Numerical simulation and experimental study of Inlet velocity on oil water separation effect by a fixed hydrocyclone.

The hydrocyclone can achieve the separation of oil and water through a swirling centrifugal process based on the density difference between the two media. However, for a fixed hydrocyclone, both the concentration of the mixture and the process parameters are important factors that affect the separation efficiency. In this paper, we establish the Euler multiphase flow model via numerical simulation to study the influence of process parameters (e.g., overflow split ratio 0.08) on the separation performance of the finalized hydrocyclone, and investigate the effects of inlet flow rate and oil content on phase distribution, radial flow velocity, flow field properties, and other characteristics of the oil-water medium within the hydrocyclone. By constructing an experimental platform for oil-water cyclone separation, we explored the impact of inlet flow rate on separation efficiency for mixtures with oil contents ranging from 10-30%.The results show that after cyclone separation, the denser aqueous medium is primarily distributed on the outer side of the cyclone, exhibiting obvious wall attachment characteristics. It exits through the underflow port, with its volume fraction gradually increasing as it moves toward the outer conical section. The lower-density oil phase is concentrated near the cyclone's central axis and exits through the overflow port; the closer to the overflow port's central axis, the higher the oil phase volume fraction. When the oil content is 10%, the separation efficiency reaches 99.89%. However, as the inlet flow velocity increases from 1.0 m/s to 8.0 m/s, the underflow separation efficiency decreases from 99.89 to 96.11%. Additionally, as the oil content of the mixture increases, the hydrocyclone's separation efficiency declines. Notably, when the oil content exceeds 20%, increasing the inlet flow rate improves separation efficiency, rising from 85.35% at 2.0 m/s to 93.68% at 8.0 m/s.