Performance Characteristics Of Pump Research Articles

CFD-Based Investigation of the Operation Process of Radial Labyrinth Machinery Under Different Geometrical Configurations

This study explores the performance and flow characteristics of radial labyrinth pumps (RLPs) under various geometrical configurations and operating conditions. Experimental investigations and numerical simulations were conducted to evaluate the impact of design parameters such as blade geometry, channel width and blade angle on pump hydraulic performance. The numerical model, developed using the realizable k-ε turbulence model, was validated with experimental data, achieving satisfactory convergence (4.8%—bladed active disc operating with a smooth passive disc and 3.0%—bladed active disc operating with a bladed passive disc). Analysis of the velocity profiles and vortex structures formed between the active and passive discs was performed. These findings underscore the importance of optimizing disc geometry to balance centrifugal effects and momentum exchange. The obtained head for the model with a bladed active disc operating with a smooth passive disc was H = 24.1 m, while, for the bladed active disc operating with a bladed passive disc, it was almost 1.7 times higher at H = 40.3 m. Additionally, the research identifies potential zones within the pump where energy transfer processes differ, providing insight into targeted design improvements. The findings provide valuable information on the optimization of RLP designs and their broader applicability.

Performance characteristics of rotary lobe pumps for high viscosity food medium

Abstract This paper analyses the effects of food media with high viscosity on the performance of rotary lobe pumps. Rotary lobe pumps have long been used in the food industry for pumping highly viscous media and are designed to operate for long periods of time without replacement of any parts. The study utilised publicly available data from factory tests of the PLP 3-4 pump for pumping food media of various viscosities μ (μ above 10,000 cP). The paper presents the results of processing these data, which allow us to draw some conclusions. It is established that the power input of the pump PLP 3-4, due to the viscosity of the food medium, is directly proportional to the rotor speed and increases with its increase. Thus the power spent on overcoming back pressure depends on rotor speed nonlinearly. At the same rotor speed the increase in pressure drop and dynamic viscosity coefficient do not affect the productivity, but lead to a significant increase in power consumption. The obtained results allow to draw a conclusion that it is not necessary to connect the increase of hydraulic efficiency of rotary lobe pump with improvement of energy efficiency of unit utilisation and to take into account the reason of increase of discharge pressure.

ЧИСЛЕННОЕ МОДЕЛИРОВАНИЕ ГИДРОДИНАМИЧЕСКИХ ПРОЦЕССОВ В ГЕРОТОРНОМ НАСОСЕ СИСТЕМЫ СМАЗКИ ДИЗЕЛЬНЫХ ДВИГАТЕЛЕЙ

This article presents the results that serve as a methodological basis for creating a digital twin of a diesel engine lubrication system. At the first stage, mathematical and computer models have been created for the oil pump of the engine lubrication system. At the second stage, numerical modeling of hydrodynamic processes during pump operation has been carried out in order to verify and validate models based on experimental data. Next, a method of reverse engineering of pump performance characteristics is proposed, and its performance characteristic is constructed. Based on the calculations performed, recommendations have been developed to improve the accuracy of constructing mathematical and computer models of digital twins of a gerotor oil pump. Calculations were carried out for the pump with a modified design.

Calculations of Performance Characteristics of Submerged Cargo Pumps with Hydraulic Drive and Constant Torque Controllers, Taking into Account the Energy Efficiency of the Drive Motor

Submerged cargo pumps installed on board tankers are one of the most important components of their cargo system. As they are installed directly in the cargo tanks, they are usually equipped with a hydraulic drive whose power and capacity are controlled by constant-torque controllers. These have a significant impact on the technical and performance characteristics of the cargo pumps. This paper presents a methodology for calculating the performance characteristics of submerged cargo pumps, taking into account the energy efficiency of their hydraulic drive motors. Due to their number and power, the cargo pumps are powered from the ship’s hydraulic central loading system. This paper describes the main parts of the hydraulic power system structure and the functions of the constant torque controller of the STC type. A mathematical model has been developed to use the basic characteristics of submerged cargo pumps made for the base cargo (water) sent by the pump manufacturer for the case of handling liquid cargo with different parameters. The model considers the characteristics of the hydraulic drive, including a Bosch Rexroth A2FM type hydraulic drive motor and a constant torque controller. The results of simulation calculations of the performance characteristics of an example cargo pump are presented and compared with measurements of the characteristics of this pump on a product tanker. The mathematical model presented in this paper is of utilitarian value, enabling calculations to be carried out without the need for time-consuming CFD numerical methods, making it useful for port and fuel terminal logistics services, ship crews and services managing the operation of product tanker fleets.

