| Because the bluff-body is placed in the pulverized coal burner, the recirculating flow zone comes into being in the pulverized-coal-airstream, which plays a good role in the igniting and flame stabilization of the pulverized coal. The study of the flow characteristics of the recirculating zone in the bluff-body burner is attached importance to. In this paper, a notion that there is steady recirculating zone in the flow field of asymmetry bluff-body is presented, based on the foregone mechanism of flame stabilization. Firstly, a flame stabilization analytical model is set up, considering the combustion of both volatile matter and fixed carbon. Several typical recirculating zones are analyzed with the model and the characteristic size of the recirculating region for flame stabilization is found; then, the recirculating flow fields behind asymmetry bluff-body and symmetry one have been measured in the cold state, respectively. The distribution of velocity and stream function in the six kinds of flow fields are obtained; in the end, the numerical simulation of the two-dimension steady field has been done with computational fluid dynamics soft ware fluent6.0 and the result of the computation is close to that of the experiment. The results of experiment and numerical simulation show that the recirculating flow zone length behind the asymmetry bluff-body is lengthened in comparison with that of the symmetry one and the dissymmetry of the eddy pair is more obvious with bluff-body fixed in the departure of the center of the field than in the center. As a result, the asymmetry bluff-body should be top-priority to be used in the burner. |
PDF Full Text Request