Numerical simulation of supersonic unsteady flow using Euler equations

Purpose Instantaneous radial force induced from unsteady flow will intensify vibration noise of the centrifugal pump, especially under off-design working conditions, which will affect safety reliability of pump operation in severe cases. This paper aims to conduct unsteady numerical computation on one centrifugal pump; thus, unsteady fluid radial force upon the impeller and volute is obtained, so as to study the evolution law of instantaneous radial force, the internal relationship between radial force and pressure pulsation, the relationship among each composition of radial force that the impeller received and the influence of leakage rate of front and back chamber on radial force. Design/methodology/approach The unsteady numerical simulation with SST k-ω turbulence model was carried out for a low specific-speed centrifugal pump using computational fluid dynamics codes FLUENT. The performance tests and pressure tests were conducted by a closed loop system. The performance curves and the pressure distribution from numerical simulation agree with that of the experiment conducted. The unsteady pressure distributions and the instantaneous radial forces induced from unsteady flow were analyzed under different flow rates. Contribution degrees of three components of the radial force on the impeller and the relation between the radial force and leakage rate were analyzed. Findings Radial force on the volute and pressure pulsation on the volute wall have the same distribution tendency, but in contrast to the distribution trend of the radial force on the impeller. In the component of radial force that the impeller received, radial force on the blade accounts for the main position. With the decrease of flow rate, ratio of the radial force on front and back casings will be increased; under large flow rate, vortex and flow blockage at volute section will enhance the pressure and radial force fluctuation greatly, and the pulsation degree may be much more intense than that of a smaller flow rate. Originality/value This paper revealed the relation of the radial force and the pressure pulsation. Meanwhile, contribution degrees of three components of the radial force on the impeller under different working conditions as well as the relation between the radial force and leakage rate of front and rear chambers were analyzed.

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Three-dimensional Numerical Simulation of Disk Rotating Detonation Engine; Unsteady Flow Structure

AIAA Scitech 2019 Forum ◽

10.2514/6.2019-1498 ◽

2019 ◽

Author(s):

Tomohiro Watanabe ◽

Nicolas H. Jourdaine ◽

Nobuyuki Tsuboi ◽

Takayuki Kojima ◽

Koichi A. Hayashi

Keyword(s):

Numerical Simulation ◽

Unsteady Flow ◽

Flow Structure ◽

Three Dimensional ◽

Rotating Detonation Engine ◽

Detonation Engine ◽

Rotating Detonation

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Numerical simulation of unsteady flow in the glottal constriction with moving boundaries

The Journal of the Acoustical Society of America ◽

10.1121/1.404765 ◽

1992 ◽

Vol 92 (4) ◽

pp. 2391-2391 ◽

Cited By ~ 1

Author(s):

Fariborz Alipour ◽

Jun Ni

Keyword(s):

Numerical Simulation ◽

Unsteady Flow ◽

Moving Boundaries

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Interpretation of Four Unique Phenomena and the Mechanism in Unsteady Flow Separation Controls

Energies ◽

10.3390/en12040587 ◽

2019 ◽

Vol 12 (4) ◽

pp. 587 ◽

Cited By ~ 3

Author(s):

Weiyu Lu ◽

Guoping Huang ◽

Jinchun Wang ◽

Yuxuan Yang

Keyword(s):

Numerical Simulation ◽

Unsteady Flow ◽

Flow Control ◽

Flow Separation ◽

Flow Instability ◽

Control Flow ◽

Separation Control ◽

Pulsed Jet ◽

Unsteady Separation ◽

Flow Theories

Unsteady flow separation controls are effective in suppressing flow separations. However, the unique phenomena in unsteady separation control, including frequency-dependent, threshold, location-dependent, and lock-on effects, are not fully understood. Furthermore, the mechanism of the effectiveness that lies in unsteady flow controls remains unclear. Thus, this study aims to interpret further the unique phenomena and mechanism in unsteady flow separation controls. First, numerical simulation and some experimental results of a separated curved diffuser using pulsed jet flow control are discussed to show the four unique phenomena. Second, the bases of unsteady flow control, flow instability, and free shear flow theories are introduced to elucidate the unique phenomena and mechanism in unsteady flow separation controls. Subsequently, with the support of these theories, the unique phenomena of unsteady flow control are interpreted, and the mechanisms hidden in the phenomena are revealed.

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