Bases on the basic structure and operating function of engine throttle

according to the actual structure of a throttle

a 3-dimensional simulation of air transient flow in the course of throttle being rotated from closed position to the full opening position was realized by using CFD together with the moving mesh technology and user defining program. The influence of the throttle movement on air flow process was studied. The velocity field

pressure field and flow noise field were analyzed at different rotational angles of the throttle. The numerical simulation results show that at the beginning period of throttle rotation

eddy appears in the flow field behind the throttle and air pressure drop between the front and back of throttle is sharp

the flow noise field appears near the top and bottom position of throttle and the maximum value of acoustic power appears when the throttle opening is near 40 degrees. With the increase of the throttle rotational angle

the eddy weakens gradually

the air pressure drop between the two sides of throttle becomes small

the flow noise firstly increases and then decreases

the maximum value of acoustic power appears behind the throttle all the time and its position is gradually away from the throttle axes. The velocity field

pressure field and flow noise become steady gradually when throttle opens completely.