Pump Noise Research Articles

Transient flow and noise characteristics of vortex-turbulence-noise interaction in centrifugal pump

Centrifugal pump operation noise is an avoidable common phenomenon in engineering practices, and its characteristics are closely influenced by the flow characteristics of the fluid. In this paper, a numerical simulation of centrifugal pump operation with different flow rates is carried out using the detached eddy simulation turbulence model and compared with the experimental results. Then the noise source and far-field radiated noise characteristics of the centrifugal pump are investigated using Lighthill’s analogy. The results show that the noise of centrifugal pump is closely related to the flow characteristics of impeller, especially the generation and development of vortex. The relationship between turbulent kinetic energy (TKE) and vortex is complex, involving the generation, development and shedding of vortex. The influence of flow rate variation on vortex structure in impeller is studied by vortex transport equation. It is found that the relative vortex stretching (RVS) term is the main driving force of vortex distribution. The distribution of the Coriolis force (CORF) term is mainly concentrated in the inlet and outlet areas of the flow channel, which is related to the rotational motion of the impeller and the dynamic characteristic of the fluid. The power spectral density inside the impeller is mainly concentrated in the low frequency region, indicating that the low frequency noise component is dominant in energy. The directivity curve of far-field noise pressure level is influenced by hydrodynamic effect, impeller rotation direction and pump design structure, and will have a certain deviation. The spectral curve analysis of velocity, vorticity, pressure and sound pressure level shows that these physical quantities have strong correlation on the spectrum, in which the low frequency component is large, and the high frequency component is complex and volatile.

Noise optimization of hydraulic piston pump

With the development of electrification, the internal combustion engine (ICE) is gradually replaced by the electric motor. Lack of the ICE noise occultation, the noise of hydraulic piston pump becomes prominent. It is significant to decrease the noise of hydraulic piston pump for improving the driving comfort. The present study detailed investigates the simulation method for modal and noise calculation of the hydraulic piston pump. The noise prediction of hydraulic pump agrees well with measurements on the distribution of sound pressure vs. frequency. According to modal and noise distribution characteristics, the housing structure of hydraulic piston pump has been optimized to shift the modal frequency and decrease the noise. The simulation data proves that optimized hydraulic pump housing has great potential to decrease the noise. Compared with the original hydraulic pump housing, the sound pressure overall lever of optimized hydraulic piston pump is validated to decrease by 2-3dBA.

An efficient predicting approach for blade frequency line-spectrum noise of marine centrifugal pumps

The paper introduces an innovative and efficient calculation method for the spectral flow noise of the pump system based on the spatial distribution dipole, which predicts the blade frequency radiation noise at the pipe flange of the pump system under different operating conditions. First, the unsteady flow simulation of the centrifugal pump is calculated using computational fluid dynamics (CFD). Then, the pressure on each segmented blade surface is decomposed into lift and drag forces. After that, each segment is decomposed into several dipole point sources based on the blade noise theory. Finally, the simplified dipole point sources are considered sound sources, and the blade frequency line spectrum noise at the pipe flange of the pump system is predicted using acoustic-structure coupling. The results indicate that the simplified method provides high prediction accuracy while significantly improving the computational efficiency of blade frequency line spectrum noise calculation for centrifugal pumps.

Advancing noise reduction strategies for domestic air-source heat pumps

With the increasing adoption of heat pump technology in the energy sector, addressing noise emissions is crucial for public acceptance, regulatory compliance, and sustainable urban planning. Air-Source Heat Pump's noise emission, noise sources, reduction strategies, problematic frequency ranges, and noise transmission within buildings are considered. Various noise reduction strategies, including the strategic siting, enclosures, and vibration isolation techniques, are discussed. This study considered a scenario of heat pump noise emission which generated noise complaints. The heat pump noise source is investigated though 24 hour monitoring of far field acoustics in a suburban residence. A commercial implementation of ISO 9613 is used to predict the environmental noise impact. Results demonstrated that levels exceeded natural background by as much as 10-15 dB but that this could be mitigated through strategic placement of the heat pump. This study underscores the importance of implementing comprehensive noise control strategies for Air-Source Heat Pumps in urban areas to safeguard community well-being and ensure regulatory compliance. By integrating innovative noise reduction technologies and considering factors such as strategic location of Air-Source Heat Pump, installation practices, building design, and proper urban planning policies can enhance Air-Source Heat Pump's reliability while promoting a sustainable urban development.

