Effects of the Radial Gap Between Impeller Tips and Volute Tongue Influencing the Performance and Pressure Pulsations of Pump as Turbine

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Sun-Sheng Yang ◽  
Hou-Lin Liu ◽  
Fan-Yu Kong ◽  
Bin Xia ◽  
Lin-Wei Tan
Keyword(s):  
High Frequency ◽  
Pressure Pulsation ◽  
Low Frequency ◽  
Pressure Pulsations ◽  
Unsteady Pressure ◽  
Pressure Fields ◽  
Rotor Stator Interaction ◽  
Rotating Impeller ◽  
Overall Performance ◽  
Radial Gap

The radial gap between the impeller tips and volute tongue is an important factor influencing the overall performance and unsteady pressure fields of the pump as turbine (PAT). In this paper, a numerical investigation of the PAT's steady performance with different radial gaps was first performed. The results show that there is an optimal radial gap for a PAT to achieve its highest efficiency. An analysis of the PAT's unsteady pressure fields indicates that the rotorstator interaction of a rotating impeller and stationery volute would cause high frequency unsteady pulsation within the volute and low frequency unsteady pressure pulsation within the impeller. The high frequency unsteady pressure pulsation would propagate through the PAT's flow channel. Thus, the unsteady pressure field within the impeller is the combined effect of these two kinds of pressure pulsations. The unsteady pressure pulsation within the outlet pipe is mainly caused by the propagation of unsteady pressure formed within the volute. With the increase of the radial gap, the amplitude of high frequency unsteady pressure pulsation within the volute caused by the rotor-stator interaction is decreased, while the amplitude of the low frequency unsteady pressure pulsation caused by the rotor-stator interaction within the impeller remains unchanged.

Effects of the staggered blades on unsteady pressure pulsations and flow structures of a centrifugal pump

2021 ◽  
pp. 095765092098732
Author(s):  
Ning Zhang ◽  
Bo Gao ◽  
Chao Li ◽  
Dan Ni ◽  
Guoping Li
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Pulsation ◽  
Second Harmonic ◽  
Simulation Method ◽  
Pump Efficiency ◽  
Pressure Amplitude ◽  
Pressure Pulsations ◽  
Unsteady Pressure ◽  
Negative Effect

Effects of the staggered blades on unsteady pressure pulsations of a centrifugal pump with a specific speed ns=147 are investigated by the numerical simulation method. The obtained results are compared with the original blades. To clarify the resulting effects, eight monitoring points are used to extract pressure signals at three typical working conditions, and component at the blade passing frequency fBPF is emphasized. Results show that the pump efficiency and head will be reduced by the staggered blades, and at the nominal flow rate, the reduction is about 1.5% from comparison with the original blades. For all the eight points, the staggered blades contribute to the reduction of pressure amplitudes at fBPF when the pump works at three flow rates. The averaged reduction is 15.5% at the nominal flow rate. However, the negative effect on the second harmonic of fBPF will be caused by the staggered blades, and the corresponding pressure amplitude will increase at 2fBPF. It means that the pressure pulsation energy will be redistributed among the discrete components in pressure spectrum by the staggered blades. From the TKE distribution, it is found that the TKE values on the blade pressure side will be significantly affected by the staggered blades.

Experimental Investigation on Unsteady Pressure Pulsation in a Centrifugal Pump With Special Slope Volute

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Ning Zhang ◽  
MinGuan Yang ◽  
Bo Gao ◽  
Zhong Li ◽  
Dan Ni
Keyword(s):  
Experimental Investigation ◽  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
High Amplitude ◽  
Operating Conditions ◽  
Stable Operation ◽  
Flow Induced Vibration ◽  
Unsteady Pressure ◽  
Rotor Stator Interaction ◽  
Nonlinear Components

