Numerical simulation on internal flow characteristics in the discharge chamber of an afterburning fuel pump under off-design conditions

The unsteady flow in an afterburning oil pump on a certain type of aero-engine was simulated for the uncommon cavitation damage problem near its casing tongue,with arbitrary sliding mesh technology.The discharge chamber internal flow characteristics at off-design conditions were investigated to find out possible conditions causing the casing tongue cavitation.The results showed that:under large flow-rate condition,there are two separated vortices of different sizes located in the cone-shaped tube passage,while the fuel flowed past the casing wall without obvious separation in the annular chamber,which hardly trigger cavitation;under small flow-rate condition,the two separated vortices extend to take up most part of the cone-shaped passage,incoming flow of the diffuser is choke up with a part of the fuel blocked at right side flowing back to the annular chamber around the tongue.As a result,serious flow separation is raised with a high pressure decrease,which is expected to generate cavitation and following damage on the casing tongue.