Uploaded November 2017 | Updated September 2026, 2 weeks ago
One of the important variables in determining how much thrust a rocket can produce is the mass flow rate. In this video, we will derive an expression for the mass flow rate through a converging or converging diverging nozzle.
===== NOTES =====
► This expression only works when the flow is choked. For a converging-diverging (CD) nozzle, the flow should always be choked (although you still need to check). A little more care is needed when using the expression for a converging nozzle, because a lot of converging nozzles operate under conditions where they are not necessarily choked.
===== RELEVANT VIDEOS =====
→ Rocketdyne F-1 Mass Flow Rate Example
goo.gl/Ezp54H
→ Converging-Diverging Nozzle
goo.gl/jrsyoJ
→ Sonic State (Critical, Star)
goo.gl/vhjESy
→ Area-Mach Number Relation [CPG]
goo.gl/j4FwQX
===== REFERENCES =====
► Notes by Matt MacLean
► Modern Compressible Flow, Anderson
► Elements of Gasdynamics, Liepmann and Roshko
► Gas Dynamics, Zucrow and Hoffman
===== THUMBNAIL IMAGE =====
By NASA (NASA Human Space Flight Gallery (image link)) [Public domain], via Wikimedia Commons
One of the important variables in determining how much thrust a rocket can produce is the mass flow rate. In this video, we will derive an expression for the mass flow rate through a converging or converging diverging nozzle.
===== NOTES =====
► This expression only works when the flow is choked. For a converging-diverging (CD) nozzle, the flow should always be choked (although you still need to check). A little more care is needed when using the expression for a converging nozzle, because a lot of converging nozzles operate under conditions where they are not necessarily choked.
===== RELEVANT VIDEOS =====
→ Rocketdyne F-1 Mass Flow Rate Example
goo.gl/Ezp54H
→ Converging-Diverging Nozzle
goo.gl/jrsyoJ
→ Sonic State (Critical, Star)
goo.gl/vhjESy
→ Area-Mach Number Relation [CPG]
goo.gl/j4FwQX
===== REFERENCES =====
► Notes by Matt MacLean
► Modern Compressible Flow, Anderson
► Elements of Gasdynamics, Liepmann and Roshko
► Gas Dynamics, Zucrow and Hoffman
===== THUMBNAIL IMAGE =====
By NASA (NASA Human Space Flight Gallery (image link)) [Public domain], via Wikimedia Commons
![Explained: Area-Mach Number Relation [CPG]](https://i.ytimg.com/vi/bdcxN0u5hMs/mqdefault.jpg "Explained: Area-Mach Number Relation [CPG]
Can we approximate the exit Mach number of a rocket nozzle knowing only the area ratio? With a few assumptions, we certainly can! In fact, if we know how the area changes along a nozzle from the throat to the exit, we can calculate how the Mach number varies throughout the entire nozzle.
NOTES
► Ill make sure to never use my orange marker again
► If you download my Method of Characteristics MATLAB code from my GitHub (link below), you can see that the results of both match very closely!
HOW TO SOLVE AREA-MACH NUMBER RELATION
http://www.joshtheengineer.com/2016/11/16/solving-the-area-mach-number-relation/
ROCKET NOZZLE - METHOD OF CHARACTERISTICS
https://github.com/jte0419/Rocket_Nozzle_Design
RELEVANT VIDEOS
Area-Mach Number Differential Form
https://goo.gl/tDzBtM
Sonic State
https://goo.gl/j6yCxD
Stagnation-to-Static Relations
https://goo.gl/r5JZSQ
Normal Shock Relations
https://goo.gl/E5Lwac
REFERENCES
► Notes by Matt MacLean
► Modern Compressible Flow, Anderson
► Elements of Gasdynamics, Liepmann and Roshko
► Gas Dynamics, Zucrow and Hoffman
THUMBNAIL IMAGE
By NASA (http://mix.msfc.nasa.gov/abstracts.php?p=2388) [Public domain], via Wikimedia Commons")
![Explained: Pitch Stiffness [Flight Dynamics]](https://i.ytimg.com/vi/bo68hptU6YA/mqdefault.jpg "Explained: Pitch Stiffness [Flight Dynamics]
Explained: Pitch Stiffness [Flight Dynamics]")
![Explained: Static Text GUI [MATLAB]](https://i.ytimg.com/vi/cWZLGpaVwwE/mqdefault.jpg "Explained: Static Text GUI [MATLAB]
Static text fields can be used to indicate the status of your program, or simply to write text or numbers. This video describes how to set the static text field in a MATLAB GUI.")
