Week 4.1: Project - Steady state simulation of flow over a throttle body
Title: Steady state simluation of a flow over throttle body.
Aim:
To post process the results and show pressure and velocity contours.
To show the mesh (i.e surface with edges)
To show the plots for pressure, velocity, mass flow rate and total cell count.
Introduction:
Throttle valve is a type of valve which regulates the supply of working substance (charge) to the engine. The position of the throttle valve directly determines the performance of the engine. Position of throttle valve is controlled by accelerator pedal. Alternately we can say that, throttle valve is an Mechanism by which engines power output can be controlled.
Figure: Throttle valve
Figure: Cross-section of throttle valve
As shown in above diagrams, throttle valve has a circular disc which can rotate to controll the supply of fluid. Position of throttle valve decides the volume flow rte of fluid.
Geometry used for simulation
Figure: Elbow
Figure: Cross-section of elbow
Geometry modifications / Extraction of fluid volume
As can be seen from above figures, elbow has has a thickness. As fas as fluid flow simulation inside the elbow is concerned, there is no need to have thickness. Hence thickness is removed as follows.
But in above figure there are errors of open edges in geoemetry, as shown below.
This error can be removed as shown below.
Closing of open edges as shown below.
Boundary flagging/Renaming of boundaries
Case setup:
1) Application type
2) Materials
3) Simulation parameters
Steady-state simulation
Pressure based solver is used
4) Boundary conditions
Outlet: Outflow
Elbow-wall: Wall
Trottle: Wall
Elbow-wall
Velocity boundary condition, Wall motion type: Stationary, Surface movement: Fixed
Temperature: Specified value (300 K)
Turbulent kinetic energy: Zero normal gradient
Inlet: Inflow
Temperature: Specified value (300 K)
Pressure boundary condition: Specified value (150000 Pa)
Velocity boundary condition: Zero normal gradient
Outlet: Outflow
Temperature: Specified value (300 K)
Pressure boundary condition: Specified value (100000 Pa)
Velocity boundary condition: Zero normal gradient
Throttle: Wall
Velocity boundary condition, Wall motion type: Stationary, Surface movement: Fixed
Temperature: Zero normal gradient
Turbulent kinetic energy: Zero normal gradient
Turbulent dissipation boundary condition: Wall model
5) Initial conditions and events
Solution is initialised with the temperature of 300 K and pressure of 101325 Pa
6) Physical models
7) Grid controll
Meshing is done with fix emebeding
Results:
Mesh
Velocity contour
Velocity vectors
Pressure contour
Pressure countour over a throttle valve
Total cell
Mass flow rate
Average velocity at inlet and outlet
Static pressure at inlet and outlet
Results and discussion
- From velocity contour it see that, velocity is maximum where there is minimum gap between throttle and elbow wall.
- From pressure contour it see that, there is suddent reduction in pressure due to presence of throttle valve.
- From mass flow rate contour it see that, after 250 cycles, mass flow rate is approximately same as that at inlet and outlet, which ensures conservation of mass.