Flow measurement for the pre-stage of jet pipe servo valve using 2D -PIV technique

ABSTRACT In order to investigate the internal flow field characteristic for the pre-stage of jet pipe servo valve, a large-scale low-speed flow field visualisation experimental platform was developed. The internal flow field for the pre-stage of jet pipe servo valve was measured directly by particle image velocimetry (PIV), and its internal flow characteristics were obtained. The experimental results show that four vortices exist in the upper area and the lower area of the lower chamber of pre-stage. The upper chamber has two wide range of vortex in the pre-stage of jet pipe servo valve, and the vortex scale increases with the increase of flow rate. With the flow rate increases, the vortex in the upper area will disappear. The scale of the vortex in the lower area gradually increases with the increase of the flow rate, and the position gradually moves upwards. Under different deflection angles of jet pipe, the main characteristics of the vortex pre-stage are roughly the same, but the size and core of the vortex are different. The results provide a reference for the structural optimisation of the jet pipe servo valve.