|
[Sponsors] |
Discrepancy in Exit Mach Number: Validation with Experimental Nozzle Data |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
January 6, 2024, 01:20 |
Discrepancy in Exit Mach Number: Validation with Experimental Nozzle Data
|
#1 | |
Member
Sean
Join Date: May 2023
Posts: 52
Rep Power: 3 |
I am currently working on validating my CFD results using experimental nozzle data. The experimental conditions specify a total pressure of 517100 Pa, total temperature of 843.33 K, and a wall temperature set to 0.5 times the total temperature. Additionally, the exit Mach number is expected to be 2.5.
However, upon running the simulation with the provided boundary conditions, I am getting an exit Mach number of 1.9 instead of the expected 2.5. I have attached my configuration file for your reference. Quote:
|
||
January 8, 2024, 02:55 |
No reply in 2 days.
|
#2 |
Member
Sean
Join Date: May 2023
Posts: 52
Rep Power: 3 |
I don't understand why this thread is not addressed yet ?
|
|
January 8, 2024, 04:28 |
|
#3 |
Senior Member
bigfoot
Join Date: Dec 2011
Location: Netherlands
Posts: 605
Rep Power: 18 |
Dear Sean,
Please understand that the SU2 community is an open source community run by volunteers and the researchers answering questions on cfd-online do that on a voluntary basis. It might be that your question is difficult to answer, does not contain enough information to give an answer (please see: Guide: How to ask a question on the forums) or that 2 days is simply not enough time to expect a response, especially considering that it was asked in the weekend. My rule of thumb is that you can only expect a (high quality) answer if you ask a high quality question. Just giving a config file and saying that it does not give you the expected result is not sufficient. You might consider adding: 1. which case you are trying to simulate, preferably with a reference to a website or journal paper. 2. A link to the mesh or additional results so the problem can be reproduced by the reader. Note that most people will not take the effort to submit a 500M cell mesh to a cluster just to help answering a problem, so the problem should be small. 3. What you tried yourself to investigate the problem: Converged? Mesh-independent solution? Setup according to literature? Hope this helps. |
|
January 8, 2024, 04:45 |
|
#4 | |
Member
Sean
Join Date: May 2023
Posts: 52
Rep Power: 3 |
Quote:
I appreciate your response and the insights you provided regarding the SU2 community on cfd-online. I understand that the community is driven by volunteers, and I want to express my gratitude for the effort put into answering questions. As a new member seeking insights, I also value the importance of asking high-quality questions to receive meaningful responses. I acknowledge your suggestions on providing additional information, and I will make an effort to improve the clarity and detail of my future queries. While I understand that it may take time to address complex questions, I was hoping to receive some guidance or suggestions to steer me in the right direction. I am eager to learn and contribute to the community, and any assistance or inquiries related to my initial post would be greatly appreciated. |
||
January 8, 2024, 06:17 |
|
#5 |
Senior Member
bigfoot
Join Date: Dec 2011
Location: Netherlands
Posts: 605
Rep Power: 18 |
Maybe you can tell us which case you are simulating [supersonic wedge?].
Maybe you can tell us which data you have found that you are comparing to so we can check the physics setup. |
|
January 8, 2024, 06:58 |
|
#6 | |
Member
Sean
Join Date: May 2023
Posts: 52
Rep Power: 3 |
Quote:
in a Convergent–Divergent Nozzle,” International Journal of Heat Mass Transfer.(CASE 262) A converging–diverging nozzle with a throat diameter of 0.0458 m and an exit diameter of 0.1227 m. High-pressure air was heated by the internal combustion of methanol and flowed along a cooled constant area duct with a length of 0.4572 m and a diameter of 0.355 m before entering the nozzle. The gas could be treated as a calorically perfect gas with a ratio-of-specific heats γ of 1.345. The nozzle exit Mach number was approximately 2.5. The molecular viscosity and thermal conductivity were assumed to vary according to Sutherland’s law. |
||
January 8, 2024, 07:05 |
|
#7 | |
Member
Sean
Join Date: May 2023
Posts: 52
Rep Power: 3 |
Quote:
https://drive.google.com/file/d/1CAS...usp=drive_link |
||
January 8, 2024, 07:34 |
|
#8 |
Senior Member
bigfoot
Join Date: Dec 2011
Location: Netherlands
Posts: 605
Rep Power: 18 |
Thanks. The link has restricted access, can you open access to everybody?
