离心型径向固定床分气流道内局部动量交换系数

针对离心型径向固定床气体流道内变质量流动特点，在一套冷模实验装置上，分别采取Π型和Z型操作模式，测量并分析了两气流道内压力分布，发现分气流道内的压力沿气体轴向流动方向呈增加趋势，集气流道与之相反。根据颗粒床层压降分布不均匀度和采用Ergun方程求得的径向气速轴向分布，发现离心Π型均略优于离心Z型。通过对气流道内微元控制体进行流量和动量衡算，由颗粒床层径向气速轴向分布可依次得到分气和集气流道内气速、局部动量交换系数计算方程。相较于集气流道，分气流道内动量交换系数对压力测量误差的敏感度较小。分气流道中，整体动量系数几乎不随操作模式、气体流量和轴向位置发生变化；而局部动量交换系数仅是流速比u/u0的函数，随流速比增大先降低后保持稳定。根据实验结果，回归得到的分气流道局部动量交换系数计算方程的误差在11%以内，有望为气流道内局部压力计算和结构优化设计提供参考。

Local momentum exchange coefficient in distribution channel of centrifugal radial fixed bed

For the characteristic of gas variable mass flow in distribution/collection channels of centrifugal radial fixed bed, the pressure distribution was measured and analyzed in these two channels under both Π-type and Z-type operation modes in a set of cold experimental apparatus. The pressure had an increasing trend along the gas flow direction in the distribution channel, while it had opposite trend in the collection channel. According to the uneven index of pressure distribution in particle bed and the axial distribution of gas radial velocity obtained by Ergun equation, it was found that the centrifugal Π-type was slightly better than the centrifugal Z-type. With the gas radial velocity distribution in particle bed, the flow and momentum balances were applied in the elemental body of the channels to obtain the gas velocity in distribution/collection channels and the local momentum exchange coefficient. Compared to the collection channel, the sensitivity of local momentum exchange coefficient to pressure change was relatively small in the distribution channel. In the distribution channel, the overall momentum coefficient almost unchanged with the operating mode, gas flow rate, and axial position. While the local momentum exchange coefficient was only a function of the flow rate ratio u/u0 (or axial position), which first decreased and then remained unvaried with the flow rate ratio. According to the experimental results, the equation of the local momentum exchange coefficient were obtained by the regression method within 11% error. It was anticipated to provide reference for the calculation of local pressure in the gas channels and the designation of the structural optimization.