短语词组短语converging -diverging nozzle 缩扩喷嘴;收缩;收缩扩张喷管Converging -Diverging Nozzle Flow 渐缩及渐扩流Nozzle diverging 放射管嘴diverging parts of the nozzle 喷管扩散部分 返回 diverging nozzle