The effect of fan-type inducer blade tip geometry on cavitation behavior and noise in an industrial centrifugal pump

Cavitation is one of the biggest problems in industrial centrifugal pumps because it causes serious vibration and noise. Therefore, there is a demand for pump manufacturers to prevent problems due to the cavitation before delivering products to the site. Noise is considered to increase due to the development of cavitation at the tip of the inducer blades. In this study, the location of cavitation development was controlled by changing the inducer blade tip geometry to reduce noise. A centrifugal pump with a fan-type inducer was operated to measure noise at various cavitation numbers and flow rates with a microphone set up on the outer wall near the inducer. A visualization experiment using an acrylic casing around the inducer, a high-speed camera, and strobe light was also conducted to observe the behavior of cavitation development. The relationship between cavitation form and noise was investigated in detail.

Loudness and preference judgments for noises of a heat pump

An increasing number of heat pumps have recently been installed to replace conventional heating systems to provide more environmentally friendly and energy-efficient indoor heating. Most commonly, air-to-water heat pumps are chosen. However, the sounds of their fan and compressor can lead to noise complaints and can reach the limit of noise emission regulations. To achieve a more pleasant environment, research is conducted to reduce the perceived noise of heat pumps. As part of an interdisciplinary research project, this study aims to investigate the annoyance ratings of a heat pump and characterize them in terms of equivalent loudness and preference penalties. The study uses a two-alternative forced-choice (2AFC) method with a 1-up-1-down rule to measure the point of subjective equality for six stimuli representing different operation states of the investigated device. This experiment aims to identify differences between loudness and preference, and combined with an evaluation of psychoacoustic parameters, its results are used to improve the acoustics of heat pumps and the overall user experience.

Understanding human responses to air source heat pump noise: examining tonal changes and operating cycles

Air Source Heat Pumps are pivotal in the Government of the United Kingdom's target of achieving net zero carbon emissions by 2050. However, their widespread adoption faces challenges, with noise being among the main barriers to entry and a restricting factor at the planning stages. This study addresses concerns regarding noise propagation from outdoor units to indoor environments through a two-part experiment, aiming to capture human responses to Air Source Heat Pump noise based on the changes in the characteristics of noise emissions at various operating conditions, background noise levels, and source distances. The first part evaluates peoples' responses under static operating conditions to 20-second recordings, using the Self-Assessment Manikin scale and an annoyance scale. Following each recording, they used the Self-Assessment Manikin pictorial scale and an annoyance scale to report their response. In the second part, responses to transient Air Source Heat Pump operation cycles are assessed using 60-second recordings. Participants evaluated each recording at two points: after a transition in the operating cycle and at the end of the recording. The findings of the study provide insights into the human response to heat pump noise, essential for developing strategies to facilitate wider Air Source Heat Pump adoption.

Higher-fidelity analysis of air source heat pump noise via scanning intensity measurement

The need to shift to reduce carbon emissions to hit Net Zero is currently driving plans for large scale rollouts of Air Source Heat Pumps (ASHPs), due to their increased thermal efficiency and lack of direct carbon emissions. Concern exists, however, over the potential environmental noise impact that these units could generate. The noise generated by ASHPs is measured according to BS EN 12102-2:2019. This allows a choice of several laboratory test procedures for the acoustic part, but in each of these methods only overall sound power is measured. Such measurements are crucial, but they cannot give insight into the directivity of the noise from the unit - as is required for accurate acoustic propagation modelling - and they cannot give diagnostic information that would aid improvements to designs, e.g., by showing which parts of an ASHP radiate the most noise. This paper explores the benefits offered by scanning intensity measurement, here using a Microflown Scan and Paint 3D system. This can provide a map of active and reactive intensity around the unit - in addition to pressure and particle velocity - allowing noise from components and directivity to be estimated. Advantages and challenges are discussed.

