Pump Flow Research Articles

The One-Dimensional Flow Pressure Loss Correction Model Based on the Particle Flow through Concrete Bend

The rheological behavior of concrete pumping in the bend section is complex. The existing conversion calculation for pumping pressure loss based on the straight pipe section often fails to meet engineering precision requirements. This paper develops a pressure loss correction model for a concrete pumping bend section based on a new one-dimensional flow model for the straight pipe section simulation of particle flow; the study analyzes the impact of parameters such as elbow shape and pumping flow rate on pressure loss. An equivalent conversion relationship between the bend section and the straight section is established. The comparison with the measured pressure values from the project shows that the relative error between the pressure loss values calculated by the correction model and the actual measurements is 15.8%.

Development of geopolymer and cement-based shotcrete mortar: Impact of mix design parameters and spraying process

Shotcrete mortar is used in various construction works, including repair, tunneling, mining, and slope stabilization, among others. Traditionally, cement is used to produce shotcrete mortars with high viscosity, flowability, and early strength. Geopolymers (GP) have the potential to replace cement in shotcrete mortars, owing to their ability to reduce the material’s environmental footprint without compromising performance. This investigation assesses the feasibility of utilizing fly ash and blast furnace slag-based GP mortars produced with dune sand in shotcrete applications while comparing them to cement-based mixtures. The GP and cement-based shotcrete mortars were designed to have similar yield stress values. The evaluated properties included the initial flow, thickness layer, rebound material, rheological properties, setting time, compressive strength, ultrasonic pulse velocity, and pull-off bonding strength. Test results showed direct relationships between the yield stress and initial flow values, as well as between the buildup thickness and plastic viscosity, revealing that GP mortars were suitable for shotcrete applications, specifically those produced with flow values of 18.5 cm or less. GP mixtures produced with higher slag content than fly ash, higher sand content compared to binder, higher SH molarity, and lower solution content achieved higher buildup thickness owing to their higher viscosity. In the second phase, the performance of four mixes with different initial flows was assessed at various pumping flow rates and distances between the wall and machine pipe nozzle. The findings confirmed that these spraying parameters are crucial to improve the shotcrete performance of GP mortar with varying fresh behaviors.

Application of operating scenarios and analysis of unstable flow characteristics at various angles of inlet guide vane.

In this study, we analyzed the performance characteristics of an axial flow pump with different angles of internally installed inlet guide vanes (IGVs). We predicted the pump's performance based on changes in the IGV angle and analyzed the impact of these angle variations on pump operation in the low-flow region. Additionally, we used real operational data from two sewage treatment plants to propose efficient operational scenarios. For turbulence flow analysis, the Reynolds-averaged Navier-Stokes equations were discretized based on the finite volume method. The grid formation was evaluated using the grid convergence index to select the optimal grid. Then, the internal flow was analyzed in detail through transient-state analysis. Through fast Fourier transform analysis, we confirmed that adjusting the IGV angle during pump operation in the low-flow region in response to load changes results in more stable operation compared with the existing method (valve control). Overall, our findings verified that energy reduction and efficient operation can be achieved through IGV angle adjustment compared with valve control.

Evaluation of the Expression of SIM and NDM Genes in Pseudomonas Aeruginosa Isolated from Clinical Sources

Pseudomonas aeruginosa has recently been labeled a major threat to public health due to its resistance to almost all commonly used antibiotics. Many factors have been suggested for P. aeruginosa's antibiotic resistance. The goal of this study is to find out what role SIM and NDM, which are related to carbapenem resistance, play in P. aeruginosa isolates from local clinical sources. In this study, out of 110 different clinical specimens, 50 were identified as P. aeruginosa from hospitalized patients. All of the isolates were characterized based on the biochemical test and confirmed using the VitekII compact system. P. aeruginosa isolates were tested for antibiotic susceptibility using 8 antibiotics, including: amikacin, tobramycin, ciprofloxacin, levofloxacin, imipenem, meropenem, piperacillin/tazobactam, ticarcillin, and clavulanate. Susceptibility testing results revealed that every isolate was highly resistant to Piperacillin/Tazobactam, with lower resistance to Ticarcillin/clavulanate (TCC). Using the broth dilution method, the minimum inhibitory concentration (MIC) of P. aeruginosa isolates resistant to meropenem ranged from 32µg/100µl to 128 µg/100µl. The EDTA combined disc test was used to detect the ability of P. aeruginosa isolates to produce carbapenemase, and the results showed that all isolates were carbapenemase producers. Additionally, conventional PCR confirmed the identification of P. aeruginosa using 16S. Real-time PCR was adopted to assess the expression of the NDM and SIM genes in 25 of the identified P. aeruginosa isolates. The mean of gene expression results for NDM showed increased expression compared to the control sample of 1.74, while the SIM gene showed expression of 0.95. These genes, SIM and NDM in class B (which are important for resistance in Pseudomonas aeruginosa), result from chromosomal changes that mutate the membrane permeability flow pump, causing excessive expression.

