Transient state simulation flow over a throttle body.

Objective:

• To setup a case for transient state flow simulation over a throttle valve and post process the results in paraview.
• Plotting the presuure, velocity, mass flow rate, total cell count for transient flow.
• Results of presuure of velocity contours using Paraview.

Geometry:

The pre modelled throttle body was imported to converge and checked for the errors and the open edges and fixed that and rescaled the geometry finally flagged the boundries.

Case setup :

Fluid used:- Air.

Solver :- Transient solver

Start Time:- 0 sec

End Time :- 0.01 sec

Initial and Minimum time steps :- 1e-09

Maximum time step :- 1

Turbulence modeling :- RNG k-ε

Inlet Pressure :- 1.5bar

Outlet Pressure :- 1bar

Elbow wall and Throttle wall Temperatures :- 300k (Law of wall)

Throttle movement:

The throttle was made to move 25 degree from 0 to 2ms and then from 2 to 4ms valve should be 25 degree after that it should reatin to 0 degree i.e to original position at 8ms.

Geometry mesh:

A base grid size of 2e-3 was provided and also fixed embedded for the scale of 2 near the throttle and after post processing in paraview the slice looked like shown in the below contour.

Below shows the throttle movement of mesh:

Velocity contour:

The magnitude of velocity reaches an upward of 3.3e2 when the throttle valve is opened. Towards the outlet side of the valve where there is a flow seperation, velocity reduces and even reaches zero.

Velocity flow lines of moving throttle valve :

Velocity flow with steam:

Pressure contour:

Pressure flow over a throttle body:

When the flow encounters the throttle valve, the pressure is higher towards the face of the valve that is directly in line of the flow which also shows the restricted area of flow. therfore the pressure drop occurs at athe throttle.

veloctiy plot:

Pressure plot:

mass flow rate plot:

The mass flow rates also take a longer time to reach a steady state value and during the intial simulation it varies a lot.

Total cell count plot:

When running the simulation in transient state, the cell count never reaches a steady state value, instead it keeps updating at every time-step. However in the steady-state condition the number of cells remain constant over the entire duration of simulation.