Experimental Study on the Erosion–Corrosion Synergism of Elbow in the Case of Liquid–Solid Swirling Flow

The influence of swirling flow on the elbow erosion–corrosion (E-C) synergism was studied by experiment and numerical simulation. The numerical values of four components of E-C rate at different parts of elbow in the case of liquid–solid swirling flow and non-swirling flow were quantified and compared. It is demonstrated that there are obvious differences between E-C synergism at elbow under the two flowing conditions. Compared with non-swirling flow, in the case of swirling flow, the percentage of pure erosion rate in total E-C rate decreases from 0.47-4.67 to 0.23-2.20% (at a twist ratio of 6.2), 0.23-2.42% (at a twist ratio of 7.4) and 0.14-2.63% (at a twist ratio of 8.8), while, the percentage of pure corrosion rate in total E-C rate increases from 6.53-23.61 to 15.59-53.41% (at a twist ratio of 6.2), 7.47-26.80% (at a twist ratio of 7.4) and 8.54-25.30% (at a twist ratio of 8.8). The fluid dynamic characteristics of swirling flow gradually change the dominant factor of E-C behavior at the elbow. Due to the elbow structure and the complexity of the flow for swirling flow in the elbow, a certain swirling intensity is required as a precondition for the swirling flow to inhibit elbow E-C. The swirling flow with strong swirling intensity induced by the twist tape with a twist ratio of 6.2 significantly mitigates the E-C at the elbow.