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.

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.

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 The Action Mechanism of Rotor–Stator Interaction on Hydraulic and Hydroacoustic Characteristics of a Jet Centrifugal Pump Impeller and Performance Improvement

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 465
Author(s):  
Guo ◽  
Li ◽  
Zhang ◽  
Han
Keyword(s):  
Flow Field ◽  
Pressure Fluctuation ◽  
Transient Flow ◽  
Guide Vane ◽  
Hydraulic Performance ◽  
Action Mechanism ◽  
Optimization Scheme ◽  
Fluctuation Intensity ◽  
Blade Number ◽  
Rotor Stator Interaction

The aim of this study was to investigate the action mechanism of the rotor–stator interaction (RSI) on the transient flow field and hydrodynamic noise field inside the impeller of jet centrifugal pumps (JCPs) and optimize effects of the guide vane on the hydraulic and hydroacoustic characteristics of the impeller. The numerical method of CFD (computational fluid dynamics) coupled with CFA (computational fluid acoustics) was used to analyze the correlation between the guide vane and the flow/sound performances of the impeller. The orthogonal test method, with the hydroacoustic performance of the impeller taken as the objective, was used to optimize the structural parameters of the guide vane for the stability of the hydraulic performance of the JCP. The results show that the RSI leads to a significant increase in the hydroacoustic level of the impeller, but it is indispensable for improving the hydraulic performance of the pump. The RSI effect on the fluctuation intensity of the transient flow field inside the impeller is much more sensitive than the time-average, and the fluctuation intensity of the flow field is positively correlated with the vortex intensity inside the impeller. When the impeller geometry is constant, the evolution processes of the flow field inside the impeller are mainly related to the blade number of the guide vane; when the number of guide vanes is given, the RSI effect on the hydroacoustic characteristic of the impeller is characterized by a positive correlation between the total sound pressure level (SPL) and the fluctuation intensity of the flow field. The frequency spectrum characteristics of the hydroacoustic SPL of the impeller are not consistent with the pressure fluctuation characteristics inside the impeller. The pressure fluctuation characteristics are related not only to the blade number and speed of the impeller but also to its wake characteristics determined by the guide vane. The optimization scheme for the stable hydraulic performance of the JCP significantly reduced the total SPL of the impeller compared with the original scheme, which verifies the feasibility of using the weight matrix optimization method to obtain the global optimization scheme.

scholarly journals Numerical Research on Effects of Splitter Blades to the Influence of Pump as Turbine

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Yang Sun-Sheng ◽  
Kong Fan-Yu ◽  
Fu Jian-Hui ◽  
Xue Ling
Keyword(s):  
Performance Prediction ◽  
Pressure Field ◽  
Performance Enhancement ◽  
Positive Impact ◽  
Pressure Head ◽  
Field Analysis ◽  
Centrifugal Pumps ◽  
Small Hydropower ◽  
Unsteady Pressure ◽  
Numerical Research

Centrifugal pumps can be operated in reverse as small hydropower recovery turbines and are cheaper than bespoke turbines due to their ease of manufacture. Splitter blades technique is one of the techniques used in flow field optimization and performance enhancement of rotating machinery. To understand the effects of splitter blades to the steady and unsteady influence of PAT, numerical research was performed. 3D Navier-Stokes solver CFX was used in the performance prediction and analysis of PAT’s performance. Results show that splitter blades have a positive impact on PAT’s performance. With the increase of splitter blades, its required pressure head is dropped and its efficiency is increased. Unsteady pressure field analysis and comparison show that the unsteady pressure field within PAT is improved when splitter blades are added to impeller flow passage. To verify the accuracy of numerical prediction methods, an open PAT test rig was built at Jiangsu University. The PAT was manufactured and tested. Comparison between experimental and numerical results shows that the discrepancy between numerical and experimental results is acceptable. CFD can be used in the performance prediction and optimization of PAT.