Rotor–stator interaction, a major source of high amplitude pressure pulsation and flow-induced vibration in the centrifugal pump, is detrimental to stable operation of pumps. In the present study, a slope volute is investigated to explore an effective method to reduce high pressure pulsation level, and its influence on flow structures is analyzed using numerical simulation. The stress is placed on experimental investigation of unsteady pressure pulsation inside the slope volute pump. For that purpose, pressure pulsations are extracted at nine locations along the slope volute casing covering sensitive pump regions. Results show that distinct pressure pulsation peaks at fBPF, together with nonlinear components are captured. These peaks are closely related to the position of pressure transducer and operating conditions of the pump. The improvement of rotational speed of the impeller results in rapid increase of pressure fluctuation amplitude at fBPF and corresponding root mean square (RMS) value within 10–500 Hz. A comparison with conventional spiral volute pump is implemented as well, and it is demonstrated that slope volute contributes significantly to the decline of pressure pulsation level.

Influence of the Blade Trailing Edge Profile on the Performance and Unsteady Pressure Pulsations in a Low Specific Speed Centrifugal Pump

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Bo Gao ◽  
Ning Zhang ◽  
Zhong Li ◽  
Dan Ni ◽  
MinGuan Yang
Keyword(s):  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Pressure Pulsations ◽  
Trailing Edge ◽  
Unsteady Pressure ◽  
Pulsation Amplitude ◽  
Trailing Edges ◽  
Edge Profile ◽  
Low Specific Speed ◽  
Specific Speed

The blade trailing edge profile is of crucial importance for the performance and pressure pulsations of centrifugal pumps. In the present study, numerical investigation is conducted to analyze the effect of the blade trailing edge profile influencing the performance and unsteady pressure pulsations in a low specific speed centrifugal pump. Five typical blade trailing edges are analyzed including original trailing edge (OTE), circle edge (CE), ellipse on pressure side (EPS), ellipse on suction side (ESS), and ellipse on both sides (EBS). Results show that the well-designed blade trailing edges, especially for the EPS and EBS profiles, can significantly improve the pump efficiency. Pressure amplitudes at fBPF and 2fBPF are together calculated to evaluate the influence of the blade trailing edge profile on pressure pulsations. The EPS and EBS profiles contribute obviously to pressure pulsations reduction. In contrast, the CE and ESS profiles lead to increase of pressure pulsation amplitude compared with the OTE pump. Vorticity distribution at the blade trailing edge demonstrates that the EPS and EBS profiles have an effective impact on reducing vortex intensity at the blade trailing edge. Consequently, rotor–stator interaction could be attenuated leading to lower pressure pulsation amplitude. It is thought to be the main reason of pressure pulsations reduction obtained with the proper modified blade trailing edges. The results would pave the way for further optimization of the blade trailing edge profile.

Bacterial Foraging Algorithm Based Image Fusion in Contourlet Domain

2011 ◽  
Vol 271-273 ◽  
pp. 291-296
Author(s):  
Miao Ma ◽  
Yan Li Liu ◽  
Xiao Fei Dang
Keyword(s):  
Image Fusion ◽  
Swarm Intelligence ◽  
High Frequency ◽  
Low Frequency ◽  
Visual Effects ◽  
Bacterial Foraging ◽  
Optimal Weights ◽  
Fused Image ◽  
Overall Performance ◽  
Bacterial Foraging Algorithm

To improve the overall performance of image fusion, this paper proposes a Bacterial Foraging Algorithm (BFA) based method. First, this method selects several objective standards to construct an index representing the overall performance of fused images. Second, after the source images were decomposed by Contourlet transform, we obtain the coefficients of low-frequency and high-frequency in Contourlet domain. Then, the swarm intelligence of BFA is introduced to determine the proportions of high-frequency coefficients, i.e. the optimal weights. Finally, we use the high-frequency coefficients fused by the optimal weights and the average of low-frequency coefficients to reconstruct the optimal fused image. Experimental results show that the method not only can provide with good visual effects, but also is superior to eight widely-used methods.

