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Zi D.,China Agricultural University | Wang F.J.,China Agricultural University | Yao Z.F.,China Agricultural University | Xiao R.F.,China Agricultural University | And 2 more authors.
IOP Conference Series: Earth and Environmental Science | Year: 2016

Pipes are usually adopted in those conditions for which the pump house is far from water source. As for fore-bay, flow of headrace pipe can be considered as jet-flow. Jet-flow has a high velocity, and creates large pressure gradient between jet-flow and near wall flow, which contributes to large scale circulation. In that circumstance, a single rectification measure cannot effectively improve the flow pattern of intake flow field. For large scale pumping station, there is enough space to arrange complex anti-vortex devices. Thus, a new type of combined diversion piers composed of double-I type pier, three-I type pier and cross anti-vortex baffle was proposed. In order to investigate the influences of combined division piers on flow pattern, four cases with different geometry and location parameters are designed. The results of numerical simulation and site tests show that the combined diversion piers could effectively improve the intake flow field of pumping station with headrace pipe. As for pumping station with headrace pipe, the distance between inlet section of fore-bay and leading edge of double-I type diversion pier should be 0.25L-0.53L (where L is the length of fore-bay). The distance between inlet section of fore-bay and trailing edge of double-I type diversion pier should be 0.5L-0.73L. The total length of double-I type pier should be 0.2L-0.25L.


Yao Z.F.,China Agricultural University | Wang F.J.,China Agricultural University | Xiao R.F.,China Agricultural University | He C.L.,China Water Resources Beifang Investigation Design and Research Co.
IOP Conference Series: Earth and Environmental Science | Year: 2012

Cavitation is a common fault which has a close relationship with pressure instabilities in centrifugal pumps. In order to investigate the hydroacoustic response to cavitation phenomena, a pressure fluctuation experimental is carried out on a double-suction centrifugal pump. Frequency spectrum analysis and time-frequency joint analysis of pressure fluctuations in semi-spiral suction chamber and volute casing are presented based on fast Fourier transform (FFT) and adaptive optimal-kernel time-frequency representation (AOK TFR) methods. The results show that in semi-spiral suction chamber, as the available NPSH value continuously decreases, the frequencies affected by cavitation transfer to a lower frequency range and become relative higher concentrate in time-frequency representation. In volute casing, blade passage frequency (BPF), specific frequency at 1/2 of blade passage frequency (147 Hz) and some frequency bands are well captured. The amplitudes of BPF and BPF/2 are shown to have a reasonable dependence on available NPSH value, though the measuring location relative to volute tongue should be taken into account. Strong pulsation characteristics are observed on relative low available NPSH value conditions. Pressure fluctuation at impeller rotating frequency is shown to be sensitive with cavitation process, of which the amplitude sharply increases at first and then decreases. © Published under licence by IOP Publishing Ltd.


Zhao Z.-C.,China Water Resources Beifang Investigation Design and Research Co. | Feng S.-Y.,China Agricultural University | Huo Z.-L.,China Agricultural University | Jiang J.,China Agricultural University | Qin J.-T.,China Agricultural University
Chinese Journal of Applied Ecology | Year: 2010

A field experiment was conducted to study the distribution characteristics of water and salt in a spring wheat soil under brackish water irrigation. Three irrigation quota ( 100% ETc, 80% ETc, and 60% ET C) and three water salinity levels (0. 7, 3 and 6 g -L-1) were installed. The results showed that soil water distribution was affected by irrigation quota and soil texture. Sufficient irrigation made the irrigation water stored in deeper soil layers ; while insufficient irrigation made the irrigation water more stored in top soil layer. Under the same irrigation quota, the salt accumulation in soil body increased with increasing water salinity; while under the same water salinity, the salt content and salt accumulation depth in soil body increased with increasing irrigation quota. Successive brackish water irrigation in the whole growth period of spring wheat induced soil salinization, and insufficient irrigation made the salt more accumulated in surface soil layer, compared with sufficient irrigation.