Research on the jet active control mechanism of gas-liquid separation in helical-axial multiphase pumps

In the field of deep-water oil and gas extraction, the intermittent gas blocking phenomenon in helical-axial multiphase pumps leads to decreased pump performance and reliability, severely limiting their large-scale application and promotion in engineering projects. To address this challenge, this study is based on the principle of jet flow field control to flow separation, utilizing external energy for active intervention to suppress the separation phenomena and improve the hydraulic efficiency within the impeller flow channel. The research reveals that the jets achieved a reconstruction of the internal flow in the helical-axial gas-liquid mixed transport pumps. Using orthogonal experimental methods, a preliminary predictive analysis of the factors influencing the effectiveness of the jet system was conducted. The study explored the impact of jet parameters on enhancing the performance of helical-axial gas-liquid mixed transport pumps from the perspective of diminishing gas aggregation at the trailing edge of the rotor cascade and curtailing backflow conditions, and established a mathematical model for the head and efficiency of helical-axial multiphase pumps under jet active control. Research indicates that the jet velocity significantly impacts the efficiency enhancement of multiphase pumps, with an optimal jet speed coefficient, Cjet = 10, identified. Beyond this speed, the benefits brought by increased jet velocity do not compensate for the costs of introducing high-speed jets, and instead, may lead to a reduction in the efficiency of the pump. Jet flow field control methods alleviate the suction side gas aggregation downstream of the jet holes and in the flow domain traversed by the jets, effectively reducing the aggregation of gas phases in the rear channel of the rotor and suppressing backflow near the trailing edge of the rotor cascade. Jet control measures strengthen the working capacity of the blade in the flow direction beyond 0.35 times the length of the streamline, expanding the working range of the blade and enhancing the work efficiency of the multiphase mixed transport pump. Higher jet velocities result in more significant enhancements of blade working power, especially under conditions of high initial gas content, where the relative increase in blade load is more pronounced.

The association between introduction of the micro-axial flow pump Impella in hospitals and in-hospital mortality in patients treated with extracorporeal membrane oxygenation: interrupted time-series analyses.

The micro-axial flow pump Impella, a new mechanical circulatory device for cardiogenic shock, is still only available in a limited number of hospitals, due to the facility certification requirements and insufficient evidence of the benefit of introducing Impella in hospitals. This study aimed to evaluate the impact of introducing Impella in hospitals on in-hospital mortality of patients treated with extracorporeal membrane oxygenation (ECMO). Using a nationwide Japanese inpatient database, we identified patients who received ECMO during hospitalization between 1 April 2014 and 31 March 2021. A hospital-level propensity score-matched cohort was created matching hospitals that introduced Impella (exposure group) to those that did not introduce Impella (control group). The inclusion period in each hospital was divided into two time periods according to the time of Impella introduction in the exposure group and the corresponding hospital in the control group (before and after exposure). The primary outcome was in-hospital mortality. Uncontrolled and controlled interrupted time-series analyses involved before-after exposure comparison and exposure-control comparison. Out of 34,379 eligible patients, we created a matched cohort of 8351 patients from 86 hospitals with Impella introduction (exposure group) and 7230 patients from 86 hospitals without Impella introduction (control group). In-hospital mortality before and after exposure was 62.5% and 59.3, respectively, in the exposure group; and 66.8% and 63.7%, respectively, in the control group. Uncontrolled interrupted time-series analysis showed no significant level change or trend change in the before-after exposure comparison in both the exposure and the control groups. Controlled interrupted time-series analysis also showed no significant level change (-0.01%; 95% confidence intervals -5.36% to + 5.33%) or trend change (+ 0.10%, -0.30% to + 0.40%) after exposure in the exposure-control comparison. This nationwide inpatient database study showed no association between Impella introduction in hospitals and in-hospital mortality of patients who underwent ECMO. Because this study confined itself to analze of the impact of the introduction of Impella solely at the hospital level, further detailed studies are warranted to assess its efficacy at the patient level.

