Numerical investigation of a pump-jet with ring rotor using an unstructured mesh technique

다국어 초록 (Multilingual Abstract)

In the present study, the hydrodynamic characteristics of a pump-jet were numerically investigated using an incompressible RANSflow solver based on pseudo-compressibility. The focus of the study is the assessment of the flow characteristics and performance, particularlyof a ring rotor with the rotor blades interconnected with a circumferential ring at the tip. For this purpose, a vertex-centered finite-volume method on unstructured meshes was used in conjunction with second-order Roe’s FDS to discretize the inviscid fluxes,while the viscous fluxes were computed based on central differencing. For the unsteady time integration, a dual-time stepping methodand the Gauss-Seidel iteration were employed. An unstructured overset mesh technique was adopted to treat the relative motion betweenthe rotor and the main body of the pump-jet. For the closure of turbulence, the Spalart-Allmaras one equation model was employed. Tovalidate the flow solver, the calculations were initially made for the High Reynolds number pump (HIREP) configuration at several advancingratios. Reasonable agreements were obtained between the present results and the experiment in terms of the pressure coefficienton the blade surface, velocity distribution, and integrated blade loadings. To investigate the effect of the ring on the flow characteristicsand propulsion performance of the pump-jet, additional calculations were made for the HIREP configuration installed with the circumferentialring at the rotor blade tip, and the results were compared with those of the original HIREP configuration. The addition of thering at the blade tip helped reduce the tip vortex strength, which might be beneficial in suppressing the formation of water vapor. Furthermore,the cavitation performance on the suction surface of the rotor blades was degraded by the reduced axial velocity because of thepassage area reduction after the ring was attached. With the addition of the ring, the blade loadings of the pump-jet, such as the thrust andtorque, were reduced even though the efficiency, defined as the ratio of thrust and torque, was maintained.

참고문헌 (Reference)

1 J. J. Dreyer, "Solution of the averagedpassage equations for the incompressible flow through multiple-blade-row turbomachinery" The Pennsylvania State University 1994

2 H. K. Lee, "Ring rotor-type pump-jet propulsion device of underwater moving mass"

3 P. L. Vosfer, "Pumpjet propulsion - a British splendid achievement" 36 (36): 1996

4 S. Ivanell, "Hydrodynamic simulation of a torpedo with pumpjet propulsion system" Royal Institute of Technology 2011

5 Y. T. Lee, "Flow analysis in a single-stage propulsion pump" 118 (118): 240-248, 1996

6 Ch. Suryanarayana, "Experimental evaluation of pumpjet propulsor for an axi-symmetric body in wind tunnel" 대한조선학회 2 (2): 24-33, 2010

7 W. S. Yu, "Computation of three-dimensional viscous flow in high Reynolds number pump guide vane" 118 (118): 698-705, 1996

8 H. N. Das, "CFD examination of interaction of flow on high speed submerged body with pump-jet propulsor" 2006

9 P. L. Roe, "Approximate Riemann solvers, parameter vectors and difference scheme" 43 : 357-372, 1981

10 W. C. Zierke, "An experimental investigation of the flow through an axial flow pump" 117 (117): 485-490, 1993

11 C. I. Yang, "A simulation of viscous incompressible flow through a multiple-blade-row turbomachinery with a highresolution upwind finite-differencing scheme" 227 : 11-18, 1995

12 M. S. Jung, "A parallel unstructured hybrid overset mesh technique for unsteady viscous flow simulations" 2007

13 P. R. Spalart, "A one-equation turbulence model for aerodynamic flows" AIAA 1992

14 A. J. Chorin, "A numerical method for solving incompressible viscous flow problems" 2 (2): 12-26, 1967

15 O. Furuya, "A new pumpjet design theory" DTIC 1988