A study on the internal vortex structure within a single-blade pump via numerical methods and particle image velocimetry experiments

This study investigates the performance and internal flow characteristics of a single-blade centrifugal pump through a comprehensive analysis integrating performance tests, Particle Image Velocimetry (PIV) tests, and numerical simulations. Across the operational speed range of 1470–2940 rpm, the predicted pump (head-flow rate curve)performance error between the numerical simulation results and the test results of the pump underrated flow conditions is found to be only 3.4%, demonstrating the high accuracy of the selected numerical method in predicting both performance metrics and internal flow structures. Key findings highlight the presence of significant circumferential and axial secondary flows in the region where the blade wraps back, resulting in the formation of high-intensity vortex structures and subsequent energy dissipation. The interaction of the blade's trailing jet with the volute casing's tongue induces periodic changes in the intensity and spatial size of these vortex structures. Furthermore, pronounced reverse vortex pairs are identified within the volute casing, attributed to axial non-uniformity in impeller outflow. These vortex pairs are associated with the preferential accumulation of solid particles, potentially contributing to wear in the volute casing of single-blade centrifugal pumps. The revelation of the evolution characteristics of vortex structure in single-blade centrifugal pumps provides theoretical support for reducing pressure pulsation and radial force of single-blade centrifugal and provides a potential solution to the technical difficulties of low efficiency and poor stability of single-blade centrifugal pumps. Overall, this study provides valuable insights into optimizing the design and operational efficiency of single-blade centrifugal pumps by elucidating their complex flow dynamics and performance characteristics under varying operational conditions.

Influence of staggered vane shunt plate on performance characteristics of reactor coolant pump

In order to explore the influence of the axial position of the shunt plate of staggered guide vane on reactor coolant pump(RCP), a mixed-flow RCP was taken as the model for numerical simulation. Based on the entropy production theory, the energy loss in the flow component under different flow conditions was analyzed, and the vortex core distribution in volute and the pressure pulsation at the hydrodynamic interface were studied. The results show the staggered guide vane reduces the head and efficiency slightly, the optimal scheme decreases by 0.9% and 0.6%. Placement of the shunt plate significantly influences entropy production within the guide vane and volute, especially when positioned near the front and back plates. When shunt plate is set centrally, the energy loss due to staggered guide vane is relatively smaller and closer to the original structure. The entropy production rate of guide vane inlet and shunt plate leading edge is higher, but with the increase of flow rate, the shunt plate leading edge is no longer the main location of energy dissipation. Middle placement of staggered guide vanes effectively reduces the outflow vortex band by Omega vortex analysis, and the amplitude of pressure pulsation at the interface decreases obviously.

Numerical Simulation and Model Test on Pressure Fluctuation and Structural Characteristics of Lightweight Axial Flow Pump

In order to explore the relationship between the hydraulic performance, pressure pulsation, and structural characteristics of lightweight axial flow pumps, this paper takes the axial flow pump as the research object and analyzes pressure pulsation and structural characteristics by changing the blade length and thickness to realize the lightweight design of the axial flow pump impeller. Compared with the initial scheme (Scheme 1), the mass of the impeller is reduced by 17.2% (Scheme 2) and 29.9% (Scheme 3), respectively. The lightweight axial flow pump (Scheme 2 and Scheme 3) has a lower pressure pulsation amplitude at the impeller outlet monitoring point under large flow conditions. After the lightweight design of the axial flow pump impeller, the blade becomes shorter, the mass becomes lighter, and the cavitation performance will become worse. The maximum equivalent stress of Scheme 2 and Scheme 3 is increased by 2.8% and 31.9%, respectively, compared to Scheme 1. The maximum deformation of Scheme 3 increased by 27% compared to Scheme 1. This research can provide guidance for the lightweight optimization design of the axial flow pump.