Comparison GDP and conventional CPB impact on metabolism in cardiac center Sardjito general hospital

Abstract* Background Goal-directed perfusion (GDP) aims to balance oxygen delivery (DO2) and consumption (VO2) in cardiac surgery. Elevated lactate during CPB is common and linked to higher morbidity and mortality. Evaluating lactate with base excess (BE) is vital due to their relationship. Reducing severe BE and lactate predicts cardiac surgery outcomes better. Methods Fifty adult patients undergoing cardiac surgery with CPB were randomly assigned to either the GDP group or the conventional group. In the GDP group, the priming solution was adjusted to target a hematocrit (HCT) level of 24 to 27% with a pump flow of 1.8 to 2.2 L/min/m2 to maintain mean arterial pressure (MAP) between 60 and 65 mmHg. The primary outcomes was oxygen delivery index (DO2i). Results There were increasing trends in lactate levels and decreasing trends in BE levels at all timeframes. The GDP mean difference of lactate [1.504 (1.52); p < 0.001] and BE [-0.87 (2.93); p = 0.22] levels showed better value in the GDP group, with statistically significant increased values in the control group for BE [-1.667 (2.93); p = 0.017] and lactate levels [2.215 (2.919); p < 0.001]. The postoperative outcome showed a significant difference in AKI and ventilator time. Conclusions The GDP low flow CPB compared with conventional flow CPB maintained DO2 matched with VO2 with a better clinical values in the lactate and BE levels and significantly lowered AKI and ventilator duration in cardiac surgery.

A robust decision-making approach for designing coastal groundwater quality monitoring networks.

This paper presents a new approach to the spatiotemporal design of groundwater quality monitoring networks for coastal aquifers. A fusion model combines the outputs of several developed simulation models to make estimates more accurate. A modified GALDIT method is used to incorporate the aquifer vulnerability to saltwater intrusion. The value of information (VOI) theory is applied to determine sufficient monitoring wells. The groundwater quality monitoring network is designed by employing a robust decision-making (RDM) approach under different management strategies and economic considerations. This approach incorporates the deep uncertainties of some critical variables, including water level and total dissolved solids (TDS) concentration at the coastline and pumping flow rates of agricultural wells. The new methodology is implemented in the coastal Qom-Kahak aquifer, Iran. The results illustrate that the combination model has significantly improved evaluation criteria compared to individual prediction models. The fusion model results indicate that thirty monitoring wells would be ideal. The RDM-based analyses in the Qom-Kahak aquifer showed that an optimal network with 30 monitoring wells outperforms the current network regarding various criteria, such as VOI and variance of estimation error. The new well configuration also demonstrates a suitable spatial distribution. Given that the current sampling frequencies are unsuitable for areas with varying vulnerabilities, we recommend sampling every 3months in areas with moderate vulnerabilities and once every three seasons in areas with low vulnerabilities, based on the information transfer index. Finally, a management strategy in which the pumping rate should be less than 60% of the current rate is suggested to prevent saltwater intrusion into the aquifer.

Optimization of Ansys CFX Input Parameters for Numerical Modeling of Pump Performance in Turbine Operation

The paper deals with the issue of determining the optimal setting of input variables in Ansys CFX for modeling pump flow in turbine operation (PAT). The pump model was created in Autodesk Inventor. The mesh for numerical simulations was created using Ansys Fluent Meshing, considering the mesh quality parameters’ skewness and aspect ratio. The Ansys CFX computational model was experimentally verified on an actual pump by measuring the performance parameters on a test circuit and using the PIV (particle image velocimetry) method. The research indicated that the most suitable setting for the model input variables was the inlet pressure and PAT flow rate combination. Another option was to adjust the pressure at the pump inlet and outlet. However, the calculation time in this case was up to 30% longer. The comparison of the model results with the experiment showed that the deviations in the numerical model performance values did not exceed 10% of the values measured on the test circuit. Only the calculated torque was 1.2 ± 0.13 Nm higher on average than the torque measured on the test circuit. This difference is most likely due to the simplification of the geometry of the computational mesh in order to reduce the computation time.

