Numerical Investigation on the Influence of Nozzle Lip Thickness on the Flow Field and Performance of an Annular Jet Pump

Long-Zhou Xiao^1,2,Xin-Ping Long^1,2, Xue-Long Yang^1,2

(1.School of Power and Mechanical Engineering, Wuhan University, Wuhan 43000 China; 2.Key Lab of Jet Theory and New Technology of Hubei Province, Wuhan 43000 China)



Abstract:

The performance of an annular jet pump (AJP) is determined by its area ratio A(ratio of cross sectional area of throat and annular nozzle) and flow rate ratio q (ratio of primary and secondary flow rate, Q_s/Q_j), while the nozzle lip thickness is neglected in the present studies. This paper presents a study on the effect of the thickness on the flow field and performance of an AJP with A=1.75. With the increasing flow rate ratio and nozzle lip thickness, a small vortex forms at the nozzle lip and keeps on growing. However, as the flow rate ratio or nozzle lip thickness is extremely low, the vortex at the lip vanishes thoroughly. Moreover, the recirculation width varies conversely with the nozzle lip thickness when the flow rate ratio q≤0.13. While the deviation of the recirculation width with different nozzle lip thickness is negligible with q≥0.13. Additionally the existence of nozzle lip hinders the momentum exchange between the primary and secondary flow and leads to a mutation of velocity gradient near the nozzle exit, which shift the recirculation downstream. Finally, based on the numerical results of the streamwise and spanwise vortex distributions in the suction chamber, the characteristics of the mixing process and the main factors accounting for the AJP performance are clarified.

Key words:  annular jet pump  nozzle lip  recirculation  streamwise vortex  spanwise vortex

DOI：10.11916/j.issn.1005-9113.2014.03.009

Clc Number:TB752+.3

Fund: