Interstage difference and deterministic decomposition of internal unsteady flow in a five-stage centrifugal pump as turbine

Li, Xiaojun; Ouyang, Tao; Lin, Yanpi; Zhu, Zuchao

doi:10.1063/5.0150300

Cited by 19 publications

(3 citation statements)

References 37 publications

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“…The time step is 4.27351 3 10 -5 . The convergence criterion is the continuity, the root-mean-square residuals of the momentum and energy equations are less than 1 3 10 -5 (Li et al, 2024a;Li et al, 2024b;Li et al, 2017;Wang et al, 2020;Huang et al, 2023;Chen et al, 2024;Li et al, 2023).…”

Section: Detail Of Each Component Gridmentioning

confidence: 99%

Lagrangian coherent structure combined with entropy production theory for the analysis of vortex build-up on the impeller top in a high-speed fuel pump

Lu,

Tao,

Zhu

et al. 2024

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PurposeThis study focuses on the CFD numerical simulation and analysis of the vortex stacking problem at the top of the impeller of a high-speed fuel pump, mainly using LCS and entropy production theory to visualize the vortex at the top of the impeller as well as quantitatively analyzing the energy loss caused by the vortex at the top of the impeller. By combining the two methods, the two are well verified with each other that the stacking problem of the vortex at the top of the impeller and the location of the energy loss caused by the vortex are consistent with the vortex location. Such a method can reveal the problem of vortex buildup at the top of the lobe well, and provide a novel guidance idea for improving the performance of high-speed fuel pumps.Design/methodology/approachBased on CFD numerical simulation and analysis, this study mainly uses LCS and entropy production theory to visualize the top vortex of the impeller. Through the combination of the two methods, the accumulation problem of the top vortex of the impeller and the location of the energy loss caused by the vortex can be well revealed.Findings(1) The CFD numerical simulation analysis of the high-speed fuel pump is carried out, and the test is conducted to verify the numerical simulation results. The inlet and outlet pressure difference? P is used as the validation index, and the error analysis shows that the error between numerical simulation and test results is within 10%, which meets our requirements. Therefore, we carry out the next analysis with the help of CFD numerical simulation. By analyzing the full working condition simulation, its inlet and outlet differential pressure? P and efficiency? Are evaluated. It is found that its differential pressure decreases with the flow rate and its efficiency reaches its maximum at Qv = 9.87 L/s with a maximum efficiency of 78.32%. (2) We used the LCS in the analysis of vortices at the top of the impeller blades of a high-speed fuel pump. One of the metrics used to describe the LCS in fluid dynamics is the FTLE. The high FTLE region represents the region with the highest and fastest particle trajectory stretching velocity in the fluid flow. We performed a cross-sectional analysis of the FTLE field on the different height surfaces of the impeller on 25% Plane, 50% Plane, and 75% Plane, respectively. And a quarter turn of the rotor rotation was analyzed as a cycle divided into 8 moments. It is found that on 25% Plane, the vortex at the top of the lobe is not obvious, but there are high FTLE values on the shroud surface. On 50% Plane, the lobe top vortex is relatively obvious and the number of vortices is three. The vortex pattern remains stable with the rotating motion of the rotor. At 75% Plane, the lobe top vortex is more visible and its number of vortices increases to about 5 and the vortex morphology is relatively stable. The FTLE ridges visualize the vortex profile. This is a good guide for fluid dynamics analysis. (3) At the same time, we use the entropy production theory to quantitatively analyze the energy loss, and define the entropy production rate Ep. Through the entropy production analysis of the impeller shroud surface and the suction surface of the pressure surface of the blades at eight moments, we find that the areas of high energy loss are mainly concentrated in the leading and trailing edges of the blades as well as in the shroud surface close to the leading edge of the blades, and the value of the entropy production rate is up to 106 W/m3/K. The areas of high energy loss in the leading edge of the blades as well as the trailing edge show a curved arc, and the energy loss is decreasing as it moves away from the shroud surface and closer to the hub surface. The high energy loss areas at the leading and trailing edges of the blades are curved, and the energy loss decreases as they move away from the shroud surface and closer to the hub surface. The energy loss at the pressure surface of the blade is relatively small, about 5 × 105 W/m3/K, which is mainly concentrated near the leading edge of the blade near the shroud surface and the trailing edge of the blade near the hub surface. Such energy loss corresponds to the vortex LCS at the top of the impeller, and the two mirror each other.Originality/valueThis study focuses on the CFD numerical simulation and analysis of the vortex stacking problem at the top of the impeller of a high-speed fuel pump, mainly using LCS and entropy production theory to visualize the vortex at the top of the impeller as well as quantitatively analyzing the energy loss caused by the vortex at the top of the impeller. By combining the two methods, the two are well verified with each other that the stacking problem of the vortex at the top of the impeller and the location of the energy loss caused by the vortex are consistent with the vortex location. Such a method can reveal the problem of vortex buildup at the top of the lobe well, and provide a novel guidance idea for improving the performance of high-speed fuel pumps.

