# Axisymmetric nozzle design using the MOC

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 August 19, 2010, 13:56 Nozzle #21 New Member   Join Date: Aug 2010 Posts: 5 Rep Power: 4 I do have one question which may solve everything before I send through the data so I dont waste your time: If you use the method of characteristics to find a contour, does that mean once u define your throat height in the MOC calculations, that the exit height will be in the order of the area ratio necessary for design condition? Or once you find the contour u then need to apply the area ratio? Regards, R. C

 August 19, 2010, 14:31 Moc #22 Member   ali Join Date: May 2009 Posts: 62 Rep Power: 5 sometime ago i read RAO method for contouring. if you know the throat diameter ( meaning you know mass flow rate) so for the mass flow rate given , you give length of nozzle divergent as input.and maximize the thrust within that length. Generally if u r desiging ideal nozzle (for gamma and moleculaer mass of gas) , for certain mach number .... chk kernel region as the last charcteristic on initial expansion will be ur exit mach number. so the location is important .check tollerance on the location (x) . but normally ideal nozzle is about L=50rt very long so not practicle. use TIC truncated ideal contoured nozzle, and in advance give length to be truncated , normally 15 to 20 percent less than 15deg conical nozzle.

 August 19, 2010, 14:33 Moc #23 Member   ali Join Date: May 2009 Posts: 62 Rep Power: 5 one more thing the design criteria i think are 1. mach number and area ratio or 2. area ratio and length

 August 20, 2010, 02:30 Moc #24 New Member   hrz Join Date: Aug 2010 Posts: 1 Rep Power: 0 Please send the code to me also. My email id: hrz5433@hotmail.com Thanks Hrz

 August 20, 2010, 04:25 Moc #25 Member   ali Join Date: May 2009 Posts: 62 Rep Power: 5 Dear R.C can you check the mass flow rate from last charateristic startinf from point A and intersecting at center line. .... compare with the reflected charateristic from axis to point E. check chart 6 1. black line :: throat area decreases in initial stage , not sure how , it will increase area ratio 2. red line :: why the initial straight portion ? and exit radius decrease ? not sure why?? hope it helps I think some problem in the code . check chart 1 inflection point is far from throat even the angle is very small less less than 14, normally it is greater than 25 .... and arc length joing the bell and throat is equal to :: l = r*theta one more point all characteristic start from point A normally last characteristic orignates from point of inflection and is the design mach number.... regards alikami aeroguna likes this.

 August 23, 2010, 12:25 nozzle #26 New Member   Join Date: Aug 2010 Posts: 5 Rep Power: 4 Hi there I have looked at it and I now have a new contour, however, I also have found a report that has solved for the profile using method of characteristics. I used this profile from the report and I am still getting Mach 3! Do you have a code or know where i can find one to compare my steps against? regards R.C A big thank you also for looking at what I have completed, much appreciated!

 August 24, 2010, 03:47 Moc #27 Member   ali Join Date: May 2009 Posts: 62 Rep Power: 5 Can you mail me report? May b some problem in FLUENT simulation.... I dont have a profile design code, one of my friend made some 3D MOC for analysis, presently he is out, i think he will be bac in 10 days. I will ask him to check on his code.... If you have simulated the nozzle from report , send me the case file Regards Alikami

October 28, 2010, 01:09
2D MOC code
#28
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pure
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Quote:
 Originally Posted by Vivek Ahuja I am guessing you mean contouring the shape of the required nozzle for maximum thrust? I believe you might want to take a look at this code that I had developed some time back. Let me know if we are talking about the same thing. I have put an image of the code output for the contour design of a supersonic nozzle contour design for given performance parameters. I can send the code to you (via email etc) but the forum software wont allow me to upload it since it exceeds the size. Regards

Hello,

I am also trying to solve the nozzle design about symmetric nozzle using method of characteristics. So could you share me that code to me?

Thanks ..

 October 29, 2010, 06:57 Moc #29 Member   ali Join Date: May 2009 Posts: 62 Rep Power: 5 I am not sure which code you need. i have 3d MOC code for axisymetric nozzle. I can send you that irrespective of whether you send me this code of yours or not. my email is a1k1s1@yahoo.com send me your email ID regards Ali

October 29, 2010, 08:22
#30
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pure
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Quote:
 Originally Posted by alikami I am not sure which code you need. i have 3d MOC code for axisymetric nozzle. I can send you that irrespective of whether you send me this code of yours or not. my email is a1k1s1@yahoo.com send me your email ID regards Ali
Thank Ali, I'd already sent my email ID to your mail. ^^

 October 29, 2010, 08:43 moc #31 Member   ali Join Date: May 2009 Posts: 62 Rep Power: 5 your email?... cant understand

October 29, 2010, 08:46
#32
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pure
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Quote:
 Originally Posted by alikami your email?... cant understand
Hello, I mean I sent my email ID to your mail a1k1s1@yahoo.com.

