Transient analysis of flow over a throttle body

OBJECTIVE
To set up a transinet flow over a throttle body for different throttle angles using CONVERGE.

SIMULATION SET UP

• Steady state flow simulation of fluid over a throttle body is carried out using Pressure-based steady solver.
• Reynolds Averaged Navier-Stokes method is used to solve the compressible fluid flow inside the bent pipe and RNG-K epsilon turbulence model is chosen.
• Fixed embedding option is enabled in the grid controls, to obtain results with high resolution at required regions.
• 0.5 Bar pressure drives the flow and air is chosen as the medium of flow.
• The throttle body boundary condition is a rotationg boundary condition specified as follows:

1. The total simulation time is 8ms.
2. After 1 ms the throttle rotates by an angle of 10 degrees
3. After 2ms the throttle rotates by an angle of an additional 10 degrees
4. This rotation goes on till 8 ms till the throttle reaches an angle of 80 degrees and stops rotating any further.

Throttle body CADD model:

Mesh generated is shown below.

The following show the velocity and pressure contours within the flow for different time instants and throttle angles.

PRESSURE CONTOURS

The top most right image is the flow at 0ms. The 2nd image to the right is the flow at 1ms and so on.

It can be seen that in the last image at 8ms the throttle is almost completely closed and hence the pressure at the inlet side increases drastically as evident by the red colour and at the oulet reduces as evident by the blue colour.

VELOCITY CONTOURS

The top most right image is the flow at 0ms. The 2nd image to the right is the flow at 1ms and so on.It can be seen that in the last image at 8ms the throttle is almost completely closed and hence the velocity on both sides has become almost zero as evident by the blue colour.

MASS FLOW RATE VARIATION

It can be observed that with time as the throttle angle increases the mass flow rate keeps on decreasing.At 8ms the inlet and outlet mass flow rate reach almost zero.