Vertical Pump Research Articles

Investigation on flow instability in the hump region of the large vertical centrifugal pump under cavitation conditions based on proper orthogonal decomposition

Investigation on flow instability in the hump region of the large vertical centrifugal pump under cavitation conditions based on proper orthogonal decomposition

Study on flow characteristics and structural properties of vertical axial pump with low guide vane height

Abstract With the full construction of the South to North Water Diversion Project and the renovation of pumping stations, vertical axial flow pump devices have been widely used in various pumping station projects. This article uses the streamlined method to design the impeller and guide vanes of a vertical axial flow pump device. To analyze the hydraulic and structural characteristics, this paper uses CFD numerical simulation and fluid-structure interaction calculation methods. And the trend of output power change under different flow conditions was divided into three stages, elucidating the reasons for the sudden change in output power under flow conditions of 0.8Q-1.0Q. This article focuses on analyzing the internal flow state of the designed lower height guide vane segment to explore the problem of low guide vane height that is prone to occur during the design process. According to the research results, it is found that the lower height guide vane can also play a good role in stabilizing flow and recovering circulation under certain operating conditions. This article also studied the structural characteristics of the impeller and guide vanes, explaining the stress and strain distribution under design flow conditions.

Study on the impact of turbulent spatiotemporal propagation in the outlet passage on the performance of vertical axial flow pumps.

Abstract Pumping station engineering is crucial for our country’s national economy as a part of water conservancy infrastructure. The vertical axial flow pump commonly used in pumping station construction features a high flow rate and low discharge pressure. Understanding the impact of turbulence on the flow of water entering and leaving the pump unit is crucial for the efficient and reliable operation of a pumping station. This paper examines the internal flow and hydraulic characteristics of the device for vertical axial flow pump at a pumping station through numerical simulation technology and experimental validation. It is inferred that turbulent flow develops in the outlet flow passage while the pump device is currently functioning, impacting the impeller’s outlet bend and guide vane. This leads to the formation of vortices, backflow, and folding flow at the guide vane and outlet bend. As water flows out through the outlet passage, bias and backflow develop, causing erosion on both sides of the outlet pool and impacting the pump unit’s overall head and efficiency.

Modal Analysis and Optimization of Fluid-Structure Coupling for Rotor and Inner Cylinder of Vertical Condensate Pump

Background: Low-frequency resonance is one of the common issues encountered during the variable-frequency operation of condensate water pumps. There have been numerous patents and papers proposing solutions to address the low-frequency resonance problem in condensate water pumps. However, the solutions for resonance problems often need to be tailored to specific circumstances. Methods: Based on the acoustic method, the dynamic model of the rotor and inner cylinder of Jiangsu Guohua Chenjiagang Power Plant 2B condensate pump is established to compare the difference between dry modal and fluid-structure coupling modal, the influence of perpendicularity, concentricity and bearing wear on the natural frequency of rotor is studied. Results: The rotor is rigid under normal conditions. When the bearing is worn, the frequency of the rotor will be greatly reduced and may fall into the frequency conversion operation range to excite resonance. The deviation of perpendicularity and concentricity will not directly lead to the decrease of rotor modal but will lead to the increase of bearing stress, aggravate bearing wear, and then affect the rotor modal. As the inner cylinder only relies on the fixed support at the top, the structure stiffness is low, which may lead to low-frequency resonance. By adding two support structures at the guide vane, the first-order modal frequency of the inner cylinder can be increased from 3.29 Hz to 28.88 Hz, effectively avoiding the operating frequency range of the system. Conclusion: This study can guide the optimization of similar pump structures.

The Influence of Pre-Lift Gate Opening on the Internal and External Flow Characteristics During the Startup Process of an Axial Flow Pump

