螺杆泵定子热力耦合的计算方法研究

Computational Method for Thermal-Mechanical Coupling of Progressing Cavity Pump

温度是井下螺杆泵的工作性能的重要影响因素,过高的温度会降低其性能,减少泵的使用寿命,高温还会导致橡胶衬套的膨胀,增大螺杆泵运行时的扭矩。提出了一种橡胶生热计算模型:首先得到螺杆泵橡胶的应力应变,然后利用傅里叶级数拟合其应力应变,通过生热模型计算橡胶的生热率,最后建立了螺杆泵定子橡胶的温度场分析模型。常规螺杆泵和等壁厚螺杆泵的最高温度都在直线段橡胶衬套中点处,但等壁厚螺杆泵的温度分布更加均匀;转速对于螺杆泵定子橡胶衬套的最大温升的影响是成正比的;相同条件下,仅仅考虑橡胶衬套的许可的温度,等壁厚螺杆泵的许用转速比常规螺杆泵更高,这表明在流量变化范围大的领域里(比如煤层气排采),等壁厚螺杆泵更有优势。

Temperature is the important factor influencing the workability of downhole progressing cavity pump （PCP）, high temperatures will reduce its performance and service life. On the other hand, high temperature can cause expansion of rubber, and increase the working torque. A calculation model for heat generation of PCP is proposed. The strain and stress of the rubber are obtained using the finite element method at first, then Fourier series is utilized to fit the stress and the strain of rubber in the rolling process, heat generation can be calculated according to this model, the temperature research model of the PCP is set up. Meanwhile, the conventional PCP is contrasted with uniform-thickness PCP, the highest temperature of conventional PCP and uniform-thickness PCP are both at the center of the area where the straight part of contour line is, but temperature distribution of uniform-thickness PCP is more uniform; The maximum temperature rise is proportional to the rotational speed; The uniform-thickness PCP allows higher speed than conventional PCP under the same conditions, this conclusion indicates that uniform- thickness PCP has more advantages than conventional PCP in the field that the range of flow is wide （for example, Drainage Gas Recovery in CBM well）.