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Section: Detail Of Each Component Gridmentioning

confidence: 99%

Lagrangian coherent structure combined with entropy production theory for the analysis of vortex build-up on the impeller top in a high-speed fuel pump

Lu,

Tao,

Zhu

et al. 2024

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“…Processes 2023, 11, x FOR PEER REVIEW 3 of 17 of multistage PATs is rare [25,26]. Therefore, further research is necessary to achieve a flatter H-Q curve in the process industry.…”

Section: Theoretical Analysismentioning

confidence: 99%

Influence of Positive Guide Vane Geometric Parameters on the Head-Flow Curve of the Multistage Pump as Turbine

Wang,

Yang,

2023

Processes

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In order to reduce the impact of production changes on the performances of pumps as turbines (PATs) in the process industry, it is imperative to lessen head variations at different mass flow rates. This study established a relationship equation between theoretical head and geometric parameters for multistage PATs. The influence of these parameters on the flatness of the head-flow (H-Q) curve was determined through derivation methods. The original PAT was a two-stage pump, and 12 PAT models were designed by modifying the geometric parameters of the positive guide vanes. Fluent software was employed for numerical simulations. The study found that numerical calculations aligned well with theoretical derivations for the flat H-Q curve. Considering the geometric variations in the positive guide vane, increasing the outlet placement angle, blade number, and throat area or decreasing the base circle diameter was able to flatten the H-Q curve effectively; at the best efficiency point, the throat area had the most significant impact on a slope, followed by the outlet placement angle, blade number, and base circle diameter, respectively. The individual contributions to reducing the slope were 0.53, 0.24, 0.1, and 0.09. In terms of the best efficiency point (BEP) of PATs, increasing the throat area appropriately was able to improve the BEP of the PAT by around 1.65% and shifted its BEP towards higher flow rates. However, in other cases, the BEPs all decreased. Increasing the outlet placement angle of the positive guide vane by 3° led to the BEP being reduced by 0.79%. When the number of positive guide vane blades was increased from 8 to 10, the BEP decreased by 1.24%. When the diameter of the base circle of the positive guide vane was decreased, the BEP of the turbine decreased by 0.06%. This study provides theoretical support and can serve as a reference for the design of multistage hydraulic turbines with flatter H-Q curves.

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“…Multi-axis machining of complex shaped parts such as impellers, vanes and blades is an extremely important task [1][2][3][4][5]. In production conditions, difficulties are often encountered in the implementation of technological preparation for the production of such products.…”

Section: Introductionmentioning

confidence: 99%

A new algorithm for recreating the technological process of high-speed multicoordinate processing based on improving key indicators of image recognition

Pivkin,

Ershov,

Grechishnikov

et al. 2024

Optics, Photonics, and Digital Technologies for Imaging Applications VIII

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Solving the problem of reverse engineering as a key element of the production process and its technological preparation has a key role. This work demonstrates for the first time the possibility of preparing production and collecting key indicators, which allows you to recreate a digital twin of the technological process and display the technological aspects of the design as a result of collecting key indicators. Such indicators include the width of the cut layer, the cutting zone of a conical cutter during multi-axis positioning, obtained based on the results of processing a group of images of processed products. Actual technological indicators of the technological process can be identified and numerically formalized by assessing the shape of the helical surface on a class of parts obtained as a result of multi-coordinate processing, which proves the possibility of applied application of the method in the structure of the production process in real time. As a result, the use of a new algorithm will reduce the likelihood of receiving defective products and recreate the technological process based on processing a set of product images. The work constructs an analytical model for the automated creation of processing paths based on improved B-splines, which can significantly improve smoothness compared to numerical methods for generating paths. The actual technological indicators of the machining process can be identified and numerically formalized dependencies by determining the influence of the helical surface on the precise positioning of the end mill with compensation along each axis during 5-axis machining, obtained as a result of multi-axis machining, which proves the possibility of applied application of the method in the production process in the mode real time.

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Interstage difference and deterministic decomposition of internal unsteady flow in a five-stage centrifugal pump as turbine

Cited by 19 publications

References 37 publications

Lagrangian coherent structure combined with entropy production theory for the analysis of vortex build-up on the impeller top in a high-speed fuel pump

Lagrangian coherent structure combined with entropy production theory for the analysis of vortex build-up on the impeller top in a high-speed fuel pump

Influence of Positive Guide Vane Geometric Parameters on the Head-Flow Curve of the Multistage Pump as Turbine

A new algorithm for recreating the technological process of high-speed multicoordinate processing based on improving key indicators of image recognition

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