Sound Generation by a Centrifugal Pump at Blade Passing Frequency

1998 ◽  
Vol 120 (4) ◽  
pp. 736-743 ◽  
Author(s):  
M. Morgenroth ◽  
D. S. Weaver
Keyword(s):  
Flow Rate ◽  
Acoustic Pressure ◽  
Flow Behavior ◽  
Pressure Fluctuations ◽  
Standing Waves ◽  
Acoustic Resonance ◽  
Piping System ◽  
Hydraulic Pressure ◽  
Pump Speed ◽  
Blade Passing Frequency

This paper reports the results of an experimental study of the pressure pulsations produced by a centrifugal volute pump at its blade passing frequency and their amplification by acoustic resonance in a connected piping system. Detailed measurements were made of the pressure fluctuations in the piping as a function of pump speed and flow rate. A semi-empirical model was used to separate acoustic standing waves from hydraulic pressure fluctuations. The effects of modifying the cut-water geometry were also studied, including the use of flow visualization to observe the flow behavior at the cut-water. The results suggest that the pump may act as an acoustic pressure or velocity source, depending on the flow rate and the cut-water geometry. At conditions of acoustic resonance, the pump acted as an open termination of the piping, i.e., as a node in the acoustic pressure standing waves. Rounding the cut-water had the effect of reducing the amplitude of acoustic resonance, apparently because of the ability of the stagnation point to move and thereby reduce the vorticity generated.

Experimental Investigation of Pressure Fluctuations on Inner Wall of a Centrifugal Pump

2019 ◽  
Vol 36 (4) ◽  
pp. 401-410 ◽  
Author(s):  
Xiao-Qi Jia ◽  
Bao-Ling Cui ◽  
Zu-Chao Zhu ◽  
Yu-Liang Zhang
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
High Flow ◽  
Low Flow ◽  
Centrifugal Pumps ◽  
Flow Rates ◽  
Pressure Distributions ◽  
Blade Passing Frequency

Abstract Affected by rotor–stator interaction and unstable inner flow, asymmetric pressure distributions and pressure fluctuations cannot be avoided in centrifugal pumps. To study the pressure distributions on volute and front casing walls, dynamic pressure tests are carried out on a centrifugal pump. Frequency spectrum analysis of pressure fluctuation is presented based on Fast Fourier transform and steady pressure distribution is obtained based on time-average method. The results show that amplitudes of pressure fluctuation and blade-passing frequency are sensitive to the flow rate. At low flow rates, high-pressure region and large pressure gradients near the volute tongue are observed, and the main factors contributing to the pressure fluctuation are fluctuations in blade-passing frequency and high-frequency fluctuations. By contrast, at high flow rates, fluctuations of rotating-frequency and low frequencies are the main contributors to pressure fluctuation. Moreover, at low flow rates, pressure near volute tongue increases rapidly at first and thereafter increases slowly, whereas at high flow rates, pressure decreases sharply. Asymmetries are observed in the pressure distributions on both volute and front casing walls. With increasing of flow rate, both asymmetries in the pressure distributions and magnitude of the pressure decrease.

Phase Characteristics of Vortex Shedding From Tube Banks on Acoustic Resonance

2017 ◽  
Author(s):  
Hiromitsu Hamakawa ◽  
Satoshi Hino ◽  
Eiichi Nishida ◽  
Eru Kurihara
Keyword(s):  
Vortex Shedding ◽  
Lift Force ◽  
Acoustic Pressure ◽  
Pressure Fluctuations ◽  
Side Wall ◽  
Sound Field ◽  
Peak Level ◽  
Acoustic Resonance ◽  
Coupling Condition ◽  
Tube Banks

This paper investigates the phase characteristics of vortex shedding from tube banks on acoustic resonance. We measured the time variation of a phase between surface pressures related to the lift force on a tube and acoustic pressure on a side wall related to the acoustic particle velocity when acoustic resonance occurred in in-line tube banks. The measured tube was installed at the second rows in the tube banks. As the peak level of spectrum of surface pressure fluctuations increased, the coherence between vortex shedding and wall acoustic pressure in the tube banks also increased. The phase delay between the lift force and acoustic pressure on the side wall was calculated by using a proposed modeling method. In addition, we discuss the verification of the synchronization feedback for a coupling condition between a sound field and wake oscillator.

