Fluids

Fluids

2D Engine Inlet

    • awernick
      Subscriber

       Hi All,


      I am running a 2D simulation of a cross-section of an aircraft and am having trouble determining the best boundary condition to use for the inlet of the aircraft's engine. Please let me know if you have any suggestions.


      Thanks!

    • Vishal Ganore
      Ansys Employee

      Can you describe your problem in detail? Schematic of your geometry or image showing your model would help to understand your case and probable BCs.

    • awernick
      Subscriber

      I do not believe I can share a schematic via a public post, however I will try my best to describe the problem in more details. I am modeling flow over a 2D aircraft and need to analyze the flow just before the inlet of the aircraft's engine. In order to obtain the most accurate model, I want to be able to simulate the effects of the engine. Since the model is in 2D, there is no way to exactly simulate the workings of the engine, so our model instead uses a "black box" (represented by an un-meshed region) and we want to be able to set the boundary conditions of the "black box" such that the front pulls in flow like an engine inlet, and that the back pushes out flow like an engine outlet. The most important feature is that the inlet and exit of the "black box" must have the same (or close to the same) mass-flow-rate.


      At the moment we have found that the mass-flow-inlet boundary condition seems to work well to represent the exit of the "black box". However we are struggling to find a boundary condition that can accurately simulate flow being pulled into the "black box". We have tried using a pressure-outlet boundary condition for the inlet and setting a target mass-flow-rate, however, this has produced reverse flow in the flow field and the mass-flow-rate did not match the target mass-flow-rate well nor did it match the mass-flow-rate of the "black box" exit.


      Please let me know if you have any suggestions or if you need any clarifications.

    • Raef.Kobeissi
      Subscriber

      Hi,


      I am not sure what do you exactly mean by Back Box in this particular example, can you upload the case file please?


      Best Regards

    • awernick
      Subscriber

      Yes. I have uploaded a copy that I can share. What I am calling a Black Box is the internals of the engine. Since we cannot model the internals of an engine in 2D space, I have replaced it with a void in the mesh and want to use the boundaries to simulate flow coming in and out of the engine at a constant mass flow rate. Below is a sketch of the geometry in the case file that I have attached, the part circled in red is the engine and the black region is the void in the mesh representing the internals. Please let me know if you need any more information to help clarify the problem.


    • awernick
      Subscriber


    • awernick
      Subscriber

      it will not let me upload the case file. I am getting an error saying "File extension not allowed". Is there another way for me to upload it?

    • raul.raghav
      Subscriber

      See the image below. You can upload the workbench archive file.


       



       


       


       

    • awernick
      Subscriber

      I am not using Workbench. I am working directly from Fluent and do not have access to Workbench. Fluent does not have the same option to create an archive file, or at least it is not in the same location.


    • raul.raghav
      Subscriber

      You can open the Workbench and double on "Fluent" from the "Analysis Systems" toolbox on the left hand side. Now in the project schematic, you can right click on the "Setup" --> "Import Fluent Case". Now archive this workbench file and attach it here. See screenshot below:





       

    • awernick
      Subscriber

      I do not have access to Workbench. I only have access to Fluent. My university switched to Ansys AIM and did not renew their Ansys Workbench License. Ansys AIM did not appear to have the capability to work in 2D which is why I am working directly out of Fluent.

    • raul.raghav
      Subscriber

      In that case would you be able to zip the case file and attach it here. The forum lets you upload zip files. If you're file is too big, you share it through google drive or onedrive?

    • Raef.Kobeissi
      Subscriber

      As Rahul said if you Zip the .CAS and .dat file and upload then we could have a look.


      Cheers

    • awernick
      Subscriber

      Attached should be the .zip file. My latest case and data files should be inside the folder.

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