Performance Characteristics Of Pump Research Articles

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.

Влияние масштабирования на энергоэффективность нефтяных насосов

Multistage centrifugal oil pumps have been used in oil production for about a century. The design of their stages has not changed for a long time, only the geometric dimensions vary, which still makes it possible to improve the performance characteristics of pumps. One of the widely used methods of changing the geometric dimensions of the stages is the scaling of stages to other dimensions. Pres-sure and flow characteristics of scaled stages are recalculated by similarity criteria and practically coincide with the results of bench tests. The efficiency of stages scaled from larger to smaller di-mensions is always lower than that of the original stages. The purpose of this work was to establish the reasons for this phenomenon. The influence of such factors as the flow channel roughness, leak-age and disk friction was evaluated. It is shown that roughness and leakage are the determining fac-tors. The similarity method showed that as a result of scaling the effect of roughness can be reduced and even compensated by increasing the shaft speed, which was confirmed by calculations and bench tests.

Performance Testing of Centrifugal Pump Type with 3 Hp Power

Pumps are fluid machines whose uses are very broad and important, ranging from industry to household needs. Selection of pump performance characteristics is very important and must be adjusted to the needs which include: discharge, head, power, and rotation. The performance characteristics of the pump are obtained through testing. In connection with the importance of information about pump performance characteristics, through this research activity efforts will be made to test centrifugal pumps using 3 hp of power. In this research, the data obtained from the direct test results will be entered, where the test is carried out at the Machine Performance Test Laboratory. In this test, the pump pressure data obtained from the gauge gradually with several valve openings, then the data is entered into the data table that has been prepared. The test was carried out to test the ability of the centrifugal pump test equipment using 3 HP power which was prepared as one of the laboratory pump test equipment for engine performance testing. In testing the centrifugal pump there are 3 variables that will be used to carry out the test, namely the first by using a tachometer which is useful for measuring shaft rotation, the second by using a Bordoun manometer which is useful for measuring fluid pressure, the third by using an orifice which functions to measure speed fluid.

Comparative Analysis of the Environmental Load of Natural Refrigerant (R290)

Due to the detrimental environmental consequences of synthetic refrigerants, natural refrigerants have gained renewed interest as alternative refrigerants for a variety of applications due to their minimal ozone depletion potential (ODP) and insignificant global warming potential (GWP). This study compares the performance characteristics of R32-based Air Source Heat Pump (ASHP) to those of R290 and R410A refrigerants. In this study, analyses of the cooling effect, heat output, compressor work input, and coefficient of performance (COP) for various refrigerants will be undertaken. Additionally, the environmental consequences of R32, R410A, and R290 are discussed. The results indicate that R290 is the most efficient refrigerant in terms of performance coefficient, followed by R410A and R32. Considering environmental protection aspects, R290 is a favorable substitute medium.

Experimental investigation on heating performance of a gas engine-driven heat pump system with R410A

• A novel energy-efficient GHP experimental platform is designed based on scroll compressors with R410A. • The effects of five factors on heating performances of the GHP system are systematically investigated. • The mode-4, which only recovers waste heat using the heating water, can improve the heating performance of the GHP system. • In mode-4, the PER is between 0.981 and 2.155, and the rate of waste heat recovery is between 49.12 % and 77.70 %. In this study, the performance characteristics of a gas engine-driven heat pump (GHP) system for heating applications were experimentally investigated. A novel energy-efficient air-source GHP experimental platform was designed based on scroll compressors with R410A. The changes in heating capacity ( Q h ), gas consumption power ( P gas ), compressor power ( P comp ), primary energy ratio ( PER ), and coefficient of performance ( COP ) were obtained under varying conditions of condenser water flow rate G w (6.10–15.25 m 3 /h), water inlet temperature t w,in (24.0–44.2 ℃), engine speed N eng (1200–2400 r/min), and ambient air temperature T amb (−15–7 ℃). The performances of the four heating modes (mode-1 to mode-4) were compared at an ambient air temperature of −20 ℃. The results showed that t w,in , N eng , and T amb had significant influences on heating performance, whereas G w had a slight impact. Compared with other heating modes, mode-4, wherein the recovered waste heat was only transferred to the heating water, could improve the heating performance of the GHP system. In the mode-4 heating experiments, PER was between 0.981 and 2.155, the rate of waste heat recovery was between 49.12 % and 77.70 %, and the engine thermal efficiency was between 27.02 % and 33.24 %.

