Flow Analysis of the Guide Vanes Region of Pump Turbine at the Slight Opening in the Pumping Startup Process

2016 ◽  
Author(s):  
Honggang Fan ◽  
Qingfeng Ji ◽  
Weili Liao ◽  
Haixia Yang
Keyword(s):  
Guide Vane ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Main Flow ◽  
Three Dimensional Model ◽  
Pump Turbine ◽  
Guide Vanes ◽  
Abrupt Changes ◽  
Dimensional Simulation ◽  
Pumped Storage

The unit of a Pumped Storage Power Station experienced abnormal noise and vibration in the guide vanes at the slight opening when the pump turbine was in the process of startup in the pumping mode. Based on this phenomena, the three dimensional model of the pump turbine was established, RNG k-epsilon two equations turbulence model was selected for the flow numerical simulation in the pump turbine because this model can simulate both the flow separation and vortex dynamics, and it is more accurate in the near wall areas. The governing equations were discretized with the finite volume method. The computation was carried out with three steps, 1.steady calculation, 2.unsteady calculation with constant guide vane opening, 3.unsteady calculations with the increase of the opening of guide vanes, by using the results of the last step as the initial condition. According to the three dimensional simulation results, the main flow between the guide vanes was deflected from attaching to the one vane to the other vane with the opening of the guide vanes. The calculation of complete 3D flow indicated that the deflections of the flows between the different adjacent guide vanes were basically the same, however, the deflections starting times had a few differences. The variation of the torque on the guide vane was also investigated, and the results shown the abrupt changes occurred during the deflection process of the main flow. When the torque produced by the servomotor cannot adapt quickly enough to the abrupt changes, the vibration and loud scrape noise might occur.

scholarly journals Optimization of Pump Turbine Closing Operation to Minimize Water Hammer and Pulsating Pressures During Load Rejection

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1000 ◽  
Author(s):  
Jiawei Ye ◽  
Wei Zeng ◽  
Zhigao Zhao ◽  
Jiebin Yang ◽  
Jiandong Yang
Keyword(s):  
Guide Vane ◽  
Water Hammer ◽  
Nsga Ii ◽  
Pump Turbine ◽  
Guide Vanes ◽  
Multi Objective ◽  
Spiral Case ◽  
Transitional Processes ◽  
Pumped Storage ◽  
Load Rejection Process

In load rejection transitional processes in pumped-storage plants (PSPs), the process of closing pump turbines, including guide vane (GVCS) and ball valve closing schemes (BVCS), is crucial for controlling pulsating pressures and water hammer. Extreme pressures generated during the load rejection process may result in fatigue damage to turbines, and cracks or even bursts in the penstocks. In this study, the closing schemes for pump turbine guide vanes and ball valves are optimized to minimize water hammer and pulsating pressures. A model is first developed to simulate water hammer pressures and to estimate pulsating pressures at the spiral case and draft tube of a pump turbine. This is combined with genetic algorithms (GA) or non-dominated sorting genetic algorithm II (NSGA-II) to realize single- or multi-objective optimizations. To increase the applicability of the optimized result to different scenarios, the optimization model is further extended by considering two different load-rejection scenarios: full load-rejection of one pump versus two pump turbines, simultaneously. The fuzzy membership degree method provides the best compromise solution for the attained Pareto solutions set in the multi-objective optimization. Employing these optimization models, robust closing schemes can be developed for guide vanes and ball valves under various design requirements.

Mechanism and influence factors of hydraulic fluctuations in a pump-turbine

2021 ◽  
pp. 095765092110285
Author(s):  
Xiaolong Fu ◽  
Deyou Li ◽  
Hongjie Wang ◽  
Guanghui Zhang ◽  
Xianzhu Wei
Keyword(s):  
Guide Vane ◽  
Three Dimensional ◽  
Influence Factors ◽  
Simulation Method ◽  
Power Station ◽  
Pump Turbine ◽  
Available Energy ◽  
Exciting Forces ◽  
Pump Storage Power ◽  
Pumped Storage