Optimization of the effective volume of urban sewage pumping station based on the fuzzy optimization method

ABSTRACT To improve the operational economy of sewage pumping stations, this paper combines the total volume of the drainage network and sewage pumping station to optimize the effective volume of the pumping station reservoir to reduce operating costs without overflow. Taking a residential area in Ningbo city as the study area, the drainage system was simulated based on Infoworks ICM to obtain the changes of sewage under different volumes of pumping station reservoirs. By combining the daily electricity costs of the pump station, pump start-stop times, and flood depth, the fuzzy optimization method was applied to optimize the effective volume of sewage pumping station reservoirs, selecting the optimal solution to reduce operating costs. A sensitivity analysis of the three factors, pump flow rate, the total population, and drainage network volume, was conducted, and the results showed that under the optimal scenario, the optimal effective volume of the pumping station reservoir increases with the increase in pump flow rate, drainage network volume, and total population. This study can provide theoretical support for the optimization of drainage pumping station reservoir volume as well as economical operation.

Pump-driven clinical infusions: laboratory comparison of pump types, fluid composition and flow rates on model drug delivery applying a new quantitative tool, the pharmacokinetic coefficient of short-term variation (PK-CV)

Pump-driven clinical infusions: laboratory comparison of pump types, fluid composition and flow rates on model drug delivery applying a new quantitative tool, the pharmacokinetic coefficient of short-term variation (PK-CV)

Enhancing commercial check valves in downhole pump applications through laboratory testing system development

In this study, we aim to enhance the performance and longevity of downhole pumps employed in crude oil extraction in the oil industry. Downhole pumps play a pivotal role in the rod-pump system, comprising traveling and standing valves that function similarly to ball check valves. However, these valves often experience premature wear and tear. To address this concern, we embarked on experiments involving various check valve alternatives to conventional ball valves within downhole pumps. The testing conditions were controlled precisely. Furthermore, we evaluated four distinct check valve types, the original (representing the incumbent ball valves), spring-poppet (C), spring-ball (CB), and spring-poppet with soft-seated (S6C) check valves, within a controlled laboratory environment. We employed a TEXAPON N70 solution to replicate the properties and temperature conditions of crude oil. A portable ultrasonic flow meter was used to quantify the pump flow rate and assess its volumetric efficiency. In addition, we recorded data on the polished-rod load and plunger displacement to generate dynamometer cards, thereby enabling a comprehensive evaluation of the operational performance of the pump. Furthermore, we conducted a vacuum test to scrutinize valve leakage, which is a crucial indicator of the operational lifespan of a downhole pump. Our findings show that incorporating the CB check valve with the RHB pump in oil wells operated by the PTT Exploration and Production Public Company Limited (PTTEP) could result in a 15 % increase in volumetric efficiency and a remarkable 160 % improvement in durability compared to the original ball check valve.

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.

Impacts of impeller blade number on centrifugal pump performance under critical cavitation conditions

The number of impeller blades is a significant geometric parameter that considerably impacts centrifugal pump performance. A transient numerical analysis of a centrifugal pump is conducted to examine the influence of the variable impeller blade number on pump performance under critical cavitation conditions. Six different impellers with 3, 5, 7, 8, 9, and 11 blades are examined numerically at a rotational speed of 2900 r/min when other impeller parameters remain unchanged. Fields of interior flow and properties of centrifugal pumps are studied concerning static pressure, velocity magnitude, and vapor volume fraction using ANSYS Fluent to perform the numerical simulation. The results show that numerical analysis can accurately predict centrifugal pump internal flow. The current results match experimental and numerical data for the NPSH, with a 4.65% discrepancy. Blade numbers affect the flow field and pressure amplitude, especially at the outlet region. As blade numbers increase, pressure increases, and the impeller with 11-blade has the maximum pressure amplitude. The impeller with a seven-blade achieved its highest efficiency level, exhibiting a 0.48% improvement under non-cavitation conditions and a 1.4% improvement under critical cavitation conditions compared to the original model. Furthermore, the cavity size on an individual blade of a model with three-blade is more extensive compared to other models. In addition, the impeller with a nine-blade exhibits the lowest value of the vapor volume percentage. This research analyses the influence of different blade numbers on the performance of centrifugal pumps while operating under critical cavitation conditions. It aims to provide novel insights into the flow characteristics associated with such circumstances.