Influence of axial distance between impeller and diffuser on the hydraulic performance and flow loss characteristics of bulb tubular pump

Abstract Bulb tubular pumps used in regional water transfer projects consume substantial power. Optimizing the geometric parameters of tubular pumps is crucial for enhancing efficiency and minimizing hydraulic losses. ANSYS CFX is used to investigate the axial distance between the impeller and the diffuser on the hydraulic performance and flow loss characteristics of the rear-bulb tubular pump, and the numerical simulation results are compared with the experimental data. Then, the entropy production theory is introduced to analyze flow losses. As the axial distance increases, the diffuser’s rectification effect on the flow at the impeller outlet deteriorates, leading to increased flow losses and decreased head and efficiency of the device. Flow losses in the bulb tubular pump are ranked from largest to smallest as follows: impeller, outflow channel, diffuser, inlet channel. The impeller exhibits the highest entropy production ratio, reaching 61.05% at an axial distance of 25 mm. By elucidating the energy loss distribution of each component under varying axial distances, this paper offers insights for the hydraulic optimization design of bulb tubular pumps.

Experimental study on hydraulic performance and cavitation characteristics of a R134a refrigerant self-lubricating centrifugal pump

As the primary power equipment in pump flooding cooling systems, the efficiency and performance of mechanical pumps play a crucial role in two-phase cooling systems. A high-speed centrifugal pump with self-lubricating working fluid was designed with a speed of 7500 rpm and a flow coefficient of 0.0506. The hydraulic and cavitation performance of the pump were tested with R134a as the working fluid. The results show that the working fluid pump is capable of efficiently pumping R134a with an efficiency of 40.3 % and a head coefficient of 0.988 under the design condition. Within the tested range of inlet temperature from 5°C to 15°C, the flow coefficient from 0.01 to 0.105, and the height of the refrigerant tank from 1.4 m to 5 m, lower net positive suction heads available at the same flow rate will reduce the pump head, increase power consumption, and decrease efficiency. Increasing the pump speed from 3000 rpm to 7500 rpm can improve the pump's performance. At 6000 rpm, the critical cavitation number of the working fluid pump increases with the increase in flow coefficient. At 7500 rpm, the critical cavitation number has a minimum value when the flow coefficient φ = 0.0434. At the design speed and flow rate, both the critical cavitation coefficient and fracture cavitation number increase as the inlet temperature decreases. The inducer can significantly reduce the critical cavitation number of the pump. Finally, an empirical correlation considering the thermodynamic effects is proposed to predict the increase in the critical cavitation number.

Numerical analysis of performance and internal flow characteristics of a gas-liquid multiphase rotodynamic pump

Abstract Inlet Gas Void Fraction (IGVF) and rotating speed are key parameters influencing the flow characteristics of gas-liquid multiphase pumps. To explore the influence of these two factors on the flow characteristics of gas-liquid multiphase rotodynamic pumps, CFD simulations were carried out based on the Euler two-fluid model to analyze the flow characteristics in an axial-flow pump at three different rotating speeds (1450 r/min, 2200 r/min, 2950 r/min) with different IGVFs. The numerical results indicate that the pump efficiency and head are first increased and then decreased with the increase of IGVF. When the IGVF is 5%, the head and efficiency reach their maximum values. This is attributed to the minimum vorticity and turbulence kinetic energy in the impeller passage at IGVF= 5%, and the small vortex range at the hub of the guide vane, thus resulting in the stable two-phase flow state in the impeller and guide vane. At the same IGVF, with the increase of the rotating speed, the head and efficiency of the multiphase pump increase accordingly. This is closely related to the smallest vortex range formed by gas-liquid flow separation at n=2950 r/min, indicating a better flow state.

