In example 2 (30:15) after Prof. calculated A1/At=(12.5/10)=1.25, he goes to Table B-2 but I think he should have checked Table B-1 because we are before the shock wave we are not calculating across the shock wave. Please let know if I'm wrong.
I noticed the same. I think the use of Table B2 is correct because, where the shock wave is, A1=A2, I think. Also, it seems he interpolated the value of A1/At = 1.25 incorrectly. The Me number should have been around 1.8. The other issue is that in problem 9.57 the exit A1 is 14 cm from the figure.
I agree with you. The Mach number is obtained from Table B-1. Table B-2, we need A2*/A1*, obviously, while A2* is unknown. I think it is just a typo, all the other deductions are correct.
Hi everyone, I am sorry, I still don't get the point what really happens if incompressible fluid flow through the CD nozzle? why the density change can affect the acceleration of the compressible fluid thanks
Why did sir use table B.2 at 30:09 because both points are before shockwave so we have to use table B.1( from my point of view). If anybody knows the answer please help me in understanding this point. Thanks
P1 is the actual pressure of the fluid at point 1, whilst P01 is the Stagnation pressure of the fluid at point 1. If the process is isentropic, then PO1 is the same value as the reservoir stagnation pressure. Hope that makes sense?
I understand what happens in the converging and then the diverging portions of the duct in terms of the acceleration of the gas particles to M=1 at the throat and then beyond it in the diverging portion. BUT... what exactly is responsible for the formation of the strong shock inside the divergent portion of the duct?
(Sorry to reply 8 months later) I've just been binge watching these for the first time since this morning, so this is new to me, but my understanding is that once supersonic flow is achieved, the proper parameters must be met to maintain supersonic flow. If they are not, the gas will bring itself back to subsonic flow. The transition from super- to subsonic flow will always create a shock wave because rapid deceleration causes a sudden spike in pressure/density in a very thin band. (The shock wave) in an earlier lecture, Dr. Biddle described it with a metaphor of a car slamming it's brakes in the middle of a freeway where traffic is flowing at high speed. The sudden deceleration will cause a high-energy impact from the cars behind it, creating a pocket (pile-up) of high car density and pressure. Any car (particle) that goes through and comes out the other side will have lost a significant amount of energy and velocity. It's a very tragic metaphor, but it makes sense.
You legend thank you for the great video, was wondering can you use the concept of a converging diverging nozzle for say an axial fan to increase thrust? Or would a regular nozzle be justvas goood?
I've never been one for the hard sciences but have watched a half dozen of these lectures to better understand car engine exhaust system designs. there's so much unintentional misrepresentation on old threads online from the last 20 years.
This video covered what my instructor was trying to explain for hours. Thanks a lot!
You're welcome!
At 30:37 it should be Table B.1, since it is not shock wave region.
what a great instructor and great video. Thank you!!
I usually don't comment, but this video is exceptional. Thx a lot
🙏🙏🙏🙏
you're genuinely a god
In example 2 (30:15) after Prof. calculated A1/At=(12.5/10)=1.25, he goes to Table B-2 but I think he should have checked Table B-1 because we are before the shock wave we are not calculating across the shock wave.
Please let know if I'm wrong.
I noticed the same. I think the use of Table B2 is correct because, where the shock wave is, A1=A2, I think. Also, it seems he interpolated the value of A1/At = 1.25 incorrectly. The Me number should have been around 1.8. The other issue is that in problem 9.57 the exit A1 is 14 cm from the figure.
I agree with you. The Mach number is obtained from Table B-1. Table B-2, we need A2*/A1*, obviously, while A2* is unknown. I think it is just a typo, all the other deductions are correct.
It was a typo on his end. He used M1 = 1.60 which is from Table B.1 at A1/A* = 1.25. Numerical value is still correct.
This one is a Legend
Nice video and course, thank you :)
You're welcome.
Where u got M3?=0.330 also where is the value of got P3/Po3= .928 ? Plz guide it any one knows
I am stuck at the same point right now
Lets see Dr John Biddles lecture. Thank you for your teaching.
this is incredible
Well, it's at least "pretty good".
If my gas dynamics exams turns out good on Monday... I'd be here to show gratitude
Bro😂❤
@@afolabitolulopecaleb7522 Kashamadupe
Thanks for saving my ass. God bless you sir!
Thank you sir!
Hi everyone, I am sorry, I still don't get the point what really happens if incompressible fluid flow through the CD nozzle? why the density change can affect the acceleration of the compressible fluid
thanks
Thank you Sir, God bless!
thank you king
from UET AE thanks sir
What happens if we reduce the throat area?
Why did sir use table B.2 at 30:09 because both points are before shockwave so we have to use table B.1( from my point of view). If anybody knows the answer please help me in understanding this point. Thanks
I believe he used table B.1 and found Mach number there then he used table B.2 to find P2/P1 value. He might have written the B.2 in the wrong place.
@@cansezerer2868 I got it. Thanks
Is it possible to have link to tables B.1 & B.2 please?
You can find it in Fluid mechanics by Frank m. White.
Please, what is the difference between P1 and P01?
P01 is stagnation pressure and P1 is the static pressure.
P1 is the actual pressure of the fluid at point 1, whilst P01 is the Stagnation pressure of the fluid at point 1. If the process is isentropic, then PO1 is the same value as the reservoir stagnation pressure. Hope that makes sense?
I understand what happens in the converging and then the diverging portions of the duct in terms of the acceleration of the gas particles to M=1 at the throat and then beyond it in the diverging portion. BUT... what exactly is responsible for the formation of the strong shock inside the divergent portion of the duct?
(Sorry to reply 8 months later) I've just been binge watching these for the first time since this morning, so this is new to me, but my understanding is that once supersonic flow is achieved, the proper parameters must be met to maintain supersonic flow. If they are not, the gas will bring itself back to subsonic flow. The transition from super- to subsonic flow will always create a shock wave because rapid deceleration causes a sudden spike in pressure/density in a very thin band. (The shock wave) in an earlier lecture, Dr. Biddle described it with a metaphor of a car slamming it's brakes in the middle of a freeway where traffic is flowing at high speed. The sudden deceleration will cause a high-energy impact from the cars behind it, creating a pocket (pile-up) of high car density and pressure. Any car (particle) that goes through and comes out the other side will have lost a significant amount of energy and velocity. It's a very tragic metaphor, but it makes sense.
You legend thank you for the great video, was wondering can you use the concept of a converging diverging nozzle for say an axial fan to increase thrust? Or would a regular nozzle be justvas goood?
You would only use a converging diverging nozzle to increase thrust if you have the potential for supersonic flow.
I've never been one for the hard sciences but have watched a half dozen of these lectures to better understand car engine exhaust system designs. there's so much unintentional misrepresentation on old threads online from the last 20 years.
hello sir....