| Vortex diode is used in the nuclear industry and other high-risk liquid transportation systems because of no rotating parts and leakage. Its principle is similar to the diode in circuit, when the fluid enters in the axial port and out of the tangential port, the vortex diode gives low resistance. On the other hand, in the reverse flow condition, great resistance can be achieved because of confined swirling flow due to tangential velocity.The scientists have fined that the pressure in center of swirling flow may be lower than vaporization pressure of liquid if the tangential velocity is high enough, which can lead to cavitation flow in vortex diode. Cavitation flow has great influence in vortex diode performance. In this paper, a deep study has been carried out about the cavitation mechanism and flow resistance characteristic of vortex diode through experiment and CFD.CFD simulations were carried out on vortex diode. We hope to research the detail of flow field and its internal mechanism. The CFD can also be used to study the optimization of structure which is difficult for testing. The modals with different structure of tangential port, axial port and chamber are simulated to research the methods of optimization design.Besides the CFD simulations, we test the development process of cavitation flow in vortex diode through the testing equipment made up of glass and PIV system with color-coded test functions. Study the effects on cavitation of the inlet Reynolds number and outlet pressure. Based on above testing results, we research on the source of cavitation flow and its impact on overall performance of the vortex diodeThe above-mentioned results show that the cavitation flow is made up of the vapor and the non-condensing gas, the size of cavitation flow is influenced by inlet velocity and outlet pressure, the performance of vortex diode is deeply affected by cavitation flow due to the forced vortex. |
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