Transient State Simulation of Flow over a Throttle Body

Aim:

To simulate the flow over a moving throttle body (transient state) and post process the results.

Theory:

• This project is used to simulate the flow of air (used as the standard medium) over a moving throttle body in a bent pipe.
• The Transient State solver is used to solve the problem. 'No Hydrodynamic' option is selected to check if the correct mesh generation takes place.
• Reynolds Averaged Navier-Stokes (RANS) method is used to solve the flow of air inside the bent pipe .The Turbulence Model selected is RNG-K epsilon.
• The Base Grid values are 0.002 in the dx,dy & dz co-ordinates respectively.
• A pressure difference of 50000 pascal drives the flow of air in the bent pipe.
• Under the 'Boundary' option, rotating motion is provided for the throttle and the following conditions are chosen as per the challenge instructions:
  • From 0 to 2 ms, the valve should rotate by 25 degrees.
  • From 2 to 4ms ,it should stay at 25 degrees.
  • After which,by 8ms ,the valve should get back to it’s original position.

Observation and Results:

Fig 1: The opaque structure of the geometry

Fig 2: The cut section along the Z- axis

It is visible from the image that the mesh around the throttle is more dense. This can be achieved by increasing the value of \'Scale\' and \'Embedded Layers\' under the \'Fixed Embedding\' option. A finer mesh can be generated by increasing the cell count in the \'Base Grid\' option.

Fig 3: Flow direction with the throttle open

Fig 4: Flow Streamline

The different coloured streamlines represent the velocity variations occuring in the flow inside the pipe when the throttle is open by 25 degrees. The streamlines also gives us an apt representation of how the flow occurs with a rotating throttle.

Fig 4.1: Full body view

Video 1: Veocity animation

Video 2: Streamline animation