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.

Performance and Vibration of a Double Volute Centrifugal Pump: Effect of Impeller Trimming

2014 ◽  
Author(s):  
Atia E. Khalifa
Keyword(s):  
Pressure Pulsation ◽  
Pressure Fluctuations ◽  
Design Flow ◽  
Centrifugal Pumps ◽  
Impeller Blade ◽  
Pump Performance ◽  
Pump Head ◽  
Rotor Stator Interaction ◽  
Flow Induced Vibrations ◽  
Centrifugal Model

The fluid-structure interaction phenomenon, as manifested by the pressure pulsation excited by rotor-stator interaction, is the main cause of flow-induced vibrations at the blade passing frequency in large and high pressure centrifugal pumps. This phenomenon is strongly influenced by the clearance gap between impeller and volute diffusers/tongues and the geometry of impeller blade at exit. One way to reduce the effects of this interaction is to increase the effective gap by trimming the impeller. However, trimming the impeller will affect the pump performance and the flow pattern inside the pump volute. In the present work, experiments are carried out using a single stage, double-volute centrifugal model pump to investigate the effect of increasing the clearance gap by trimming the impeller on pump performance and vibration. Pressure fluctuations around the impeller inside pump volute are monitored and recorded. The clearance gap was increased three times by trimming the impeller radius by 1 mm, 2 mm, and 3 mm; respectively. Results showed that trimming the impeller reduces the pump vibration at the expense of the developed pump head. The minimum vibration was measured at the best efficiency point of the pump and the vibration amplitude increases when the pump operates at off-design conditions. Impeller trimming is more effective at flow rates equal to and higher that the design flow rate.

Numerical investigation of flow features in the vaneless region of a centrifugal pump by large eddy simulation

2018 ◽  
Vol 35 (1) ◽  
pp. 395-410 ◽  
Author(s):  
Xianbei Huang ◽  
Yaojun Li ◽  
Zhuqing Liu ◽  
Wei Yang
Keyword(s):  
Experimental Data ◽  
Transport Equation ◽  
Centrifugal Pump ◽  
Reynolds Stress ◽  
Pressure Pulsation ◽  
Third Order ◽  
Production Term ◽  
Content Type ◽  
Blade Passing Frequency ◽  
Rotor Stator Interaction

Purpose The purpose of this paper is to obtain a better understanding of the rotor–stator interaction in the vaneless region of a centrifugal pump. Design/methodology/approach A third-order sub-grid scale (SGS) model containing the rotation rate tensor named the dynamic cubic non-linear model (DCNM) is used for simulating the flow field in a centrifugal pump with a vaned diffuser. The pressure coefficient and velocity distributions are compared with the experimental data. Focusing on the vaneless region, the pressure pulsation, Reynolds stress pulsation and Reynolds stress transport equation are analyzed. Findings The comparison of the calculation results with the experimental data indicates that the DCNM can accurately capture the distributions of pressure and velocity in the vaneless region. Based on the instantaneous pressure signals, the pressure pulsation is analyzed to show that in the vaneless region, the dominant frequency near the impeller is twice the blade passing frequency, whereas it is equal to the blade passing frequency near the diffuser. Further exploration of the Reynolds stress pulsation shows the correlation between the two variables. Additionally, the extreme low frequency of Reynolds stress near the diffuser is found to be related to the rotation instability. To explore the turbulence characteristics in the vaneless region, the Reynolds stress transportation equation is studied. In the vaneless region, the rotation term of the Reynolds stress transport equation is negligible compared to the production term, although the rotation instability is obvious near the diffuser. The production of the Reynolds stress plays the role of redistributing the energy from the uu component to the vv component, except for the region near the impeller outlet. Originality/value The third-order SGS model DCNM has proved to be promising in simulating the rotor–stator interaction. The analysis of the rotation instability and the Reynolds stress transport equation shed light on the further understanding of the rotor–stator interaction.

scholarly journals Numerical Study on the Characteristics of Pressure Fluctuations in an Axial-Flow Water Pump

2014 ◽  
Vol 6 ◽  
pp. 565061 ◽  
Author(s):  
Zhi-Jun Shuai ◽  
Wan-You Li ◽  
Xiang-Yuan Zhang ◽  
Chen-Xing Jiang ◽  
Feng-Chen Li
Keyword(s):  
Numerical Simulations ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Axial Flow ◽  
Rotation Frequency ◽  
Dominant Frequency ◽  
Water Pump ◽  
Flow Induced Vibration ◽  
Impeller Blade