Investigation and comparison of heat pump noise in the lab and field

The presentation covers a contribution from the publicly funded HP-QUEEN MENESA project on the characterisation of a heat pump in the laboratory with comparisons in the field at comparable operation conditions. The data in the lab are obtained from a hemi-anechoic chamber that is equipped with temperature control to allow standardized measurements at -7 °C and 7 °C, for example. In this environment spherical sound radiation pattern are determined on a movable hemi-circle microphone arrangement allowing the assessment of source location and radiation contribution as well as sound power determination at the different operation points of the heat pump. These data are compared and analysed to measurements with the same heat pump in the field at model houses at the Fraunhofer-IBP location in Holzkirchen. Furthermore, we are also investigating the transmission path from the noise of the heat pump outdoors into the building taking sound reduction index of i.e., windows into account. It is planned to connect a psychoacoustic analysis together with a questionnaire to these investigations that allows assessment of the final sound characteristics inside the building.

Research on flow-induced radiated noise of twin-screw pumps based on the Lighthill acoustic analogue theory

Abstract To optimize the control of twin-screw pumps (TSP), it is essential to ensure performance while simultaneously preventing noise levels from exceeding specified limits. In order to investigate the flow characteristics and the mechanism of flow-induced radiated noise under various operating conditions, a coupled numerical simulation approach using Computational Fluid Dynamics (CFD) and Computational Acoustics (CA) was employed, and the findings were validated through experiments. The study reveals that the highest sound pressure levels of radiated noise occur near the rotor outlet surface, and the dynamic-static interference at the rotor-boundary interface is the primary cause of flow-induced noise in TSP. The flow-induced noise in TSP exhibits dipole characteristics, with the overall sound pressure level gradually increasing and then sharply rising with the increase in rotational speed (or flow rate). It stabilizes near the design operating point and continues to increase steadily with further increases in rotational speed (or flow rate). Modal testing using a dual-distributed measurement technique highlights significant interference effects between the rotor inlet and the dynamic rotor for the first two Blade Passing Frequencies (BPF) in TSP. The results of this study provide a theoretical foundation for the low-vibration and low-noise design and operation of TSP.

Introducing the rubber plate impact method: a versatile alternative to close proximity test for tire-pavement noise characterization on asphalt highways

Despite its widespread use, the close proximity (CPX) test for tire-pavement noise is limited to existing pavements, posing challenges for timely and effective corrections of noisy pavements. Additionally, the CPX test entails significant procurement and operation costs. Addressing these issues, this study introduces the rubber plate impact (RPI) method as a simple experimental technique for assessing tire-pavement noise in both laboratory and field settings. The RPI test utilizes the folding motion of the treaded rubber plate on the road surface to simulate air pumping and tread impact noise as two main contributors to tire-pavement noise. Indoor RPI tests on asphalt concrete samples of dense graded asphalt and porous asphalt mixes revealed dominant effects of air void content and associated surface texture on the level of noise. The RPI testing procedure was verified at 17 highway test sections, where both CPX and RPI tests were conducted for comparison. Multiple linear regressions between RPI and CPX data were analyzed to propose CPX prediction models at different speeds (80, 100, 120 km/h), and the performance of these prediction models was validated with independent noise datasets collected from four different highway routes. The findings suggest promising prospects for the RPI test as a cost-effective and versatile alternative to CPX for tire-pavement noise characterization on asphalt-surfaced roads, with implications for road materials design and noise mitigation strategies.

