scholarly journals Four-quadrant Characterization of Hydrodynamic Phenomena in a Low Specific Speed Centrifugal Pump

2021 ◽  
Vol 25 ◽  
Author(s):  
Hernan Dario Bolaños ◽  
Francisco Botero
Keyword(s):  
Centrifugal Pump ◽  
Classical Method ◽  
Characteristic Curve ◽  
Frequency Domain Analysis ◽  
Rotating Stall ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Four Quadrant

Objective: Identify and characterize subsynchronous hydrodynamics phenomena in a low specific speed centrifugal pump based on its four-quadrant characteristic curve. Materials: A 1.5 HP ITT Goulds pump instrumented with pressure transductors, an accelerometer, a torque sensor and a tachometer. Flow rate measurement was done with an ultrasonic transit time clamp-on flow meter. Methods: Time and frequency domain analysis with phase analysis were used to identify spectral components linked to hydrodynamic phenomena such as rotating stall and surge. Results and discussion: This work approaches an alternative method to calculate the phase angle using pressure signals without filtering. Related with hydrodynamic phenomena, the evidence collected suggests the presence of rotating stall in some operation points of the four-quadrant characteristic curve. Furthermore, in the third quadrant, rotating stall coexist with surge. Conclusions: The instrumentation and methods regarded in this work allow to collect evidence to identify in-phase and out of phase subsynchronous hydrodynamic phenomena. The classic cross-correlation-based method was improved to ease the diagnosis of subsynchronous phenomena by visual inspection. A new quantitative approach was introduced to detect subsynchronous phenomena, based on the Fourier analysis; it was validated with a case study for which the classical method was not suitable.

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.

Optimal hydraulic design of an ultra-low specific speed centrifugal pump based on the local entropy production theory

2019 ◽  
Vol 233 (6) ◽  
pp. 715-726 ◽  
Author(s):  
Hucan Hou ◽  
Yongxue Zhang ◽  
Xin Zhou ◽  
Zhitao Zuo ◽  
Haisheng Chen
Keyword(s):  
Entropy Production ◽  
Centrifugal Pump ◽  
Orthogonal Design ◽  
High Energy ◽  
Geometrical Parameters ◽  
Production Theory ◽  
Local Entropy ◽  
Hydraulic Design ◽  
Low Specific Speed ◽  
Specific Speed

The ultra-low specific speed centrifugal pump has been widely applied in aerospace engineering, metallurgy, and other industrial fields. However, its hydraulic design lacks specialized theory and method. Moreover, the impeller and volute are designed separately without considering their coupling effect. Therefore, the optimal design is proposed in this study based on the local entropy production theory. Four geometrical parameters are selected to establish orthogonal design schemes including blade outlet setting angle, wrapping angle volute inlet width, and throat area. Subsequently, a 3D steady flow with Reynolds stress turbulent model and energy equation model is numerically conducted and the entropy production is calculated by a user-defined function code. The range analysis is made to identify the optimal scheme indicating that the combination of local entropy production and orthogonal design is feasible on pump optimization. The optimal pump is visibly improved with an increase of 1.08% in efficiency. Entropy production is decreased by 16.75% and 6.03% in impeller and volute, respectively. High energy loss areas are captured and explained in terms of helical vortex and wall friction, and the turbulent and wall entropy production are respectively reduced by 3.82% and 14.34% for the total pump.

scholarly journals Optimal Design of Slit Impeller for Low Specific Speed Centrifugal Pump Based on Orthogonal Test

2021 ◽  
Vol 9 (2) ◽  
pp. 121
Author(s):  
Yang Yang ◽  
Ling Zhou ◽  
Hongtao Zhou ◽  
Wanning Lv ◽  
Jian Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Large Scale ◽  
Internal Flow ◽  
Orthogonal Test ◽  
Centrifugal Pumps ◽  
Initial Model ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Four Levels

Marine centrifugal pumps are mostly used on board ship, for transferring liquid from one point to another. Based on the combination of orthogonal testing and numerical simulation, this paper optimizes the structure of a drainage trough for a typical low-specific speed centrifugal pump, determines the priority of the various geometric factors of the drainage trough on the pump performance, and obtains the optimal impeller drainage trough scheme. The influence of drainage tank structure on the internal flow of a low-specific speed centrifugal pump is also analyzed. First, based on the experimental validation of the initial model, it is determined that the numerical simulation method used in this paper is highly accurate in predicting the performance of low-specific speed centrifugal pumps. Secondly, based on the three factors and four levels of the impeller drainage trough in the orthogonal test, the orthogonal test plan is determined and the orthogonal test results are analyzed. This work found that slit diameter and slit width have a large impact on the performance of low-specific speed centrifugal pumps, while long and short vane lap lengths have less impact. Finally, we compared the internal flow distribution between the initial model and the optimized model, and found that the slit structure could effectively reduce the pressure difference between the suction side and the pressure side of the blade. By weakening the large-scale vortex in the flow path and reducing the hydraulic losses, the drainage trough impellers obtained based on orthogonal tests can significantly improve the hydraulic efficiency of low-specific speed centrifugal pumps.

The effect of front streamline wrapping angle variation in a super-low specific speed centrifugal pump

2018 ◽  
Vol 232 (23) ◽  
pp. 4301-4311 ◽  
Author(s):  
Dong Liang ◽  
Zhao Yuqi ◽  
Liu Houlin ◽  
Dai Cui ◽  
Gradov D Vladimirovich ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Energy Performance ◽  
Sweep Angle ◽  
Angle Variation ◽  
Noise Characteristics ◽  
Ansys Cfx ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Element Method

In this research, super-low specific speed centrifugal pump ( ns = 25, Chinese units: ns = 3.6 nQ1/2/ H3/4) is studied. The effect of the front streamline wrapping angles variation (135°, 139° and 145°) of the turbine on energy performance is considered. The pressure pulsation, interior and exterior noise characteristics and the performance of the impeller are thoroughly evaluated both experimentally and numerically. The pump has been modeled by means of computational fluid dynamics code of commercial software ANSYS CFX 11.0 to estimate energy performance and pressure pulsation. Boundary element method and finite element method are used to investigate the interior and exterior noise characteristics of the centrifugal pump by varying the front sweep angle. The front sweep angle variation was found to have insignificant influence on centrifugal pump performance characteristics. However, it influences fluid hydrodynamics around the volute tongue. In addition, the decreasing of the front streamline sweep angle slightly reduces the sound pressure level for the exterior acoustics, but the radiation distribution of the acoustic field does not change. In its turn, the modified trailing edge of the blades can reduce the peak value of the superposition decreasing the pressure pulsations at the blade passing frequency and its harmonic frequencies.

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.

Part Load Instability and Rotating Stall in a Multistage Low Specific Speed Pump

2021 ◽  
Author(s):  
Erik Vermunt ◽  
Martijn Van Der Schoot ◽  
Bruurs Bruurs ◽  
Bart Van Esch
Keyword(s):  
Rotating Stall ◽  
Part Load ◽  
Low Specific Speed ◽  
Specific Speed
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