Analysis of the high-speed jet in a liquid-ring pump ejector using a proper orthogonal decomposition method

Jiang, Lijie; Zhang, Renhui; Chen, Xuebing; Guo, Guangqiang

doi:10.1080/19942060.2022.2089733

Cited by 8 publications

(1 citation statement)

References 45 publications

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“…It can reduce the time and energy consumed in experimental studies and reveals more flow field details than in experimental studies [31]. It can be associated with some experimental optimization methods, such as response surface methodology (RSM) [31,32], proper orthogonal decomposition (POD) [33], etc., to optimize different HC processes. With cavitation flow, as a typical multiphase flow problem, when using CFD for HC numerical simulations, cavitation models, turbulence closures, and multiphase modeling approaches are needed [34].…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of Hydrodynamic Cavitation Pretreatment of Food Waste: Effect of Pressure Drop on the Cavitation Behavior

Zhou,

Zhong,

Zhu

2024

Processes

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Hydrodynamic cavitation (HC) has a wide range of application scenarios. However, there are few studies on the HC treatment of food waste (FW). A Venturi device is designed and operated and plays a clear role in changing the characteristics of FW. The medium viscosity is often neglected when studying cavitation behavior by numerical simulations. We use the Herschel–Bulkley model to describe the viscosity curves of artificial FW samples obtained experimentally. RANS numerical simulation is carried out with a simplified 2D axisymmetric CFD-based model considering the non-Newtonian fluid properties. A numerical simulation study is carried out for FW (TS = 10.0 wt%) at pressure drop (ΔP = 0.05–0.4 MPa). The numerical simulation results show the variation of flow characteristics, viscosity, vapor volume, turbulent viscosity ratio, cavitation number, and pressure loss coefficient. With the increase in ΔP, the flow rate in the Venturi throat increases, and the average viscosity decreases. It reduces the inhibition effect of viscosity on cavitation. The position of incipient vacuoles at the moment of cavitation is constant and unrelated to the variation of ΔP. Under the effect of increasing ΔP, the average vapor volume fraction is increased, and the cavitation effect is enhanced; the cavitation number (σ) is decreased, and the cavitation potential is improved. A larger ΔP should be selected to increase the cavitation efficiency E of the device.

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Section: Introductionmentioning

confidence: 99%

Numerical Study of Hydrodynamic Cavitation Pretreatment of Food Waste: Effect of Pressure Drop on the Cavitation Behavior

Zhou,

Zhong,

Zhu

2024

Processes

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Investigation of the unsteady pressure fluctuation mechanism in a regenerative flow pump based on proper orthogonal decomposition

Li,

Tang,

Lou

et al. 2024

Physics of Fluids

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The regenerative flow pump (RFP) derives its name from the circular flow pattern akin to a vortex. However, the presence of numerous vortices results in highly turbulent flow and pressure fluctuation. This study delves into the characteristics of the internal unsteady flow in two distinct RFP models featuring different blade shapes. Numerical simulations are employed to obtain the pressure field, which is subsequently scrutinized using the proper orthogonal decomposition (POD) method. The results show that the average pressure in the peripheral direction undergoes minimal variation during the flow developing stage, experiences a sharp increase in the fully developed stage, and finally exhibits substantial changes in the stripper. The transient pressure in the time domain fluctuates periodically, and the dominant blade passing frequency in the frequency domain demonstrates a similar trend along the circumferential direction as the average pressure. Moreover, the fluctuating intensity of pressure diminishes along the impeller's rotating direction but intensifies significantly in the stripper. Comparative analysis indicates that the exchange intensity is influenced by the flow at different developmental stages, and the exchange flow conditions could reflect the fluctuating intensity. Furthermore, the study reveals that the frequency amplitude of the time coefficient gradually decreases as the mode order increases. The first and second modes exhibit a gradually changing trend associated with pressure increase patterns, whereas the third and fourth modes highlight the emergence of localized modulation phenomena linked to exchange flow. Thus, the POD method offers a unique perspective for comprehending the flow mechanisms within RFPs.

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Unsteady flow analysis in a pump as turbine impeller based on proper orthogonal decomposition and dynamic mode decomposition methods

Miao,

Liu,

Wang

et al. 2024

Physics of Fluids

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Pump as turbine (PAT) is an efficient, simple, and cost-effective equipment combining pump and turbine and is one of the excellent energy recovery devices. It is helpful to master the flow characteristics of the key component impeller for the further optimization and design of the PAT. To analyze the unsteady flow features in the impeller of a double-suction pump operating as a turbine, numerical simulations were conducted using the shear stress transport (SST) k-ω turbulence model at the designed operating conditions. By utilizing proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) methods on the unsteady velocity field of a single cycle, the dominant modes up to the fourth order, along with their respective space–time information, can be extracted. The velocity field and vorticity field analysis were performed on the first four modes extracted using two different methods. Additionally, the vortex structures were extracted using the Ω method. The analysis demonstrates that the POD and DMD methods effectively decompose the intricate flow characteristics within the impeller into dynamic–static interference modes, fundamental modes, and dissipative modes. The dynamic–static interference mode is dominant, reflecting the flow characteristics influenced by the stationary components within the impeller. The vortex structure is mainly small tubular vortex and point vortex. The fundamental mode captures the steady flow field characteristics caused by the blade channel geometry. The vortex structure is mainly continuous tubular vortex and the diameter becomes larger. The dissipative mode reflects the flow separation generated on the blades by disturbances from the stationary components. The vortex structure is dominated by point vortex and discontinuous tubular vortex. Comparing the outcomes of the two modal analysis methods shows that the POD method has a distinct advantage in showcasing key changing nodes. In contrast, the DMD method is superior in isolating modes with a single frequency and in determining their stability.

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Analysis of the high-speed jet in a liquid-ring pump ejector using a proper orthogonal decomposition method

Cited by 8 publications

References 45 publications

Numerical Study of Hydrodynamic Cavitation Pretreatment of Food Waste: Effect of Pressure Drop on the Cavitation Behavior

Numerical Study of Hydrodynamic Cavitation Pretreatment of Food Waste: Effect of Pressure Drop on the Cavitation Behavior

Investigation of the unsteady pressure fluctuation mechanism in a regenerative flow pump based on proper orthogonal decomposition

Unsteady flow analysis in a pump as turbine impeller based on proper orthogonal decomposition and dynamic mode decomposition methods

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