双螺杆泵多点啮合型转子设计与内部流动特性

Design of multi-point meshing rotors and internal flow field characteristics of twin-screw pump

针对传统双螺杆泵螺杆转子螺旋面啮合区磨损严重、内泄漏大等问题,根据啮合原理,建立椭圆弧及其共轭曲线的啮合模型,构建传动比为2∶3的主从螺杆端面型线,提出一种新型多点啮合型螺杆转子结构.应用计算流体动力学方法对新型双螺杆泵内部流场进行数值计算,研究了泵内部流动特性.研究结果表明:所提出的新型螺杆转子在轴截面上可实现三点啮合,在双螺杆转子上形成多重密封;采用V形凹槽的主螺杆转子齿顶压力分布均匀,采用传统结构的从螺杆转子齿顶处压力分布呈阶梯状;从螺杆转子周向啮合间隙处泄漏速度为主螺杆转子的1.8倍,表明主螺杆转子齿顶V形凹槽两侧的光滑顶棱与泵腔内壁面形成的类迷宫密封可有效减小周向啮合间隙处的泄漏;新型螺杆转子较大改善转子的磨损适应性,有效减小了双螺杆泵的内泄漏,对提高双螺杆泵的高压环境适应能力具有重要意义.

In view of the problems of serious wear and large leakage in the meshing area of the screw rotor in the traditional twin-screw pumps,the meshing model of elliptic arc and its conjugate curve was established by engagement theory,a pair of screw rotors with transmission ratio of 2 to 3 was obtained,and multi-point meshing screw rotors were proposed.The computational fluid dynamics(CFD)method was used to calculate the internal flow field of the proposed twin-screw pump,and the internal flow characteristics of the pump were studied.The results show that the proposed screw rotors can achieve three-point meshing in the shaft section,and multiple seals are formed on the twin-screw rotor profiles.The pressure distribution at the addendum of male screw rotor with V-shaped grooves is uniform,while the pressure distribution at the addendum of the female screw rotor with the traditional structure is stepped.The leakage rate of the circumferential meshing gap of the female screw rotor is 1.8 times that of the male screw rotor,which proves that the labyrinth-like seal formed by the edges of the male screw rotor with the V-shaped grooves and the casing can effectively reduce the leakage at the circumferential meshing gap and improve the sealing performance.The wear of the proposed twin-screw rotors is improved,and the novel screw rotors can effectively reduce the internal leakage of the twin-screw pump,which is of great significance for improving the high-pressure environment adaptability of the twin-screw pump.