Numerical Investigation of Rotor-Stator Interaction in a High-Bypass Ratio Fan Stage

2013 ◽  
Author(s):  
Zhong Yang ◽  
Hengliang Wang ◽  
Jiachao Yan ◽  
Xiangyang Deng
Keyword(s):  
Transient Flow ◽  
Guide Vane ◽  
Field Investigation ◽  
Inlet Guide Vane ◽  
Unsteady Pressure ◽  
Pressure Distributions ◽  
Rotor Stator Interaction ◽  
Fan Blade ◽  
Transonic Fan ◽  
Bypass Ratio

Both steady and time-accurate simulations of the flow through a high-bypass ratio fan stage consisting of transonic fan rotor blade (FAN), outlet guide vane (OGV) of bypass duct, and inlet guide vane (IGV) of low-pressure compressor (LPC) are performed at design operating point to address the fundamental questions regarding the impacts of unsteady rotor-stator interactions. The original ratios of fan blade number to OGV and IGV vane numbers are scaled to avoid the full wheel computation, thus reducing the amount of time-accurate computation effort. The comparison between time-averaged unsteady results and steady results shows minor differences in the performance of bypass and core ducts. The transient flow field investigation shows that the unsteady interaction between FAN and IGV is much stronger than that in the bypass duct. Considering aerodynamic response and excitation mechanism due to rotor-stator interaction, the unsteady pressure distributions are examined. The time traces and frequency contents of the unsteady pressure show complex rotor-stator interaction arising from the incoming wakes and potential effects of downstream blade rows.

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.

scholarly journals Inner Damping of Water in Conduit of Hydraulic Power Plant

2021 ◽  
Vol 13 (13) ◽  
pp. 7125
Author(s):  
Daniel Himr ◽  
Vladimír Habán ◽  
David Štefan
Keyword(s):  
Power Plant ◽  
Operating Conditions ◽  
Mathematical Apparatus ◽  
Pressure Pulsations ◽  
Hydraulic Power ◽  
Economic Operation ◽  
Compression And Expansion ◽  
Rotor Stator Interaction ◽  
Start Ups

The operation of any hydraulic power plant is accompanied by pressure pulsations that are caused by vortex rope under the runner, rotor–stator interaction and various transitions during changes in operating conditions or start-ups and shut-downs. Water in the conduit undergoes volumetric changes due to these pulsations. Compression and expansion of the water are among the mechanisms by which energy is dissipated in the system, and this corresponds to the second viscosity of water. The better our knowledge of energy dissipation, the greater the possibility of a safer and more economic operation of the hydraulic power plant. This paper focuses on the determination of the second viscosity of water in a conduit. The mathematical apparatus, which is described in the article, is applied to data obtained during commissioning tests in a water storage power plant. The second viscosity is determined using measurements of pressure pulsations in the conduit induced with a ball valve. The result shows a dependency of second viscosity on the frequency of pulsations.

Effects of Blade Outlet Width on Flow Field and Characteristic of Centrifugal Pumps

2009 ◽  
Author(s):  
Ming-gao Tan ◽  
Hou-lin Liu ◽  
Shou-qi Yuan ◽  
Yong Wang ◽  
Kai Wang
Keyword(s):  
Flow Field ◽  
Flow Curve ◽  
High Efficiency ◽  
Field Analysis ◽  
Centrifugal Pumps ◽  
Research Results ◽  
Rotor Stator Interaction ◽  
Nominal Condition ◽  
Specific Speed ◽  
Width Change

The present deficiency about numerical simulation research on blade outlet width of centrifugal pumps is pointed out. In the case of different outlet widths, the flow field in six centrifugal pumps whose specific speed vary from 45 to 260 are simulated by using commercial code FLUENT and the characteristics are predicted. The standard k-ε turbulence model and SIMPLEC algorithm are chosen in FLUENT. The simulation is steady and moving reference frame is used to consider rotor-stator interaction. The research results show that the change of impeller outlet width has obvious impacts on characteristics at design point, flow field and the shape of performance curves. At nominal condition, the change of outlet width has more important effects on moderate specific speed centrifugal pumps. The flow field analysis indicates that blade outlet width change has an important effect on the location and area of low pressure region behind the blade inlet, jet-wake structure in impellers, the secondary flow in volute cross section and the back flow in impellers. The head-flow curve becomes more flat with the increase of outlet width. For moderate and low specific speed centrifugal pumps, the high efficiency area of efficiency-flow curve get bigger with the increase of outlet width and the area will be constant within certain outlet width change scope for high specific speed centrifugal pump. The research results agree well with experiment results.

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