非对称结构文丘里施肥器数值模拟

Numerical simulation of Venturi injector with non-axis-symmetric structure

基于有关学者提出的非对称结构(偏心向上)文丘里施肥器结构参数和室内试验测试数据,采用CFD数值模拟方法,研究分析了非对称结构与对称结构文丘里施肥器在吸肥量、内部流体运动及空化等性能指标上存在差异的内在原因.结果表明:模拟结果与室内测试结果吻合,即相同吸肥量条件下,非对称结构文丘里施肥器较对称结构表现出明显降低能耗的优势,可减少25%~35%的压力损失;对称结构文丘里施肥器喉部负压呈环状分布于喉管四周,非对称结构施肥器负压则呈半环状,位于喉管下部,因而相应空化区域较小,同等压差损失下有利于提高吸肥量;非对称文丘里施肥器收缩段与扩散段在喉管上部流线过渡平滑,多方向速度碰撞少,能量损耗相对小,在扩散段产生的回旋区较小.

Based on the structural parameters of Venturi injector with non-axis-symmetric structure （eccentricity upward） proposed by some researchers and related laboratory measurement data, CFD numerical simulation method was used to analyze the reason why there were differences in performance variables such as fertilizer flow rate, internal flow field and cavitation parameter in the Venturi injectors with non-axis-symmetrical and axis-symmetrical structures. The results show that the simulated perfor- mance agrees well with the laboratory test data. At the same fertilizer flow rate, the Venturi injector with non-axis-symmetric structure has a significantly lower energy loss compared with that with axis-symmetrical structure, especially the pressure loss can be reduced by 25%-35%. The negative pressure zone in the Venturi injector with axis-symmetrical structure is distributed around the throat, but in the injector with non-axis-symmetric structure, it is in the half ring located in the lower part of the throat. As a result, the cavitation zone is smaller and beneficial to increase of suction flow rate under the same pressure difference. In the non-axis-symmetrical Venturi injector, the contraction and diffusion parts are connected smoothly in the upper part of throat, so that the collisions between fluid particles in various directions are little, the resulted energy loss is relatively small, and the reverse flow region in the diffuser is also in a small size.