Entropy production analysis in thermodynamic cavitating flow with the consideration of local compressibility

Yu, An; Tang, Qinghong; Zhou, Daqing

doi:10.1016/j.ijheatmasstransfer.2020.119604

Cited by 38 publications

(7 citation statements)

References 35 publications

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“…The instantaneous velocity is composed of time-averaged velocity and pulsation velocity, the average term of entropy production rate replaces the velocity in Eq. ( 1) with time-averaged velocity, the pulsation term of entropy production is calculated based on turbulence energy and turbulent vortex frequency in the turbulence model, and the entropy production of the wall is related to the shear stress of the wall and wall mesh velocity, and the specific calculation formulas are shown in the literature [13]. The above three items (mean entropy production, pulsation term and wall entropy production) together constitute the total entropy production, and the total entropy of the flow field can be obtained through the integration of each part.…”

Section: Entropy Production Theorymentioning

confidence: 99%

Research on cavitation characteristics of water-jet pumps with different blade tip clearances based on entropy production theory

Fei,

Guo,

Huang

et al. 2024

J. Phys.: Conf. Ser.

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Water-jet pumps are widely used in ship and other power fields. An axial-flow water-jet pump is studied with different size of tip clearance, and the cavitation characteristics are studied based on the theory of entropy production. Modified SST with curvature correction and modified Zwart cavitation model based on vortex identification are adopted, and the numerical calculation method is verified by reference experiments of a model pump. Under normal operating conditions, the results show that when the size of the tip clearance varies from 1.6‰ to 7.9‰ of the impeller diameter, efficiency takes a linear decrease accordingly, and the total entropy production increases linearly. At the same time, the main energy dissipation mode changes from wall dissipation to turbulent dissipation. Under severe cavitation conditions the total entropy production adds 30%. The water-jet pump shows that the entropy production in the impeller section is the highest, which accounts for 40%-50% and is closely related to the vortex and cavitation flow field in the tip clearance of the impeller. The tip leakage vortex region causes cavitation, but significant energy dissipation occurs at the outer edge of leakage vortex and on the nearby wall area, while the attached cavitation on the blade surface is the main source of turbulent dissipation.

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Section: Entropy Production Theorymentioning

confidence: 99%

Research on cavitation characteristics of water-jet pumps with different blade tip clearances based on entropy production theory

Fei,

Guo,

Huang

et al. 2024

J. Phys.: Conf. Ser.

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“…The empirical constants of the condensation and evaporation phases of liquid water are the default: C vap = 50 and C cond = 0.01 ; the empirical constants [23,24] of the condensation and evaporation phases of liquid oxygen are corrected as C vap = 3 and C cond = 0.0005 .…”

Section: The Boundary Conditionmentioning

confidence: 99%

“…Energies 2022,15, x FOR PEER REVIEW 10 of 25 5. The empirical constants of the condensation and evaporation phases of liquid water are the default: the empirical constants[23,24] of the condensation and evaporation phases of liquid oxygen are corrected as…”

mentioning

confidence: 99%

Cavitation Flow Characteristics of Water and Liquid Oxygen in the Inducer Considering Thermodynamic Effect

2022

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Clean energy liquid oxygen is more and more widely used in aerospace, but the research on the thermodynamic characteristics of liquid oxygen is still less. In this paper, a method for correcting the local saturated vapor pressure by thermodynamic effect is proposed, so we establish the Zwart modified cavitation model considering the thermodynamic characteristics. We choose the turbine pump inducer as the research object, and select liquid water and liquid oxygen at different temperatures as the fluid medium. Based on two different Zwart cavitation models, the cavitation flow characteristics of liquid water at different temperatures of 298 K, 320 K and 350 K are numerically simulated and analyzed, and the cavitation flow characteristics of liquid oxygen at different temperatures of 85 K, 90 K and 95 K are also numerically simulated and analyzed. According to the analysis of the simulation results, for liquid water at the temperature of 298–350 K, since the change range of its thermophysical parameters is very small, the inhibition of cavitation is not obvious, and the thermodynamic characteristics are not significant. For liquid oxygen, the cavitation effect is obvious at different temperatures. When the temperature increases gradually, the thermodynamic effect of liquid oxygen becomes more obvious, which can effectively inhibit the cavitation phenomenon of the inducer in the steady-state cavitation flow.

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“…Nevertheless, there is not much literature about the entropy production diagnostic model (EPDM) in terms of two-phase flow. Based on the assumption of homogeneous model, Wang et al 31,32 put forward the EPDMS in cavitation flow and introduced it to the hydraulic machinery after simplifying the model of Bilicki et al 33 After that, Yu et al 27,34 studied dynamic characteristics of irreversible loss with the development of cavitation by EPDMS. He found that the elongation of sheet cavity is virtually beneficial to drag reduction.…”

Section: Introductionmentioning

confidence: 99%

Evaluating of the effect of the cavitation-vortex interaction on the energy conversion in a two-stage LNG cryogenic submerged pump

Wang

Zhang

Yuan

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part A:

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The quantitative investigation on the unsteady interaction of the thermodynamic cavitation-vortex dynamics has been conducted via the developed entropy production diagnostic model in a two-stage liquefied natural gas cryogenic submerged pump. A thermodynamic cavitation modeling framework and Liutex method are applied to capture the characteristics of the formation, development and collapse of the cavities and vortex. It is found that the increasing flow rate and temperature both intensify the thermodynamic effect of cavitation. As the increase of flow rate, the thermodynamic effect suppresses the growth of cavities, thus raising the maximum temperature drop by 0.65 K at NPSH3% and 0.87 K at NPSH5% with the same temperature. Massive bubbles collapse causes the twist, deformation and breakdown of U-type vortex at the interface, which directly leads to the significant increase of interface entropy production rate in heat transfer entropy production rate (HTEPR). As the increase of temperature, the thermodynamic effect both shortens the cavity size and development period under the same flow rate. The strong shear and rotation regions drive upstream and the pressure rebounds rapidly downstream that weakens the backflow. The shrinkage of upstream cavity and the accelerated collapse of small-scale cloud cavity reduce the HTEPR and viscous flow entropy production rate

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Entropy production analysis in thermodynamic cavitating flow with the consideration of local compressibility

Cited by 38 publications

References 35 publications

Research on cavitation characteristics of water-jet pumps with different blade tip clearances based on entropy production theory

Research on cavitation characteristics of water-jet pumps with different blade tip clearances based on entropy production theory

Cavitation Flow Characteristics of Water and Liquid Oxygen in the Inducer Considering Thermodynamic Effect

Evaluating of the effect of the cavitation-vortex interaction on the energy conversion in a two-stage LNG cryogenic submerged pump

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