Pumped-storage power technology is currently the only available energy storage technology in the grid net, and its reliability is receiving attention increasingly. However, when a pump-turbine unit undergoes runaway transitions, hydraulic fluctuations intensively affect the reliable operation of a pumped-storage power station. To reduce hydraulic fluctuations, this study investigated the formation mechanism of hydraulic fluctuations and explored its influence factors. In this study, a developed one-dimensional and three-dimensional (1 D-3D) coupling simulation method was adopted. Transient runaway transitions of a pump-turbine with three different inertias (0.5 J, 1 J, and 2.0 J) at three different guide vane openings (21°, 15°, and 12°, respectively) were simulated and compared. The results suggest that, at smaller guide vane openings (15° and 12°), water hammer owing to the increase in rotational speed is the primary unstable issue compared to the pulsation of radial hydraulic exciting forces on the runner. However, at a larger guide vane opening (21°), the latter owing to the back-flow near the runner inlet is the primary unstable issue. Moreover, it is found that a sufficiently large inertia improves the hydraulic fluctuations of the pump-storage power station, particularly in reducing the pulsation of radial hydraulic exciting loads on the runner. The findings of this study provide a valuable reference for determining suitable rotor inertia.

Hydraulic Characteristics of the New Type Bulb Turbine With Micro-Head

2013 ◽  
Author(s):  
Lingyu Li ◽  
Yuan Zheng ◽  
Daqing Zhou ◽  
Zihao Mi
Keyword(s):  
Numerical Simulation ◽  
Cfd Simulation ◽  
Guide Vane ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Three Dimensions ◽  
Guide Vanes ◽  
Runner Blade ◽  
Cfd Method ◽  
Bulb Turbine

The head of low-head hydropower stations is generally higher than 2.5m in the world, while micro-head hydropower resources which head is less than 2.5m are also very rich. In the paper, three-dimensional CFD method has been used to simulate flow passage of the micro-head bulb turbine. The design head and unit flow of the turbine was 1m and 3m3/s respectively. With the numerical simulation, the bulb turbine is researched by analyzing external characteristics of the bulb turbine, flow distribution before the runner, pressure distribution of the runner blade surface, and flow distribution of the outlet conduit under three different schemes. The turbine in second scheme was test by manufactured into a physical model. According to the results of numerical simulation and model test, bulb turbine with no guide vane in second scheme has simpler structure, lower cost, and better flow capacity than first scheme, which has traditional multi-guide vanes. Meanwhile, efficiency of second scheme has just little decrease. The results of three dimensions CFD simulation and test results agree well in second scheme, and higher efficiency is up to 77% which has a wider area with the head of 1m. The curved supports in third scheme are combined guide vanes to the fixed supports based on 2nd scheme. By the water circulations flowing along the curved supports which improve energy transformation ability of the runner, the efficiency of the turbine in third scheme is up to 82.6%. Third scheme, which has simpler structure and best performance, is appropriate for the development and utilization of micro-head hydropower resources in plains and oceans.

scholarly journals Design and Testing of Swept and Leaned Outlet Guide Vanes to Reduce Stator-Strut-Splitter Aerodynamic Flow Interactions

1998 ◽  
Author(s):  
A. R. Wadia ◽  
P. N. Szucs ◽  
K. L. Gundy-Burlet
Keyword(s):  
Dimensional Analysis ◽  
Test Performance ◽  
Potential Flow ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Angle Distribution ◽  
Two Dimensional ◽  
Guide Vanes ◽  
Flow Interactions ◽  
Design And Testing