Yao Z.-F.,China Agricultural University | Wang F.-J.,China Agricultural University | Xiao R.-F.,China Agricultural University | He C.-L.,China Water Resources Beifang Investigation Design and Research Co.
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2012

Pressure fluctuations in double-suction centrifugal pumps caused by internal flow are the primary sources of operation instability. By means of pressure transducers installed in suction chamber and volute wall, fluctuating pressure signals were obtained and recorded at various operation conditions. The signals in time and frequency domains of the signals were analyzed by using the fast Fourier Transform Method. The results show that rotating frequency and some lower frequencies are dominative in suction chamber. The latter is adjacent to the 1/3 rotating frequency at the design and higher flow rates. While at partial flow rates, the magnitudes as well as the range of the lower frequencies become notably larger. Blade passage frequency dominates the pressure fluctuations in volute, of which the magnitude becomes relatively smaller when the position is far away from the volute tongue in peripheral direction. The peak-peak value of pressure fluctuation increases remarkedly as the flow rates deviate from the designed one and reaches 4~5 times higher at the partial flow rates.


Yao Z.,China Agricultural University | Wang F.,China Agricultural University | Yang M.,China Agricultural University | Qu L.,China Agricultural University | And 3 more authors.
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2011

The pressure fluctuations in double-suction centrifugal pumps caused by internal flow are the primary sources of operation instability. In order to investigate the effects of impeller types on pressure fluctuations for double-suction centrifugal pumps, five impeller configurations are tested with the same experimental facilities. By arranging pressure transducers on the walls of suction chamber and spiral casing, fluctuating pressure signals are collected at various test flows. The signals in time domain are analyzed by using the FFT method and the frequencies are obtained. Results show that blade passing frequency, rotating frequency and some lower frequencies always exist in double-suction centrifugal pumps. Compared with the traditional impeller, the double suction impeller with bilateral blades staggered can reduce the level of pressure fluctuation. By adjusting the blade outlet shape and increasing the warp angle of the blade near the back shroud side, the amplitude of the pressure fluctuation at blade passing frequency becomes small. The impeller with splitter blades optimizes the flow state, lessens the pressure fluctuation in suction chamber region and improves the characteristic of pressure fluctuations in the spiral casing under small flow rate condition. © 2011 Journal of Mechanical Engineering.


Yao Z.,China Agricultural University | Wang F.,China Agricultural University | Xiao R.,China Agricultural University | Yang M.,The Aerospace Corporation | He C.,China Water Resources Beifang Investigation Design and Research Co.
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2015

Flow passage coating can effectively improve the resistance to wear, and reduce the hydraulic loss. However, the effect of the flow passage coating on pressure fluctuations for double suction centrifugal pumps has not been understood yet. The experiments for a centrifugal pump with and without flow passage coating were carried out. The fluctuating pressure signals were obtained and recorded at various operating conditions, then time and frequency domains of the signals were analyzed by using the Fast Fourier Transform method. The results show that the flow passage coating decreased the surface roughness, reduced the hydraulic loss and eventually increase the efficiency. However, flow passage coating had changed the pressure fluctuation characteristics. For the suction chamber, the operating range of pump stability was narrowed. And the peak to peak value of pressure fluctuation in suction chamber with coated surface may reached 2.8 times as large as that with original one, which enhanced the operating instability at partial flow rates. For the volute region, the pressure fluctuation at the monitoring location relatively closed to the volute tongue remarkably increased at the partial flow rates. While the pressure fluctuation at the monitoring location relatively far from volute tongue increased at high flow rates. The effect of flow passage coating on pressure fluctuation was not obvious on the design flow rate. To develop the synthetic benefits of flow passage coating technology and ensure the stable operation of pumps, the pump with flow passage coating should not operate at the flow rates that are derived from the design flow rate, especially at the flow rates below 75% of design flow rate. ©, 2015, Shuili Xuebao/Journal of Hydraulic Engineering. All right reserved.


