Steady State Analysis in a throttle valve
Throttle Valve: A throttle is simply any mechanism especially used for regulating the power or speed of the vehicle . Such as vehicles acceleration, speed etc. In automobiles, throttle valve is typically used in IC Engines. It is used to regulate the flow of fluid into the engine. The fuel is regulated depending upon the acceleration given by the driver at the pedal.
Simulation procedure :
The boundary flagging has to be done appropriately in the case of elbow throttle. The conditions of inlet and outlet are both pressure. The elbow and throttle are both walls. Now the base grid size has to be given appropriately and fixed embedding has to be given with two layers and scaling of 2.
Fixed embedding is given for throttle boundary. This is done so as to capture the boundary of the throttle wall properly.
Boundary conditions:
inlet:
: 1.5e5 pascal
Temperature: 300k
Velocity: zero gradient
Outlet:
Pressure : 1.0e5 pascal
Temperature: 300k
Velocity: zero gradient
Throttle wall:
Wall boundary condition
Temperature = 300k
Law of wall function is selected as turbulent model is used for this simulation.
Elbow Wall:
Wall boundary condition
Temperature = 300k
Law of wall function is selected as turbulent model is used for this simulation.
Results:
Mesh:
The sectional view of the elbow and throttle. Boundary flgagging is used to obtain a finer mesh around the boundary of the throttle valve.
Pressure contour: It can be observed that as the fluid is flowing from inlet and flowing past the throttle valve, as it hits the throttle, the pressure iss increasing and as it flows past the throttle wall, the pressure drops and becomes least. This is because flow separation happens as the fluid passes past the throttle.
As it can be seen from the contours that the velocity is maximum at the regions where the pressure is low and the velocity is low where the pressure is high. This is perfectly in accordance with the continuity equation.
Velocity vectors from inlet to outlet
Inlet mass flow rate, the negative value indicates that the fluid is entering the elbow at the inlet
Outlet mass flow rate: positive sign indicates that the fluid is exiting the elbow at the outlet.
As it can be seen that the mass flow rate of fluid entering is equal to the mass flow rate of fluid exiting. This is in accordance with the conservation of mass.
Average velocity of the fluid at inlet
Average velocity of the fluid at outlet
Total pressure inlet
Static pressure outlet
The wall boundary phenomenon is very important part . Hence accurately capturing the boundary near the throttle valve is very important. Since separation happens near the boundary it is important to have a finer mesh with a couple of layers as the calculations happen accurately in this region.