Study on Slip Phenomenon of Pumps As Turbines in Different Working Conditions

2017 ◽  
Author(s):  
Wang Xiaohui ◽  
Yang Junhu ◽  
Xia Zhengting
Keyword(s):  
Working Conditions ◽  
Working Condition ◽  
Suction Side ◽  
Hydraulic Loss ◽  
Hydraulic Efficiency ◽  
High Discharge ◽  
Flow Parameters ◽  
Slip Factor ◽  
Point Condition ◽  
Slip Phenomenon

Slip phenomenon is known to strongly influence the performance of pump as turbine (PAT). It is of interest to investigate the influence of flow parameters on the slip factor and obtain the effective value of slip factor over the whole range of their working conditions. In the present work, the slip phenomenon of PAT at different working condition was studied, slip factor was calculated in every point of the flow. Furthermore, the relative eddy within the impeller passage was evaluated and the hydraulic performance of PAT was analyzed. The result shows that the slip factor decreases with the increasing flow rate, slip phenomenon induces additional hydraulic loss in impeller passage, it weakened in over-load region, as a consequence, hydraulic efficiency is relatively high. On the contrary, the slip phenomenon strengthened in part-load region, therefore, hydraulic efficiency of PAT is relatively low. It was observed that a relative eddy take place within the impeller passage, the eddy occurs near pressure side of blade at design-point condition, it motions to suction side at high discharge, and divides into two separated eddy at partial discharge condition. The relative eddy cause pressure fluctuate in PAT impeller, which affects the energy recovery of PAT.

scholarly journals Investigation of Rotating Stall Phenomenon and Optimization in Mixed-Flow Waterjet Propulsion Device

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Can Luo ◽  
Di Zhang ◽  
Congcong Zhang ◽  
Shuaihao Lei ◽  
Chenzhi Xia ◽  
...  
Keyword(s):  
Flow Rate ◽  
Static Pressure ◽  
Orthogonal Experiment ◽  
Suction Side ◽  
Rotating Stall ◽  
Hydraulic Loss ◽  
Static Pressure Difference ◽  
Small Flow ◽  
Point Condition ◽  
Cfd Method

The rotating stall is a kind of flow phenomenon in the impeller harming the navigation speed of vessels propelled by a waterjet propulsion device when the waterjet propulsion device operates at the small flow rate conditions. The numerical simulated hydraulic performance was compared with experimental results so that the reliability of the CFD method was verified. The grooves are proposed before the inlet of an impeller to suppress the rotating stall. The orthogonal experiment is designed to seek the appropriate values of the parameters such as the length, width, depth, and number of the groove. The results show that the width of groove has the greatest influence on the performance of the device, followed by the number, the depth, and the length. The width, number, depth, and length of the selected groove scheme are 3.10 × 10−2D, 72, 3.10 × 10−2D, and 7.75 × 10−2D, respectively. At the rotating stall conditions, the selected groove scheme is numerically calculated. In contradistinction to the original scheme, it is found that the groove can improve the flow in the impeller and enhance the head of valley point condition, but the efficiency drops due to the increasing local hydraulic loss near the groove. When the groove is installed, the positive slop region on the flow rate-head curve disappears related to the static pressure difference on the blade, especially depending on the static pressure on the suction side. The flow pattern on the span surface of the vortex core is smooth, and then, the head increases. On the contrary, the head decreases. The outcome is beneficial to improve the performance of the waterjet propulsion device and enrich the rotating stall theory.

BP-AdaBoost Algorithm Based on Variational Mode Decomposition Optimized by Envelope Entropy for Diagnosing the Working Conditions of a Slideway Seedling-Picking Mechanism

2021 ◽  
Vol 37 (4) ◽  
pp. 665-675
Author(s):  
Zhitao He ◽  
Haiyang Zhang ◽  
Jun Wang ◽  
Xin Jin ◽  
Song Gao ◽  
...  
Keyword(s):  
Empirical Mode Decomposition ◽  
Working Conditions ◽  
Working Condition ◽  
Recognition Accuracy ◽  
Variational Mode Decomposition ◽  
Adaboost Algorithm ◽  
Layer Number ◽  
Entropy Minimization ◽  
Mode Decomposition ◽  
Penalty Factor

