Numerical Simulation Of Tea Winnowing And Optimal Design Of Winnowing Macheine

Tea winnowing machine is an important equipment in the tea refined process, the separating effect has a great impact not only on the value of the product, but also on the efficiency of next operation.Base on the particular requirement of tea winnowing, the tea particles are approximated as spherical particles through aerodynamics; movement trajectory and horizontal drift of different weight particles, in different inlet flow field (different air velocity distributions and angel of air velocity direction) of the tea winnower air inlet, are investigated through numerical calculation; distribution of vortex in winnowing chamber and impact of winnowing machine outlets flow on vortex are investigated, air outlet pressure control model is established; being combined with experimental verification. The research shows that:(1) To ensure the the winnowing quality, drift spacing between tea of different aerodynamic characteristics is the bigger the better;in the same winnowing room, in the case of air velocity distribution rising from the top to the bottom, the effective drift spacing between particles of different weight is greater than the other air velocity distributions; under the premise of the air velocity distribution rising from the top to the bottom, appropriate increasing the tea free-fall space, could improve the quality of the tea winnowing and reduce the energy consumption required for winnowing; the angel of air velocity direction a=163o and air velocity distribution coefficient β=0.17are the most favorable air inlet flow field parameters.(2) In tea bucket and upper part of the winnowing chamber of the existing eco-friendly tea winnowing machine,there are vortexes affectting the winnowing quality;the spoiler set in tea buckets can effectively inhibit vortexes in tea buckets.(3) There is a amount of air outlet flow for eliminating vortex in upper part of the winnowing chamber, when air outlet flow is greater than the amount, vortexes in flow field start to be weakened and even disappear; in the case of air outlet pressure less than Opa, the spoiler is still effective; there is a mathematical relationship between air outlet flow and air inlet flow, air flow control coefficient h is proposed, in the case of0.74<h<0.77, the winnowing room is most conducive to winnowing.The above study on flow field in winnowing machine, with engineering and practical significance, provides a theoretical basis for new design or improvement existing tea winnowing machine.