Analysis of the effect of cavitation on internal fluid excitation characteristics of centrifugal pumps

To explore the influence of cavitation on the internal fluid excitation characteristics of pumps, numerical simulations and performance testing evaluations were performed on the IS65-50-125 centrifugal pump. The prototype pump's exterior characteristic and cavitation performance curves, as well as its bubble volume distribution, were successfully replicated using numerical computations. The effect of cavitation on the internal pressure pulsation characteristics of the centrifugal pump under various operating situations was comprehensively investigated, indicating a relationship between the degree of cavitation and the root mean square values of pressure pulsation. Special emphasis was placed on the changes in features at intermediate and high frequencies, as well as the processes of rising bubble volume and vortex shedding at the impeller trailing edge on pressure pulsation. To validate the simulation results, a centrifugal pump vibration and noise testing platform was built, and studies on vibration intensity and internal sound field noise were conducted. The experimental results revealed that the vibration intensity and internal sound field sound pressure level of the centrifugal pump rose as cavitation conditions deteriorated, confirming the modeling results. This study's significant innovation is the precise identification of the pump's performance changes under different operating conditions by monitoring pressure pulsation changes at various frequencies, as well as an in-depth discussion of the impact mechanism of cavitation phenomena on the internal fluid excitation behavior of centrifugal pumps. The study demonstrates differences in pressure pulsation characteristics on the suction and pressure sides under various cavitation situations, as well as the process of vortex creation and shedding generated by bubbles in the impeller input channel during severe cavitation. This gives new theoretical basis for pump vibration and noise reduction, as well as significant improvements in centrifugal pump performance and stability.

Research on the effects of volute area ratios on centrifugal pump internal flow and noise

Centrifugal pumps, which are essential for the transfer of fluids, are extensively utilized in industries like aerospace and new energy vehicles. These fields require pumps to meet rigorous standards in terms of reliability, efficiency, and vibrational noise while also imposing stringent restrictions on their size and weight. Therefore, achieving optimal performance in terms of both efficiency and noise reduction for centrifugal pumps in limited space poses a considerable difficulty. This study investigates the impact of different volute area ratios on the internal flow properties and noise levels of centrifugal pumps, using area ratio theory as a foundation. Both experimental and computational simulations are used, with the pump dimensions kept constant. The results demonstrate that an augmentation in the volute area ratio greatly improves the pump's exterior properties, notably decreases internal vorticity, and boosts flow conditions. The pressure fluctuations in the pumps show an overall decrease, accompanied by changes in their distribution patterns. In addition, the sound pressure levels in the exterior sound field of the pumps typically decrease, accompanied by obvious changes in directivity. The sound pressure levels within the internal sound field are significantly reduced, especially in areas of the volute wall that were previously known for having high sound pressure. By analyzing the relationship between sound pressure and pressure pulsation on the wall surface of the volute, as well as the impact of area ratio on pressure pulsation distribution in the sound field of the centrifugal pump, it is evident that the theory of area ratio can be utilized to effectively decrease pressure pulsation in the centrifugal pump, thereby reducing the noise generated by the pump.

Separation of tire tread vibration noise and air pumping noise using frequency band noise data

Separation of tire tread vibration noise and air pumping noise using frequency band noise data

