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Study on the Effect of Gas-Liquid Two-Phase Medium on PAT Performance
Shi Fengxia,Yang Junhu,Wang Xiaohui,Miao Senchun,Guo Rui 한국유체기계학회 2021 International journal of fluid machinery and syste Vol.14 No.3
A pump as turbine is optimized firstly, then the distribution of gas, the vortex structure evolution, the force characteristic and energy conversion characteristic are analyzed under pure liquid and gas-liquid two-phase conditions. The result manifests that because of the existence of gas, the pressure gradient decreased and the normal flow of high-pressure fluid in the turbine is inhibited by gas. The radial force vector, the time domain value and the main frequency amplitude are all smaller than that of pure liquid condition, and hydraulic vibration is more likely to be caused by the flow uncertainty of gas. The energy conversion performance of the unit is worse.
Effect of Different Blade Numbers on the Radial Force of Pump as Turbine in Transient Process
FengXia Shi,DeDong Ma,WanYong Zhao,HuTing Peng,YunSheng Liang 한국유체기계학회 2021 International journal of fluid machinery and syste Vol.14 No.2
In order to analyze the influence of the number of blades on the radial force characteristics of pump as turbine during the variable flow rate transition process, six impellers with different number of blades are designed. On the basis of verifying the correctness of the numerical calculation method by the external characteristic experiment, the steady and unsteady numerical simulation of each scheme is carried out by ANSYS-CFX software, the radial force characteristics on impellers with different schemes are compared and analyzed. The results show that during the transition process of variable flow rate, the radial force vector and its fluctuation range on the impeller gradually decreases with the increase of the number of blades. The radial resultant force obviously increases with the increase of time in the transition to large flow rate, and obviously decreases with the increase of time in the transition to small flow rate. The dominant frequency of the radial force is equal to leaf frequency, and the pulsation amplitude of the radial force of Z9 is the minimum in both transition processes. In the transition process of variable flow rate, when the number of blades is Z9, the efficiency is the highest, the radial force on the impeller is the minimum, and the pulsation amplitude of the radial force is also the smallest, so for this pump as turbine, the value of blade number equals 9 is the optimal.
Effect of Different Guide Vane Numbers on Transient Radial Force of Pump as Turbine
Shi, FengXia,Yang, JunHu,Wang, XiaoHui Korean Society for Fluid machinery 2018 International journal of fluid machinery and syste Vol.11 No.1
Guide vane was added to pump as turbine (PAT), the transient flow characteristics of PAT were calculated and experimented under different guide vane numbers. The results show that after the PAT was added guide vane, the distribution of speed streamline and blade load is more uniform than before, and the unsteady radial force on impeller decreased greatly, which is good for the stability of PAT's operation. When the guide vane number is equal to 9, both the maximum radial force difference and dominant frequency amplitude of radial force are the minimum. So there is an optimal guide vane number, for the given geometric parameters of PAT.
Analysis on Characteristic of Pressure Fluctuation in Hydraulic Turbine with Guide Vane
Shi, FengXia,Yang, JunHu,Wang, XiaoHui Korean Society for Fluid machinery 2016 International journal of fluid machinery and syste Vol.9 No.3
An unsteady three-dimensional simulation based on Reynolds time-averaged governing equation and RNG $k-{\varepsilon}$ turbulence model, was presented for pump-as-turbine, the pressure fluctuation characteristic of hydraulic turbine with guide vane was obtained. The results show that the time domains of pressure fluctuation in volute change periodically and have identical cycles. In volute tongue and inlet pressure fluctuations are light, while in dynamic and static coupling interface pressure fluctuations are serious; In impeller blade region the pressure fluctuation of pressure surface are lighter than that of suction surface. The dominant frequencies of pressure fluctuation concentrate in low frequency region, and concentrate within 2 times of the blade passing frequency.
Analysis on Characteristic of Pressure Fluctuation in Hydraulic Turbine with Guide Vane
FengXia Shi,JunHu Yang,XiaoHui Wang 한국유체기계학회 2016 International journal of fluid machinery and syste Vol.9 No.3
An unsteady three-dimensional simulation based on Reynolds time-averaged governing equation and RNG k-ε turbulence model, was presented for pump-as-turbine, the pressure fluctuation characteristic of hydraulic turbine with guide vane was obtained. The results show that the time domains of pressure fluctuation in volute change periodically and have identical cycles. In volute tongue and inlet pressure fluctuations are light, while in dynamic and static coupling interface pressure fluctuations are serious; In impeller blade region the pressure fluctuation of pressure surface are lighter than that of suction surface. The dominant frequencies of pressure fluctuation concentrate in low frequency region, and concentrate within 2 times of the blade passing frequency.
Effect of Different Guide Vane Numbers on Transient Radial Force of Pump as Turbine
FengXia Shi,JunHu Yang,XiaoHui Wang 한국유체기계학회 2018 International journal of fluid machinery and syste Vol.11 No.1
Guide vane was added to pump as turbine (PAT), the transient flow characteristics of PAT were calculated and experimented under different guide vane numbers. The results show that after the PAT was added guide vane, the distribution of speed streamline and blade load is more uniform than before, and the unsteady radial force on impeller decreased greatly, which is good for the stability of PAT’s operation. When the guide vane number is equal to 9, both the maximum radial force difference and dominant frequency amplitude of radial force are the minimum. So there is an optimal guide vane number, for the given geometric parameters of PAT.
Fengxia Shi,Quanbo Yu,Wei Huang,Chaochao Tan 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.5
Recently, some global cases of 2019 novel coronavirus (COVID-19) pneumonia have been caused by second- or third-generation transmission of the viral infection, resulting in no traceable epidemiological history. Owing to the complications of COVID-19 pneumonia, the first symptom and imaging features of patients can be very atypical and early diagnosis of COVID-19 infections remains a challenge. It would aid radiologists and clinicians to be aware of the early atypical symptom and imaging features of the disease and contribute to the prevention of infected patients being missed.
Luo, Dingyuan,Yang, Fengxia,Yang, Xiaojun,Yao, Junhu,Shi, Baojun,Zhou, Zhenfeng Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.9
The study was conducted to investigate the effects of different levels of xylanase on performance, blood parameters, intestinal morphology, microflora and digestive enzyme activities of broilers. The wheat-based diets were supplemented with 0, 500, 1,000, 5,000 U/kg xylanase. Xylanase supplementation significantly (p<0.05) improved the feed:gain ratio of broilers from 1 to 21 d and 1 to 42 d. Supplementing 500 U/kg and 1,000 U/kg xylanase improved (p<0.05) the villus height and the ratio of villus height to crypt depth in the small intestine. Excess supplementation of xylanase (5,000 U/kg) increased the villus height in the ileum (p<0.01) and the ratio of villus height to crypt depth in the duodenum and ileum (p<0.05). The microflora in the ileum and caecum, digestive enzyme activities in the small intestine and the concentrations of serum glucose, uric acid, insulin and IGF-I were not affected by the supplementation of xylanase. Excess level of xylanase (5,000 U/kg) had a tendency to induce the multiplication of E. coli and total aerobes. The results suggested that supplementing 500 U/kg and 1,000 U/kg xylanase was beneficial for broilers and excess xylanase supplementation resulted in no further improvement or negative effects.