Effects of a Detached Eddy Simulation-Curvature Correction (DES-CC) Turbulence Model on the Unsteady Flows of Side Channel Pumps

A side channel pump is a pump with a high head and a small flow that is widely used in various industrial fields. Many scientists have studied the hydraulic performance, pressure fluctuation characteristics, and gas-liquid mixed transport characteristics of this type of pump. However, these studies mainly focused on the single-stage impeller of the side channel pump, without considering the inter-stage connection channel and the multistage timing effect. These characteristics affect the hydraulic performance and pressure-pulsation characteristics of the side channel pump. Therefore, we carried out a numerical simulation and an experimental comparison on the multistage side channel pump to explore its flow characteristics during the stages. This study focused on the influence of different turbulence models on the numerical simulation of multistage side channel pumps. Shear stress transport (SST), detached eddy simulation (DES), and detached eddy simulation-curvature correction (DES-CC) turbulence models were selected for consideration. By studying the pressure and velocity streamline distribution, the turbulent kinetic energy, and the shape and volume of the vortex core area simulated by the three models, we concluded that the DES-CC model, when compared to the other models, can more fully reflect the vortex characteristics and the simulation results that are closer to the experimental data. The results of this study can be used as the basis for future research on multistage side channel pumps.

Optimal compressor discharge pressure and performance characteristics of transcritical CO2 heat pump for crude oil heating

The compressor discharge pressure is an important parameter for optimizing the performance of a transcritical CO2 heat pump system. In this study, the factors influencing the optimal compressor discharge pressure of an air source transcritical CO2 heat pump system were examined experimentally. The results showed that the optimal compressor discharge pressure is affected by the gas cooler water inlet temperature and gas cooler CO2 outlet temperature. Consequently, a correlation formula for the optimal compressor discharge pressure appropriate for a more comprehensive temperature range and higher prediction accuracy was determined based on the experimental data. Compared with the experimental results, the maximum error was less than 10%, which is minor considering the lower gas cooler CO2 outlet temperature. In addition, a control strategy for the optimal compressor discharge pressure based on the degree of superheat correction was proposed. Subsequently, under variable operating conditions, the air source transcritical CO2 heat pump crude oil heating system was continuously operated based on this control strategy. The results showed that the compressor discharge pressure agreed with the optimal compressor discharge pressure calculated using the new correlation formula. Compared with the control strategy of constant opening under a variable frequency mode, the results showed that the system could operate under the control strategy proposed in this paper, the thermodynamic perfection of the system being higher.

Optimization Design for the Centrifugal Pump under Non-Uniform Elbow Inflow Based on Orthogonal Test and GA_PSO

The non-uniform inflow caused by the elbow inlet is one of the main reasons for the low actual operation performance of a centrifugal pump. Orthogonal experiment and GA_PSO algorithm are used to improve the head and efficiency of a centrifugal pump with an elbow inlet based on the method combining numerical simulation and prototype experiment in this paper. The effects of the design parameters, including elbow inlet radius ratio, blade inlet angle, blade number, blade wrap angle, blade outlet angle, impeller outlet diameter, blade outlet width and flow area ratio, on the pump head and efficiency are studied in the orthogonal experiment. The blade inlet angle is the major factor to match the non-uniform inflow and reduce the flow loss in the impeller inlet to contribute to enhancing the pump performance and cavitation characteristics. The particle swarm optimization (PSO) algorithm is optimized by integrating the genetic algorithm (GA), which ensures that the PSO-calculation result avoids falling into the local optimization and the global optimal solution is obtained as quickly as possible. The centrifugal pump with an elbow inlet is optimally designed by the GA_PSO algorithm. According to the performance test results, the efficiency of the optimized pump is 4.7% higher than that of the original pump.