NON-DIMENSIONAL DISTRIBUTION PATTERN ANALYSIS OF PARTICLE TRANSPORTATION IN SIMPLIFIED PIPELINE SYSTEM

2015 ◽  
Vol 77 (12) ◽  
Author(s):  
Mohd Zamani Ngali ◽  
Kahar Osman ◽  
Nazri Huzaimi Zakaria
Keyword(s):  
Fluid Flow ◽  
Flow Rate ◽  
Flow Behavior ◽  
Solid Sphere ◽  
Rate Variation ◽  
Pipeline System ◽  
Piping System ◽  
Weight Variation ◽  
Dimensional Simulation ◽  
Particle Weight

Sustainable preservation of pipeline system that deal with particle transportation is more appealing these days. In petroleum industries for instance, sand transported through the pipelines pose serious problems ranging from blockage, corrosion, abrasion and reduction in pipe efficiency to loss of pipe integrity. Accurate four-dimensional simulation that caters the transient effect of the phenomena is used to promote sustainability in design, evaluation and maintenance procedures. This is employed to minimize conventional practices which are costly and inefficient. This work demonstrates the advantages of applying four-dimensional Splitting Fluid-Particle Solver to simulate particle transportation within a simplified pipeline system. Single-phase fluid with solid sphere particles are the assumptions while drift and gravitational forces are taken into account. Effect of fluid flow rate and particle weight alterations are observed within vertical curled and 2-1-2 segmental pipeline. Flow rate variation on multiple inputs shows that proper simulation is essential in order to predict fluid flow behavior prior to pipeline construction. Particle weight variation shows that simulation can lead to better prediction of potential areas of blockage, corrosion, abrasion and other piping system issues. This work proves that four-dimensional simulation can promote sustainability, cost effectiveness and efficiency of pipeline system management. 

Experimental Investigation of Time-Frequency Characteristics of Pressure Fluctuations in a Double-Suction Centrifugal Pump

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Zhifeng Yao ◽  
Fujun Wang ◽  
Lixia Qu ◽  
Ruofu Xiao ◽  
Chenglian He ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Operating Conditions ◽  
Design Flow ◽  
Flow Rates ◽  
Time Frequency ◽  
Blade Passing Frequency ◽  
Design Flow Rate

Pressure fluctuation is the primary reason for unstable operations of double-suction centrifugal pumps. By using flush mounted pressure transducers in the semispiral suction chamber and the volute casing of a double-suction pump, the pressure fluctuation signals were obtained and recorded at various operating conditions. Spectral analyses were performed on the pressure fluctuation signals in both frequency domain and time-frequency domain based on fast Fourier transform (FFT) and an adaptive optimal-kernel time-frequency representation (AOK TFR). The results show that pressure fluctuations at the impeller rotating frequency and some lower frequencies dominated in the semispiral suction chamber. Pressure fluctuations at the blade passing frequency, the impeller rotating frequency, and their harmonic frequencies were identified in the volute casing. The amplitude of pressure fluctuation at the blade passing frequency significantly increased when the flow rate deviated from the design flow rate. At 107% of the design flow rate, the amplitude increased more than 254% than that at the design flow rate. The time-frequency characteristics of these pressure fluctuations were affected greatly by both operating conditions and measurement locations. At partial flow rates the pulsation had a great irregularity and the amplitudes at the investigated frequencies were much larger than ones at the design flow rate. An asymmetrical pressure fluctuation structure in the volute casing was observed at all flow rates. The pulsation behavior at the blade passing frequency was the most prominent near the volute tongue zone, and the pressure waves propagated in both the radial and circumferential directions.

scholarly journals Hysteresis in Oil Flow through a Rotating Tube with Twin Exit Branches

1997 ◽  
Vol 3 (4) ◽  
pp. 249-258 ◽  
Author(s):  
Sun-Wen Cheng ◽  
Wen-Jei Yang
Keyword(s):  
Flow Rate ◽  
Transmission Lines ◽  
Rotational Speed ◽  
Flow Behavior ◽  
Piping System ◽  
Air Bubbles ◽  
Two Phase ◽  
Oil Flow ◽  
Flow Through ◽  
Total Oil

Oil enters a horizontal rotating tube through a radially-attached duct at one end. The tube with the other end closed is attached with radial twin exit branches permitting oil to exit into open air. Air begins to enter through one of the two branches into the tube when its rotational speed reaches certain critical values. An experimental study is performed to investigate this air-oil two-phase flow behavior. Both the tube and the branches are transparent to allow illumination and flow visualization during spin-up and spin-down processes. The branch-totube diameter ratio, rotational speed, and oil flow rate are varied. Changes in oil flow rates are measured as a function of rotational speed. A comparison is made between cases of a varying total oil flow rate due to rotation effects and a constant one under control. It is disclosed that cavitation in oil flow is induced by air entering the branches opposite to the ejecting oil flow. Subsequently air bubbles progress in the tube. The origin of this intrusion depends on the hydraulic head loss of the piping system. This study can be applied to oil lubrication analysis of rotating machinery, such as automotive transmission lines.