Numerical Investigation of Pressure Pulsation in Vaneless Region of a High Speed Centrifugal Pump

2019 ◽  
Author(s):  
Yongshun Zeng ◽  
Min Yang ◽  
Yuqing Zhai ◽  
Zhifeng Yao ◽  
Fujun Wang ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
High Speed ◽  
Pressure Pulsation ◽  
Simulation Method ◽  
Operating Conditions ◽  
Pressure Pulsations ◽  
Flow Rates ◽  
Rotor Stator Interaction ◽  
Frequency Components ◽  
Good Agreement

Abstract The pressure pulsation due to rotor-stator interaction (RSI) is unavoidable for high-speed centrifugal pump when operating under different conditions. The frequency components of pressure pulsation in the vaneless region are the most complex, and the pressure pulsation characteristic plays an important role in pump structural stress analysis. A numerical simulation method is used to obtain the hydraulic performances of a high-speed centrifugal pump with 9857 r/min at the range of flow rates between 48.1 to 155.0 m3/h. The head and efficiency under different operating conditions have good agreement with experimental results, with maximum deviations in 3.82% and 5.37%, respectively. The results show that the level of the pressure pulsation from the inlet to the outlet of the impeller increased gradually, and the pressure pulsations between the short blades are greater than that between the long and short blades. In the diffuser, the pressure pulsation is the highest near the tongue, whereas it is lower in the region between the two tongues, and this region is defined as the vaneless region. The pressure contours in the vaneless region almost have no change, while they near the tongue are densely distributed, revealing the mechanism of uneven pressure pulsation distribution. Moreover, there is a high radial velocity distribution near the tongue in the vaneless region, indicating that there may be a jet-wake pattern occured in this region.

Influence of Blade Number on the Performance and Pressure Pulsations in a Pump Used as a Turbine

2012 ◽  
Vol 134 (12) ◽  
Author(s):  
Sun-Sheng Yang ◽  
Fan-Yu Kong ◽  
Xiao-Yun Qu ◽  
Wan-Ming Jiang
Keyword(s):  
Pressure Field ◽  
Transient Flow ◽  
Control Volume ◽  
Field Tests ◽  
Field Analysis ◽  
Pressure Pulsations ◽  
Unsteady Pressure ◽  
Blade Number ◽  
Rotor Stator Interaction ◽  
Flow Induced Noise

The rotor-stator interaction of a rotating impeller and a stationary volute could cause strong pressure pulsations and generate flow induced noise and vibration in a pump used as a turbine (PAT). Blade number is one of the main geometric parameters of the impeller. In this paper, a numerical investigation of the PAT’s unsteady pressure field with different blade numbers was performed. The accuracy of global performance prediction by computational fluid dynamics (CFD) was first verified through comparison between numerical and experimental results. Unsteady pressure fields of the PAT with different blade numbers were simulated, and the pulsations were extracted at various locations covering the PAT’s three main hydraulic parts. A detailed analysis of the unsteady pressure field distributions within the PAT’s control volume and comparison of unsteady pressure difference caused by the increase of blade number were performed. The transient flow results provided the unsteady pressure distribution within PAT and showed that increasing the blade number could effectively reduce the amplitude of pressure pulsations. Finally, unsteady pressure field tests were performed and some unsteady results obtained by unsteady field analysis were validated.

scholarly journals Experimental Investigation of the Effect of Radial Gap and Impeller Blade Exit on Flow-Induced Vibration at the Blade-Passing Frequency in a Centrifugal Pump

2009 ◽  
Vol 2009 ◽  
pp. 1-9 ◽  
Author(s):  
A. Al-Qutub ◽  
A. Khalifa ◽  
Y. Khulief
Keyword(s):  
Pressure Pulsation ◽  
Pressure Fluctuations ◽  
Flow Induced Vibration ◽  
Impeller Blade ◽  
Blade Passing Frequency ◽  
Rotor Stator Interaction ◽  
Flow Induced Vibrations ◽  
Experimental Findings ◽  
Radial Gap ◽  
Selection Of