Influence of different turbulence models on tip vortex prediction

Abstract Tip vortex cavitation usually occurs in marine propellers and axial-flow turbines, the cavitation in the tip vortex could potentially result in blade erosion, at the same time, it will cause the pump vibration and noise emission. The tip vortex mainly occurs in rotating machinery with complex three-dimensional flow, but the prediction of the hydrofoil tip vortex can provide a basis for the study of the blade tip vortex in rotating machinery by simplifying the blade model. Hence, in this paper, we use the commercial software CFX to investigate the impact of distinct turbulence models on the configuration of tip vortex distribution in the NACA 16-020 hydrofoil, including SST (Shear Stress Transport), DES (Detached Eddy Simulation), LES (Large Eddy Simulation) turbulence models which are widely used in the field of rotating machinery. At the same time, the axial and radial velocity distributions at different locations downstream of the tip of the hydrofoil are compared to analyse the effects on the velocity distribution near the vortex core line stemming from various turbulence models. By comparing with the experimental data, the most accurate turbulence model for tip vortex prediction is obtained, which will provide guidance for the next step tip vortex prediction and the control of tip vortex flow.

Influence of structural parameters of distributor disk on flow pulsation in axial piston pumps

Firstly, a virtual prototype of axial piston pump AMESim is used to observe the effects of outlet pressure, swashplate inclination, bulk modulus (compressibility), density, dynamic viscosity, air viscosity, air content, dead space volume, leakage of mating clearance of the moving parts, plunger cylinder clearance, eccentricity, contact length of the copper bushing of the high-pressure piston pump, and the over-flow area of the flow distributing disk on the swashplate torque, the pressure in the plunger chamber, the pulsation in the flow rate, and the backing-up. To explore the influence of fluid noise, mechanical noise and air noise. After comparison, the overflow area of the disk, which has the greatest influence on the noise, is selected as the research object, in which the structural parameters of the disk are the most important influencing factors. Finally, it is found that too large or too small overflow area will aggravate the fluid noise and mechanical noise of the piston pump. Therefore, the optimized design of the structure of piston pump flow distribution plate is of great significance to reduce the vibration and noise of the hydraulic system. This study catches the optimization method of axial piston pump flow distribution shock, which can provide a reference for the design and optimization of axial piston pumps.

Noise analysis of dry scroll vacuum pump based on experiment and CFD

The scroll vacuum pump is a dry vacuum pump with a wide range of applications. The radiated noise of a multi-stage scroll vacuum pump under different suction pressures is tested. The discharge velocity field is measured by the PIV technique. When the suction pressure changes from 101 kPa to 5 Pa, the average sound pressure level of the scroll pump decreases from 80.37 dB to 58.13 dB, which is reduced by 22.24 dB. The maximum and minimum sound power levels are 97 dB and 74.76 dB, respectively. The spectrum characteristics and the distribution law of radiated noise are analyzed. The measured noises at the rear of all operating conditions are the smallest, followed by the positions above the front part, and the next is the directly above position. Aeroacoustics is the main noise source in the scroll pump. Based on the CFD method, the simulation calculation is carried out at different suction pressures and the maximum simulation error is −5.7%. The location and formation mechanism of the aeroacoustics source are analyzed. In different working processes, the main excitation sources of aeroacoustics are different. The results are helpful to the noise source identification and aeroacoustics improvement of the scroll vacuum pump.

Study on Mechanism and Suppression Method of Flow-Induced Noise in High-Speed Gear Pump

The flow-induced noise mechanism of a 5000 rpm high-speed gear pump is explored. On the basis of the CFD technology and the Lighthill acoustic analogy theory, a numerical model of the flow-induced noise of a high-speed gear pump is constructed, and the effect of oil suction pressure (0.1–0.2 MPa) on the internal flow field and flow-induced noise characteristics of the high-speed gear pump is investigated. To evaluate the accuracy of the numerical simulation, a noise testing platform for high-speed gear pumps was developed. Adding an oil replenishment groove to the high-speed gear pump suppresses its flow-induced noise. The results indicate that the discrete noise at the fundamental frequency and its harmonic frequency is the primary component of the flow-induced noise of the pump and that the oil-trapped area is the principal source of vibration. The overall sound pressure level of flow-induced noise in the inlet and outlet areas decreases with distance from the oil-trapped area, and the sound pressure level in the outlet area is greater than that in the inlet area. The oil replenishment groove may considerably minimize cavitation noise, enhance the oil absorption capacity, and reduce the outer field’s overall sound pressure level by 4–5 dB.

