Study of Flow Instability in a Miniature Centrifugal Pump Based on Energy Gradient Method

Abstract

Flow instability in a miniature centrifugal pump is numerically simulated with the RANS equations and the SST k-ω turbulence model. The energy gradient method is adopted to analyze the flow instability at design load and two off-design loads, and the results are compared with those analyzed by Q-criterion. The regions with large magnitude of energy gradient function (K) indicate pronounced turbulent intensity and poor flow stability. Internal flow stability is investigated in details for both the near blade surfaces region and the impeller passages.To study the mechanism of energy gradient method, internal flow parameters such as the velocity and total pressure, the transverse gradient of total mechanical energy and the work done by shear stresses are investigated respectively. The results show that the energy dissipation reaches its maximum around the leading edge of suction surface. The value of the energy gradient function K presents a different magnitude for the near blade surfaces region and the impeller passages, and the K in the impeller passage is much larger. Regions with maximum of the work done by shear stresses are concentrated on the suction surface, regions with large transverse gradient of total mechanical energy is concentrated on the hub surfaces or shroud surfaces. It is further found that the K can reflect the influence of the outer boundaries of vortex on the flow near blade surface.

Flow Stability in a Miniature Centrifugal Pump under the Periodic Pulse Flow

“…The maximum of the energy gradient function represents the most unstable position in the flow field. The method has been successfully applied to analyze the flow stability in rotating devices [21] and centrifugal pumps [16] as well as centrifugal compressors [22].…”

“…Regions with large magnitudes of K are more unstable than those with low magnitudes of K, and the position with the maximum K max is the most dangerous position in terms of initiating instability. For a given flow, Dou [15][16][17][18][19] proposed that the K can be expressed as follows for shear-driven flows,…”

“…The finite volume method (FVM) was employed to solve the system of equations with the ANSYS-CFX (Canonsburg, P.A., USA). The SST k-ω turbulence model was employed to couple governing equations, similar to Li et al [16] and Wu et al [17]. Numerical investigation of the hydraulic performance of the miniature centrifugal pump was conducted on the working station with 48 cores (Intel Xeon at 3.0 GHz, INSPUR Co., Ltd., Jinan, China).…”

“…Li et al [16] studied the flow instability in a miniature centrifugal pump at a constant flow rate based on the energy gradient method. The unstable zones in the impeller were identified using energy gradient analysis.…”

Effects of Bionic Volute Tongue Bioinspired by Leading Edge of Owl Wing and Its Installation Angle on Performance of Multi-Blade Centrifugal Fan

“…For the steady numerical simulation, ensuring the accuracy of calculation (Dong and Li (2020), Peng et al 2020;Li et al 2019), the advection term is approximated by the second-order upwind scheme.…”