锤片式饲料粉碎机内自由流的流场特性分析

Analysis of flow field characteristics of free flow in hammer feed mill

在锤片式饲料粉碎机内部,以环流层为界,可将气流分为加速流和自由流。自由流不仅对饲料颗粒产生曳力作用,影响饲料的粉碎、破围和收集,而且对粉碎机能耗大、饲料过粉碎、饲料温升高、锤片磨损严重等问题也较大的影响。为了较为准确地预报自由流的流动状况,该文采用数值模拟的方法,对其速度场、压力场和湍动能场的分布特征和变化规律进行深入分析。结论认为,气流在粉碎腔上部的大幅度降速不利于自由流的下行,会影响饲料的粉碎、破围和收集;湍动能场的存在是引起气流大幅度降速的直接原因,可适当改进结构以减小湍动能场的分布范围。该研究结论可为锤片式饲料粉碎机的结构改进和相关领域的研究起到参考作用,也可完善锤片式饲料粉碎机研究的基础理论。

In the hammer f^ed grinder, take the circulation layer as boundary, airflow can be divided into accelerated flow and free flow. Free t]ow nol only has the drag effect on feed particles, affects the smoolhness of feed grinding, breakthrough and discharge process, but also has a grealer impact on en- ergy consumption, feed mill crushing and high temperature, hammer wear serious problem. In order to predict the flow state of free flow more accurately, this paper use a numerical simulation method, has a in-depth analysis of velocity fiehl, presst,re fiehl and turbulen! kinetic energy field of free flow. The （：onclusion is Ihat, substantially reducing of the velocity of airflow is disadvantage fi）r downstream of free flow, can affect the smoothness of feed grinding, breakthrough and discharge process. The exis- tence of the tt,rbulent kinetic energy fieht is the direct cause of the substantially reducing of airflow, can improve the structure of hammer feed grinder to reduce the distribution range of the turbulent ki- netic energy fiehl. The conclusion of this study can be used as reference for the improvement of the structure of hammer feed grinder and the research in related felds, can also improve the basic theory of hammer teed grinder research.