Mr. SHIJU JOHN 0 Report post Posted October 15, 2014 I am trying to design a submarine as part of my Masters project. My Prof. has suggested me to try using SHIPFLOW. Basically, I would like to use SHIPFLOW for the following: 1. Resistance estimation of Submarine in deep submerged condition.2. Self Propulsion Tests (using Pump-Jet propulsor) in deep submerged condition.3. Maneuverability (Straight line tests and Rotating Arm) of Submarine Please advice if its possible to do such simulations in SHIPFLOW. Is it possible to switch off the free surface effects?Is there a separate module for maneuvering? Regards,Shiju John Share this post Link to post Share on other sites
Matthias Maasch 21 Report post Posted October 15, 2014 Hi John, First things first: I am not 100 % sure about the following facts (or guesses), so please contact support@flowtech.se for clarification. 1. It is possible to run resistance computations for submarines as there is a hull type "SUBMARINE". XGRID will generate a grid that is a half of a cylinder.XMESH and XPAN will assume a fully submerged body. 2. Self-propulsion computations are possible. The propeller is represented by a lifting line actuator disc.If this fits your expectations you can model the nozzle as a XCHAP-Volume-Grid. 3. Most likely not possible! As far as I know shipflow does not offer such code. 4. XFlow allows flows with and without free surface. 5. In the ExamplesManual which comes with the shipflow software you can find some more detailed descriptions with regard to submarines, such as offset files and command files. If you don't have the ExamplesManual available I can surely upload it here. I hope this helps. Sounds quite challenging :-) Kind regards Matthias Share this post Link to post Share on other sites
Mr. SHIJU JOHN 0 Report post Posted October 16, 2014 Thankyou Maasch, "3. Most likely not possible! As far as I know shipflow does not offer such code." I have seen a couple of published papers in which maneuvering of surface ships were carried out using SHIPFLOW. (linear derivatives of velocity and accelerations)So I hope there should be a method to extend it to submarines. "5. In the ExamplesManual which comes with the shipflow software you can find some more detailed descriptions with regard to submarines, such as offset files and command files. If you don't have the ExamplesManual available I can surely upload it here." Please upload the examples file. It would be very helpful. And finally, ya it seems very challenging. We also have PARAMARINE here which is a lot easier for submarines.But I hope I can crack it with SHIPFLOW as well. Thanks a lot for your encouraging reply.Shiju JohnScientist, DRDOM.Tech Scholar, IIT Madras Share this post Link to post Share on other sites
Matthias Maasch 21 Report post Posted October 16, 2014 Hi Shiju, I contacted Flowtech and got an promising answer, here we are:It is possible to do the steady drift and rotation the same way as for a monohull. You can take a look at kvlcc2m_cg_drift06 and kvlcc2m_cg_turn then combine it with a submarine example sub_xchap.Please find attached the files mentioned and in addition the ExamplesManual and the UsersManual. If you have further questions do not hesitate to ask. Cheers Matthiasshipflow_files.zip Share this post Link to post Share on other sites
Mr. SHIJU JOHN 0 Report post Posted October 21, 2014 Hi Maasch, Very encouraging to see your mail.Thankyou. I am going through these files.Hope to start working once initial hull form is finalised. Regards,Shiju John Share this post Link to post Share on other sites
Mr. SHIJU JOHN 0 Report post Posted November 24, 2014 I have modified the submarine offset file off_sub for my design.I am trying to run xpan it through SHIPFLOW GUI using this offset. First, I imported the offset file. The 3D view shows my sub as ok.But, on running i am getting an error message as follows: ***ERROR (401) - FILE COULD NOT BE OPENEDSYSTEM DEPENDENT ERROR STATUS NUMBER = 29LOGICAL UNIT = 4FILENAME = ../off_subxferrm: Error Pls help.I am attaching the fdb file for reference.trial1.fdb Share this post Link to post Share on other sites
Mr. Mattia Brenner 6 Report post Posted November 25, 2014 Hi John, if you are running the case through the SHIPFLOW GUI, you have to make sure that the offsets are exported. In the XFLOW/OFFSET/FILE configuration entry you just had the string "off_sub", which means that this file is located on the harddrive. But this file did not exist, since your offsets are inside the project. Therfore the error message. To make sure that they are exported to a file before the computation is started, you have to use this command Then it works fine. Cheers,Mattia Share this post Link to post Share on other sites
Mr. SHIJU JOHN 0 Report post Posted November 27, 2014 Thankyou. It worked. Regards,Shiju John Share this post Link to post Share on other sites
Mr. SHIJU JOHN 0 Report post Posted November 27, 2014 Hi, When you run XPAN for a deep submerged submarine, the resistance should be zero. (D'Alembert's paradox)What is this basic resistance coeff that XPAN gives for deep submerged submarine? Is it the pressure coeff or any residual error? Basic model resistance coefficient (force/0.5*density*Sref*U*U)CXPI -0.000833CYPI 0CZPI 0.0022034 Pls explain.Regards,Shiju John Share this post Link to post Share on other sites
Mr. Paul Riesen 0 Report post Posted December 16, 2014 Hi Shiju, have you managed to run a propulsion computation of your subm? I am working on my bachelor thesis. Therefore I need to get the propulsion results of an AUV. Would you mind to help me with your configuration data specifically for the propul. calc.? Resp. did you use the ITTC78 command? Would be great!Regards,Paul Share this post Link to post Share on other sites
Mr. Paul Riesen 0 Report post Posted December 16, 2014 Actually why are using XPAN? You don’t need the potential calc. because it is submerged. You can use XCHAP only, isn’t it?!? Share this post Link to post Share on other sites
Mr. SHIJU JOHN 0 Report post Posted December 26, 2014 So far I have not used the propulsion calculations. But I am heading into it soon. I tried using XPAN to get the velocity contours. Share this post Link to post Share on other sites