蜗壳式旋风分离器内流场的特点

用五孔探针和热线风速仪测定了蜗壳式旋风分离器内的速度场和压力场,分析了上部入口结构、芯管插入深度和锥体长度对流场的影响.测定表明,蜗壳式旋风分离器内流场是一个非轴对称的三维湍流场.上部环形空间内有明显的顶部二次流存在,因而形成上灰环.芯管末端附近有较大的向心径向速度,呈短路流现象.在锥体下部有较大的偏心流,因而造成排尘口处粉尘返混,降低分离效率.斜底入口结构的旋风分离器可以减少二次流的流量,增加环心空间的径向速度,而对下部流场影响很小.芯管插入深度对芯管末端附近的径向分布有影响,而对短路流量影响很小.

FLOW FIELD CHARACTERISTICS OF CYCLONE SEPARATOR WITH A SPIRAL INLET

The pressure field and the velocity field in a cyclone separator were measured with five-hole probe and hot-wire anemometer respectively. The measurement results showed that in a cyclone with a spiral inlet there was a non-symmetrical, three dimensional turbulent flow field. The cyclone could be divided into the upper and lower annular spaces at the end of the exit pipe. There was a secondary flow in the upper annular space, which caused the upper dust circle. A large radial velocity formed a short circuit flow at the end of the exit pipe. The flow field in the cyclone separator was affected by the inlet structure, the depth of the exit pipe and the length of the cyclone cone. The amount of secondary flow could be reduced and the radial velocity of the annular space increased in a separator with an inclined inlet. The inclined inlet structure had little influence on the lower flow field. The depth of the exit pipe had some influence only on the distribution of radial velocity at the end of the exit pipe. An increase in the cone length could reduce the centripetal velocity in the radial direction and separate the dust entrained from the dust bunker. Some calculation equations were derived.