Large circumferential varying pressure levels produced by aerodynamic flow interactions between downstream stators and struts present a potential noise and stability margin liability in a compression component. These interactions are presently controlled by tailoring the camber and/or stagger angles of vanes neighboring the fan frame struts. This paper reports on the design and testing of a unique set of swept and leaned fan outlet guide vanes (OGVs) that do not require this local tailoring even though the OGVs are closely coupled with the fan frame struts and splitter to reduce engine length. The swept and leaned OGVs not only reduce core-duct diffusion, but they also reduce the potential flow interaction between the stator and the strut relative to that produced by conventional radial OGVs. First, the design of the outlet guide vanes using a single bladerow three-dimensional viscous flow analysis is outlined. Next, a two-dimensional potential flow analysis was used for the coupled OGV-frame system to obtain a circumferentially non-uniform stator stagger angle distribution to further reduce the upstream static pressure disturbance. Recognizing the limitations of the two-dimensional potential flow analysis for this highly three-dimensional set of leaned OGVs, as a final evaluation of the OGV-strut system design, a full three-dimensional viscous analysis of a periodic circumferential sector of the OGVs, including the fan frame struts and splitter, was performed. The computer model was derived from a NASA-developed code used in simulating the flow field for external aerodynamic applications with complex geometries. The three-dimensional coupled OGV-frame analysis included the uniformly-staggered OGVs configuration and the variably-staggered OGVs configuration determined by the two-dimensional potential flow analysis. Contrary to the two-dimensional calculations, the three-dimensional analysis revealed significant flow problems with the variably-staggered OGVs configuration and showed less upstream flow non-uniformity with the uniformly-staggered OGVs configuration. The flow redistribution in both the radial and tangential directions, captured fully only in the three-dimensional analysis, was identified as the prime contributor to the lower flow non-uniformity with the uniformly-staggered OGVs configuration. The coupled three-dimensional analysis was also used to validate the design at off-design conditions. Engine test performance and stability measurements with both uniformly- and variably-staggered OGVs configurations with and without the presence of inlet distortion confirmed the conclusions from the three-dimensional analysis.

Domain Partitioned Transformation of Pump-Turbine Characteristic Curves in 3-D Space

2014 ◽  
Author(s):  
Wei Zeng ◽  
Jiandong Yang ◽  
Yongguang Cheng
Keyword(s):  
Guide Vane ◽  
Theoretical Method ◽  
Transformation Method ◽  
Measured Data ◽  
Pump Turbine ◽  
Characteristic Curves ◽  
Hydraulic Transient ◽  
Transient Simulations ◽  
Pumped Storage ◽  
Conventional Representation

Pump-turbine characteristic curves are the most important boundary condition in the hydraulic transient simulation of a pumped-storage hydropower station. Conventional representation of them, however, has serious defects, For instance, the “S” and “hump” shapes, composed of multiple values and steep twists, lead to the difficulty in interpolation between known guide-vane opening curves, which is necessary in hydraulic transient simulations. Here, a new transformation method was figured out to settle this problem thoroughly and to improve the accuracy of interpolation between the constant opening curves. Prior to the transformation, the characteristic curves are partitioned into eight domains. Curves of each domain were transformed through different formulae that fit the curves well. Eight characteristic surfaces in the 3-D space can be obtained by adding the guide vane opening as the coordinate axis. The theoretical method has been validated by the excellent agreements achieved by comparing the curves interpolated on the characteristic surfaces with the measured data.

Microscale fluid flow analysis in a human osteocyte canaliculus using a realistic high-resolution image-based three-dimensional model

2012 ◽  
Vol 4 (10) ◽  
pp. 1198-1206 ◽  
Author(s):  
Hiroshi Kamioka ◽  
Yoshitaka Kameo ◽  
Yuichi Imai ◽  
Astrid D. Bakker ◽  
Rommel G. Bacabac ◽  
...  
Keyword(s):  
Fluid Flow ◽  
High Resolution ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Resolution Image ◽  
High Resolution Image ◽  
Fluid Flow Analysis

scholarly journals Optimization Study of Guide Vanes for the Intake Fan-Duct Connection Using CFD

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1555
Author(s):  
Juan Pablo Hurtado ◽  
Bryan Villegas ◽  
Sebastián Pérez ◽  
Enrique Acuña
Keyword(s):  
Fluid Dynamics ◽  
Energy Savings ◽  
Guide Vane ◽  
Three Dimensional ◽  
Radius Of Curvature ◽  
Penetration Length ◽  
Curvature Ratio ◽  
Guide Vanes ◽  
Ventilation Shaft ◽  
Shock Loss