Experimental Investigation of Relationship Between Pressure Fluctuations and Vibrations for a Double Suction Centrifugal Pump

2011 ◽  
Author(s):  
Zhifeng Yao ◽  
Fujun Wang ◽  
Ruofu Xiao ◽  
Chenglian He ◽  
Zhuqing Liu
Keyword(s):  
Flow Rate ◽  
Large Scale ◽  
Pressure Fluctuations ◽  
Primary Source ◽  
Internal Flow ◽  
Rotational Frequency ◽  
High Flow ◽  
High Flow Rate ◽  
Centrifugal Pumps ◽  
Blade Passing Frequency

Double-suction centrifugal pumps are widely employed in large-scale pumping stations, which generally run in the conditions of large discharge with huge energy consumption. Pressure fluctuation caused by internal flow due to tongue-impeller interaction is the primary source of pump vibration. In this paper, pressure fluctuations and vibrations signals on volute casing wall were experimentally obtained at five flow rates ranging from 59% to 121% of nominal flow rate. Time and frequency domains of the signals were mainly analyzed by using statistical and fast Fourier transform methods. The results show that rotational frequency, blade passing frequency and their harmonic frequencies of pressure fluctuations as well as vibrations are clearly identified. The magnitude at blade passing frequency has close relationship with the measurement location related to the volute tongue, and becomes larger when the flow rate deviates from the nominal flow rate. The magnitudes at blade passing frequency can increase by 70% and 151% at high flow rate over that at the nominal flow rate for pressure fluctuations and vibrations, respectively. While the magnitude of vibration at rotational frequency keeps nearly constant at partial flow rate, and decreases at high flow rate.

scholarly journals Comprehensive Numerical Investigations of Unsteady Internal Flows and Cavitation Characteristics in Double-Suction Centrifugal Pump

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Xuelin Tang ◽  
Mingde Zou ◽  
Fujun Wang ◽  
Xiaoqin Li ◽  
Xiaoyan Shi
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuations ◽  
Dominant Frequency ◽  
Secondary Flows ◽  
Design Flow ◽  
Sharp Drop ◽  
Blade Loading ◽  
Blade Passing Frequency ◽  
Design Flow Rate

The RNG k-ε turbulence model combined with cavitation model was used to simulate unsteady cavitating flows inside a double-suction centrifugal pump under different flow rate conditions based on hexahedral structured grid. The numerical external characteristic performances agree well with the experimental performances. The predicted results show that the turbulence kinetic energy and the turbulence dissipation rate inside the impeller at design flow rate are lower than those at other off-design flow rates, which are caused by various vortexes. Based on frequency-domain analyses in the volute casing, the blade passing frequency is the dominant one of the pressure fluctuations except the vicinity of volute tongue for all operating cases, and the dominant frequency near the volute tongue ranges from 0 to 0.5 times the blade passing frequency for other off-design points, while the blade passing one near the volute tongue is the dominant one of the pressure fluctuations at design point. The increase of flow rate reduces the pressure fluctuations amplitude. For cavitation cases, the blade loading of the middle streamline increases a bit during the initial stage, but, for serious cavitation, the blade loading near the blade inlet reduces to 0 and even negative values, and the serious cavitation bubbles block the blade channels, which results in a sharp drop in pump head. Under noncavitation condition, the predicted power related to the pressure in the impeller channels increases from the inlet to the exit, while, under different cavitation conditions at the design flow rate, these power-transformation distributions in the impeller channels show that these power conversions are affected by the available NPSHa and the corresponding work in leading regions of the blades increases increases gradually a bit, and then it increases sharply in the middle regions, but it decreases in the blade trailing regions and is greatly influenced by secondary flows.

