井下离心增压器流量突减过程瞬态数值模拟

Numerical Simulation of Transient Behavior of Downhole Centrifugal Supercharging Device during Flow Sharp Reduction Process

井下环境复杂多变,机器人运送工具时易遇卡,导致机器人出现瞬时工作突变。为研究遇卡时流量突变对离心增压器外部瞬态特性和内部流动机理的影响规律,对离心增压器在不同流量递减规律下的特性进行数值模拟。模拟结果表明:扬程瞬态增量和流量变化率成正比;叶轮功率变化趋势和流量变化趋势相同;瞬态过程中的扬程驼峰和流量变化规律有关,合理的流量变化规律可以消除瞬态过程中的扬程驼峰及驼峰对内流场的影响;监测反导叶导流器单流道内9个点的总压变化,流量变化率增大前,反导叶叶片工作面进口处总压最大,叶片背面出口处总压最小,流量变化率增大前、后总压变化规律不同;分析反导叶导流器中间截面的流场演化图,流量减小或流量变化率增大,瞬态流动结构更加紊乱,流量越小,瞬态流场演化滞后于准稳态流场的现象越明显。研究结果对于推动水平井技术的发展具有一定的促进作用。

The complex and changeable downhole environment makes the robot conveying tool is easy to stuck , leading to the instantaneous work abrupt change ol robot. In order to study the influence ol llow abrupt change on the external transient characteristics and internal llow mechanism ol the centrilugal supercharging d ev ic e, the characteristics ol the centrilugal supercharging device under dillerent llow decreasing rules were numerically simulated. The simulation results show that the transient increase ol the hydraulic head is proportional to the rate ol llow change. The impeller power and the llow have the same trend. The hydraulic head peak in transient process is related to the transient llow change proved by using a model with small head peak. Proper llow change can eliminate the hydraulic peak and its influence on the internal llow field in the transient process. By monitoring the total pres-sure change ol 9 points in the single channel ol the d il lu se r, belore the increase ol llow change r a te , the maximum total pressure occurs at the inlet ol the blade working lace , the minimum total pressure occurs at the outlet ol the blade back lace . The total pressure change rule varies belore and alter the increase ol the llow rate. By analyzing the llow lield evolution ol the middle section ol the diffuser,the llow rate decrease or the llow rate change increase makes the transient llow structure more chaotic. The smaller the llow rate , the more obvious ol the transient llowlield evolution lags behind quasi-steady state llow lield . The study results could promote the development ol horizon-tal well technology.