Assessment of Noise Signature for a Cavitating Centrifugal Pump

2021 ◽  
pp. 1-25
Author(s):  
Christopher Stephen ◽  
Dhanasekaran Arumugam ◽  
Kumaraswamy Sivasailam
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Mobile Application ◽  
Cavitation Noise ◽  
Normal Operating Condition ◽  
Operating Condition ◽  
Low Specific Speed ◽  
Current Operating Condition ◽  
Noise Signature ◽  
Current Operating

Abstract In recent days, sophisticated instruments have emerged to obtain an online measurement of performance parameters from centrifugal pump of different kinds and the signals can be directed to the hands of pump user through mobile application. With this in mind, a centrifugal pump of low specific speed was chosen for cavitation studies from 80% to 120% of nominal flow rate and for three different speeds. An assessment was carried out for cavitation noise signature from those operating condition of that pump. The result of cavitation noise based on peak magnitude as well as average revealed a nature in relation to cavitation coefficient and it greatly depends on the flow rate with respect to nominal flow rate. The noise envelope for the flow rate at best efficiency and above was having similar trend whereas at flows less than the nominal, it was totally different. So the criteria for finding the deviation in noise cannot be uniform for all flow rates. In this paper, the method adapted was to impose a trend line to the measured cavitation noise information and to find out the deviation with respect to normal operating condition. It was concluded that detection of abnormality in pumps due to cavitation effects requires the current operating condition to be diagnosed first and then proper criteria for deviation in noise has to be imposed.

Assessment of Noise Signature for a Cavitating Centrifugal Pump

2019 ◽  
Author(s):  
Christopher Stephen ◽  
Kumaraswamy Sivasailam
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Mobile Application ◽  
Online Measurement ◽  
Performance Parameters ◽  
Cavitation Noise ◽  
Normal Operating Condition ◽  
Operating Condition ◽  
Low Specific Speed ◽  
Noise Signature

Abstract In recent days, sophisticated instruments have emerged to obtain an online measurement of performance parameters from centrifugal pump of different kinds and the signals can be directed to the hands of pump user through mobile application. With this in mind, a centrifugal pump of low specific speed was chosen for cavitation studies from 80% to 120% of flow rate and for three different speeds. An assessment was carried out for cavitation noise signature from those operating condition of pumps. The result of cavitation noise based on peak magnitude as well as average of noise revealed a nature and it depends on the flow rate with respect to nominal flow rate. The noise envelope for the flow rate at best efficiency and above was having similar trend whereas at flows less than duty point it was totally different. So the criteria for finding the deviation in noise cannot be uniform for all flow rates. In this paper, the method adapted was to impose a trend line to the measured cavitation noise information to find out the deviation with respect to normal operating condition. It was concluded that detection of abnormality in pumps due to cavitation effects requires the operating condition to be diagnosed first and the proper criteria for deviation in noise has to be imposed.

Effects of short blades on performance and inner flow characteristics of a low-specific-speed centrifugal pump

2017 ◽  
Vol 231 (4) ◽  
pp. 290-302 ◽  
Author(s):  
Can Kang ◽  
Ning Mao ◽  
Chen Pan ◽  
Yang Zhu ◽  
Bing Li
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Low Flow ◽  
Back Surface ◽  
Flow Rates ◽  
Pump Operation ◽  
Low Specific Speed ◽  
Specific Speed

A low-specific-speed centrifugal pump equipped with long and short blades is studied. Emphasis is placed on the pump performance and inner flow characteristics at low flow rates. Each short blade is intentionally shifted towards the back surface of the neighboring long blade, and the outlet parts of the short blades are uniformly shortened. Unsteady numerical simulation is conducted to disclose inner flow patterns associated with the modified design. Thereby, a comparison is enabled between the two schemes featured by different short blades. Both practical operation data and numerical results support that the deviation and cutting of the short blades can eliminate the positive slope of pump head curve at low flow rates. Therefore, the modification of short blades improves the pump operation stability. Due to the shortening of the outlet parts of the short blades, velocity distributions between impeller outlet and radial diffuser inlet exhibit explicitly altered circumferential flow periodicity. Pressure fluctuations in the radial diffuser are complex in terms of diversified periodicity and amplitudes. Flow rate influences pressure fluctuations in the radial diffuser considerably. As flow rate decreases, the regularity of the orbit of hydraulic loads exerted upon the impeller collapses while hydraulic loads exerted upon the short blades remain circumferentially periodic.