Can you share figures where you compare your simulations with the measurements? |
|
January 8, 2024, 08:27 |
|
#9 |
Senior Member
bigfoot
Join Date: Dec 2011
Location: Netherlands
Posts: 605
Rep Power: 18 |
One thing I noticed is that this is a round nozzle, you can simulate it in 2D with axisymmetry, so you need to set AXISYMMETRY=YES
But you need to then set the turbulence model to SST because we did not implement the axisymmetric terms for SA. |
|
January 9, 2024, 01:09 |
|
#10 | |
Member
Sean
Join Date: May 2023
Posts: 52
Rep Power: 3 |
Quote:
Thank you for this suggestion. Earlier I was using axisymmetric condition with SA model but my simulation used to fail. Now following your suggestion, as I could see, I am getting Mach number 2.4 (simulation is still running) , It seems convincing. Earlier I used to get Mach 1.9 only. Once simulation is over and let me compare my results, I will update here. |
||
January 9, 2024, 02:51 |
|
#11 |
Member
Giovanni Medici
Join Date: Mar 2014
Posts: 48
Rep Power: 12 |
Sorry for the slight detour on this topic, but I noticed that in the configuration FREESTREAM_TEMPERATURE= 843.33 (K) which is the total_temperature, not the static one.
The SU2 documentation is not strictly univocal as, for example in : SU2 Physical Definition FREESTREAM_TEMPERATURE is referred as static temperature, while in NICFD_nozzle tutorial it is referred as stagnation temperature (and I can tell that this tutorial is somewhat similar to the run @bgulzar22 is carrying out). I understand that this parameters drive the initialization of the simulation, so at the end, the solution will be driven by the Boundary Conditions, anyways, can anybody please check/clarify on that? Ok, nevermind, I noticed that the MACH_NUMBER is close to 0 so the configuration is initializing with stagnation conditions the flow ( total pressure and temperature, 0 velocity), and then let expand out ... Last edited by giovanni.medici; January 9, 2024 at 03:20. Reason: I noticed the MACH_NUMBER in the configuration |
|
January 9, 2024, 03:33 |
|
#12 | |
Member
Sean
Join Date: May 2023
Posts: 52
Rep Power: 3 |
Quote:
|
||
January 9, 2024, 04:28 |
|
#13 | |
New Member
Join Date: Feb 2022
Posts: 19
Rep Power: 4 |
Quote:
|
||
January 9, 2024, 05:40 |
|
#14 |
Senior Member
bigfoot
Join Date: Dec 2011
Location: Netherlands
Posts: 605
Rep Power: 18 |
Let us know the progress, would be nice to see some more comparison with the measurements.
|
|
Tags |
internal flow, mach number, nozzle flow |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Foam::error::PrintStack | almir | OpenFOAM Running, Solving & CFD | 92 | May 21, 2024 07:56 |
decomposePar problem: Cell 0contains face labels out of range | vaina74 | OpenFOAM Pre-Processing | 37 | July 20, 2020 05:38 |
[OpenFOAM] How to get the coordinates of velocity data at all cells and at all times | vidyadhar | ParaView | 9 | May 20, 2020 20:06 |
[OpenFOAM.org] OF2.3.1 + OS13.2 - Trying to use the dummy Pstream library | aylalisa | OpenFOAM Installation | 23 | June 15, 2015 14:49 |
[blockMesh] --> foam fatal error: | lillo763 | OpenFOAM Meshing & Mesh Conversion | 0 | March 5, 2014 10:27 |