Research on the Unsteady Flow Characteristics of Solid–Liquid Two-Phase Flow in a Deep-Sea Mining Lift Pump and Model Experimental Verification

The deep-sea mining lift pump is one of the pivotal components in deep-sea mineral transportation systems and its internal flow is very complex; consequently, unraveling its unsteady flow behavior pattern holds immense practical value. This study adopts numerical methods to analyze the time-averaged distribution characteristics of the internal flow field in mining lift pumps, as well as the flow field’s pulsation intensity distribution characteristics, the vortex’s spatiotemporal evolution process in both moving and static cascades, and the time- and frequency-domain pulsation characteristics of internal pressure in each flow passage component under four different flow conditions are also investigated. The hydraulic properties of mining lift pumps under these four different conditions are also evaluated, and the outcomes are benchmarked against those of numerical predictions. Our findings reveal that the interplay between impeller blades and guide vanes significantly influences the pump’s flow characteristics, with the pump’s unsteady flow influencing its hydraulic properties. Experimental validation of this system confirms that the pump under study is in line with design specifications in terms of hydraulic properties. The method validation test on the prototype pump shows that the SST k-ω model is capable of successfully forecasting instability in the flow features of deep-sea mining lift pumps. These results will serve as a theoretical reference for regulating the flow state inside deep-sea mining lift pumps.

Contemporary optimal therapeutic strategy with escalation/de-escalation of temporary mechanical circulatory support in patients with cardiogenic shock and advanced heart failure in Japan.

The utilization of temporary mechanical circulatory support (MCS) in the management of cardiogenic shock is experiencing a notable surge. Acute myocardial infarction remains the predominant etiology of cardiogenic shock, followed by heart failure. Recent findings from the DanGer Shock trial indicate that the percutaneous micro-axial flow pump support, in conjunction with standard care, significantly reduced 6-month mortality in patients with acute myocardial infarction-related cardiogenic shock compared to those receiving standard care alone. However, real-world registry data reveal that the 30-day mortality among patients with acute myocardial infarction-related cardiogenic shock, who received concomitant veno-arterial extracorporeal membrane oxygenation support along with micro-axial flow pump, remain suboptimal. The persistent challenge in the field is how to incorporate, escalate, and de-escalate these temporary MCS to further improve clinical outcomes in such clinical scenarios. This review aims to elucidate the current practices surrounding the escalation and de-escalation of temporary MCS in real-world clinical settings and proposes considerations for future advancements in this critical area.

Identification of Single-Blade Angle Variation in Axial Flow Pumps Based on the Variational Mode Decomposition Method

Pressure pulsations are crucial data within the flow field of a pump, and the characteristics of these pulsations can reveal changes in the internal flow. Based on model experiments, this paper obtained pressure pulsation data under two blade conditions and compared direct time-domain observations, peak-to-peak value changes, and the VMD decomposition method. The results show that even when it is known that one blade condition has changed, it is not possible to determine this through direct observation of pressure pulsation changes. The peak-to-peak value changes indicate that under special flow conditions, they are easily affected by different operating conditions, which can interfere with the results. In contrast, the VMD method, which decomposes the signal into low-frequency components, can better display anomalies within the pressure pulsation cycle and is less susceptible to the interference of flow conditions, offering some reference significance for diagnosing the blade operating conditions of the main pump.

Investigating Flow-Induced Corrosion of Magnesium in Ophthalmological Milieu.

