Study On Flow Characteristic Of Solenoid Valve Region In Electronic Unit Pump

High pressure fuel system is the key component of high performance diesel engine.The connection and disconnection of high pressure fuel and low pressure fuel iscontrolled by solenoid valve. When it is opened, due to the fast movement of controlvalve needle and the small size of valve port, the high-pressure fuel flows with highvelocity from the narrow cross-section into the low-pressure fuel line. This process hasshort duration, and a large pressure gradient, so there is a complicated flow to generatebubble, cavitation occur. Furthermore, the pressure wave within the complex flowregion will affects the movement of solenoid valve, at last, it will has the significanteffect on the injection characteristics and property of the whole fuel system.This study presents both experimental and numerical investigations into the flowcharacteristics within the solenoid valve region of a diesel fuel system. A test rig wasbuilt to examine the transient flow characteristic of the solenoid valve using the highspeed camera and transient pressure sensors. In order to better understand thecomplicated flow inside the solenoid valve,3D numerical simulation based oncavitation model was conducted by using CFD software. By means of experiment andsimulation method, the force characteristic of the control valve in the electronic unitpump (EUP) is studied. The resultant force on the valve is obtained based on itsdisplacement data acquired through test. The fluid force generated on needle calculatedby CFD simulation.Both the experiment and simulation show that the cavitation phenomenon occurswithin the solenoid valve when the valve opens. The results indicate that this cavitationphenomenon may be induced by high-speed flow and great pressure drop in the valveas the needle moves. The cavitation has great influence on behavior of the valve. It willgenerate a flow force that prevent opening process of solenoid valve.