The flow dynamics of the pulse-jet gas around a rectangular slot-nozzle was analyzed numerically to predict the effects of nozzle shape and dimension on the pulse cleaning performance. The entrainment ratio and pressure magnitude along the nozzle axis were analyzed using Computational Fluid Dynamics (CFD) around a 3-D rectangular slot-nozzle of venturi shape and specified as the index to evaluate the cleaning effect. The influence of both the convergent ratio in the narrow direction (R-ch) and in the wide direction (R-cw) as well as the divergent ratio (R-dw) in the wide direction of the nozzle was discussed, respectively. It was discovered that among of R-ch, R-cw and R-dw, the flow dynamics were most sensitive to changes of R-ch. Thus, the entrainment effect increased with increases of R-ch, R-cw and R-dw, respectively, while the total mass of the entrained-air increased inversely. The dimensionless correlations for the entrainment ratio according to the relative variables of R-ch, R-cw and R-dw were also developed to predict the entrainment ratio for the nozzle of different sizes compared with the reference novel nozzle proposed in the study. (C) 2016 Elsevier B.V. All rights reserved.