Although the impact of local fluid dynamics in the biodegradation of magnesium is well known, currently no studies in the literature address the degradation effects of ocular vitreous on bioresorbable devices made of magnesium, which could be developed as drug delivery carriers. The aim of this study was to investigate the flow-induced corrosion mechanism of magnesium in an ophthalmological environment for future applications in ophthalmic drug delivery. To achieve this, experimental and computational methods were combined. Specifically, a CFD model was employed to design experimental conditions that replicate the ocular flow-induced shear stress (FISS) on manufactured magnesium samples. Pure Mg samples were tested in a bioreactor system capable of imposing the ocular CFD calculated values of FISS on the Mg samples' surface by varying the pump flow rate. Optimal flow rates for a range of different FISS values specific to the ophthalmological fluid dynamics affecting the device were indeed determined before running the experiments. After conducting customized corrosion tests, morphological observations and profilometric maps of the eroded surfaces of Mg samples were obtained using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). These maps were then post-processed for the parametric evaluation of corrosion rates. Pre-existing localized superficial defects did affect the final corrosion pattern. SEM images and CLSM data confirmed a uniform corrosion mechanism, with corrosion rates of 1.9, 2.7, and 3.4 μm/day under different shear stress conditions (0, 0.01, and 0.032 Pa, respectively). More generally, uniform corrosion on pure Mg samples increased with higher FISS values, and at higher shear stress values (FISS = 0.032 Pa), a notable washing-out effect of the corrosion products was observed. The removal of corrosion products at higher shear stresses suggests that the dynamic ocular environment, influenced by saccadic movements, plays a significant role in the corrosion mechanism of pure magnesium. The corrosion rates determined in this study, in conjunction with clinical drug release requirements, are crucial for designing potential drug-release devices for ocular applications.

DEVELOPMENT OF LEAK DETECTION METHODS FOR USE IN FIELD PIPELINE TRANSPORT

Today, most existing leak detection methods are effective only for stationary operating conditions of pipelines. During transient (dynamic) pumping modes, a significant decrease in the sensitivity of the methods occurs, or inoperability of leak detection systems (LDS) based on them is observed.Accordingly, for the operation of the LDS in the presence of transient processes in pipelines, it is necessary to use special approaches that take into account the features and interrelation of the monitored indicators of the dynamically changing pumping regime with each other. One solution to this problem is the use of a dynamic thermal-hydraulic model of the pipeline, which makes it possible to calculate pumping indicators at intermediate and boundary points of the pipeline at each moment in time.The article presents the developed digital model of a pipeline transporting single-phase flows, as a system of equations obtained from the laws of conservation of mass, momentum and energy. The model describes all significant processes and effects during the movement of the pumped flow through a pipeline and allows you to calculate the main characteristics of the flow, including finding the pressure and temperature distributions along the pipeline route.The method for detecting leaks from field pipelines operating under transient (dynamic) conditions is to compare the actual measured flow rate at the end point of the pipeline with the flow rate calculated using a dynamic model of this pipeline, into which the measured pumping indicators at the inlet of a real object are previously transferred. If there are significant deviations between the calculated pumping flow rate at the outlet of the pipeline in the model and the flow rate measured at the pipeline, a leak is concluded.In order to check the performance of the proposed solutions, modeling of leaking pipelines was carried out in specialized software at various flow rates, media viscosities and leak volumes. Based on the data obtained, a conclusion was made about the efficiency of the developed method.Thus, thanks to the proposed approach, it will be possible to promptly detect and eliminate leaks and withdrawals through unauthorized taps on field pipelines operating in unsteady mode, which in turn will significantly reduce operating costs associated with eliminating the consequences of failures.

Research of the calculation formula for working clearance leakage flow of the hydrogen circulation pump

The hydrogen circulation pump (HCP), a device for recovering unconsumed hydrogen gas in fuel cell systems to improve efficiency, is an important equipment in fuel cell systems. Efficient calculation of the output flow rate of the HCP is crucial for accelerating the product development process, but there is a lack of an effective calculation formula for the working clearance leakage. In this paper, a series of HCP models with different working clearances are established and calculated using an overlapping grid simulation method, verifying that the traditional Roots blower leakage flow formula is feasible for HCP, although the maximum calculation error reaches 10.71%. Further study the pressure distribution law inside the HCP chamber, and revise the traditional calculation formula accordingly, so that the average calculation error of the series models is reduced from 5.75% to 3.82%, and the maximum error is also reduced to 7.73%. Compared with the prototype test data, though the flow values obtained from the two calculation formulas are slightly higher, the calculation error of the correction formula is relatively smaller. The research results indicate that the correction formula can more accurately predict the flow rate of HCP and has important application value.