3 Replies Latest reply on Jul 11, 2018 4:37 PM by Ryan Dark

    Transient Thermal Simulation with small slots for air flow.

    Hao Tang
    Hao Tang Jun 26, 2018 9:03 AM

      Hello,

       

      I'm trying to model a balloon launch with temperature changes with time as it rises.

       

      The current simulation with the payload box entirely closed shows the battery getting too hot, so we definitely need a slotted hole for extra convection near the battery to better cool it down, but I don't know how to model that. I've tried adding a convection value along the sides of the slot or on top of the battery but that just gives unreal values, such as 20000°C battery. I've also tried adding an external temperature to the sides of the slots and that is better but it only works for conduction and doesn't simulate cold airflow through the slots to cool down the batteries. Any suggestions?

       

      Thanks,

        • Re: Transient Thermal Simulation with small slots for air flow.
          Ryan Dark
          Ryan Dark Jun 26, 2018 1:46 PM (in response to Hao Tang)

          Hi Hao,

          If you are using Flow Simulation the act of cutting these slots should allow for the airflow to release the hot gas and keep the system at a "true to life" temperature.  If you are trying to analyze this system with Thermal Simulation then you would need to adjust the convection constants for all interior faces to accommodate natural convection off all internal surfaces.  For Thermal Simulation this would be a somewhat complex calculation to find the appropriate convection constant.

           

          These are just general suggestions.  If you post the model or images of the model and the study/project setup we can all probably take a look and offer some better advice.

            • Re: Transient Thermal Simulation with small slots for air flow.
              Hao Tang
              Hao Tang Jul 11, 2018 3:59 PM (in response to Ryan Dark)

              Thanks for the reply Ryan. I am able to create a variable convection coefficient and external atmospheric temperatures wrt time so I got that covered in the Thermal Simulation. However, If I create holes that expose the interior of the box, would applying a convection coefficient in the hole allow the cold air to come into the box and would that be able to factor in the temperature due to convection through that hole?

              image.png

              Thanks,

              Hao