Flow induced vibration due to the dynamics of rotor-stator interaction in an axial-flow pump is one of the most damaging vibration sources to the pump components, attached pipelines, and equipment. Three-dimensional unsteady numerical simulations were conducted on the complex turbulent flow field in an axial-flow water pump, in order to investigate the flow induced vibration problem. The shear stress transport (SST) k-ω model was employed in the numerical simulations. The fast Fourier transform technique was adopted to process the obtained fluctuating pressure signals. The characteristics of pressure fluctuations acting on the impeller were then investigated. The spectra of pressure fluctuations were predicted. The dominant frequencies at the locations of impeller inlet, impeller outlet, and impeller blade surface are all 198 Hz (4 times of the rotation frequency 49.5 Hz), which indicates that the dominant frequency is in good agreement with the blade passing frequency (BPF). The first BPF dominates the frequency spectrum for all monitoring locations inside the pump.

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.

Influence of Flow Coefficient on the Unsteady Impeller Loading Induced by the Impeller-Diffuser Interaction

2018 ◽  
Author(s):  
Dongjae Kong ◽  
Seung Jin Song
Keyword(s):  
Pressure Fluctuations ◽  
Transformation Method ◽  
Flow Coefficient ◽  
Navier Stokes ◽  
Impeller Blade ◽  
Unsteady Simulation ◽  
The Difference ◽  
Fourier Transformation Method ◽  
Unsteady Loading ◽  
Radial Gap

Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulation has been conducted to investigate how flow coefficient affects unsteady impeller loading. Simulations have been carried out at three flow coefficients — near stall, design, and near choke conditions — for a radial gap of 1.04. For computational efficiency, the unsteady simulation has been conducted for two impeller and diffuser passages via Fourier Transformation method. Both steady and unsteady simulations have been validated against experimental data. The unsteady loading (the difference between the maximum and minimum loadings) is the largest at the near stall condition; second largest at the near choke condition; and smallest at the design condition. Flow coefficient effects on the unsteady impeller loading are mostly due to the variations in pressure fluctuations on the pressure side of the impeller blade. Relative to the design condition, the near stall condition shows lower minimum loading and the near choke condition shows higher maximum loading. Thus, both off design conditions result in higher unsteady loading than the design condition. Such differences stem from the variations in the pitch-wise static pressure at the diffuser vane inlet caused by the flow incidence onto the diffuser vanes.

scholarly journals Analysis of Pressure Pulsation Induced by Rotor-Stator Interaction in Nuclear Reactor Coolant Pump

2017 ◽  
Vol 2017 ◽  
pp. 1-18 ◽  
Author(s):  
Xu Zhang ◽  
Pengfei Wang ◽  
Xiaodong Ruan ◽  
Zhongbin Xu ◽  
Xin Fu
Keyword(s):  
Flow Rate ◽  
Pressure Pulsation ◽  
Operating Conditions ◽  
Impeller Blade ◽  
Coolant Pump ◽  
Guide Vanes ◽  
Rate Distribution ◽  
Reactor Coolant ◽  
Rotor Stator Interaction ◽  
Phase Differences

The internal flow of reactor coolant pump (RCP) is much more complex than the flow of a general mixed-flow pump due to high temperature, high pressure, and large flow rate. The pressure pulsation that is induced by rotor-stator interaction (RSI) has significant effects on the performance of pump; therefore, it is necessary to figure out the distribution and propagation characteristics of pressure pulsation in the pump. The study uses CFD method to calculate the behavior of the flow. Results show that the amplitudes of pressure pulsation get the maximum between the rotor and stator, and the dissipation rate of pressure pulsation in impellers passage is larger than that in guide vanes passage. The behavior is associated with the frequency of pressure wave in different regions. The flow rate distribution is influenced by the operating conditions. The study finds that, at nominal flow, the flow rate distribution in guide vanes is relatively uniform and the pressure pulsation amplitude is the smallest. Besides, the vortex shedding or backflow from the impeller blade exit has the same frequency as pressure pulsation but there are phase differences, and it has been confirmed that the absolute value of phase differences reflects the vorticity intensity.