Unsteady Flow Behaviors and Vortex Dynamic Characteristics of a Marine Centrifugal Pump under the Swing Motion

Due to the effects of swing motion, the performances and internal flow characteristics of marine centrifugal pump undergo some unsteady variations in the marine environment. The hydraulic test system with six degree of freedom parallel motion platform is established to study the pump performance characteristics at the different heel angles of steady roll position and pitch position. The pump head gradually decreases as heel angle increases. The pump head has decreased by 7% to reach the minimum at the 15° heel angle of roll position. At the same heel angle, the head at the roll position is lower than that at the pitch position under the rated flow condition. The fluid in the impeller passage is subjected to the additional inertial force of roll motion or pitch motion under unsteady swing motion, inducing some flow bias phenomena in the velocity field. The unsteady development of flow velocity induces the intense vortex motion, and the shedding and dissipation of interblade vortices are affected. The periodic flow-induced pulsation characteristics obviously appear in the impeller passage. The pulsation periodicity and pressure amplitude are influenced due to the swing motion. The pitch motion induces the greater hydraulic excitation and fluid-induced vibration amplitude. In addition to the pressure pulsation at the low frequencies, the pulsation amplitude at 20 times the shaft frequency is evident under pitch motion.

Numerical prediction of passive speed and performance for multistage pump without power drive in natural flow process

With the development of engineering applications and the increase in system complexity, some particular fields, such as liquid rocket engine turbopumps, aircraft engine fuel systems, and marine natural flow cooling systems, are increasingly focusing on the performance characteristics of pumps under natural flow conditions. The pump is in the form of resistance components under natural flow conditions without a power drive. The impeller undergoes passive rotation by the impact of inlet flow. Due to the specificity of its operating conditions and performance indicators, the pump's natural flow performance cannot be evaluated by regular methods. Therefore, this paper proposed a numerical prediction method for pump natural flow performance based on a coupled computational fluid dynamics coupled with six-degrees-of freedom model. The performance of a multistage pump with guide vanes was evaluated under different natural flow conditions, and the accuracy was verified by experimental measurements. The transient variation mode of pump performance parameters with time at the initial stage of natural flow impact was analyzed. The flow field's transient evolution characteristics and the wall shear stress variation during natural flow were investigated. It was found that the impeller's passive rotational speed increases linearly with the natural flow rate, while the hydraulic loss shows an exponentially increasing trend. Meanwhile, the natural flow loss coefficient shows an exponentially decreasing trend and gradually tends to a stable value. The high turbulent kinetic energy inside the impeller is mainly distributed in the flow separation region and large velocity gradients. The distribution of shear stresses is closely related to the flow behavior inside the pump and the geometrical features of the hydraulic components.

Performance Prediction of Centrifugal Norm Pumps Operating as Turbines

Pump-as-turbines (PAT) has been widely used during the last decade as one of the most interesting technologies in the field of energy recovery. Many studies and papers have been published in which the performance of the pumps in the turbine operating regime were analysed. Since horizontal single stage centrifugal norm pumps are most commonly used as PATs, their performances are analysed in this paper. Most of the research was related to individual pump aggregates or smaller groups and to obtaining their performance curves in turbine random mode. In this work, extensive experimental, numerical, and theoretical investigations were conducted to obtain complete dimensionless performance characteristics of single stage centrifugal norm pumps operating as turbines. One of the goals was to form a simple analytical expression that will, for this type of aggregate, map the pump operating characteristic to the appropriate turbine operating regime. By using the expressions obtained and presented in the paperwork, engineers are enabled to make the appropriate choice of pump aggregate for operation in turbine random mode for potential locations. For this purpose, the procedure for choosing the appropriate PAT aggregate or parallel operation of aggregates and the analysis of their operation on the existing system are presented in the paper. This innovative procedure allows us to select quickly PAT aggregates for a potential location and carry out appropriate techno-economic analyses and analyses of possible energy savings.

