Steady and Unsteady Flow Characteristics of a Multi-stage Centrifugal Pump under Design and Off-design Conditions

2019 ◽  
Vol 12 (1) ◽  
pp. 64-70
Author(s):  
Jin-Hyuk Kim ◽  
Bo-Min Cho ◽  
Sung Kim ◽  
Yong-Kab Lee ◽  
Young-Seok Choi
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Flow Characteristics ◽  
Multi Stage

Unsteady Flow Effect on Nonequilibrium Condensation in 3-D Low Pressure Steam Turbine Stages

2013 ◽  
Author(s):  
Satoshi Miyake ◽  
Satoru Yamamoto ◽  
Yasuhiro Sasao ◽  
Kazuhiro Momma ◽  
Toshihiro Miyawaki ◽  
...  
Keyword(s):  
Unsteady Flow ◽  
Steam Turbine ◽  
Cross Sections ◽  
Rotor Blade ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Low Pressure ◽  
Multi Stage ◽  
Pressure Steam ◽  
Nonequilibrium Condensation

A numerical study simulating unsteady 3-D wet-steam flows through three-stage stator-rotor blade rows in a low-pressure steam turbine model experimentally conducted by Mitsubishi Heavy Industry (MHI) was presented in the last ASME Turbo Expo by our group. In this study, the previous discussion is extended to the discussion how nonequilibrium condensation is influenced by unsteady wakes and corner vortices from prefaced multi-stage blade rows. Unsteady 3-D flows through three-stage stator-rotor blade rows are simulated assuming nonequilibrium condensation. Flows with a different inlet flow condition are calculated and the results are compared with each other. Instantaneous condensate mass fractions are visualized at different spans and cross sections in the three-stage stator and rotor blade rows. Also the time and space dependent values are plotted and the obtained unsteady flow characteristics are explained.

scholarly journals Effect of Blade Outlet Angle on the Flow Field and Preventing Overload in a Centrifugal Pump

Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 811
Author(s):  
Guangjie Peng ◽  
Qiang Chen ◽  
Ling Zhou ◽  
Bo Pan ◽  
Yong Zhu
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
Flow Characteristics ◽  
Working Surface ◽  
Outlet Angle ◽  
Working Face ◽  
Multi Stage ◽  
Pressure Area ◽  
Low Specific Speed ◽  
Direction Opposite

The influence of the blade outlet angle on preventing overload in a submersible centrifugal pump and the pump performance characteristics were studied numerically for a low specific speed multi-stage submersible pump. The tested blade outlet angles were 16°, 20°, 24°, 28°, and 32°. The results show that the blade outlet angle significantly affects the external flow characteristics and the power curve can be controlled to prevent overload by properly reducing the blade outlet angle. Increasing the blade outlet angle significantly increases the low pressure area at the impeller inlet, which makes cavitation more likely. Therefore, β2 = 16° provides the best anti-cavitation flow field. Increasing the blade outlet angle also increases the flow separation near the blade working face, which increases the size of the axial vortex along the blade working surface, which rotates in the direction opposite to the impeller rotation and then extends towards the impeller inlet.

Unsteady flow characteristics in centrifugal pump based on proper orthogonal decomposition method

2021 ◽  
Vol 33 (7) ◽  
pp. 075122
Author(s):  
Zhengchuan Zhang ◽  
Hongxun Chen ◽  
Junlian Yin ◽  
Zheng Ma ◽  
Qi Gu ◽  
...  
Keyword(s):  
Unsteady Flow ◽  
Proper Orthogonal Decomposition ◽  
Centrifugal Pump ◽  
Decomposition Method ◽  
Flow Characteristics ◽  
Orthogonal Decomposition ◽  
Proper Orthogonal

Unsteady flow characteristics of energy conversion in impeller of centrifugal pump as turbine

2021 ◽  
pp. 095440622110207
Author(s):  
Senchun Miao ◽  
Hongbiao Zhang ◽  
Jiawei Zhang ◽  
Xiaohui Wang ◽  
Fengxia Shi
Keyword(s):  
Unsteady Flow ◽  
Energy Conversion ◽  
Centrifugal Pump ◽  
Time Domain ◽  
Power Loss ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Input Power ◽  
Impeller Blade ◽  
The Time Domain

To study unsteady flow characteristics of energy conversion in impeller of centrifugal pump as turbine (PAT), the overall and sub-section methods are used to calculate the unsteady flow of the PAT under six working conditions. Through numerical calculations, the net input power of the impeller, the time domain change law of the fluid's work on the impeller, the time domain change law of power loss in the impeller, and the time domain change law of energy conversion in different regions of the impeller are analyzed. Results show that: the dynamic and static interference between the impeller blades and the tongue caused the fluctuation of energy conversion; with the increase of area between the head of the impeller blade and the opposite tongue, the power loss in the impeller decreases. And when the blade head completely deviates from the position of the tongue about 10°, the power loss in the impeller is minimized. The power output of the PAT at different flow rates is related to its internal flow conditions and the geometric structure of each region of the impeller. The above research results can provide guidance on how to operate the PAT impeller stably and efficiently.