Highlights A method of monitoring the working conditions of a slideway seedling-picking mechanism based on variational mode decomposition (VMD), envelope entropy, and energy entropy is proposed. Based on the criterion of envelope entropy minimization, the combination of the decomposition layer number and penalty factor in VMD is optimized to yield a satisfactory decomposition effect of the analyzed vibration signal. The BP-AdaBoost algorithm is used to improve the working condition classification performance for the slideway seedling-picking mechanism. The working-condition identification effect with the proposed method are compared with those through EMD-based, LMD-based, and EEMD-based methods. Abstract . The slideway seedling-picking mechanism is a type of rotating machinery. This study proposes a novel method of identifying the working conditions of slideway seedling-picking mechanisms for early fault diagnosis by utilizing a back-propagation adaptive boosting (BP-AdaBoost) algorithm based on variational mode decomposition (VMD) optimized by the envelope entropy. The experimental results demonstrate that the proposed method can effectively verify the four working conditions (normal state, slideway failure, cam failure, and spring failure). The overall recognition accuracy reaches 90.0% under the optimal combination of the decomposition layer number K and penalty factor a in VMD determined through the envelope entropy minimization criterion. Classification comparisons with empirical mode decomposition (EMD), local mean decomposition (LMD) and ensemble empirical mode decomposition (EEMD) integrated into the BP-AdaBoost algorithm indicate that the overall recognition accuracy of the proposed method is 18.1%, 16.9%, and 15.6% higher than the accuracies of the three conventional methods, respectively. Compared with the K-means, support vector machine (SVM) algorithms, BP-AdaBoost algorithm demonstrates a more dependable capability for identifying the working conditions. This study provides a useful reference for monitoring the working conditions of slideway seedling-picking mechanisms. Keywords: BP-AdaBoost algorithm, Energy entropy, Envelope entropy, Slideway seedling-picking mechanism, Variational mode decomposition, Working conditions.

Conversion Methods of Efficiency for Hydraulic Machinery Using Model Under Influence of Roughness

2008 ◽  
Author(s):  
Long Li ◽  
Ze Wang ◽  
Xuelin Yang ◽  
Dan Li
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Computational Method ◽  
Hydraulic Loss ◽  
Simple Computation ◽  
Hydraulic Efficiency ◽  
Hydraulic Machinery ◽  
Computation Process ◽  
Efficiency Conversion ◽  
The Difference

The hydraulic efficiency conversion method of Moody formula based on H. Blasius friction coefficient formula for the “Hydraulically smooth zone” was analyzed. The method of model to prototype that involves the influence of the surface roughness of hydraulic machinery was advised. The conversion result was compared among the Haaland fomula, the Swamee-Jain formula, and the different proportion of hydraulic loss type. It was contrasted with the standard method. The difference of prototype efficiency is no bigger than 0.0025 in the prototype roughness 0.025mm range. The proposed computational method is provided with the same characteristics with the flowing zone, and possessed the clear physics significance, the simple computation process and the high conversion precision. It is satisfied with the efficiency conversion under the influence of the surface roughness.

Winding-Autofrettage Study on Reinforced Thermoplastics Vessel Based on ANSYS ACP

2018 ◽  
Author(s):  
Jinhao Huang ◽  
Chenghong Duan ◽  
Liang Wu ◽  
Xiangpeng Luo
Keyword(s):  
Stress Distribution ◽  
Internal Pressure ◽  
Working Conditions ◽  
High Density Polyethylene ◽  
Working Condition ◽  
Filament Winding ◽  
Working Pressure ◽  
Cooling Method ◽  
Plastic Stage ◽  
Reinforced Thermoplastics

The process, by applying an internal pressure higher than the working pressure in advance after completion of the winding to cause the liner entering the plastic stage and producing the corresponding permanent plastic deformation for the purpose of improving the carrying capacity of the vessel, is called internal pressure autofrettage. In this paper, for the high-density polyethylene liner filament winding vessels which are winded by the equivalent cooling method, the ANSYS ACP module is used to analyze the stress distribution under autofrettage condition and working condition. The influence of autofrettage pressure and cooling temperature on the stress distribution under the working conditions of the vessel is addressed. This study could provide a reference for the optimization of winding process.