Pressure Fluctuation of the Low Specific Speed Centrifugal Pump

2012 ◽  
Vol 152-154 ◽  
pp. 935-939 ◽  
Author(s):  
Qiang Fu ◽  
Shou Qi Yuan ◽  
Rong Sheng Zhu
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
High Frequency ◽  
Pressure Fluctuations ◽  
Radial Force ◽  
Design Flow ◽  
Rate Condition ◽  
Low Specific Speed ◽  
Specific Speed

In order to study the rules of pressure fluctuation and the radial force under different positions in a centrifugal pump with low specific speed, and to find the relationship between each other, the three-dimensional ,unsteady Reynolds-averaged Navier-stokes equations with shear stress transport turbulent models were solved. The pressure fluctuation was obtained. The results showed that the pressure fluctuations were visible. The pressure fluctuations in the volute were relatively low at the design flow rate condition. The blade passing frequency dominates the pressure fluctuations, high frequency contents were found on the outlet of impeller but no high frequency information occured in casing. The radial force on the impeller was unsteady especially at the small flow rate.

Unsteady flow characteristic of low-specific-speed centrifugal pump under different flow-rate conditions

2015 ◽  
Vol 24 (1) ◽  
pp. 17-23 ◽  
Author(s):  
Baoling Cui ◽  
Desheng Chen ◽  
Wenjing Xu ◽  
Yingzi Jin ◽  
Zuchao Zhu
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Flow Characteristic ◽  
Low Specific Speed ◽  
Specific Speed

Numerical Investigation on Impeller-Volute Interaction in the Centrifugal Pump With Radial Gap and Tongue Profile Variation

2008 ◽  
Author(s):  
Pengcheng Guo ◽  
Xingqi Luo ◽  
Weili Liao ◽  
Guojun Zhu
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
High Efficiency ◽  
Fluid Flows ◽  
Maximum Efficiency ◽  
Pressure Amplitude ◽  
Commercial Code ◽  
Operation Stability ◽  
Low Specific Speed ◽  
Radial Gap

Numerical simulations on impeller-volute interactions in a low specific speed centrifugal pump equipped with three different outlet diameter impellers and variable tongue profiles were carried out using a commercial code CFX-10. The numerical results indicated that the maximum efficiency point is shifted along the lower flow rate direction with the increasing of impeller-volute radial gap. There is no linear relation between the radial gap variation and the pressure amplitude and it is possible to get an optimum value of the radial gap, which can improve notably the pressure pulsating characteristic while the head dropping of the pump is very small. The effects of three different tongue profiles on the flow field indicated that the influence of the different tongue profiles on the performance and operation stability of the centrifugal pump is very remarkable. The high-efficiency range of the centrifugal pump can be widened to some extent while the profile of the tongue is replaced from sharp tongue to middle tongue, and the maximum efficiency point is shifted along the higher flow rate direction. The operation stability of the centrifugal pump may be influenced while the fluid flows in the diffuser of the centrifugal pump with short tongue. The amplitude of pressure fluctuation in the tongue zone drops notably while the pump equipping with the middle tongue or the short one is in running.

Analysis of the Pressure Pulsation and Vibration in a Low-Specific-Speed Centrifugal Pump

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Baoling Cui ◽  
Yingbin Zhang ◽  
Yakun Huang
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Vortex Core ◽  
Pressure Pulsation ◽  
Radial Force ◽  
Design Flow ◽  
Low Flow ◽  
Pressure Pulsations ◽  
Low Specific Speed ◽  
Specific Speed

Abstract Unsteady pressure pulsation and fluid force induced by flow instabilities in the centrifugal pump is an important cause of vibration, which is detrimental to the safe operation of the pump. In this study, we numerically investigated the pressure pulsation and radial force in a low-specific-speed centrifugal pump by using the detached-eddy simulation method. We also performed a vibration displacement experiment on the shaft of the centrifugal pump. The vortex identification method was introduced to clarify the internal correlation between unsteady flow structures with pressure pulsations. The results showed that the pressure pulsations at the impeller outlet were closely associated with the periodic vortex shedding from the blade pressure surface. The rotor–stator interaction between a relatively big trailing vortex core and volute tongue generated larger pressure pulsation and radial force in the pump at a low flow rate. Under a large flow rate, the trailing vortex core was easily broken and dispersed, and this resulted in smaller pressure pulsation and radial force compared with that at a low flow rate. Under the design flow rate, the pressure pulsation intensity and the radial force in the impeller were smaller than that under the off-design flow rate. Compared with the spectra between the radial force on the impeller and radial displacement on the shaft, they both presented higher amplitude at the shaft frequency. The vibration of the pump shaft was closely related to the radial force on the impeller.

scholarly journals Transient Behavior of a Prototype Centrifugal Pump with Abrupt Decreasing Flow Rate

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yan-Juan Zhao ◽  
Yu-Liang Zhang
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Transient Flow ◽  
Three Dimensional ◽  
Transient Behavior ◽  
Sliding Mesh ◽  
Engineering Requirement ◽  
Low Specific Speed ◽  
Volume Method