Guide vane angle and reactor coolant pump performance during idling

In order to study the influence of different guide vane angle variation on performance characteristics of reactor coolant pump (RCP) during idling process, the external characteristics of RCP model with five different guide vane angles at idling process state were analyzed. Radial force characteristics and blade load characteristics of RCP were analyzed. The results show that the head and torque changes of pump with different guide vane angles in different idle period are consistent. The head of DY1model (Guide vane angle increases sharply first and then decreases gently, which convexity is large) is the highest and torque is small. The head drop rate of DY5 model (Guide vane decreases first and then increases, and the concavity is large) is the highest and torque is the largest. With the idling, the radial force of impeller and guide vane decreases gradually. The radial force of DY5 model impeller is small and the fluctuation range is weak. The radial force of DY4 model (Guide vane shows concavity change with gentle increase) impeller before idling is the largest. In the nonlinear transition of idle period, the total radial force of DY4 model is 235 N when idling for 32 s, which is nearly 30 times lower than that before idling, and the radial force decreases the most. In different idling periods, the radial force amplitude of guide vane of DY5 model is the largest, and the radial force decrease amplitude of guide vane of DY4 model is the largest in the whole idling period. The impeller blade load of DY4 and DY5 model pumps with concavity guide vane angle change law is significantly higher than that of other model pumps after the relative position of streamline is 0.6. When the relative position of the guide vane along the streamline direction is less than 0.5, the load fluctuation of the guide vane of each model pump is large. When the relative position is greater than 0.5, the blade load fluctuation is relatively small.

Centrifugal pump performance improvement using back cavity filling

Centrifugal pumps consume majority of energy used by the electric motor driven systems among all end users of the industrial sector. Only in European region, a 1% improvement in efficiency (η) of the centrifugal pump is capable enough to reduce CO2 emissions by at least 572 tons per day. The prime motive of this research is to assess the applicability of the novel back cavity filling (BCF) in reducing the disk friction losses of centrifugal pumps without changing the pump's original design. By adding a solid ring to the bearing housing's back-cover plate, the BCF was applied to a medium specific speed pump (Ns = 54 rpm), resulting in a 1 mm back axial clearance from 13 mm. Numerical simulations and experiments were carried out to investigate the effect of BCF on pump performance under two conditions: with and without BCF at best efficient point (BEP) and various partload conditions for 1450 rpm (rated) as well as 1000 rpm. Pump performance characteristics were enhanced by BCF at both rpms for the whole flow rate range. At 1450 rpm, BCF resulted in an average 0.74% increment in total head, 2.08% reduction in input torque, and 2.70% increment in overall efficiency over the flow rate range. While an average 2.04% improvement in total head, 1.33% reduction in input torque, a 3.30% enhancement in overall efficiency were obtained at 1000 rpm. Performance parameter enhancement was higher at lowest part load compared to the BEP on rated rpm.

토출유량변화에 따른 배수용 수중펌프 성능 특성에 대한 해석적 연구

Abnormal weather owing to climate change has become commonplace. Large and small floods have steadily occurred annually, increasing damage owing to flooding of agricultural land. Recently, owing to torrential rain, three of four rainwater pumping stations installed in Cheongyang-gun, Chungcheongnam-do, had failed to operate properly, thereby flooding several buildings and facility houses. In this study, an analytical study was conducted on the performance characteristics of centrifugal submersible pumps according to changes in the discharge flow rate. The results confirmed that the efficiency of the submersible pump for the experiment and analysis was within ±3.4% with the discharge flow rate.

Maximized thermal energy utilization of surface water-source heat pumps using heat source compensation strategies under low water temperature conditions

Surface water-source heat pumps (SWHPs) are expected to replace conventional cooling and heating systems owing to their high energy efficiencies. However, the risk of freezing during heating operations makes it impossible to operate SWHPs when the surface water temperature approaches the freezing point. Accordingly, this study proposes a heat source compensation operation for maximizing the use of the water's thermal energy, allowing the SWHP to use the thermal energy storage as a supplementary heat source at low river water temperatures. The performance characteristics of a compensation-based water-source heat pump (CWHP) and hybrid compensation-based water-source heat pump (HCWHP) are analyzed using a transient simulation tool under various operating conditions. Their environmental and economic performances are also analyzed and compared with those of a conventional cooling and heating system (CCHS) based on water temperature measurements of the Han River in South Korea. As a result, the CWHP shows a 10.6 % lower lifecycle climate performance and 20.2 % lower lifecycle cost (LCC) than the CCHS. The HCWHP exhibits the lowest greenhouse gas emissions in all periods but shows a 19.5 % higher LCC than the CWHP.