Jiang J.,China Agricultural University | Feng S.,China Agricultural University | Feng S.,Yangzhou University | Huo Z.,China Agricultural University | And 2 more authors.
Mathematical and Computer Modelling | Year: 2011

The agro-hydrological Soil-Water-Atmosphere-Plant (SWAP) model was calibrated and validated to simulate water-salt transport based on field experiments in an arid region of China. The simulation results show lower soil water content but higher salt concentration under deficit irrigation. Soil water and salinity below 95 cm at 80% evapotranspiration (ETc) treatments and 65 cm at 60% ETc treatments were hardly affected by irrigation. With deficit irrigation, the maximum water uptake and salt accumulated layer moved upward. The SWAP model was also used to predict long-term deficit irrigation with saline water. The salinization process reached equilibrium after utilization of saline water for a few years. In summary, the numerical model proves to be a useful tool for studying water-salt transport under different scenarios and for evaluating irrigation practices for a long period. © 2010.


Jiang P.,Dongbei University of Finance and Economics | Qin S.,Lanzhou University | Wu J.,Lanzhou University | Sun B.,China Water Resources Beifang Investigation Design and Research Co.
Mathematical Problems in Engineering | Year: 2015

Wind speed/power has received increasing attention around the earth due to its renewable nature as well as environmental friendliness. With the global installed wind power capacity rapidly increasing, wind industry is growing into a large-scale business. Reliable short-term wind speed forecasts play a practical and crucial role in wind energy conversion systems, such as the dynamic control of wind turbines and power system scheduling. In this paper, an intelligent hybrid model for short-term wind speed prediction is examined; the model is based on cross correlation (CC) analysis and a support vector regression (SVR) model that is coupled with brainstorm optimization (BSO) and cuckoo search (CS) algorithms, which are successfully utilized for parameter determination. The proposed hybrid models were used to forecast short-term wind speeds collected from four wind turbines located on a wind farm in China. The forecasting results demonstrate that the intelligent hybrid models outperform single models for short-term wind speed forecasting, which mainly results from the superiority of BSO and CS for parameter optimization. © 2015 Ping Jiang et al.


Wang X.-L.,Tianjin University | Jiang Z.-Y.,China Water Resources Beifang Investigation Design and Research Co Ltd. | Zhou S.-S.,Tianjin University | Zhou Z.-Y.,Tianjin University | Zhang Z.-Q.,Tianjin University
Gongcheng Lixue/Engineering Mechanics | Year: 2011

The ice damage of diversion channel is dangerous to the hydropower station operation, even results in great life losses, so the operation mode of the ice delivery and sluicing is key to diversion-type hydropower station in winter. A 3D unsteady Eulerian two-phase model is developed. The momentum transfer term includes the drag, virtual mass, lift forces, and density difference. The results under different turning radius are as follows: When the turning radius is 200m, the water flow is steady, the water velocity distribution is homogeneous, the amount of floating ice reaches its maximum, and the ice removal efficiency is the highest. Therefore, the optimum turning radius is 200m, and the reasonable design of ice gate can ensure the smooth removal of ice and the safety operation of hydropower station. The prediction by the present model for ice removal of bend channel is confirmed by the experimental results of open channel bend reported by Blanckaert.


Qin S.,Lanzhou University | Liu F.,Lanzhou University | Wang J.,Dongbei University of Finance and Economics | Sun B.,China Water Resources Beifang Investigation Design and Research Co.
Atmospheric Environment | Year: 2014

The analysis and forecasting of PM concentrations play a significant role in regulatory planning on the reduction and control of PM emission and precautionary strategies. However, accurate PM forecasting, which is needed to establish an early warning system, is still a huge challenge and a critical issue. Determining how to address the accurate forecasting problem becomes an even more significant and urgent task. Based on gray correlation analysis (GCA), Ensemble Empirical Mode Decomposition (EEMD), Cuckoo search (CS) and Back-propagation artificial neutral networks (BPANN), this paper proposes the CS-EEMD-BPANN model for forecasting PM concentrations. Prior to establishing this model, gray correlation has been uniquely used to search for possible predictors of PM among other air pollutants (CO, NO2, O3 and SO2) and meteorological environments (wind speed, wind direction, temperature, humidity and pressure). The proposed method was investigated in four major cities of China (Beijing, Shanghai, Guangzhou and Lanzhou) with different characteristics of climatic, terrain and emission sources. The results of the gray correlation analysis indicate that CO, NO2 and SO2 are more related to PM and that the incorporation of these predictors can significantly improve the model performance predictability, suggesting the effectiveness of our developed method. © 2014 Elsevier Ltd.

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