Numerical Prediction of Unsteady Pressure Field Within the Whole Flow Passage of a Radial Single-Blade Pump

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Ji Pei ◽  
Shouqi Yuan ◽  
Friedrich-Karl Benra ◽  
Hans Josef Dohmen
Keyword(s):  
Pressure Fluctuation ◽  
Pressure Field ◽  
Absolute Pressure ◽  
Pressure Side ◽  
Transient Pressure ◽  
Flow Passage ◽  
Magnitude Distribution ◽  
Unsteady Pressure ◽  
Rotor Stator Interaction ◽  
Blade Pump

In this paper, the periodically unsteady pressure field caused by rotor-stator interaction has been investigated numerically by computational fluid dynamics (CFD) calculation to evaluate the transient pressure variation in a single-blade pump for multiconditions. Side chamber flow effect is also considered for the simulation to accurately predict the flow in a whole-flow passage. The strength of the pressure fluctuation is analyzed quantitatively by defining the standard deviation of the pressure fluctuation of a revolution period. The analysis of the results shows that higher pressure fluctuation magnitudes can be observed near the blade pressure side and high gradients of fluctuation magnitudes can be obtained at the trailing edge near the pressure side of the blade. An asymmetrical distribution of fluctuation magnitudes in the volute domain can be clearly obtained. On the cylindrical surface around the impeller outlet, although the absolute pressure value is higher for the Q = 11 l/s condition, the magnitude distribution of fluctuations is lower, and a relatively symmetrical fluctuation distribution is obtained for the Q = 22 l/s condition when clearly asymmetrical distributions of fluctuation magnitude can be observed for the design point and for large flow rates. Obvious periodicity can be observed for the pressure fluctuation magnitude distribution on the circumference with different radii in the volute domain, and some subpeaks and subvalleys can be found. The effects of unsteady flow in the side chambers on the entire passage flow cannot be neglected for accurately predicting the inner flow of the pump. The results of unsteady pressure fluctuation magnitude can be used to guide the optimum design of the single-blade pump to decrease the hydrodynamic unbalance and to obtain more stable performance of the pump.

scholarly journals Numerical Analysis of Pressure Fluctuation Intensity for a Low-Speed Sewage Centrifugal Pump

2014 ◽  
Vol 6 ◽  
pp. 929672 ◽  
Author(s):  
Ji Pei ◽  
Shouqi Yuan ◽  
Wenjie Wang
Keyword(s):  
Intensity Distribution ◽  
Pressure Fluctuation ◽  
Back Side ◽  
Centrifugal Pumps ◽  
Transient Pressure ◽  
Flow Rates ◽  
Low Speed ◽  
Unsteady Pressure ◽  
Fluctuation Intensity ◽  
Blade Pump

Sewage centrifugal pumps can operate at different flow rates with variable rotating speeds to meet different performance requirements and achieve certain energy consumption criteria in pipeline systems. In this paper, the unsteady pressure field has been investigated numerically by CFD calculation to evaluate the transient pressure variation in a single-blade pump running with low rotating speeds. Based on the CFD results, the pressure fluctuation intensity was analyzed quantitatively by defining the standard deviation of the pressure fluctuation of a revolution period. The analysis of the results shows that the flow rate can influence the fluctuation intensity distribution obviously, and the same intensity distribution law can be found in the volute domain for the same flow rates with different rotating speeds. Obvious asymmetrical distributions can be observed in both front and back side chamber channels, and the pressure fluctuation intensity in back side chamber is weaker than in front side chamber. This work can obtain the knowledge of unsteady pressure phenomenon for typical flow rates in the low-speed running single-blade pump and can provide basis to optimize and to obtain more reliable pump at variable rotating speeds.

scholarly journals Numerical Investigation of Periodically Unsteady Pressure Field in a High Power Centrifugal Diffuser Pump

2014 ◽  
Vol 6 ◽  
pp. 159380 ◽  
Author(s):  
Ji Pei ◽  
Wenjie Wang ◽  
Shouqi Yuan ◽  
Jieyun Mao
Keyword(s):  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Heat Removal ◽  
Centrifugal Pumps ◽  
Unsteady Pressure ◽  
Fluctuation Intensity ◽  
Rotor Stator Interaction ◽  
Operational Flow ◽  
Downstream Flow ◽  
Pressure Characteristics

Pressure fluctuations are the main factors that can give rise to reliability problems in centrifugal pumps. The periodically unsteady pressure characteristics caused by rotor-stator interaction have been investigated by CFD calculation in a residual heat removal pump. Side chamber flow effect is also considered for the simulation to accurately predict the flow in whole flow passage. The pressure fluctuation results in time and frequency domains were considered for several typical monitoring points in impeller and diffuser channels. In addition, the pressure fluctuation intensity coefficient (PFIC) based on standard deviation was defined on each grid node for entire space and impeller revolution period. The results show that strong pressure fluctuation intensity can be found in the gap between impeller and diffuser. As a source, the fluctuation can spread to the upstream and downstream flow channels as well as the side chamber channels. Meanwhile, strong pressure fluctuation intensity can be found in the discharge tube of the circular casing. In addition, the obvious influence of operational flow rate on the PFIC distribution can be found. The analysis indicates that the pressure fluctuations in the aspects of both frequency and intensity can be used to comprehensively evaluate the unsteady pressure characteristics in centrifugal pumps.