This paper focuses on a vertical axial flow pump and employs a 1D-3D coupling method to investigate the effects of different gate pre-opening angles on the internal and external flow characteristics of the axial flow pump during startup. Through comparative analysis, the following conclusions are drawn: In the study, a fully open gate is defined as 1, while a fully closed gate is defined as 0. When starting the axial flow pump with different valve pre-opening degrees, backflow occurs within the first 20 s of startup, and the backflow rate inside the pump gradually increases with the increase in the valve pre-opening degree. At a valve pre-opening degree of 0.6, the maximum backflow rate inside the pump reaches 5.89% of the rated flow rate. When starting the pump with the valve fully open, the maximum backflow rate reaches 10.98% of the rated flow rate, and the efficiency is affected by the backflow rate. The valve pre-opening degree has little impact on the axial force acting on the impeller during startup. When starting with a valve pre-opening degree of 0.6, the internal pressure difference in the pump is minimized. Within the first 20 s of startup, the internal pressure difference in the impeller is 28.96% higher and the flow velocity is 14.62% higher with valve pre-opening degrees of 0.8 and 1.0 compared to a 0.6 degree opening. During the initial stage of pump startup, with valve pre-opening degrees of 0.8 and 1.0, the pressure fluctuation amplitude inside the pump is minimal, with maximum relative amplitudes of only 0.621 and 0.525, which are 41.00% and 28.51% lower than the maximum amplitudes at 0 and 0.2 degrees, respectively. In summary, the peak pressure inside the pump is minimized when the valve pre-opening degree is around 0.8, while the pressure difference and flow velocity are relatively lower at a pre-opening degree of 0.6. It is recommended to start the pump with a valve pre-opening degree of around 0.6 to 0.8.

Regional-Scale Assessment of the Potential for Shallow Geothermal Energy Development Using Vertical Ground Source Heat Pumps

Shallow geothermal energy (SGE) is a widely prevalent geological resource underground, and its utilization offer significant energy conservation and emission reduction benefits, contributing to the achievement of carbon neutrality goals. Assessing the development potential of regional SGE can ensure sustainable development of these resources and prevent adverse effects induced by overexploitation. Jiangsu Province, a developed region in the eastern coastal area of China, has a strong demand for cooling and heating in urban buildings. The primary form of utilizing SGE in this area is through vertical ground source heat pumps (VGSHP). Based on the analysis of the impact of regional geological conditions on the development of SGE, this study specifically evaluated the suitability of developing SGE through VGSHP. After excluding areas unsuitable for development, the heat exchange capacity, heating or cooling area per unit area, and energy conservation and emission reduction benefits of VGSHP were calculated. The results indicate that the area suitable and moderately suitable for developing SGE through VGSHP in Jiangsu Province amounts to 76,453 km2. The total heat exchange capacity for summer is 1.21 × 109 kW, which can provide cooling for an area of 1.21 × 1010 m2. The total heat exchange capacity for winter is 8.70 × 108 kW, which can provide heating for an area of 1.09 × 1010 m2. The annual available resource amount is 2.68 × 1012 kWh, equivalent to 3.30 × 108 tons of standard coal, and a CO2 reduction of 7.86 × 108 tons.

Internal flow stability analysis of vertical mixed-flow pump device based on EGT and FFT

With the purpose of researching the internal flow stability of the vertical mixed-flow pump device (VMFPD), the entire flow field was solved through the very large-eddy simulation (VLES) k- ω model and the internal flow characteristics of the pump device were quantitatively analyzed with the use of the energy gradient theory (EGT) along with the physical parameters of the flow field. The research elucidates the variety rule of the pressure along the VMFPD and the energy gradient function K as well as the time-frequency features of the pressure pulsation (PP) in the impeller and guide vane. The results demonstrate that the solid wall restriction of the guide vane and the impeller rotation cause a significant shift in the velocity and direction of the water flow. This causes a significant pressure difference between the water bodies, which makes it easier to create an unstable flow. The suction surface of the impeller blade possesses the great concentration of the area with energy gradient function K > 107, which is the critical area influencing the internal flow stability of the pump device.

Study on the Transition Process of Normal Shutdown of Large Vertical Submersible Mixed Flow Pump Unit

_ Water pump units are essential in water conservation projects. Axial flow pumps, crossflow pumps, and mixed-flow pump units are commonly implemented in new pumping station projects. The technology related to water pump units has been substantially developed in recent years. Nonetheless, the large vertical submersible mixed-flow pump unit is still considered a relatively novel pumping station unit. The operational status of a submersible pump unit can be influenced by the gate or flapper door of the outlet during its startup and shutdown process. During this process, the pump speed, flow rate, and other external characteristic parameters of the unit undergo significant changes in a short time period. The appearance of unstable flow phenomena, such as flow separation and vortex, inside the unit has a significant impact on its safety and stability. Hence, studying the normal shutdown process of the pump unit is essential to investigate factors influencing the unit’s stability. This paper presents a numerical simulation and analysis of the normal shutdown process of a large vertical submersible mixed-flow pump unit. Analysis of the results revealed that the “backflow” phenomenon of water flow occurs during all four cases of the normal shutdown transition process. The unit’s operating conditions are largely determined by the closing time of the flapper door. The unit will experience runaway conditions when the flapper door’s closing time is longer (4 seconds). Keywords vertical submersible mixed flow pump; normal shutdown process; numerical simulation