scholarly journals Numerical Study of the Unsteady Flow Characteristics of a Jet Centrifugal Pump under Multiple Conditions

Processes ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 786
Author(s):  
Rong Guo ◽  
Rennian Li ◽  
Renhui Zhang ◽  
Wei Han
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Temporal Evolution ◽  
Guide Vane ◽  
Flow Characteristics ◽  
The Other ◽  
Flow Passage ◽  
Evolution Laws ◽  
Multiple Conditions

To study the reasons for the low efficiency of jet centrifugal pumps (JCPs) and the mechanism of unsteady flow characteristics under multiple conditions, taking a JET750G1 JCP as the object, three-dimensional steady and unsteady numerical calculations of the model pump were carried out using the k–ω turbulence model. The transient fluctuation characteristics of the flow field in the major flow passage components and the spatial and temporal evolution laws of vortices in the rotor–stator cascades were analyzed. The accuracy of the numerical method was verified by experiments. The results show that there are various scales of flow distortion phenomena in the chamber of the JCP, such as eddies, blockage of the flow passage, recirculation, secondary flow, and circulation, which not only cause great hydraulic loss, but also destroy the flow stability, symmetry, and balance in the other flow passage components. This is an important reason for the obviously lower efficiency of a JCP compared to a general centrifugal pump. The spatial and temporal evolution laws of vortices in the rotor–stator cascades are mainly related to the relative positions of the impeller blades and guide vane blades. The formation mechanism of the unsteady flow field fluctuation characteristics of JCPs is mainly related to the number of blades in the rotor–stator cascades and the operation parameters of the pump. The fluctuation intensity of the flow field inside the impeller and guide vane is obviously greater than that in the other flow areas, reflecting that the rotor–stator interaction is the decisive factor affecting the unsteady flow characteristics of a JCP under multiple conditions.

scholarly journals Study on Flow Characteristics in Volute of Centrifugal Pump Based on Dynamic Mode Decomposition

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Yi-bin Li ◽  
Chang-hong He ◽  
Jian-zhong Li
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
Rate Condition ◽  
Blade Passing Frequency ◽  
Mode Decomposition

To investigate the unsteady flow characteristics and their influence mechanism in the volute of centrifugal pump, the Reynolds time-averaged N-S equation, RNG k-ε turbulence model, and structured grid technique are used to numerically analyze the transient flow-field characteristics inside the centrifugal pump volute. Based on the quantified parameters of flow field in the volute of centrifugal pump, the velocity mode contours and oscillation characteristics of the mid-span section of the volute of centrifugal pump are obtained by dynamic mode decomposition (DMD) for the nominal and low flow-rate condition. The research shows that the first-order average flow mode extracted by DMD is the dominant flow structure in the flow field of the volute. The second-order and third-order modes are the most important oscillation modes causing unsteady flow in the volute, and the characteristic frequency of the two modes is consistent with the blade passing frequency and the 2x blade passing frequency obtained by the fast Fourier transform (FFT). By reconstructing the internal flow field of the volute with the blade passing frequency for the nominal flow-rate condition, the periodic variation of the unsteady flow structure in the volute under this frequency is visually reproduced, which provides some ideas for the study of the unsteady structure in the internal flow field of centrifugal pumps.

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 Pressure Pulsation Characteristics Analysis of Rotating Stall in Centrifugal Pumps Under Off-Design Conditions

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Xiaoran Zhao ◽  
Yexiang Xiao ◽  
Zhengwei Wang ◽  
Yongyao Luo ◽  
Lei Cao
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Flow Characteristics ◽  
Rotating Stall ◽  
Normal Operation ◽  
Centrifugal Pumps ◽  
Pressure Pulsations ◽  
Stall Cells ◽  
The Impact

Unsteady flow phenomena like rotating stall frequently occur in centrifugal pumps under off-design conditions. Rotating stall could lead to flow instabilities and pressure pulsation, which affect the normal operation of pumps. The mechanism of rotating stall has not been sufficiently understood in previous researches. In this study, the impact of rotating stall in the impeller on centrifugal pump stability and pressure pulsation is numerically investigated. This paper aims to detect the unsteady flow characteristics inside the centrifugal pump by computational fluid dynamics technology, to analyze pressure pulsations caused by rotating stall and to explore the propagation mechanism of rotating stall. Unsteady numerical simulations are performed by ANSYS 16.0 to model the unsteady flow within the entire flow passage of a centrifugal pump under 0.4QBEP and 0.6QBEP working conditions. Through flow characteristics research, the generation and propagation of rotating stall are discovered. Flow separation appears near the leading edge of the pressure side and transforms into vortices, which move along the passage. Meanwhile, the stall cells rotate circumferentially in the impeller. Additionally, frequencies and amplitudes of pressure pulsations related to rotating stall are investigated by spectrum analysis. The results detect a possible characteristic frequency of rotating stall and show that the interaction between stall cells and the volute tongue could have an influence on rotor–stator interaction (RSI).

Sign in / Sign up

Export Citation Format

Share Document