scholarly journals Deep Transfer Learning-Based Fault Diagnosis for Gearbox under Complex Working Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zitong Wan ◽  
Rui Yang ◽  
Mengjie Huang
Keyword(s):  
Fault Diagnosis ◽  
Transfer Learning ◽  
Working Conditions ◽  
Evaluation Method ◽  
Working Condition ◽  
Negative Effects ◽  
Gear Fault ◽  
Diagnosis Method ◽  
Fault Feature Extraction ◽  
Better Than

In the large amount of available data, information insensitive to faults in historical data interferes in gear fault feature extraction. Furthermore, as most of the fault diagnosis models are learned from offline data collected under single/fixed working condition only, this may cause unsatisfactory performance for complex working conditions (including multiple and unknown working conditions) if not properly dealt with. This paper proposes a transfer learning-based fault diagnosis method of gear faults to reduce the negative effects of the abovementioned problems. In the proposed method, a cohesion evaluation method is applied to select sensitive features to the task with a transfer learning-based sparse autoencoder to transfer the knowledge learnt under single working condition to complex working conditions. The experimental results on wind turbine drivetrain diagnostics simulator show that the proposed method is effective in complex working conditions and the achieved results are better than those of traditional algorithms.

scholarly journals Design and Analysis of Refined Inspection of Field Conditions of Oilfield Pumping Wells Based on Rotorcraft UAV Technology

Electronics ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1504 ◽  
Author(s):  
Yu Zhou ◽  
Chunxue Wu ◽  
Qunhui Wu ◽  
Zelda Makati Eli ◽  
Naixue Xiong ◽  
...  
Keyword(s):  
Real Time ◽  
Working Conditions ◽  
Working Condition ◽  
Oil Well ◽  
Monitoring Method ◽  
The Real ◽  
Multi Target Tracking ◽  
Key Factor ◽  
Real Time Detection ◽  
Rotorcraft Uav

The traditional oil well monitoring method relies on manual acquisition and various high-precision sensors. Using the indicator diagram to judge the working condition of the well is not only difficult to establish but also consumes huge manpower and financial resources. This paper proposes the use of computer vision in the detection of working conditions in oil extraction. Combined with the advantages of an unmanned aerial vehicle (UAV), UAV aerial photography images are used to realize real-time detection of on-site working conditions by real-time tracking of the working status of the head working and other related parts of the pumping unit. Considering the real-time performance of working condition detection, this paper proposes a framework that combines You only look once version 3 (YOLOv3) and a sort algorithm to complete multi-target tracking in the form of tracking by detection. The quality of the target detection in the framework is the key factor affecting the tracking effect. The experimental results show that a good detector makes the tracking speed achieve the real-time effect and provides help for the real-time detection of the working condition, which has a strong practical application.

scholarly journals Slip Factor Correction in 1-D Performance Prediction Model for PaTs

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 565 ◽  
Author(s):  
Tommaso Capurso ◽  
Michele Stefanizzi ◽  
Giuseppe Pascazio ◽  
Sergio Ranaldo ◽  
Sergio Camporeale ◽  
...  
Keyword(s):  
Prediction Model ◽  
Performance Prediction ◽  
Distribution Systems ◽  
Water Distribution ◽  
Fluid Dynamic ◽  
Outlet Section ◽  
Prediction Errors ◽  
Slip Factor ◽  
Specific Speed ◽  
Slip Phenomenon

In recent years, pumps operated as turbines (PaTs) have been gaining the interest of industry and academia. For instance, PaTs can be effectively used in micro hydropower plants (MHP) and water distribution systems (WDS). Therefore, further efforts are necessary to investigate their fluid dynamic behavior. Compared to conventional turbines, a lower number of blades is employed in PaTs, lowering their capability to correctly guide the flow, hence reducing the Euler’s work; thus, the slip phenomenon cannot be neglected at the outlet section of the runner. In the first part of the paper, the slip phenomenon is numerically investigated on a simplified geometry, evidencing the dependency of the lack in guiding the flow on the number of blades. Then, a commercial double suction centrifugal pump, characterized by the same specific speed, is considered, evaluating the dependency of the slip on the flow rate. In the last part, a slip factor correlation is introduced based on those CFD simulations. It is shown how the inclusion of this parameter in a 1-D performance prediction model allows us to reduce the performance prediction errors with respect to experiments on a pump with a similar specific speed by 5.5% at design point, compared to no slip model, and by 8% at part-loads, rather than using Busemann and Stodola formulas.

