How Do You Calculate Air Velocity from a Nozzle?

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Discussion Overview

The discussion centers on calculating the velocity of air exiting a nozzle, specifically in relation to the height of the airflow. Participants explore various parameters such as pressure and nozzle diameter, and consider the implications of turbulence and compressibility on the measurements.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant, Uridan, inquires about calculating air velocity from a nozzle using pressure and diameter as parameters.
  • Another participant suggests using the ideal gas equation and mass flow equations to relate pressure and velocity, but does not provide a definitive method.
  • A different participant emphasizes the importance of mass flow rate over velocity and mentions factors like turbulence and compressibility that complicate the measurement of air speed.
  • One participant references an analytical solution for an axisymmetric jet as potentially relevant to the inquiry, noting that the problem's clarity depends on the required accuracy.

Areas of Agreement / Disagreement

Participants express differing views on the best approach to calculate air velocity, with no consensus on a single method or solution. The discussion remains unresolved regarding the most effective way to measure or calculate the velocity of air from a nozzle.

Contextual Notes

Participants highlight limitations such as the dependence on assumptions about flow conditions, the effects of turbulence and compressibility, and the need for accuracy in measurements.

Uridan
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Hi,

Is there a way to calculate the velocity of air as it comes out from a nozzle? The nozzle is ejecting wind upwards and I would like to find the wind velocity with respect to the height.

I currently have the pressure that is being supplied to the nozzle and also the nozzle diameter, is there a way to find the velocity with these parameters?

Thanks
Uridan
 
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use ideal gas equation..
P1. V1 = P2. V2
and debit equation
Q= A. V
and mass equation
Q1=Q2
 
Uridan said:
Hi,

Is there a way to calculate the velocity of air as it comes out from a nozzle? The nozzle is ejecting wind upwards and I would like to find the wind velocity with respect to the height.

I currently have the pressure that is being supplied to the nozzle and also the nozzle diameter, is there a way to find the velocity with these parameters?

Thanks
Uridan

Usually, we will ask for Mass flow rate instead of velocity (FAD, Free Air Delivery = volume of air comes out at 1 atm environment).

Think about turbulence and compressibility of air after the nozzle. using pito tube to obtain the speed of air after the nozzle is completely meaningless. the speed is different at each section.

You can try to have a look on ISO1217 about measurement of air compressor at school.

I believe your nozzle is some kind of flow measurement device.
 
I have a post somewhere on here of the analytical solution of an axisymmetric jet. That should be essentially what you're looking for. Try doing a search for it.

The problem is not as clear as one would think. This all really depends on the accuracy needed though.
 

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