Energy performance and flow characteristics of a slanted axial-flow pump under cavitation conditions

Cavitation is a complex flow phenomenon that hinders the efficient, safe, and stable operation of hydraulic machinery. To investigate the effect of cavitation on energy performance and flow characteristics of hydraulic machinery, cavitating flow in a slanted axial-flow pump based on entropy production theory and vortex dynamics is studied. The results show that the impeller chamber is a primary region of cavitation and energy loss generation under different cavitation conditions, including the incipient, growing, and wedge-shaped cavitation stages. In the incipient cavitation stage, as degree of cavitation strengthens, the flow at the impeller blade is smooth with little cavitation, and the variation in entropy production is constant, resulting in a stable energy performance. As it evolves into the wedge-shaped stage, the cavitation grows from the tip region near the impeller blade to the hub. At this time, the entropy production increases in the impeller chamber, resulting in a drop in energy performance. Meanwhile, flow separation appears at the impeller blade, and a secondary tip leakage vortex is promoted. The region with high vorticity basically matches the region with the high local entropy production rate. According to the relative vorticity transport equation, compressibility of cavitation strongly affects the relative vorticity in the impeller chamber, indicating that cavitation indirectly increases entropy production and energy loss by affecting the vorticity distribution, resulting in the drop in energy performance.

Study on fluid dynamic characteristics of a low specific speed centrifugal pump with emphasis on trimming operations

In the present investigation, the fluid dynamic characteristics of a narrow channel centrifugal pump are studied using numerical simulations with special emphasis on pump trimming operations. The trimming operations at optimized rate, reduce the pressure fluctuations and hydraulic noise in pumps, but at the cost of pump performance characteristics. This has been extensively studied by the researchers in the past; however, the efficacy of trimming operations on industrial pumps with narrow channel passage impellers is to be explored. A low specific speed pump with narrow channel impeller passage and radial discharge volute (M1) with specific speed of 14.7 is considered for the present investigation. Detached Eddy Simulation (DES) is used in transient simulations and Fast Fourier Transform (FFT) is used to understand the pressure fluctuations and hydraulic noise at the Blade Pass Frequency (BPF) and its harmonics. The pressure fluctuation behavior along the impeller periphery is monitored at 30 equidistant probes and 7 probes covering the volute tongue. These results are compared with the similar study for impeller with oblique trimming of 30° (M2) and impeller oblique trimming along with volute trimming (M3). The flow behavior in M1 is dominated by a Jet-wake flow in the impeller passage which acts as a primary source of flow non-uniformity. The resulting non-uniform flow on the impeller periphery interacting with the volute tongue causes vortex shedding behind the volute tongue, subsequently leading to discharge recirculation in the impeller. The coefficient of pressure fluctuations near volute tongue at BPF is reduced by 10.3% in M2, whereas it is enhanced by 24% in M3 relative to M1. The enhanced vortex shedding behind the volute tongue in addition to the vortex train along the impeller periphery causes rise of the pressure fluctuations in M3.

Investigation on performance in water jet pump under turning conditions

Turning has a significant effect on the performance of water-jet pump. Here, the axial flow water-jet pump was used as the research object, the performance and inner flow characteristics of water-jet pump under different turning angle were simulated through numerical simulation. The thrust, vorticity, bubbles in impeller, vapor volume fraction and surface load of blade were analyzed in detail when the turning angles were ±10°, ±20°, and ±30°, respectively. The results demonstrate that the thrust of the water-jet pump decreases linearly with the increase of the turning angle. At the same angle, the thrust of the water-jet pump when turning right is larger than that when turning left, and the maximum thrust difference is 9.14% of that without the turning angle. As the turning angle increases, the overall pressure of the water-jet pump decreases and the streamline distribution gets turbulent gradually. The vortex direction is the same as the turning direction basically. And the vortex distribution range is smaller when turning right under the same turning angle. The cavitation bubbles in the impeller occur firstly at the rim of the blade inlet and develop to the middle of the blade as the turning angle increases. The cavitation area is concentrated on the blade at turning side and the cavitation area when turning right is smaller than that when turning left.