Optimizing vertical pump reliability: Investigating main shaft challenges through integrated design and testing strategies

ABSTRACT Vertical pump systems are vital in industries like water treatment, power generation, and oil and gas production. Their efficiency depends on well-designed components, especially the main shaft connecting the motor to the pump impeller. Changes in shaft length greatly impact vibration, structure, and overall performance. Therefore, thorough evaluation of shaft length modifications is crucial for ensuring equipment suitability and long-term reliability. This study examines how changing shaft length in a vertical pump system, from 70 cm to 170 cm due to construction constraints, affects its performance. Using Finite Element Analysis (FEA), the study evaluates both shaft designs’ natural frequencies, critical speeds, and maximum stresses. Results reveal that the 170 cm shaft design is unsuitable, leading to increased stresses and a higher risk of vibration-induced failures compared to the original design. These findings stress the importance of controlling design parameters and conducting thorough analyses before implementing modifications to ensure reliability and operational stability. Unplanned design changes like shaft length modifications can severely impact pumping equipment performance, emphasizing the need for careful consideration and analysis prior to implementation. This research emphasizes the importance of considering shaft length in the design of vertical pump systems to ensure reliability. The findings offer valuable insights for engineers and designers to maintain long-term operational stability and performance. Ultimately, this improves safety and efficiency in industrial and municipal processes reliant on these pump systems.

Comparative carbon emission assessment of vertical and modular ground source heat pump systems

The urgent need to address climate change necessitates a reduction in carbon emissions, particularly within the building sector. To achieve carbon neutrality, innovative technologies such as carbon capture, renewable energy systems, and carbon-neutral materials have been developed. However, there remains a dearth of research quantitatively analyzing carbon emissions through a life cycle assessment while implementing these technologies in real-world building scenarios. Additionally, Ground-source Heat Pumps (GSHPs) demonstrate superior efficiency compared to Air-source Heat Pumps (ASHPs) by leveraging stable ground temperatures, yet their widespread adoption is hindered by high initial investment costs. This study compares and analyzes the carbon emissions of GSHPs with Modular Ground Heat Exchangers (MGHXs), designed to mitigate initial investment barriers, alongside Vertical Ground Heat Exchangers (VGHXs) and ASHPs. The primary objective is to evaluate technology adoption feasibility from a carbon equivalent perspective, focusing on energy demand through building energy simulation. Results indicate that MGHXs exhibit a 6.7 % reduction in carbon emissions compared to VGHXs during production and construction (stage A). However, MGHXs generate 0.57 CO2-eq more per square meter per year during building operation (stage C). The implementation of geothermal energy systems in new buildings across South Korea could potentially achieve a maximum reduction effect of 11.6 % concerning the country's NDC (Nationally Determined Contributions) 2030 carbon reduction target.

Test and analysis of energy characteristics of large vertical submersible pumps

The efficiency of the pump device is an important parameter to judge the overall dynamic performance of the pumping station. The commonly used method at home and abroad is to carry out model tests of the pump device. The performance parameters of the prototype pump and pump device are obtained by the similarity conversion formula. However, at present, there are not many device model tests for large vertical submersible pumps. Taking a large vertical submersible mixed-flow pumping station in China as an example, research predicted the performance of the pump device through a model test and a submersible pump prototype test. The results show that the model test of the large vertical submersible mixed-flow pump device has a maximum efficiency of approximately 77.8%, and the prototype test conversion device has a maximum efficiency of approximately 80.33%. The device model test and the pump factory prototype test results are compared. It is found that the performance parameters of the pump measured by the prototype test are in good agreement with the device model test under the design conditions, and there is a certain error when the deviation from the design conditions is significant. The device model test and the factory test of the pump are indispensable in the large-scale road of submersible pumps, and a large number of tests are needed to sum up the experience.