Unsteady Cavitation Analysis of the Centrifugal Pump Based on Entropy Production and Pressure Fluctuation

A numerical method using combined detached-eddy simulation (DES) and a cavitation model considering the rotation effect is used for unsteady cavitation flow field of the centrifugal pump. A closed-type pump test system was established to obtain the pump performance and pressure pulsation characteristics under different flow rates and cavitation condition, which provide boundary conditions and verification of calculations. Based on the calculation results of the unsteady flow field of the centrifugal pump cavitation, the entropy generation analysis of the flow field and an analysis of the pressure fluctuation characteristics were carried out. Then, we tried to reveal the relationship between cavitation and the deterioration of the centrifugal pump performance and the generation of the unstable operation excitation force. The internal energy loss is mainly concentrated in the impeller, volute, and pump cavity area, which accounts for more than 85% of the total entropy generation. The characteristic frequency of a Strouhal number of about 0.333 appears at the volute tongue due to the cavitation flow spread downstream.

Research on the Performance Characteristics and Unsteady Flow Mechanism of a Centrifugal Pump under Pitch Motion

Pitch motion is the key factor affecting the performance characteristics of centrifugal pumps on board ships and exacerbates hydraulic excitation to induce the unsteady vibration of pump units. A hydraulic test platform with swing motion is established to explore the effects of pitch motion on a pump’s performance characteristics. An obvious hump zone exists in the head characteristic curve in the low-flow-rate condition due to the pitch motion. The pump head in the shut-off condition has a significant decrease due to the pitch motion, compared to the static state. The head decrease gradually increases as the maximum pitch angle increases or the pitch period shortens. Specifically, the head in the rated flow condition decreases by 6.3 % to reach a minimum at the maximum pitch angle of 20 degrees in a period of 5 s. Based on a multiple-reference coordinate system, a large eddy simulation with a shear-modified eddy viscosity model is employed to simulate inner flow characteristics under the influence of pitch motion. A distinct vortex flow appears near the blade suction surface and becomes increasingly turbulent as the pitch period shortens. The pitch motion intensifies the unsteady stretching and deformation of vortices. The periodic variations in fluid-induced pressure over time present parabolic features, and the amplitude in the frequency domain reaches its maximum value within a pitch period of 5 s.

Impeller design and performance characteristics of a side channel pump

Flow non-uniformity inherent at the impeller passages is realized to have pronounced effects in hydraulic pumps, which leads to severe operational challenges. Cutting the blade tip has emerged as a research hotspot, which is deemed to be a feasible and viable approach to mitigate flow-induced problems. Therefore, this paper reveals more insight into the inner flow phenomena in a side channel pump under different impeller geometry. First, five models of impeller blades are designed with different tip cutting angles ranging from 10° to 50°. Based on the experimental data and the reliable shear stress transport k-ω model, the turbulent flow nature of the pump was established by numerical simulations. The performance curves revealed that impeller model 2 attained the highest efficiency of 37.13% at the best efficiency point, although registering 26.9% and 32.9% at part-load and over-load conditions, respectively. At over-load conditions, the efficiency of model 2 improved by 3.46%, 3.13%, 2.21%, and 8.72% compared to models 1, 3, 4, and 5, respectively. The pressure distribution at the impeller passage was higher compared to the side channel of all the impeller models. Noticeably, each type of vortex structure occupies nearly all the impeller passages of the impeller models justifying the complicated flow in the side channel pump. Impeller models 1, 2, and 3 produced better flow exchanges with the higher mass flow in and out, hence stimulating improved energy conversion. The conclusion can provide a physical foundation for designers in selecting a reasonable tip angle for specific tasks from engineering perspectives.