college of construction engineering, Jilin university
The annular foam breaker is one which uses the vacuum and shear force generated by the Coanda effect to break foam. The pressure distribution directly affects its performance. So an investigation on the flow characteristics inside the annular foam breaker is important to optimize its structure. In this paper, the computational fluid dynamics (CFD) code, FLUENT, is employed to simulate the flow phenomena. The effect of various geometric parameters on the pressure distribution inside the annular foam breaker has been evaluated, including the width of the annular slot, the Coanda surface radius and the diffuser dimensions, etc. The numerical results show that the optimum value of the annular slot d = 0.5mm, the Coanda surface radius r = 20mm, the diffuser angle θ=6°, and the ratio of the diffuser length to radius is more than 14. Based on these analyses, an optimum structure of the annular foam breaker was designed and tested in the well bore flow simulation loop laboratory equipment. Compared with the old ones, the foam-breaking efficiency of the optimized annular foam breaker is improved from 71.16% to 86.58%, which increases by some 22.61%.