Effect of Splitter Blade on Suction Performance of Vertical Multi-stage Centrifugal Pump

Effect of Splitter Blade on Suction Performance of Vertical Multi-stage Centrifugal Pump

Investigation on passive suppression method of hump characteristics in a large vertical volute centrifugal pump: Using combined diffuser vane structure

The hump characteristic is one of the unique hydraulic instability of the large vertical volute centrifugal pump (LVVCP) under part-load conditions, which is extremely detrimental to the safe and stable unit operation. To suppress the hump characteristic of LVVCP, a passive suppression method with a combined diffuser vane structure is proposed in this paper. This diffuser vane structure consists of a combination of large and small hydrofoil vanes, with the special 6 small hydrofoil vane B are arranged within 150° range of the small volute section side. To investigate the key reasons for suppression, detached eddy simulations are performed for LVVCP with original diffuser vane (Diffuser A) and combined diffuser vane (Diffuser B), and the energy loss and flow patterns are analyzed. The hump region of LVVCP with Diffuser B is narrower, the positive slope of Q-H curve is decreased and the hump margin is increased. The reduced conversion of kinetic energy to turbulent kinetic energy and the decreased Reynolds stress diffusion loss in the Diffuser B and volute are main reasons for the hump characteristic suppression. The energy loss in the volute small section side region and its corresponding diffuser region increases significantly under hump conditions, and Diffuser B can obviously reduce the energy loss in these regions. The flow pattern analysis in the diffuser shows that the weakened rotating stall in Diffuser B leads to a more regular Qm variation with time in D1∼D6. The reduced chord length and thickness of vane B results in a significant decrease of pressure surface separation vortex (PSV) and suction surface separation vortex (SSV) scales and a weakened vortex merging phenomenon, which causes a considerable drop of ΔSPRO in the Diffuser B. The Diffuser B provides a more uniform α distribution to the volute inlet, and decreases the vortex scale and vortex-induced energy loss on the volute small section side.

Numerically investigating the effect of using nanofluids on the thermal performance and coefficient of performance of a U-tube deep borehole ground source heat pump

In this study, a deep-borehole ground source heat pump was simulated using computational fluid dynamics (CFD) method. The thermal performance and coefficient of performance (COP) of the vertical ground source heat pump simulated with accuracy using CFD for water and 4 different nanofluids as working fluids were investigated. Two nanofluids contained silver and copper metallic nanoparticles and the other two nanofluids contained copper and aluminum oxide nanoparticles. For each of these nanofluids as well as water, the heat exchange rate, total exchanged heat, outlet temperature and COP were calculated and the results were compared together. The results showed that using nanofluids leads to increased exchanged heat. Nanofluids based on aluminum oxide, copper oxide, copper and silver nanoparticles resulted in 4.83, 5.76, 6.9, 7.69 percent increase in total exchanged heat, respectively. In addition to increased exchanged heat, using nanofluids increased the outlet temperature. Also, the results showed that the maximum and minimum increase in COP were 36.5% and 5.2% which were related to using silver and aluminum oxide nanoparticle-based nanofluids, respectively.

Design of a floating cage prototype with organic waste collector (food remains and excreta), produced by trout farming in lake Titicaca, Perú

InLake Titicaca, Peru, trout farming in floating cages has been a valuable opportunity for Andean residents, offering food and self-employment. However, this method has generated environmental problems by contaminating the bottom of the lake with large amounts of organic waste, such as excreta and remains of balanced feed. To address this challenge, a floating cage prototype was designed with an integrated organic waste collector, along with a vertical static settler and pump system. The objective of the research work was to mitigate the pollution of Lake Titicaca caused by the consumption of balanced feed in trout farming. A collecting cage model was built that trapped a significant amount of organic waste. 7 600 rainbow trout weighing an average of 800 g were used, fed with 300kg day-1of balanced feed ad libitum for 30 days. After 16 hours from the feed supply, an average accumulation of organic waste of 6.9 ± 0.98 kg day-1was observed, which was transported to the settler using an electric pump. A water quality analysis was carried out, finding values of total phosphorus (TP) of 1.316 ± 0.059 mg L-1, total nitrogen (TN) of 0.013 ± 0.001 mg L-1 and total organic matter (MOT) of 55.60 ± 0.30 mg L-1. L in the water column in the growing area. In conclusion, the design of the collecting cage proved to be an effective alternative to avoid the accumulation of organic waste at the bottom of the lake, and the recovered waste can be used as agricultural fertilizer, adding value to the process.

