Transient flow simulation of a throttle body

The problem of flow through a throttle valve was simulated. In this case the problem is a transient problem where the valve keeps moving. The throttle body is placed in a curved elbow. The working medium is assumed to be air. Inlet pressure is set as 1.5 bar and outlet pressure is set as 1 bar. The grid size was set as 4mm. The time to which the simulation has to be run was found out by using the velocity from the steady state case. The velocity was found to be around 220 m/s and the length of the elbow around 0.11 m. Using them, the time was found to be around 0.0005 seconds. Since the elbow is curved a factor of 3 was multiplied to the time and the simulation time was fixed as 0.0015 seconds.The valve normal was found using a triangle in the valve and the centre was rotation was assumed to be the centre of the valve.

The rotation given was of 25 degrees over the first 0.0006s.

Results from the simulation showed that turbulence effects near the throttle body were pronounced due to its movement. The coloured glyphs indicate the direction of flow after it has passed through the valve. Since it is partially opened the glyphs hit the valve and hence turbulence is created. From the stream diagram, we can see that vortices are being formed after the stream hits the valve and hence downstream flow occurs. Since the valve acts as an obstruction there is a pressure rise near it and thus a density rise also follows.