It has been recognized that the pressure pulsation excited by rotor-stator interaction in large pumps is strongly influenced by the radial gap between impeller and volute diffusers/tongues and the geometry of impeller blade at exit. This fluid-structure interaction phenomenon, as manifested by the pressure pulsation, is the main cause of flow-induced vibrations at the blade-passing frequency. In the present investigation, the effects of the radial gap and flow rate on pressure fluctuations, vibration, and pump performance are investigated experimentally for two different impeller designs. One impeller has a V-shaped cut at the blade's exit, while the second has a straight exit (without the V-cut). The experimental findings showed that the high vibrations at the blade-passing frequency are primarily raised by high pressure pulsation due to improper gap design. The existence of V-cut at blades exit produces lower pressure fluctuations inside the pump while maintaining nearly the same performance. The selection of proper radial gap for a given impeller-volute combination results in an appreciable reduction in vibration levels.

scholarly journals Characterization of the Effects of Ingested Bodies on the Rotor–Stator Interaction of Hydraulic Turbines

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6669
Author(s):  
Alfredo Guardo ◽  
Alfred Fontanals ◽  
Mònica Egusquiza ◽  
Carme Valero ◽  
Eduard Egusquiza
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Pressure Pulsation ◽  
Correct Diagnosis ◽  
Mechanical Damage ◽  
Pressure Pulsations ◽  
Pump Turbine ◽  
Rotor Stator Interaction ◽  
Hydraulic Turbines

Runner and distributor blockages in hydraulic turbines occur due to the ingestion of external bodies such as rocks or logs. These obstructions can change the amplitude and uniformity of the pressure pulsations in the machine, creating large unbalanced forces that can lead to reduced efficiency, increased vibration and mechanical damage. In this paper, the effects of obstructions caused by ingested bodies in the runner and the distributor of a pump turbine on its internal pressure pulsation were investigated by means of computational fluid dynamics. A numerical model of an unobstructed pump turbine is presented and validated against experimental data. Several cases of runner or distributor blockage were studied, and their RSI pressure pulsations were recorded and analyzed at different locations. The results obtained allow us to characterize the effect of these blockages on the machine’s RSI, which can be helpful for the correct diagnosis of these types of damage.

Pressure pulsation investigation in an electrical submersible pump based on Morlet continuous wavelet transform

2021 ◽  
pp. 095440622110000
Author(s):  
Yang Yang ◽  
Ling Zhou ◽  
Yong Han ◽  
Jianwei Hang ◽  
Wanning Lv ◽  
...  
Keyword(s):  
Wavelet Transform ◽  
Continuous Wavelet Transform ◽  
Pressure Pulsation ◽  
Low Frequency ◽  
Numerical Calculations ◽  
Continuous Wavelet ◽  
Pressure Pulsations ◽  
Frequency Signal ◽  
Multi Stage ◽  
Morlet Continuous Wavelet Transform

Electrical Submersible Pumps (ESP) are one of the most reliable and efficient ways to lift oil or water from the ground or deep-sea to the surface. How to reduce the pressure pulsation and increase reliability is a challenging issue in the ESP design processes. In this study, a typical three-stage ESP model was selected as the research object. Based on numerical calculations and validation tests, the flow-field distribution mechanism within the dynamic and static interference zones of multi-stage ESP was investigated. Meanwhile, the inter-stage variability of pressure pulsation characteristics within the main hydraulic components was explored by Morlet continuous wavelet transform. The results showed that the numerical predicted performance has an excellent agreement with the experimental results, which confirms the accuracy of the numerical calculations. The time-domain characteristics of pressure pulsation at each monitoring location within the ESP showed high disorder due to the inter-stage propagation and coupling of the pressure pulsations. The low-frequency signal in the pressure pulsation signal had not only a cascading superposition of intensity, but also a significant phase difference. It was found that the main form of propagation between pulsating signal levels is the low-frequency signal. This work may facilitate the reduction or control of the pressure pulsations and thus improve the operation stability of ESP.

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