考虑载荷模拟作用的高压弯头冲蚀数值仿真

在水力压裂过程中，地面高压管汇在管内复杂固液两相流冲击和管体恶劣载荷的耦合作用下，弯头、三通及接头等薄弱部件长期遭受严重的冲蚀磨损，极易导致管件发生断裂破坏，对现场人员及设备构成严重威胁。开展载荷作用下的高压管汇典型材料冲蚀磨损试验，根据试验结果，基于E/CRC冲蚀模型构建一种考虑应力状态影响的新型冲蚀数学模型，所构建的新模型与冲蚀试验数据之间的准确度可达95%以上。采用计算流体力学离散相模型（CFD-DPM），开展高压管汇件冲蚀性能的三维数值模拟，考察高压弯头在不同压裂工况下的冲蚀磨损程度及空间分布情况。结果表明：在固液两相流冲击下，主要冲蚀区位于靠近弯头出口处的弯头外侧，且管件的最大冲蚀率也位于该处；在弯头内侧二次流涡流的影响下，部分颗粒在流经弯头后会在下游直管内侧积聚，从而在这个区域造成次要冲蚀区；随着流动颗粒斯托克斯系数增加，主要冲蚀区面积增大，次要冲蚀区面积减小；此外，在嵌入新型冲蚀数学模型后，可观察到随着操作压力增大，高压管汇弯头部位的冲蚀磨损率明显增加。

Numerical Simulation of Erosion of High-pressure Elbow Considering Load Action

In the process of hydraulic fracturing,under the coupling effect of complex solid-liquid two-phase flow and severe loads,the weak parts of high-pressure manifold such as elbows,tees and joints suffer from severe erosion wear for a long time,which would easily lead to the fracture and damage of the pipe fittings and pose a serious threat to the personnel and equipment on site.The erosion wear experiments involving applied stress were carried out.According to the test results,a new erosion model considering the effect of stress state was developed based on E/CRC erosion model,and the agreement between the new model and the erosion test data can reach more than 95%.The three-dimensional numerical simulation of the erosion performance of the high-pressure pipe fitting was carried out using the computational fluid dynamics-discrete phase model (CFD-DPM),and the severity and spatial distribution of erosion wear under different fracturing conditions were investigated.The results show that the main erosion zone is located on the elbow extrados near the elbow exit,and the maximum erosion rate of the elbow is also located there.Under the action of the secondary flow vortex on the inside of the elbow,driven by the secondary flow vortices inside the elbow section,some particles move and accumulate in the inner wall of the downstream straight pipe near the elbow exit.Accordingly,the secondary erosion region is made apparent in this area.With the increase of the particle Stokes number coefficient,the area of the main erosion zone increases and the area of the secondary erosion zone decreases.In addition,after embedding the new erosion model,it can be observed that the erosion wear rate at the elbow of the high-pressure elbow increases significantly as the operating pressure increases.