Active Control Methods of Flow-Induced-Vibrations: Near-Wall-Turbulent-Pressure-Fluctuation Measurements

2002 ◽  
Author(s):  
Efim B. Kudashev ◽  
Leonid R. Yoblonik
Keyword(s):  
Turbulent Flows ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Control Methods ◽  
Flow Induced Vibration ◽  
Active Method ◽  
Wall Pressure Fluctuations ◽  
Turbulent Pressure ◽  
Flow Induced Vibrations ◽  
Near Wall

Near-wall pressure fluctuations in turbulent flows are of considerable interest in many engineering applications. We shall concentrate on a number of specific questions related to the resolution of components of wall pressure spectra. Our emphasis shall be on outstanding problems of experiment and theory and their relationship to one another. A study on pressure fluctuations transducer’s interaction with wall vibration resulting from near-wall turbulent flows has been performed. Piezoelectric pressure transducer generates the signal also on vibration influence. Algorithm of assign of turbulent surface pressure in conditions of flow-induced-vibration is suggested. An active method of vibration control has been developed.

scholarly journals Towards the Large-Eddy Simulation of a full engine: Integration of a 360 azimuthal degrees fan, compressor and combustion chamber. Part II: Comparison against stand-alone simulations

2021 ◽  
pp. 1-16
Author(s):  
Carlos Pérez Arroyo ◽  
Jérôme Dombard ◽  
Florent Duchaine ◽  
Laurent Gicquel ◽  
Benjamin Martin ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Combustion Chamber ◽  
Hot Spot ◽  
Pressure Fluctuations ◽  
Forward Region ◽  
Impeller Blade ◽  
Eddy Simulation ◽  
Blade Passing Frequency ◽  
Large Eddy ◽  
The Impact

Unsteady simulations of various components of a gas-turbine engine are often carried out independently and only share averaged quantities at the component interfaces. In order to study the impact and interactions between components, this work compares results from sectoral stand-alone simulations of a fan, compressor and annular combustion chamber of the DGEN-380 demonstrator engine at take-off conditions against an integrated 360 azimuthal degrees large-eddy simulation with over 2.1 billion cells of all previously listed components. Note that, at take-off conditions the compressor works at transonic conditions and generates an upstream-propagating shock that interacts with the fan modifying the shape of its wake with respect to the stand-alone simulation. Furthermore, the shock is seen as a tone in the pressure spectra at half the impeller blade passing frequency in the forward region of the engine. In the aft region, time-averaged fields are overall similar between stand-alone and integrated simulations but show a deviation in the azimuthal position of the hot-spot at the exit of the combustion chamber due to the addition of the diffuser. Pressure fluctuations generated in the compressor are captured in the combustion chamber as tones in the temperature and pressure spectra at the impeller blade-passing frequency and harmonics as well as an increase in the root-mean-square pressure.

Numerical and experimental study in pressure pulsation and vibration of a two-stage centrifugal pump under cavitating condition

2021 ◽  
Author(s):  
Shuwei Zhang ◽  
Ruiqi Tian ◽  
Kejin Ding ◽  
Hongxun Chen ◽  
Zheng Ma
Keyword(s):  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Uncertainty Estimation ◽  
Experimental Results ◽  
Center Frequency ◽  
Two Stage ◽  
Impeller Blade ◽  
Vibration Signals ◽  
Frequency Bands ◽  
Blade Passing Frequency

Instantaneous cavitating turbulent flow in a two-stage centrifugal pump with diffuser was simulated using a hybrid RANS/LES model and rotating corrected-based cavitation model in this paper. The predicted results of numerical simulation were in good agreement with the experimental results. The mechanism of pressure pulsation in the two-stage centrifugal pump was discussed. Some representative main frequencies of pressure pulsation such as main blade passing frequency, sub-blade passing frequency and intersection frequency of impeller blade and diffuser blade were analyzed systematically. Uncertainty estimation was used to ensure the accuracy of experimental results and it was also used to analyze the variation of pressure pulsation and vibration signals at different positions with the intensification of cavitation degree in the centrifugal pump. According to the results of uncertainty estimation, the center frequency of 1/3 octave band and the root mean square method were used to evaluate the energy change of the pressure pulsation signals and vibration signals at different frequency bands as the cavitation number decreases. The characteristics of pressure pulsation and vibration signals at different positions were analyzed in different frequency bands.

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.

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