The connection between an intake fan and a ventilation shaft must be designed in such a way that it minimizes the energy waste due to singularity losses. As a result, the questions of which radius of curvature to use and if guide vanes have to be included need to be answered. In that case, the variables such as the number, upstream and downstream penetration length, radius of curvature, and width of the vanes, need to be defined. Although this work is oriented to mine ventilation, these questions are usually valid in other engineering applications as well. The objective of this study is to define the previously mentioned variables to determine the optimal design combination for the radius/diameter relationship (r/D). Computational fluid dynamics was used to determine the shock loss factor of seven elbow curvature ratios for a 3 m diameter duct and fan, with and without guide vanes to estimate the best performing configuration and, therefore, to maximize the fan airflow volume. The methodology used consisted of initially developing models in 2D geometries, to optimize the meshing and the CPU use, and studying separately the number of vanes, upstream and downstream penetration, radius of curvature, and width of the vanes for each curvature ratio (r/D). Then, the best-performing variable combinations for each curvature ratio were selected to be simulated and studied with the 3D geometries. The application of the guide vane designs for three-dimensional simulated geometries is presented, first without and then with guide vanes, including the shock loss factors obtained. The methodology and obtained results allowed quantifying the energy savings and to reduce the CFD simulations steps required to optimize the design of the elbow and guide vanes. The results obtained cannot be used with elbows in exhaust fans, because fluid dynamics phenomena are different.

scholarly journals Three-Dimensional CFD Simulations of Start-Up Processes of a Pump-Turbine Considering Governor Regulation

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8507
Author(s):  
Zhiyan Yang ◽  
Yongguang Cheng ◽  
Ke Liu ◽  
Xiaoxia Hou ◽  
Xiaoxi Zhang ◽  
...  
Keyword(s):  
Rotational Speed ◽  
Three Dimensional ◽  
Load Condition ◽  
Internal Flow ◽  
Pump Turbine ◽  
Characteristic Region ◽  
Start Up ◽  
Speed Fluctuation ◽  
Pumped Storage ◽  
Cfd Method

The pumped-storage power station is an efficient stability regulator of the power grid. However, due to the instability of the pump-turbine in the S-shaped characteristic region, rotational speed fluctuation is easy to occur in the speed no-load condition, making synchronization with and connection to the grid difficult. To investigate the key factors of these difficult grid connections, the start-up processes of a practical pump-turbine under the lowest head condition were simulated by using the three-dimensional CFD method, in which the governor regulating equations with different regulating parameters were integrated successfully. The results show that the working points oscillate with the fluctuations of rotational speed, discharge, and torque, and different regulating parameters have a significant influence on the dynamic histories. In addition, the internal flow patterns, especially the backflows at the runner inlet, keep apparent values at the middle span (0.5 span) but have regular transitions near the shroud side (0.7–0.8 span). The faster the guide vanes adjust, the faster the backflows change, and the larger the macro parameters fluctuate. Overall, the instability of the start-up is the result of the periodical evolutions of backflows at the runner inlet, because the trend and period of the radial velocities at different inlet span locations are consistent with those of the discharge.

The Dynamic Simulation Study of WN Gear Pair after Coupling Tribology

2014 ◽  
Vol 577 ◽  
pp. 214-217
Author(s):  
Yu Guang Li ◽  
Guo Qing Zhang
Keyword(s):  
Dynamic Simulation ◽  
Three Dimensional ◽  
Dynamic Contact ◽  
Axial Vibration ◽  
Dimensional Model ◽  
Analysis Model ◽  
Ansys Software ◽  
Three Dimensional Model ◽  
Dimensional Simulation ◽  
The Impact

Based on WN gear characteristics and considering system error, a multi-degree-freedom (Tangential-Radial-Axial) dynamics analysis model after coupling friction was established. In this article, we established the three-dimensional solid model by using PROE and then imported WN gear’ three-dimensional model into Ansys software through the data interface of Ansys software and PROE software and conducted a three-dimensional simulation anasys of the impact of dynamic contact. By applying load, the stress analysis of WN gear was conducted and the WN gear’s the effective stress clouds was gotten. Meanwhile, basing on ANSYS / LS-DYNA, it established the rigid-flexible body of gear dynamic contact model and analyzed the dynamic simulation anasys of WN gear. The results demonstrated that the tangential and axial vibration of double arc gear was significantly greater than the radial vibration.

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