Research on inner flow and energy characteristics of air ejector for liquid-ring vacuum pump

Abstract

To analyze the complex flow characteristics, and reveal the mechanisms of energy transfer and hydraulic loss of the liquid-ring pump ejector. The numerical simulation and experiment were applied to analyze the complex shock wave structure, vortex evolution characteristics in the ejector and its influence on hydraulic performance, which provides a novelty reference for the optimization design of the ejector. Furthermore, novelty is expressed in the performance analysis of the ejector based on the performance of its matching liquid-ring pump. The results show that the λ-shock wave and Mach disk are formed inside the nozzle under the action of supersonic jet, and the triple point is formed as the incident shock wave, the reflected shock wave and the Mach disk intersect. The shock wave, as it propagates, changes from Mach reflection to regular reflection, and meanwhile, the position of triple point moves from the initial Mach disk to the new Mach disk. With the interaction of shock wave and jet boundary layer, the shock train is formed in the core region of the jet. The pressure, density and Mach number are oscillatory distributed in the shock wave region. There is a relatively large velocity gradient between the high speed primary flow and the low speed secondary flow near the outlet of nozzle, which induces the formation of opposite rotating vortices in the shear layer of the cylinder. With the evolution of the vortex, the high speed jet transfers energy through the cylindrical shear layer and is accompanied by the large hydraulic loss. The total entropy production of the ejector increases with the increase of primary flow pressure. The entropy production rate has a strong correlation with the vorticity magnitude.

Keywords

Liquid-ring pump ejector shock wave energy transfer entropy production hydraulic loss

Get full access to this article

View all access options for this article.

References

Jia

Fan

, et al. Vortex pump, Liquid ring pump Jet pump. 1th ed. Beijing, China: CMP, 1993. (in Chinese).

Zhang

Cheng

Yang

, et al. Theory and Design of Special Pumps. 1th ed. Beijing, China: CWPP, 2013. (in Chinese).

Cоколов

ЕЯ

Зингep

. Ejector. 1th ed. Beijing, China: SP, 1973. (in Chinese).

Huang

Wang

Yang

, et al. A comparative study on numerical simulation of ejector flow field for liquid-ring pump using two kinds of grids. Vacuum 2017; 54(02): 10–13. (in Chinese).

Huang

Zheng

, et al. Numerical simulation of the performance of air-ejector in liquid ring vacuum pump unit. J Xihua Univ (Nat Sci Edn) 2010; 29(03): 28–31. (in Chinese).

Huang

Ruan

Yang

, et al. Numerical simulation of performance of ejector of liquid ring vacuum pump and its testing verification. Vacuum 2009; 46(06): 17–19. (in Chinese).

Omidvar

Ghazikhani

Modarres Razavi

SMR

. Entropy analysis of a solar-driven variable geometry ejector using computational fluid dynamics. Energ Convers Manage 2016; 119: 435–443.

Jiang

Zhang

Chen

, et al. Internal flow field in ejector of liquid ring pump and its matching characteristic with liquid-ring pump. J Huazhong Univ Sci Tech (Nat Sci Edn) 2021; 49(04): 8–13. (in Chinese).

. Numerical and visual experimental investigation on the fluid flow and shock wave characteristics inside the ejector. MA Thesis. Dalian, China: Dalian Maritime University, CHN, 2019. (in Chinese).

10.

Dvorak

Safarik

. Transonic instability in entrance part of mixing chamber of high-speed ejector. J Therm Sci 2005; 14(3): 258–264.

11.

Yosri

Meulemans

, et al. Large-eddy simulation of methane direct injection using the full injector geometry. Fuel 2021; 290(2): 120019.

12.

Chen

Dou

H-S

, et al. Effects of variable specific heat on energy transfer in a high-temperature supersonic channel flow. J Turbul 2018; 19(5): 365–389.

13.

Zhang

. Optimization of ejectors based on entropy production theory. MA Thesis. Beijing, China: China University of Petroleum, CHN, 2019. (in Chinese).

14.

