Green Pump Development Based on the Analysis of Unsteady Flow

2008 ◽  
Vol 44-46 ◽  
pp. 643-650
Author(s):  
Chun Lei Shao ◽  
Bo Qin Gu ◽  
Ye Chen
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
High Speed ◽  
Radial Direction ◽  
Dynamic Pressure ◽  
Industrial Installation ◽  
Experimental Scheme ◽  
Fluid Delivery ◽  
Piv Measurement ◽  
Section Viii

Centrifugal pump is a kind of important industrial installation for fluid delivery. The research on the unsteady flow in centrifugal pump is very meaningful to reducing vibration. Particle image velocimetry (PIV) system and test pump designed for PIV measurement were introduced. The experimental scheme and the methods of numerical simulation were discussed. PIV technique was used to measure the unsteady velocity field near the volute tongue under the mode of external synchronization. The unsteady pressure field was simulated by using Sliding Mesh (SM) model provided by Fluent. The results show that the velocity and pressure fluctuate periodically with the rotation of impeller. Partial fluid flows back to the impeller passage and the velocity in the inlet of diffusion tube decreases significantly due to shunt effect of the volute tongue. On the section VIII, the magnitude and fluctuation range of velocity show a decreasing trend in radial direction. The fluctuation of circumferential velocity is related to the position of high-speed flow in impeller passage, and the fluctuation of radial velocity is influenced by blade interference and Coriolis force. The static pressure increases and the dynamic pressure decreases in the radial direction of volute. The velocity and the pressure on the section VIII and the outlet total pressure fluctuate intensively when the blade tail end passes the section VIII and the volute tongue. The vibration of pump can be reduced by increasing the volute tongue mounting angle and decreasing the blade outlet mounting angle properly.

Internal Unsteady Flow Induced Vibration in Centrifugal Pump

2012 ◽  
Vol 479-481 ◽  
pp. 1194-1199
Author(s):  
Chun Lei Shao ◽  
Jian Feng Zhou ◽  
Bo Qin Gu
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Pressure Amplitude ◽  
Flow Induced Vibration ◽  
Fluid Delivery ◽  
Pressure Disturbance ◽  
Impeller Outlet ◽  
The Time Domain ◽  
Blade Frequency

Centrifugal pump is an important installation for fluid delivery. The research on the unsteady flow in centrifugal pump is very meaningful to reducing vibration. The methods of numerical simulation were discussed. The unsteady pressure field was simulated by using Sliding Mesh (SM) model provided by Fluent. The time domain data for pressure were obtained at the monitoring points, and they were translated to frequency domain data by using FFT. The results show that the static pressure at the impeller outlet increases along the direction of impeller rotation from the position near the volute tongue. The pressure disturbance is relatively large near the volute tongue. The pressure disturbance at the impeller inlet is smaller than that at the impeller outlet. The volute tongue plays a key role in the flow induced vibration. The position, where the blade is in closest proximity to the head of volute tongue, is the turning point in the pressure fluctuation cycle. The maximum peak value of pressure fluctuation appears at 145Hz, which is the blade frequency. Other pressure peaks are evident at multiples of the blade frequency. Also the pressure amplitude decreases with increasing frequency.

scholarly journals Numerical Simulation and Computational Flow Characterization Analyses of Centrifugal Pump Operating as Turbine

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Du Jianguo ◽  
Guanghui Chang ◽  
Daniel Adu ◽  
Ransford Darko ◽  
Muhammad A. S. Khan ◽  
...  
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
High Speed ◽  
Flow Characteristics ◽  
High Price ◽  
Future Research ◽  
Rural Settlements ◽  
Small Hydropower ◽  
Pump Turbine ◽  
Wide Range

Using a pump in reverse mode as a hydraulic turbine remains an alternative for hydropower generation in meeting energy needs, especially for the provision of electricity to remote and rural settlements. The primary challenge with small hydroelectric systems is attributed to the high price of smaller size hydraulic turbines. A specific commercial pump model, with a flow rate of 12.5 m3/h, head 32 m, pressure side diameter of 50 mm, impeller out, and inlet diameters of 160 mm and 6 mm, respectively, was chosen for this research. This research aimed to investigate a pump’s flow characteristics as a turbine to help select a suitable pump to be used as a turbine for micro- or small hydropower construction. Numerical methodologies have been adopted to contribute to the thoughtful knowledge of pressure and velocity distribution in the pump turbine performance. In this study, the unsteady flow relations amongst the rotating impeller and stationary volute of the centrifugal pump made up four blades and four splitters. Intermittent simulation results of pressure and velocity flow characteristics were studied considering diverse impeller suction angles. The study was conducted by considering a wide range of rotational speeds starting from 750 rpm to 3250 rpm. From the results, it was found that PAT operation was improved when operated at low speeds compared to high-speed operation. Thus, speeds between 1500 rpm and 2000 rpm were suitable for PAT performance. This research helps to realize the unsteady flow physiognomies, which provide information for future research on PAT. This study makes useful facts available which could be helpful for the pump turbine development. Future studies should focus on cost analysis and emission generation in energy generation.

scholarly journals Unsteady Flow and Structural Behaviors of Centrifugal Pump under Cavitation Conditions

2019 ◽  
Vol 32 (1) ◽  
Author(s):  
Denghao Wu ◽  
Yun Ren ◽  
Jiegang Mou ◽  
Yunqing Gu ◽  
Lanfang Jiang
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Structural Behaviors