Investigation of Fan Casing Aerodynamic Noise at the Blade Passing Frequency

2009 ◽  
Author(s):  
Jian-Cheng Cai ◽  
Da-Tong Qi ◽  
Fu-An Lu
Keyword(s):  
Wave Equation ◽  
Flow Rate ◽  
Sound Propagation ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Sound Field ◽  
Noise Model ◽  
Aerodynamic Noise ◽  
Centrifugal Fan ◽  
Blade Passing Frequency

From our previous studies of fan casing vibroacoustics, it was found that noise caused by casing vibration was fairly small compared to its aeroacoustic counterpart. In the present work, a numerical study on the aerodynamic tonal noise of a centrifugal fan casing was carried out. A 3-D numerical simulation of turbulent unsteady flow on the whole impeller-volute configuration was performed using computational fluid dynamics (CFD) technique in order to obtain the pressure fluctuations on the casing wall which serve as aeroacoustic dipole sources. Three different flow rates were simulated: the best efficiency point (BEP), 1.382×BEP and the maximal flow rate (2.104×BEP). Fast Fourier Transform (FFT) was applied to the time series of pressure fluctuations to extract the blade passing frequency (BPF) component constituting the source term of the wave equation. Boundary element method (BEM) was used to solve the inhomogeneous frequency-domain wave equation. The influence of the casing on the sound field was taken into account in simulating the noise radiation by taking it as a rigid body. Results showed that the presence of the casing could greatly affect sound propagation. With the increase of flow rate, the radiated sound power rose drastically. The tonal blade noise was also investigated using Lowson’s formulation of rotor noise model, and the results showed that it’s smaller than the tonal casing noise.

Influence of Design Parameters on the Unsteady Flow in a Centrifugal Fan

2007 ◽  
Author(s):  
M. Younsi ◽  
F. Bakir ◽  
S. Kouidri ◽  
R. Rey
Keyword(s):  
Unsteady Flow ◽  
Acoustic Pressure ◽  
Flow Behavior ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Design Parameters ◽  
Geometrical Parameters ◽  
Far Field ◽  
Centrifugal Fan ◽  
Wall Pressure Fluctuations

The aim of this study is to evaluate the influence of design parameters on the unsteady flow in a forward-curved centrifugal fan and their impact on the aeroacoustic behavior. To do so, numerical and experimental study has been carried out on four centrifugal impellers designed with various geometrical parameters. The same volute casing has been used to study these fans. The effects on the unsteady flow behavior related to irregular blade spacing, blade number and radial distance between the impeller periphery and the volute tongue have been studied. The numerical simulations of the unsteady flow have been carried out using Computational Fluid Dynamics tools (CFD) based on Unsteady Reynolds Averaged Navier Stokes approach (URANS). The sliding mesh technique has been applied at the interfaces between the rotating and stationary zones in order to model the blades’ motion relative to the volute casing. The study is focused on the unsteadiness induced by the aerodynamic interaction between the volute and the rotating impeller blades. In order to predict the acoustic pressure at far field, the unsteady flow variables provided by the CFD calculations (pressure and velocity fluctuations acquired upon the surfaces of the rotating blades) have been used as inputs in the Ffowcs Williams-Hawkings equations (FW-H). Using this model, the acoustic pressure has been computed at the fan exit duct. The experimental part of this work concerns measurement of aerodynamic performance of the fans using a test bench built according to ISO 5801 [1] standard. In addition to this, pressure microphones have been flush-mounted on the volute tongue surface in order to measure the wall pressure fluctuations. The sound pressure level (SPL) measurements have been carried out in an anechoic room in order to remove undesired noise reflections. Finally, the numerical results have been compared with the experimental measurements and a correlation between the wall pressure fluctuations and the far field noise signals has been found.

The Influence of Geometry, Wall Thickness, and Material on the Acoustic Resonance Predictions in Closed-Ended Water-Filled Piping

2013 ◽  
Author(s):  
Alireza Mokhtari ◽  
Vijay Chatoorgoon
Keyword(s):  
Wall Thickness ◽  
Acoustic Pressure ◽  
Wave Theory ◽  
Acoustic Resonance ◽  
Piping System ◽  
Linear Wave ◽  
Acoustic Wave Propagation ◽  
Piping Systems ◽  
Acoustic Excitations ◽  
Flow Experiments

Acoustic pressure resonances in liquid-transporting pipe systems affect performance and safety. Accurate predictions of acoustic pressure resonances are a necessary requirement for any practical piping system undergoing some acoustic excitations. Thus, understanding the nature of acoustic wave propagation in water filled piping systems needs to be established based on fundamental experiments and analysis. To investigate acoustic resonance, no flow experiments with different configurations, wall thicknesses and materials were compared with theoretical and numerical calculations. This paper presents an experimental study showing that how linear wave theory, based on a transmission matrix method, and ABAQUS as commercial software do predict the acoustic resonance frequency peaks from 20 to 500 Hz, and discusses the resonant frequency shifts. Study of tube wall thickness, material (stainless steel and Aluminum), some equal and unequal branch configurations and combination of all investigated parameters for “Closed-end” tubes are discussed.

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