. Irreversible thermodynamics loss analysis of two-stage ejector refrigeration system. MA Thesis. Nanning, China: Guangxi University, CHN, 2017. (in Chinese).

15.

Dai

. Theoretical and experimental investigation on the impact of irreversibility on ejector performance . PhD Thesis. Hangzhou, China: Zhejiang University, CHN, 2014. (in Chinese).

16.

Strušnik

Marcˇic

Golob

, et al. Energy efficiency analysis of steam ejector and electric vacuum pump for a turbine condenser air extraction system based on supervised machine learning modelling. Appl Energ 2016; 173(1): 386–405.

17.

Strušnik

. Integration of machine learning to increase steam turbine condenser vacuum and efficiency through gasket resealing and higher heat extraction into the atmosphere. Int J Energ Res 2022; 46(3): 3189–3212.

18.

Guo

Zhang

. Evaluation of different turbulence models on simulation of gas-liquid transient flow in a liquid-ring vacuum pump. Vacuum 2020; 180(5): 109586.

19.

Chen

Havtun

Palm

. Investigation of ejectors in refrigeration system: Optimum performance evaluation and ejector area ratios perspectives. Appl Therm Eng 2014; 64(s1–2): 182–191.

20.

Chen

Havtun

Palm

. Parametric analysis of ejector working characteristics in the refrigeration system. Appl Therm Eng 2014; 69(1–2): 130–142.

21.

Liu

Jiang

, et al. Method for analyzing flow losses in turbomachinery by using the measured results of stereoscopic particle image velocimetry. J Aerosp Power 2009; 24(11): 2551–2557. (in Chinese).

22.

Strušnik

Avsec

. Exergoeconomic machine-learning method of integrating a thermochemical Cu–Cl cycle in a multigeneration combined cycle gas turbine for hydrogen production. Int J Hydrogen Energ 2022; 47(39): 17121–17149.

23.

Yang

Zhu

, et al. Shock waves and shock interactions in hypersonic flow. 1th ed. Beijing, China: NDIP, 2019, p. 6. (in Chinese).

24.

Matsuo

. Shock train and pseudo-shock phenomena in supersonic internal flows. J Therm Sci 2003; 12: 204–208.

25.

Payam

Sorin

Nesreddine

. The impact of internal ejector working characteristics and geometry on the performance of a refrigeration cycle. Energy 2018; 162(1): 728–743.

26.

Arun

Tiwari

Mani

. Experimental studies on a rectangular ejector with air. Int J Therm Sci 2019; 140: 43–49.

27.

Shen

Tong

. Engineering thermodynamics. 4th ed. Beijing, China: HEP, 2007, p. 6. (in Chinese).

28.

Ren

, et al. Flow loss characteristics of centrifugal pump based on entropy production. J Harbin Eng Univ 2021; 42(02): 266–272. (in Chinese).

29.

Wang

Ding

, et al. Numerical study on entropy generation characteristic of airfoil under unsteady condition. J Huazhong Univ Sci Tech (Nat Sci Edn) 2020; 48(11): 120–125. (in Chinese).

30.

Zhang

Yuan

Wei

, et al. Study on flow loss characteristic of side channel pump based on entropy production. J Mech Eng-En 2018; 54(22): 137–144. (in Chinese).

31.

Kock

Herwig

. Local entropy production in turbulent shear flows: a high-Reynolds number model with wall functions. Int J Heat Mass Tran 2004; 47(10/11): 2205–2215.

32.

Yang

Zhu

Miu

, et al. Uncertainty analysis in CFD for flow simulation around ship using RANS and DES. J Shanghai Jiaotong Univ 2012; 46(03): 430–435. (in Chinese).

33.

Chen

Zhang

. Verification and validation in CFD based on the Richardson extrapolation method. Acta Aerodyn Sin 2012; 30(02): 176–183. (in Chinese).

34.

Mao

. Verification and validation for the numerical simulation of semi-displacement craft. J Wuhan Univ Tech (Transport Sci Eng) 2017; 41(06): 999–1004. (in Chinese).