12 Replies Latest reply on Jan 25, 2013 2:00 AM by Jared Conway

Transient Analysis Flow For Car Intake System

Damien Kennedy Jan 31, 2011 1:04 PM

Hi,

I am designing an intake system for a single seater race car (central inlet - plenum - four outlet pipes).

I have the model generated and have run steady state flow simulation (air entering inlet at velocity and dispersing, four outlets set at ambient pressure). The flow works fine but I need to set a time dependant pressure drop from the outlets.

I specified everything as per this video on youtube http://www.youtube.com/watch?v=vIxK6K-XSGU
and specified the dependancies on the outlet lids.

I ran the simulation but the flow trajectory that returned was as if it was just showing the very last air flow path, straight to outlet no.4.

What am I missing to get an animation of the complete cycle

Attached is the excel data for the pressure drops and a picture of the intake system and the flow trajectiry that returned.

Re: Transient Analysis Flow For Car Intake System

David Harrold Feb 7, 2011 1:08 PM (in response to Damien Kennedy)

Hi Damien,
Is this for Formula SAE ?

I graphed your excel boundary conditions for the ports, looks good so far. Have you set up a Transient Analysis in the General Settings? A transient analysis solves the model over a specified time range. If you've already figured all that out, then perhaps you are only viewing data from one time step.
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- Re: Transient Analysis Flow For Car Intake System
  
  Damien Kennedy Feb 7, 2011 2:04 PM (in response to David Harrold)
  
  Hi David,
  
  Yes this is Formula SAE, We are competing in Silverstone in July.
  I have the analysis setup and it seems to run fine. The boundary conditions are setup as time dependant according to the graph. Yes it seems as if it is only showing one part of the analysis.
  
  I have heard about saving results might be the cause. I have setup the Saving option in 'Calculation Control Options' to save every 5 iterations.
  This makes sense to me and should return a full analysis. Is there anything i'm missing?
  
  Much appreciated
  Damien
  
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Re: Transient Analysis Flow For Car Intake System

David Paulson Feb 7, 2011 2:16 PM (in response to Damien Kennedy)

Damien,

It would be helpful if you would post the Flow feature tree showing your Boundary Conditions and Goals. Could it be that you have not created BC's for inlets 1,2,3?
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- Re: Transient Analysis Flow For Car Intake System
  
  Damien Kennedy Feb 7, 2011 2:35 PM (in response to David Paulson)
  
  Hi David,
  
  I am running another flow sim at the minute so cannot access it but I will throw it up in an hour when it finishes.
  No there are definately time dependant boundary conditions on all inlets.
  
  Thanks
  Damien
  
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- Re: Transient Analysis Flow For Car Intake System
  
  Damien Kennedy Feb 7, 2011 4:05 PM (in response to David Paulson)
  
  Here is screenshots of the analysis tree and the calculation control options.
  
  Analysis Tree With Dependencies.bmp 2.4 MB
  
  Calculation Control options.bmp 2.9 MB
  
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  - Re: Transient Analysis Flow For Car Intake System
    
    David Harrold Feb 7, 2011 7:25 PM (in response to Damien Kennedy)
    
    Hi Damien,
    You're on the right track. I created a simple intake manifold to understand the problem you're having. Basically, once the calculation finishes and the results are loaded, SW loads the results from the last iteration it calculated. You just need to make sure you're saving results from each time step (Periodic Saving), and then you can load results from any time step.
    
    Here's a picture of my settings for Periodic Saving, under Calculation Control Options. I used the period from your excel sheet.
    
    Once you've run the simulation with Periodic Saving enabled, you can go to: Flow Simulation > Results > Load Time Moment...
    this will let you choose any of the time steps (.fld files)
    
    On the Flow Simulation tab, click the Flow Simulation Display dropdown button and enable "Time Info". This will show the model's physical time at the top of the screen. I attached a picture of what I mean, called TimeInfo.jpg
    
    If you want to make an animation like the one in the youtube video you referenced, just search Animation Wizard in the flow simulation Help file and there's a pretty good writeup. I tried it and was able to watch the flow trajectories move from port to port according to the firing order.
    
    Have fun at Silverstone!
    Dave
    
    Time Info.JPG 241.3 KB
    
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    - Re: Transient Analysis Flow For Car Intake System
      
      Damien Kennedy Feb 7, 2011 9:05 PM (in response to David Harrold)
      
      Absolue legend David!!!
      
      I will give this a go in the morning as I do not have the flow simulation package on the laptop.
      So I should have been using time saving instead of iterations yes?
      I will get it going in the morning and let you know how I get on.
      
      Much appreciated
      Damien
      
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      - Re: Transient Analysis Flow For Car Intake System
        
        Damien Kennedy Feb 17, 2011 2:53 PM (in response to Damien Kennedy)
        
        Hi David,
        
        I got the flow analysis to work and it loaded the flow files for the different time movements but I am having trouble animating the flow trajectories.
        
        I have specified the scenario in the wizard and it loads all the different control points to the animation wizard but when I play it back nothing appears. Little bursts of flow appears every so often but not as if it is streaming. I have tried different frame rates to no avail.
        
        Any ideas?
        
        Thanks for help on the previous also
        
        Damien
        
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        Re: Transient Analysis Flow For Car Intake System
        
        David Harrold Feb 24, 2011 12:19 PM (in response to Damien Kennedy)
        
        hmmm... that's odd.
        It worked on my machine when I went through the Animation Wizard. I wonder if your graphics card doesn't have enough horsepower? Try reducing the number of steps in your animation and see if that helps.
        
        As a point of comparison, I am running an HP Compaq 8510p laptop with twin Core2 Duo 2.20 GHz processors, 2GB RAM, and ATI Mobility Radeon HD 2600 video card. My video card could be better, but it's ok for this.
        
        Dave
        
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        Re: Transient Analysis Flow For Car Intake System
        
        Viktor Masolov Sep 1, 2011 8:22 AM (in response to Damien Kennedy)
        
        Hi Damien.
        I have same problen with animation. Are there any progress in your analysis?
        
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        Re: Transient Analysis Flow For Car Intake System
        
        Jared Conway Jan 25, 2013 2:00 AM (in response to Damien Kennedy)
        
        Damien, try grabbing a video with jing or similar so we can see what you're seeing on the screen.
        
        what's your workflow like to create the animation?
        
        does a cutplot animate properly (Vs a flow trajectory)?
        
        dustin, setup surface parameter goals for pressure at the inlet and outlet. then create an equation goal to calculate the pressure drop right inside flow simulation as a goal. or just output the data and calculate in excel with your output data.
        
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Re: Transient Analysis Flow For Car Intake System

Dustin Macias Jan 18, 2013 5:24 PM (in response to Damien Kennedy)

How did you calculate the pressure drop across the outlet lids?

I already made an excel sheet to find the time per crank angle degree using the cam profiles.

I've been searching everywhere and asking a lot of people but with no help.
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