A Study on Simulation of Vibration Source Excited by Engine

2014 ◽  
Vol 543-547 ◽  
pp. 215-218
Author(s):  
Wei Yang ◽  
Wen Ku Shi ◽  
Chun Xue Chen ◽  
Zhi Yong Chen
Keyword(s):  
Power Unit ◽  
Working Conditions ◽  
Dynamic Method ◽  
Working Condition ◽  
Engine Block ◽  
Vibration Source ◽  
Vibration Acceleration ◽  
Unit Module ◽  
Engine System ◽  
Method Model

Vibration exciting theory of working engine was analyzed based on dynamic method. Model of engine system and mounts was established and simulated in multiple working conditions by Power Unit module of dynamics software excite. Vibration acceleration of points on engine block adjacent to each mount was extracted to characterize and evaluate the vibration excited by engine in different working condition.

Implementation of dynamic working condition seawater desalination system optimization and simulation model

2016 ◽  
Vol 16 (5) ◽  
pp. 1417-1431
Author(s):  
Zhihan Zhao ◽  
Yuan Zheng ◽  
Zaiqiang Wu
Keyword(s):  
Working Conditions ◽  
Working Condition ◽  
System Optimization ◽  
Important Research ◽  
Seawater Desalination ◽  
Development Platform ◽  
Important Research Topic ◽  
Refinement Process ◽  
Optimization And Simulation ◽  
Working Device

Freshwater is an increasingly important research topic in the 21st century, similar to the importance of coal and oil in the 19th and 20th centuries, respectively. To expand expertise on desalination systems, this study aims to design a set of seawater desalination systems with dynamic working conditions based on the visualized development platform LABVIEW. The optimization searched for the optimal working conditions and formed the seawater desalination refinement process control technology and solution. A scaled dynamic load working device safety and protection solution was obtained, and an ideal scenario compared with the real operation environment was reproduced to assist people in operating and running the system.

High-Resolution Film Cooling Effectiveness Measurements of Axial Holes Embedded in a Transverse Trench With Various Trench Configurations

2006 ◽  
Vol 129 (2) ◽  
pp. 294-302 ◽  
Author(s):  
Scot K. Waye ◽  
David G. Bogard
Keyword(s):  
High Resolution ◽  
Film Cooling ◽  
Density Ratio ◽  
Field Measurements ◽  
Suction Side ◽  
Lateral Spreading ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Flow Parameters ◽  
Adiabatic Effectiveness

Adiabatic film cooling effectiveness of axial holes embedded within a transverse trench on the suction side of a turbine vane was investigated. High-resolution two-dimensional data obtained from infrared thermography and corrected for local conduction provided spatial adiabatic effectiveness data. Flow parameters of blowing ratio, density ratio, and turbulence intensity were independently varied. In addition to a baseline geometry, nine trench configurations were tested, all with a depth of 1∕2 hole diameter, with varying widths, and with perpendicular and inclined trench walls. A perpendicular trench wall at the very downstream edge of the coolant hole was found to be the key trench characteristic that yielded much improved adiabatic effectiveness performance. This configuration increased adiabatic effectiveness up to 100% near the hole and 40% downstream. All other trench configurations had little effect on the adiabatic effectiveness. Thermal field measurements confirmed that the improved adiabatic effectiveness that occurred for a narrow trench with perpendicular walls was due to a lateral spreading of the coolant and reduced coolant jet separation. The cooling levels exhibited by these particular geometries are comparable to shaped holes, but much easier and cheaper to manufacture.

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