Theoretical performance characteristics of a travelling-wave phase-change thermoacoustic heat pump

Thermoacoustic technology is a promising approach for environmentally-benign, low-cost heat pumping. Herein, we present a theoretical investigation on phase-change thermoacoustic heat pumping employing both an ideal model (a short heat pump in a pure travelling-wave field), as well as a full-size, looped-tube thermoacoustic heat pump. In the analysis of the short heat pump, we identified and assessed the main factors and their influence on the performance of an ideal phase-change travelling-wave heat pump. The results show that, ideally, the cooling power can be significantly increased by up to one order of magnitude, and the COP (coefficient of performance) can also be improved by the incorporation of phase change into the thermoacoustic cycle. Meanwhile, the analysis of the full system provides a more practical view of the enhancement due to phase change. A significant increase of cooling power is observed in the phase-change system with a high concentration of the reactive component, but increased of the COP only occurs under small temperature differences (below 10 K). The main reason for the gap in observed performance between the ideal model and the full system is the deviation, under a large temperature difference, of the acoustic field from the requirements for effective enhancement, as revealed in the ideal model. Our results demonstrate the potential of the phase-change travelling-wave thermoacoustic heat pump for efficient and low-cost heat pumping, especially for small temperature difference applications.

Investigation on the Effect of Impeller Design Parameters on Performance of a Low Specific Speed Centrifugal Pump Using Taguchi Optimization Method

In order to investigate the effect of blade design on pump performance, a CFD analysis was carried out, and the results were compared with experimental performance data of a low specific speed radial pump, which presents a good agreement. After model verification, the effect of impeller geometrical parameters includes blade outlet angle, wrap angle, and width at the exit, was investigated on the pump’s performance. Moreover, these parameters were chosen on three levels using an L9 orthogonal standard array of the Taguchi optimization method. The efficient levels of variables were calculated using the analysis of variance (ANOVA) method. The results revealed that impeller width at exit and blade outlet angle is the most effective pump shaft power and efficiency parameters. To minimize power, the optimal levels are the outlet angle of 27∘∘, wrap angle of 150∘∘, and width at the exit of 9 mm. Further, an outlet angle of 23∘∘, a wrap angle of 155∘∘, and a width at the exit of 9 mm lead to maximum pump efficiency. According to the validation simulations, an increase of 2.4% inefficiency and a minimum power of 3.9KW were achieved. The Overall Evaluation Criteria (OEC) technique revealed that considering 23∘∘, 160∘∘, and 9 mm for outlet angle, wrap angle, and width at the exit, minimum shaft power, and maximum pump efficiency will be achieved. ANOVA introduced width at the exit as the most governing parameter of pump performance characteristics.

Experimentally determined effect of swirl on the performance of a rotodynamic pump

Pre-swirl in the approach flow towards a pump leads to a decreased efficiency or even to malfunctioning of a pump. Especially for pumping stations with large rotodynamic pumps, the risk of malfunctioning should be minimized. For this reason, hydraulic investigations are performed prior to the construction of pumping stations to assess the amount of pre-swirl in the approach flow and if needed, to design local measures to decrease it. This article presents a test set-up of a simplified pump sump in which the pump performance characteristics are measured at a real pump for a wide range of predefined corotating and counterrotating swirl angles. The swirl angles are measured in a transparent model pump at scale 1:1 with a swirl meter at four bell diameters above the bell-mouth. The findings discussed in this paper provide insight in the relation between pre-swirl in the approach flow and pump performance.