scholarly journals Case Study of Pump Failure Due to Rotor-Stator Interaction

1994 ◽  
Vol 1 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Hideo Ohashi
Keyword(s):  
Spatial Distribution ◽  
Pressure Fluctuation ◽  
Structural Damage ◽  
Pressure Field ◽  
Structural Vibration ◽  
Local Pressure ◽  
Pump Failure ◽  
Rotor Stator Interaction ◽  
Excited Resonance

Fluiddynamic interaction between rotor and stator generates local pressure fluctuation and can be a cause ofstructural vibration of turbomachines. The interaction produces a spatial distribution of pressure fluctuation with a certain diametrical mode and propagating speed, known as rotating pressure field. When the frequency and mode of a rotating pressure field coincide with those of the structural vibration, a fluid-excited resonance takes place, leading to eventual severe structural damage. An example of such damage is described in detail using the case of PLR pump failure of a BWR plant.

scholarly journals Discrete Optimization on Unsteady Pressure Fluctuation of a Centrifugal Pump Using ANN and Modified GA

2021 ◽  
Author(s):  
Wenjie Wang ◽  
Qifan Deng ◽  
Ji Pei ◽  
Jinwei Chen ◽  
Xingcheng Gan
Keyword(s):  
Genetic Algorithm ◽  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Optimization Method ◽  
Design Parameters ◽  
Optimization Strategy ◽  
Unsteady Pressure ◽  
Design Variables ◽  
Rotor Stator Interaction ◽  
Unsteady Simulation

Abstract Pressure fluctuation due to the rotor-stator interaction in turbomachinery is unavoidable, inducing strong vibration and even shortening the lifecycle. The investigation on optimization method of an industrial centrifugal pump was carried out to reduce the pressure fluctuation intensity. Considering the time-consuming transient calculation of unsteady pressure, a novel optimization strategy was proposed by discretizing design variables and genetic algorithm. Four highly related design parameters were chosen, and 40 transient sample cases were generated and simulated using an automatic simulation program. Furthermore, a modified discrete genetic algorithm (MDGA) was proposed to reduce the optimization cost by unsteady simulation. For the benchmark test, the proposed MDGA showed a great advantage over the original genetic algorithm in terms of searching speed and could deal with the discrete variables effectively. After optimization, an improvement in terms of the performance and stability of the inline pump was achieved.

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 Pressure Fluctuation Reduction of a Centrifugal Pump by Blade Trailing Edge Modification

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1408 ◽  
Author(s):  
Bin Huang ◽  
Guitao Zeng ◽  
Bo Qian ◽  
Peng Wu ◽  
Peili Shi ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Pressure Side ◽  
Centrifugal Pumps ◽  
Trailing Edge ◽  
Impeller Blade ◽  
Blade Passing Frequency ◽  
Impeller Outlet ◽  
Edge Profile ◽  
Edge Trimming

The pressure fluctuation inside centrifugal pumps is one of the main causes of hydro-induced vibration, especially at the blade-passing frequency and its harmonics. This paper investigates the feature of blade-passing frequency excitation in a low-specific-speed centrifugal pump in the perspective of local Euler head distribution based on CFD analysis. Meanwhile, the relation between local Euler head distribution and pressure fluctuation amplitude is observed and used to explain the mechanism of intensive pressure fluctuation. The impeller blade with ordinary trailing edge profile, which is the prototype impeller in this study, usually induces wake shedding near the impeller outlet, making the energy distribution less uniform. Because of this, the method of reducing pressure fluctuation by means of improving Euler head distribution uniformity by modifying the impeller blade trailing edge profile is proposed. The impeller blade trailing edges are trimmed in different scales, which are marked as model A, B, and C. As a result of trailing edge trimming, the impeller outlet angles at the pressure side of the prototype of model A, B, and C are 21, 18, 15, and 12 degrees, respectively. The differences in Euler head distribution and pressure fluctuation between the model impellers at nominal flow rate are investigated and analyzed. Experimental verification is also conducted to validate the CFD results. The results show that the blade trailing edge profiling on the pressure side can help reduce pressure fluctuation. The uniformity of Euler head circumferential distribution, which is directly related to the intensity of pressure fluctuation, is improved because the impeller blade outlet angle on the pressure side decreases and thus the velocity components are adjusted when the blade trailing edge profile is modified. The results of the investigation demonstrate that blade trailing edge profiling can be used in the vibration reduction of low specific impellers and in the engineering design of centrifugal pumps.

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