Pump Seal Design

How a US pulp and paper mill benefitted from a vertical pump seal casing upgrade

A Numerical Study on the Performance of a Pumping Station with Bell-Mouth-Based Vertical Pumps during an Accidental Shutdown

This study presents a numerical simulation of a pump’s performance during a power-cut event and connected hazards resulting from the failure of non-return flap valves. The vertical mixed-flow pumps with suction bells were mounted inside the suction basins of a pumping station. Different regimes of the pump operation during the time were analyzed based on the pump’s 4-quadrant characteristics and the dynamics of rotating parts in the pump, gearbox and electric engine. The resulting development of flow rates, rotor speed and forces in the course of time were used to analyze the hazards of failure of any pumping system component and the flooding of the suction object and its surroundings. The presented results show a deep insight into the flow phenomena in vertical mixed-flow pumps with suction bells during the runaway process and confirm that the developed methodology can be successfully applied to monitor the critical regimes in a pumping station in real time. The simulations were verified with some experimentally obtained data.

Numerical investigation on vortex dynamics characteristics of a large vertical centrifugal pump operating in the hump region under cavitation conditions

The large vertical centrifugal pump (LVCP) is widely used in major hydraulic engineering such as cross-region water transfer. This paper focuses on the hydraulic stability of LVCP under extremely operating conditions. The transient numerical simulations of cavitation in LVCP in the hump region are conducted based on delayed detached eddy simulation coupled with a homogeneous cavitation model. The main research is the effect of cavitation on the flow pattern and the vortex dynamics of the LVCP under stall conditions. The results of the numerical investigations show that the variation of the pump performance parameters is consistent with the experimental data under cavitation conditions. Under deep stall conditions, the H drop due to cavitation in the pump can happen earlier. Under the critical cavitation of the stall condition, backflow vortex cavitation, sheet cavitation and separation vortex cavitation can be observed at the impeller inlet. The vortex structures generated at the cavitation tail can result in worse flow patterns in the impeller. The vortex dynamics analysis shows that severe cavitation in the impeller deteriorates the inlet conditions of the vaned diffuser and induces sheet cavitation at the LE of vanes. The cavitations in the vaned diffuser accelerate the production and development of stall vortices and result in increased flow instability. The research in this paper can be helpful to improve the operation stability of LVCP.

Study on unsteady characteristics of the reactor coolant pump under non-uniform inflow

The primary circuit of a nuclear power plant contains a steam generator (SG) and two vertical reactor coolant pumps (RCPs). Two RCPs are installed at the bottom of the SG. The structure of the channel-head of the SG is special, which leads to uneven flow from the RCP inlet and affects the operation performance of the pump. Taking the RCP of the third-generation reactor as the research object, the unsteady characteristics of the third-generation RCP under non-uniform inflow conditions were investigated using CFD, and the pressure pulsation characteristics inside the RCP were mainly studied. A series of monitoring points were set at the channel of the channel-head, impeller, diffuser and casing section respectively to study the influence of non-uniform flow on the pressure fluctuation and radial force distribution of the RCP. The results show that non-uniform inflow can cause instability in pressure fluctuations in the “throat” region of the channel-head. The interaction between the impeller and diffuser can cause pressure pulsation from the impeller outlet to the diffuser inlet, potentially impacting the safe and stable operation of the RCP. This research provides certain theoretical support for the design of RCPs under the condition of non-uniform inflow.

Integrated design and hydraulic model optimization of model horizontal main pump based on CFD fluid dynamics analysis

There are few studies and reports related to horizontal main pumps for nuclear power plants. The installation of vertical main pumps for small reactors requires the design of special elbows on the pressure vessel. Horizontal main pump, as a new main pump structure, can reduce the diameter of the main pressure vessel and simplify the structure of the pressure vessel. Compared with the vertical main pump, the horizontal main pump needs to control its axial dimension to improve its stiffness, which makes it impossible to set a long straight pipe section at the inlet, which has an impact on the pump performance. On the other hand, the compression of the axial dimension of the pump casing makes the overflow area of the press-out chamber small, resulting in large hydraulic losses. In this paper, in order to improve the efficiency of the pump and reduce the influence of non-uniform incoming flow, the optimization design is carried out with the SST k-ω model, and it is shown that: 1. the suction port of the curved impeller is easier for the fluid to enter into the impeller in the axial direction; and 2. the axially symmetric worm gear produces more vortex flow losses.