Fluid machinery
Geometric Effects on Suction Recirculation, Cavitation, and Flow Instability of a Centrifugal Pump
A centrifugal pump may suffer severe degradation and failure when it operates at off-design conditions. In this device, three representative abnormal flow phenomena may appear: suction recirculation, cavitation, and flow instability. The suction recirculation is a phenomenon in which reverse flow and strong swirl flow develop upstream of the impeller in part-load conditions. Cavitation appears when the pressure of the liquid falls and vaporizes below the saturated pressure. Flow patterns become highly complex due to incidence or diffusion when the pump operates in part-load conditions. These finally lead to flow instability representing time-dependent unsteady characteristics. In this work, the parametric studies of the impeller and volute geometries were performed to control these flow phenomena. Also, surrogate-based optimization techniques were applied to establish the methodology of optimal pump design.
Related publications
Shim, H. S., and Kim, K. Y.*, 2022, “Effects of the number of blades on impeller-volute interaction and flow instability of a centrifugal pump,” Proc. Inst. Mech. Eng. Part A J. Power Energy, Vol. 236, No. 8., pp. 1500-1517.
Shim, H. S., and Kim, K. Y.*, 2020, “Relationship between Flow Instability and Performance of a Centrifugal Pump with a Volute,” ASME J. Fluids Eng., Vol. 142, No. 11, 111208 (13 pages).
Shim, H. S., and Kim, K. Y.*, 2020, “Design Optimization of the Impeller and Volute of a Centrifugal Pump to Improve the Hydraulic Performance and Flow Stability,” ASME J. Fluids Eng., Vol. 142, No. 10, 101211 (16 pages).
Shim, H. S., and Kim, K. Y.*, 2020, “Effects of the Cross-sectional Area of a Volute on Suction Recirculation and Cavitation in a Centrifugal Pump,” ASME J. Fluids Eng., Vol. 142, No. 5, 051204 (14 pages).
Shim, H. S., and Kim, K. Y.*, 2019, “Evaluation of Rotor-Stator Interface Models for the Prediction of the Hydraulic and Suction Performance of a Centrifugal Pump,” ASME J. Fluids Eng., Vol. 141, No. 11, 111106 (13 pages).
Shim, H. S., Kim, K.Y.* and Choi, Y. S., 2018, “Three-Objective Optimization of a Centrifugal Pump to Reduce Flow Recirculation and Cavitation,” ASME J. Fluids Eng., Vol. 140, No. 9, 091202 (14 pages).
Rotor-Stator (IGV-Rotor-Diffuser) Interaction of an Axial-Flow Pump
A submersible axial-flow pump consists of inlet guide vanes, rotor blades, and diffuser vanes to obtain hydrodynamic performance. Their relative motions may induce the rotor-stator interaction (RSI). RSI occurs when one rotor (or stator) blade passes through the wake of an upstream stator (or rotor) blade, it will clearly experience a fluctuation in the flow pattern and fluid forces. Indeed, the wakes from the upstream blades can cause a serious vibration problem for the downstream blades at blade passing frequency or some multiple thereof. This study numerically investigated the effects of the discharge angle of inlet guide vanes and the pitch angle of rotor blades on the hydrodynamic performance of a submersible axial-flow pump. Unsteady flow characteristics were also examined in off-design conditions considering the mutual effects of geometric parameters on RSI.
Related publications
Kim, Y. S., Shim, H. S., and Kim, K. Y.*, 2020, “Comparison of Effects of IGV and Blade Pitch Angles on the Performance of a Submersible Axial-Flow Pump,” Proc. Inst. Mech. Eng. Part A J. Power Energy, Vol. 235, No. 4, pp. 718-732.
Kim, Y. S., Heo, M. W., Shim, H. S., Kim, S.H. and Kim, K. Y.*, 2020, “Hydrodynamic Optimization for Design of a Submersible Axial-Flow Pump with a Swept Impeller,” Energies, Vol. 13, No. 12, 3053 (18 pages).
Kim, Y. S. Shim, H. S. and Kim, K. Y., 2019, " Investigation of Unsteady Performance Characteristics of A Submersible Axial-Flow Pump for Different IGV and Blade Pitch Angles," in Proceedings of the ASME-JSME-KSME Joint Fluids Engineering Conference 2019 (AJK Fluids 2019), San Francisco, CA, USA, July 28-August 1, AJKFLUID2019-4860.
Kim, Y. S. Shim, H. S. and Kim, K. Y., 2018, "Interactional Effects of Inlet Guide Vane and Blade Angle on Hydraulic Performance Characteristics of A Submersible Axial-Flow Pump," in Proceedings of the 5th Joint US-European Fluids Engineering Summer Conference (ASME FEDSM 2018), Montreal, Quebec, Canada, July 2018, FEDSM 2018-83126.
Liquid Transport and Atomization of a Rotary Atomizer in a Gas Turbine Engine
A rotary atomizer transports the fluid from the internal reservoir toward the outside of the disk by centrifugal force. The liquid ejected by this device disperses in various forms like droplets, jets, ligaments, or thin film. The rotary atomizer can effectively supply atomized fuel into a slinger-typed combustor without a high-pressure source. On the other hand, this device has two major concerns: the atomization and transport of the fuel. Poor atomization may be achieved when the nozzle rotates at a low speed, deteriorating the ignition performance and combustion instability. Non-annular flow modes in the rotating pipe may cause uneven distributions of fuel along the circumference, resulting in the localized hot spot in the combustor. To overcome these problems, experimental studies were performed to investigate the liquid behaviors inside and outside the rotary slinger atomizer.
Related publications
Shim, H. S., Kim, S., Kim, J., Kim, D., Ryu, G.* and Lee, J., 2023, "Experimental Investigation on Liquid Breakup and Injection Characteristics of a Rotary Slinger Atomizer", Int. J. Aeronaut. Space Sci., published online.
Seo, Y., Ryu, G., Shim, H. S. and Lee, J.*, 2023, "An experimental study on the low-temperature spray characteristics of aviation Jet A-1 fuel with rotational speeds in a slinger-type atomizer," Fuel, Vol. 331, 125899 (14 pages).
Kim, D., Shim, H. S., Ryu, G.*, Kim, J. and Lee, J., 2022, "Analysis on annular flow of liquid transported through a partially filled axially rotating pipe," Eur. J. Mech. B Fluids, Vol. 95, pp. 289-302.
심현석, 배종근, 김주평, 김신현, 김동현, 유경원, 2021, "슬링거 연소기 회전연료노즐의 유량과 회전수에 따른 분무특성에 대한 실험적 연구," 한국추진공학회지, 제25권, 4호, pp. 59-70.