The flow inside a Venturi injector was investigated numerically by Fluent software based on Reynolds-averaged Navier-Stokes equations and Standard k-ε turbulent model,and the reliability of calculations was examined and validated. 15 different throat structures constituted by inlet diameters as 4,5,and 6mm,respectively,and diameter ratio λ of outlet diamer to inlet diameter as 1.0,1.1,1.2,1.3 and 1.4,respectively,were conducted for predicting injection performance. The results showed that the throat diameter has some influence on the internal flow behaviour of throat and diffusion pipe,injection performance and efficiency.The diameter ratio λ of outlet diamer to inlet diameter for Venturi throat has more influence on the injection performance than the throat inlet diameter.According to the principle of high efficiency,the range of diameter ratio is from 1.2 to 1.3.The regression models between injection efficiency and ratio of injection rate to inlet flow rate were established when λ was either 1.2 or 1.3,and their maximum efficiency was predicted.The Venturi injector with the throat inlet diameter of 4mm and diameter ratio of 1.3 can achieve the highest effeciency of 15.5%,having no vortex inside the diffusion pipe and less average turbulent energy at the same cross sections compared with diameter ratio of 1.0.The research results provide a theoretical reference for optimal design of Venturi injector.
Lran E N, Rodrigo M P. Performance of low-cost ejectors [ J ]. Journal of Irrigation and Drainage Engineering, 2004,130(2) :122 - 128.
Reader-Harris M J,Brunton W C,Gibson J J, et al. Dis- charge coefficients of Venturi tubes with standard andnon-standard convergent angles [ J ]. Flow Measurement and Instrumentation ,2001,12 ( 2 ) : 135 - 145.