 December 6, 2010, 19:06 2D Axisymmetric MOC code #33 New Member   Join Date: Dec 2010 Posts: 1 Rep Power: 0 Hi guys, I have the location for quasi 2D Diverging nozzle: http://www.mathworks.com/matlabcentr...-nozzle-design I am looking for a code that handles an axisymmetric nozzle. First, I tried modifying this code and got it to work by changing how the area to circular sections. It, runs but the nozzle does not make sense. Does anyone have any ideas or have a good robust code that works. Thanks my e-mail is sahay@umich.edu

 October 13, 2011, 05:50 #34 New Member   gunasekar.M Join Date: Oct 2011 Posts: 2 Rep Power: 0 hi vivek ahuja Could you please send the code(design of axisymmetric nozzle) to my personal mail id aerogunasekar@hotmail.com.I am eagarly waiting for your mail...so pls With regards M.Gunasekar(aerogunasekar@hotmail.com)

 October 13, 2011, 05:58 #35 New Member   gunasekar.M Join Date: Oct 2011 Posts: 2 Rep Power: 0 hi could you like to send your code which you have used to design the axisymmetric contour...

January 31, 2012, 23:57
#36
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George Blagoev
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Hello!

Can you send me the code? My email address is edepro@inorbit.com.

Quote:
 Originally Posted by Vivek Ahuja I am guessing you mean contouring the shape of the required nozzle for maximum thrust? I believe you might want to take a look at this code that I had developed some time back. Let me know if we are talking about the same thing. I have put an image of the code output for the contour design of a supersonic nozzle contour design for given performance parameters. I can send the code to you (via email etc) but the forum software wont allow me to upload it since it exceeds the size. Regards

February 29, 2012, 00:47
Hi! can I have a copy of your code?
#37
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Lucas Hu
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Dear Vivek Ahuja,

I'm now doing shock tunnel nozzle design, it seems that your code can help me. My work is to design a nozzle which has an inlet diameter of 182mm and can accelerate the flow from Mach 7.5 to Mach 10.1.I've calculated by hand that the length of the nozzle will be around 6 to 7 meters, but I don't know wether it is wright or not.

I will be very happy if you could send the image of nozzle worked out by your program. And I will be appreciated if you could also send the code to me. My email box is yonghao.hu@uqconnect.edu.au

All the best!

Lucas

Quote:
 Originally Posted by Vivek Ahuja I am guessing you mean contouring the shape of the required nozzle for maximum thrust? I believe you might want to take a look at this code that I had developed some time back. Let me know if we are talking about the same thing. I have put an image of the code output for the contour design of a supersonic nozzle contour design for given performance parameters. I can send the code to you (via email etc) but the forum software wont allow me to upload it since it exceeds the size. Regards

 March 15, 2012, 15:11 #38 New Member   omer musa Join Date: Feb 2012 Posts: 6 Rep Power: 3 Hi plz send that code to me also.....email id:omer.musa1@hotmail.com Thanks

March 18, 2012, 16:33
3d moc nozzle
#39
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Dear Vivek Ahuja,

I have no idea if you are still around here, since the initial posts are long time ago.
Anyway, I am kindly asking if you'd share the code with me too. The output of your sample screenshot is looking awesome!

I was starting to learn programming (Python), bought several books, was reading through loads of papers and was always left frustrated by facing the same problems as you described ...
Quote:
 Originally Posted by Vivek Ahuja Also, Anderson's explanation for the axi-symmetric case in his book only describes the basic equation derivations. How to numerically integrate that equation (using finite difference schemes) and also to apply in the initial and necessary boundary conditions as well as the concept of the undefined region and its difference with the Prandtl-Meyer expansion system of 2D systems is not discussed. Frankly speaking, that left me thoroughly disappointed since we had to eventually develop that theory independently.
While there are some better sources on 2D MOC nozzles, sufficient guidance on 3D cases seem to be matter of a secret science.

I'd be more than happy if you could prevent me from going nuts.
nozzlefan@online.de

Thanks

cron

Last edited by cron; March 18, 2012 at 17:24.

May 24, 2012, 01:25
#40
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Arif
Join Date: Mar 2012
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Looking for qualified freelancer to simulate supersonic flow through C-D nozzle using fluent 6.2.16

Quote:
 Originally Posted by Vivek Ahuja Based on some prior experience writing MOC software codes for a NASA short course material, I can vouch for thet fact that the design of 3D nozzles with MOC is a very different kettle of fish as compared to the 2D model from a computational and theoretical standpoint. The problem remains with the "undefined" region between the throat line and the first Mach line for axi-symmetric cases. This is of course not "undefined" in the case of 2D flows thanks to the Prandtl-Meyer equations and hence the initialization of flows is defined along the first sonic line characteristic for 2D flow and using reflection techniques for the centerline calculations. For 3D flow, thanks to the undefined region, the computation must start from the centerline with a specified pressure distribution along that axis and must move radially outwards. The problem remains in the hit-and-trail methodology that must be used to get the proper characteristic solution for the 3D flow case with such a relatively intuitive and therefore probably unrealistic initial condition. Also, Anderson's explanation for the axi-symmetric case in his book only describes the basic equation derivations. How to numerically integrate that equation (using finite difference schemes) and also to apply in the initial and necessary boundary conditions as well as the concept of the undefined region and its difference with the Prandtl-Meyer expansion system of 2D systems is not discussed. Frankly speaking, that left me thoroughly disappointed since we had to eventually develop that theory independently. I would be very interested to be able to discuss our efforts with any members here who have worked on the 3D MOC problem as well. Regards

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