Relationship Between Unsteady Flow, Pressure Fluctuations, and Noise in a Centrifugal Pump—Part B: Effects of Blade-Tongue Interactions

1995 ◽  
Vol 117 (1) ◽  
pp. 30-35 ◽  
Author(s):  
S. Chu ◽  
R. Dong ◽  
J. Katz
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Pressure Difference ◽  
Pressure Fluctuations ◽  
Primary Sources ◽  
Pressure Measurements ◽  
Local Pressure ◽  
Pressure Distributions ◽  
Flow Pressure ◽  
Tip Of The Tongue

Maps of pressure distributions computed using PDV data, combined with noise and local pressure measurements, are used for identifying primary sources of noise in a centrifugal pump. In the vicinity of the impeller pressure minima occur around the blade and near a vortex train generated as a result of non-uniform outflux from the impeller. The pressure everywhere also varies depending on the orientation of the impeller relative to the tongue. Noise peaks are generated when the pressure difference across the tongue is maximum, probably due to tongue oscillations, and when the wake impinges on the tip of the tongue.

Numerical study on the mechanism of drag reduction for interceptors on planning boats

2021 ◽  
Author(s):  
Lianzheng Cui ◽  
Zuogang Chen ◽  
Yukun Feng
Keyword(s):  
Drag Reduction ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Numerical Study ◽  
Dynamic Pressure ◽  
Motion Model ◽  
Gauge Pressure ◽  
Reduction Effect ◽  
Pressure Resistance ◽  
Viscous Pressure

The drag reduction effect of interceptors on planning boats has been widely proven, but the mechanism of the effect has been rarely studied in terms of drag components, especially for spray resistance. The resistance was caused by the high gauge pressure under the boats transformed from the dynamic pressure, and it is the largest drag component in the high-speed planning mode. In this study, numerical simulations of viscous flow fields around a planning boat with and without interceptors were conducted. A two degrees of freedom motion model was employed to simulate the trim and sinkage. The numerical results were validated against the experimental data. The flow details with and without the interceptor were visualized and compared to reveal the underlying physics. A thinner and longer waterline could be achieved by the interceptor, which made the boat push the water away more gradually, and hence, the wave-making resistance could be decreased. The improved waterline also reduced the component of the freestream normal to the hull surface and led to the less transformed dynamic pressure, resulting in the lowAer spray resistance. Furthermore, the suppression of the flow separation could also be benefited from the interceptor; the viscous pressure resistance was therefore decreased.

scholarly journals Analysis and control of flow at suction connection in high-speed centrifugal pump

2017 ◽  
Vol 9 (1) ◽  
pp. 168781401668529 ◽  
Author(s):  
Wen-wu Song ◽  
Li-chao Wei ◽  
Jie Fu ◽  
Jian-wei Shi ◽  
Xiu-xin Yang ◽  
...  
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
High Speed ◽  
Internal Flow ◽  
Orifice Plate ◽  
Centrifugal Pumps ◽  
Pressure Area ◽  
Negative Effect ◽  
And Control ◽  
Experimental Data Analysis

The backflow vortexes at the suction connection in high-speed centrifugal pumps have negative effect on the flow field. Setting an orifice plate in front of the inducer is able to decrease the negative effect caused by backflow vortexes. The traditional plate is able to partially control the backflow vortexes, but a small part of the vortex is still in the inlet and the inducer. Four new types of orifice plates were created, and the control effects on backflow vortexes were analyzed. The ANSYS-CFX software was used to numerically simulate a high-speed centrifugal pump. The variations of streamline and velocity vectors at the suction connection were analyzed. Meanwhile, the effects of these plates on the impeller pressure and the internal flow field of the inducer were analyzed. Numerically, simulation and experimental data analysis methods were used to compare the head and efficiency of the high-speed pumps. The results show that the C-type orifice plate can improve the backflow vortex, reduce the low-pressure area, and improve the hydraulic performance of the high-speed pump.

Experimental Investigation of Combustion Dynamics in a Turbulent Syngas Combustor

2017 ◽  
Author(s):  
Nikhil Ashokbhai Baraiya ◽  
Baladandayuthapani Nagarajan ◽  
Satynarayanan R. Chakravarthy
Keyword(s):  
High Speed ◽  
Equivalence Ratio ◽  
Bluff Body ◽  
Dynamic Pressure ◽  
Fuel Mixture ◽  
High Amplitude ◽  
Acoustic Oscillations ◽  
Combustion Dynamics ◽  
Dynamic Pressure Measurement ◽  
Body Location

In the present work, the proportion of carbon monoxide to hydrogen is widely varied to simulate different compositions of synthesis gas and the potential of the fuel mixture to excite combustion oscillations in a laboratory-scale turbulent bluff body combustor is investigated. The effect of parameters such as the bluff body location and equivalence ratio on the self-excited acoustic oscillations of the combustor is studied. The flame oscillations are mapped by means of simultaneous high-speed CH* and OH* chemiluminescence imaging along with dynamic pressure measurement. Mode shifts are observed as the bluff body location or the air flow Reynolds number/overall equivalence ratio are varied for different fuel compositions. It is observed that the fuel mixtures that are hydrogen-rich excite high amplitude pressure oscillations as compared to other fuel composition cases. Higher H2 content in the mixture is also capable of exciting significantly higher natural acoustic modes of the combustor so long as CO is present, but not without the latter. The interchangeability factor Wobbe Index is not entirely sufficient to understand the unsteady flame response to the chemical composition.

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