Aircraft Propulsion·momentum-flow-rate-through-control-surface

Momentum Flow Rate Through Control Surface

Calculate the net momentum flow rate across a control surface in a steady flow system. Given the mass flow rate, velocity magnitude, and flow direction (into or out of the control volume), determine the signed momentum flow contribution at that section, accounting for the direction of velocity relative to the coordinate system and whether flow is entering or exiting.

✓ All 3 test cases pass.

Inputs

Mass flow rate

Mass per unit time crossing the control surface (kg/s)

Velocity magnitude

Speed of fluid at the control surface (m/s)

Flow direction

Sign convention: +1 if flow exits (positive coordinate direction), -1 if flow enters (negative coordinate direction or into CV)

Test cases

These cases run live in your browser every time the page loads. If any fail, the calculator is broken — file an issue.

#	Inputs	Expected	Got	Status
1	{"mass_flow_rate":10,"velocity":50,"flow_direction":1}	500	500	✓
2	{"mass_flow_rate":10,"velocity":50,"flow_direction":-1}	-500	-500	✓
3	{"mass_flow_rate":5,"velocity":100,"flow_direction":1}	500	500	✓

APIDeveloper APICall this calculator from codeexpand ↓

Endpoint

POST/api/calculators/aircraft-propulsion/momentum-flow-rate-through-control-surface/compute

Inputs (3)

mass_flow_ratenumberdefault 10
velocitynumberdefault 50
flow_directionintegerdefault 1

Example

curl -sX POST http://localhost:3001/api/calculators/aircraft-propulsion/momentum-flow-rate-through-control-surface/compute \
  -H "Content-Type: application/json" \
  -d '{"inputs":{"mass_flow_rate":10,"velocity":50,"flow_direction":1}}'

Try it live

Edit the body below, then click Call API.

Request body

Response

(click Call API to see the response)

full API docs →

Source: Pattern from: Momentum Eq.pdf. Reproduces a standard momentum-flow-rate-through-control-surface computation; problem text paraphrased.

AI disclosure: Calculator code generated by anthropic/claude-haiku-4-5-20251001; verified by 3 test cases.