Machine Learning-Based Prediction of NPSH, Noise, and Vibration Levels in Radial Pumps Under Cavitation Conditions

Cavitation, a physical phenomenon that detrimentally affects pump performance and reduces pump life, can cause wear on pump elements. Various engineering methods have been developed to identify the initiation and full development of the cavitation process. One such method is the determination of the net positive suction head (NPSH) through a 3% decrease in total head (Hm) at a constant flow rate. In radial pumps, commonly used in agricultural irrigation and industry, cavitation conditions result in a sudden drop in the Hm-Q curve, making it challenging to detect the 3% Hm value drop. This study differs from others in the literature by modelling NPSH, noise, and vibration levels using three machine learning models, specifically artificial neural networks (ANN), support vector machines (SVM), and decision tree regression (DTR). The best-performing model predicts NPSH, noise, and vibration levels corresponding to a 3% decrease in Hm level. The present study determined the NPSH values of a horizontal shaft centrifugal pump at different flow rates and constant operating speed, and the vibration and noise levels were measured for these NPSH values. For each of the NPSH, noise, and vibration levels, ANN, SVM and DTR models were created. The performances of these models were evaluated using criteria such as root mean squared error (RMSE), Mean Absolute Error (MAE) and mean absolute percentage error (MAPE). In addition, Taylor and error box diagrams were created. The ANN model and DTR yielded high accuracy predictions for NPSH values (R2 = 0.86 and R2 = 0.8, respectively). The ANN model provided the best prediction performance for noise and vibration levels. By entering the level of 3% drop in the Hm value of the pump as external data input to the ANN model, NPSH3, noise, and vibration levels were determined. The ANN models can be effectively employed to determine NPSH3, noise, and vibration levels, particularly in radial flow pumps, where detecting 3% reductions in manometric height value is challenging.

The influence of blade curvature radius on the internal unsteady characteristics of a centrifugal pump

AbstractTo study the influence of the blade curvature radius on the flow‐induced vibration and noise of the centrifugal pump, the internal sound field of the IS 80‐65‐160 centrifugal pump was numerically calculated by adjusting the blade wrap angles to change the blade curvature radius. The RNG (Reynolds Time Average Simulation) turbulence model was selected for the numerical calculation of the centrifugal pump. The numerical simulation of the whole flow channel of the centrifugal pump was carried out using Ansys Fluent software, and the external characteristic curve of the centrifugal pump was obtained. The influence of different blade wrap angles on the internal pressure, velocity and Turbulent Kinetic Energy of the centrifugal pump was obtained. On the basis of the sound–structure coupling equation, the unsteady sound field of the centrifugal pump was calculated, and the time domain and frequency domain characteristics of the pressure pulsation at each monitoring point were obtained. The calculation results showed that the dynamic and static interference between the impeller and the volute tongue mainly caused the vibration of the centrifugal pump. By appropriately increasing the blade wrap angles, the pressure pulsation in the volute fluid domain could be effectively reduced. The vibration and noise test bench of the centrifugal pump was set up to verify the test. The experimental results showed that at the double‐blade frequency, the variation trend of the experimental value and the simulated value of the outflow flow‐induced noise of the centrifugal pump were consistent, which verified the accuracy of the sound field simulation calculation. When the blade wrap angle , it could effectively reduce the internal sound pressure level and the flow‐induced vibration and noise of the centrifugal pump. By adopting measures such as grid encryption at the position of the tongue, nonstationary calculation and comparison of different turbulence models, the accuracy of the calculation results of the internal flow field and sound field of the centrifugal pump is effectively improved, and the accuracy and reliability of the experimental results are ensured. The above research results had certain reference significance and application value for improving the working efficiency of centrifugal pumps and reducing flow‐induced vibration and noise.