Numerical study of an integrated miniature ejector for catalytic micro-combustors

Abstract

In the present study, an integrated micro-ejector was proposed to provide a mixture of n-butane and air for micro-combustors. The effects of fuel jet velocity and geometrical parameters of the ejector on the entrainment ratio were numerically investigated and theoretically analyzed. The results show that the incoming air mixes with the fuel jet flow through two routes. The entrainment ratio increases with an increasing fuel jet velocity due to the increased magnitude of negative pressure. Moreover, increasing the nozzle diameter leads to a sharp decrease in the entrainment ratio. However, the entrainment ratio can be drastically augmented by increasing the diameter of the mixing section. In addition, an increase in the length of mixing section will slightly decrease the entrainment ratio of the ejector. Furthermore, increasing the total area of air inlets gives rise to a drastic decrease in the entrainment ratio. These variation tendencies have a close relationship with the negative pressure contours. The findings of this study provide a guidance to the optimal design of this kind of micro-ejectors.