Centrifugal pump often operates at different working flow rates to meet engineering requirement. To better reveal the transient behavior of centrifugal pump in the process of decreasing flow rate, the finite volume method (FVM), RNG k-ε turbulence model, sliding mesh technology, and user-defined functions (UDF) were employed to simulate the three-dimensional unsteady viscous incompressible flow in a low-specific-speed centrifugal pump during the abrupt valve-off period. The results show that the differences are very obvious between transient and quasi-steady calculations. The velocity is maximum on the wall of hub and shroud, while the velocity is minimum and uniform distribution at middle positions. The transient flow field lags behind the quasi-steady flow field, which may be related to the reasons; namely, kinetic energy cannot convert pressure energy in time.

Investigation on Rotor-Stator Interaction in a Low Specific Speed Centrifugal Pump

2015 ◽  
Author(s):  
Ning Zhang ◽  
Minguan Yang ◽  
Bo Gao ◽  
Zhong Li ◽  
Dan Ni
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Pulsation ◽  
Vortical Structure ◽  
Fluid Dynamic ◽  
High Amplitude ◽  
Operating Conditions ◽  
Rotor Stator Interaction ◽  
Low Specific Speed ◽  
Specific Speed

In centrifugal pump, due to intense rotor-stator interaction, high amplitude pressure pulsating would be induced, and it has a crucial influence on the stable operating of the pump. In this paper, a low specific speed centrifugal pump is investigated to illustrate unsteady flow within the centrifugal pump. Pressure pulsation signals are attained by mounting 20 monitoring points along the spiral volute, covering all the interested region of the model pump. FFT (Fast Fourier Transform algorithm) is applied to analyze the time-domain pressure signals. Results show that in pressure spectra, evident peaks at blade passing frequency fBPF together with its high harmonics can be identified, and the amplitudes are closely associated with operating conditions of the model pump and the positions of the monitoring points. At nominal flow rate, four vortical regions with high amplitude are captured inside the model pump. And the unsteady vortical structure at the near tongue region is related to the relative position of the impeller with respect to the tongue, and the upstream effect of the volute tongue significantly affects the vorticity distribution on the blade pressure side. At off-design conditions, the interaction pattern between the vortical structure and the volute tongue is significantly affected compared with that at the rated condition, as to the upstream effect of the tongue. At high flow rate, partial vortex would separate from the main vortex, but at low flow rate, the cutting and impingement effects of the tongue are much weaker due to almost all the vortex moving to the narrow side of the tongue. Based on the analysis of rotor-stator interaction in the model pump, some conclusions could be obtained. Pressure amplitudes at fBPF are associated with the positions of monitoring points and operating conditions of the model pump. Vorticity magnitude at blade exit increases as the impeller passes the volute tongue. And the fluid-dynamic blade-volute interaction is dominated by the vorticity shedding from blade trailing edge and their impingement on the volute tongue with subsequent cutting and distortion. And high pressure amplitude is generated with the corresponding high vorticity magnitude observed. So the intense interaction between flow structures (jet-wake pattern) and volute tongue is crucial to unsteady pressure pulsation. Thus, to lower pressure pulsation amplitude and fluid dynamic forces, controlling the vortical structure at blade trailing edge is an effective method.

Theory and application of two-dimension viscous hydraulic design of the ultra-low specific-speed centrifugal pump

2019 ◽  
Vol 234 (1) ◽  
pp. 58-71 ◽  
Author(s):  
Cong Wang ◽  
Yongxue Zhang ◽  
Hucan Hou ◽  
Zhiyi Yuan
Keyword(s):  
Boundary Layer ◽  
Centrifugal Pump ◽  
Diagnostic Model ◽  
Two Dimension ◽  
Cavitation Performance ◽  
Hydraulic Design ◽  
Displacement Thickness ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Low Efficiency

Low efficiency and bad cavitation performance restrict the development of the ultra-low specific-speed centrifugal pump (ULSSCP). In this research, combined turbulent boundary layer theory with two-dimension design and two-dimension viscous hydraulic design method has been proposed to redesign a ULSSCP. Through the solution of the displacement thickness in the boundary layer, a less curved blade profile with a larger outlet angle was obtained. Then the hydraulic and cavitation performance of the reference pump and the designed pump were numerically studied. The comparison of performance of the reference pump calculated by the numerical and experimental results revealed a better agreement. Research shows that the average hydraulic efficiency and head of the designed pump improve by 2.9% and 3.3%, respectively. Besides, the designed pump has a better cavitation performance. Finally, through the internal flow analysis with entropy production diagnostic model, a 24.8% drop in head loss occurred in the designed pump.

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