0
Calculated Chamber Pressure at Idle	0
Estimated Chamber Pressure at Idle (Q² Model)	0

The V-notch chamber model represents a flow-balancing system where seawater is pumped into a pressurized chamber and exits through uniformly sized triangular orifices. The chamber is modeled to allow pressure-driven flow out of the notches that matches the incoming pump flow. At maximum RPM, the internal gauge pressure determines how much flow exits each notch using Bernoulli-based orifice discharge theory. The number of V-notches required is then calculated to fully equalize with pump flow. At idle RPM, with the same number of notches fixed, the model computes the resulting internal chamber pressure based on reduced flow. An additional estimate is provided using a Q²-based flow-pressure relationship, assuming pressure scales with the square of volumetric flow rate.

CENTEK MARINE

Inputs

Customer Information

Operating Conditions

Backpressure & Idle Conditions

Outputs

Important Notice

Whats New:

Known Bugs:

Upcoming Improvements: