scholarly journals Numerical simulation prediction of pressure distribution of guide vanes in a high-head pump turbine

2021 ◽  
Vol 774 (1) ◽  
pp. 012038
Author(s):  
Lei He ◽  
Zhongxin Gao ◽  
Ying Chen ◽  
Jianguang Zhang ◽  
Bingquan Ma ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Pressure Distribution ◽  
Pump Turbine ◽  
Guide Vanes ◽  
High Head

Numerical Simulation of the Unsteady Flow in a High-Head Pump Turbine and the Runner Improvement

2008 ◽  
Author(s):  
Hongjuan Ran ◽  
Xianwu Luo ◽  
Yao Zhang ◽  
Baotang Zhuang ◽  
Hongyuan Xu
Keyword(s):  
Numerical Simulation ◽  
Unsteady Flow ◽  
Guide Vane ◽  
Positive Slope ◽  
Pump Turbine ◽  
Operation Conditions ◽  
Partial Load ◽  
Discharge Curve ◽  
Rotor Stator Interaction ◽  
High Head

The unsteady flow in a high-head pump-turbine whose head-discharge curve has the positive slopes at high-partial-load operation condition was investigated. It is noted that the numerical methods is very important for predicting this kind of head-discharge curve with positive slopes, and better agreement between calculation results and experimental data was achieved by using Spalart-Allmaras turbulence model and mesh strategy with y+ controlling for numerical simulation. From the analysis of hydraulic losses at different parts in the pump turbine, it is found that the head loss at the flow passage of the guide vane and stay vane was not small at pump mode. In order to make clear the reason why the positive slopes at head-discharge curve occur, the flow between the impeller exit and the inlet of spiral casing was checked carefully. Much intensive vortex was observed near the impeller shroud, and there was strong rotor stator interaction for those operation conditions with positive slope. It is suspected the instability such as positive slope at head-discharge curve was resulted from the vortex formation near the flow channel wall. Based on the flow analysis, the runner optimization was conducted so as to mitigate the intensive rotor stator interaction. It is noted that the pressure fluctuation as well as the flow pattern was improved by applying the optimized impeller.

Hydrodynamics of a Pump-Turbine at Off-Design Operating Conditions: Numerical Simulation

2011 ◽  
Author(s):  
Vlad Hasmatuchi ◽  
Steven Roth ◽  
Francisco Botero ◽  
Mohamed Farhat ◽  
Franc¸ois Avellan
Keyword(s):  
Numerical Simulation ◽  
Stokes Equations ◽  
Operating Conditions ◽  
Scale Model ◽  
Navier Stokes ◽  
Computational Domain ◽  
Pump Turbine ◽  
Navier Stokes Equations ◽  
Guide Vanes ◽  
Radial Pump

Flow numerical simulations in a low specific speed radial pump-turbine scale model are performed to investigate off-design operating conditions in generating mode. The Best Efficiency Point (BEP) and the runaway operating conditions at 10° guide vanes opening are addressed. The computational domain includes the full reduced scale model water passage from the spiral casing inlet to the draft tube outlet. The numerical simulation is performed using the Ansys CFX code, solving the incompressible unsteady Reynolds-Averaged Navier-Stokes equations. Wall pressure measurements in the stator are used to validate the numerical results. Then, detailed analysis is focused on the onset of the flow instabilities when the machine is brought from BEP to runaway. In these severe operating conditions, one single stall cell is found to rotate with the impeller at subsynchronous speed in the vaneless gap between the impeller and the guide vanes. It is found to be the effect of flow separation developed at the inlet of several consecutive impeller channels which lead to their blockage.

Influence of the Distribution of Dual Cascades on Double Vanes Based on the Solid-Liquid Two-Phase Flow

2015 ◽  
Vol 723 ◽  
pp. 186-189
Author(s):  
Fu Chun Liu ◽  
Jian Rong Zhang ◽  
Dong Wang
Keyword(s):  
Numerical Simulation ◽  
Pressure Distribution ◽  
Velocity Vector ◽  
Active Surface ◽  
Energy Performance ◽  
Phase Flow ◽  
Two Phase ◽  
Guide Vanes ◽  
Solid Liquid ◽  
The Impact

The relative positional relationship between the stay vanes and guide vanes is researched to analyze the impact on the hydraulic performance of the Turbine based on N-S equations and RNG k-ε turbulence model under the conditions of sandy water with the numerical simulation method.There are main five kinds of the relative positional relationship between the dual cascades is used to analyse the trends of the distribution about the pressure and velocity. The relative circumferential positions between the dual cascades have obviously effect on the flow verified.And the velocity vector and the pressure distribution on the surface of the guide vanes are studied further.The results show that energy performance is best if little circumferential position differences between the dual cascades in two typical conditions.However, thedistribution about the pressure and velocity is uneven on the active surface of guide vanes, exacerbating the local abrasion of the vanes.

Measurement of Unsteady Flow in Pump-Turbine for Hydropower Using PIV Method

2009 ◽  
Author(s):  
Nobuhiko Fukuda ◽  
Satoshi Someya ◽  
Koji Okamoto
Keyword(s):  
Rotational Speed ◽  
Velocity Measurement ◽  
Numerical Procedure ◽  
Hydraulic Turbine ◽  
Operating Conditions ◽  
High Time ◽  
Pump Turbine ◽  
Guide Vanes ◽  
Runner Blade ◽  
Wide Range

It is thought that the pressure fluctuation can occur due to the interaction between flow through guide vanes and flow into runner blades, resulting in a vibration of turbine and a blade cracking, in a hydraulic turbine operated in a wide range for flexible power demand. High accurate velocity measurement with high time/spatial resolution can help to clarify the mechanism of the interaction and to provide good experimental data for the validation of numerical procedure. So the aim of present study is to estimate the unstable velocity field quantitatively in the area between guide vanes and runner blades, using high time-resolved particle image velocimetry (PIV). Two types of velocity measurements were carried out, i.e., phase-locked measurement and high time sequential velocity measurement, in a pump-turbine model with 20 guide vanes and 6 runner blades. The characteristic of the flow field varied corresponding to the operating conditions such as flow rate and rotational speed. Opening angles of guide vanes were kept uniform. A clockwise vortex was generated at inside of the runner blade under smaller rotational speed. A counterclockwise vortex was separated at the backside of the runner blade under higher rotational speed. At any operating conditions, the velocity between guide vanes and runner blades oscillated periodically at the blade passing frequency.

scholarly journals Experimental research on flow field of high head pump turbine based on PIV test

2021 ◽  
Vol 627 ◽  
pp. 012016
Author(s):  
D M Liu ◽  
L B Ma ◽  
N Li ◽  
Y Z Zhao ◽  
Huan Cheng
Keyword(s):  
Flow Field ◽  
Experimental Research ◽  
Pump Turbine ◽  
High Head

scholarly journals Distribution of Pressure Fluctuations in a Prototype Pump Turbine at Pump Mode

2014 ◽  
Vol 6 ◽  
pp. 923937 ◽  
Author(s):  
Yuekun Sun ◽  
Zhigang Zuo ◽  
Shuhong Liu ◽  
Jintao Liu ◽  
Yulin Wu
Keyword(s):  
Mass Flow ◽  
Pressure Fluctuations ◽  
Dominant Frequency ◽  
Pump Mode ◽  
Pump Turbine ◽  
Guide Vanes ◽  
Path Direction ◽  
Mass Flow Rates ◽  
Operating Points ◽  
Spiral Casing

Pressure fluctuations are very important characteristics in pump turbine's operation. Many researches have focused on the characteristics (amplitude and frequencies) of pressure fluctuations at specific locations, but little researches mentioned the distribution of pressure fluctuations in a pump turbine. In this paper, 3D numerical simulations using SSTk − ω turbulence model were carried out to predict the pressure fluctuations distribution in a prototype pump turbine at pump mode. Three operating points with different mass flow rates and different guide vanes’ openings were simulated. The numerical results show how pressure fluctuations at blade passing frequency (BPF) and its harmonics vary along the whole flow path direction, as well as along the circumferential direction. BPF is the first dominant frequency in vaneless space. Pressure fluctuation component at this frequency rapidly decays towards upstream (to draft tube) and downstream (to spiral casing). In contrast, pressure fluctuations component at 3BPF spreads to upstream and downstream with almost constant amplitude. Amplitude and frequencies of pressure fluctuations also vary along different circumferential locations in vaneless space. When the mass flow and guide vanes’ opening are different, the distribution of pressure fluctuations along the two directions is different basically.

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.

Numerical Investigation on Unsteady Characteristics in Different Rim Seal Geometries: Part A

2020 ◽  
Author(s):  
Xie Lei ◽  
Wang RuoNan ◽  
Liu Guang ◽  
Lian ZengYan ◽  
Du Qiang
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Pressure Distribution ◽  
Engine Efficiency ◽  
Ansys Cfx ◽  
Geometry Configuration ◽  
Numerical Simulation Methods ◽  
Unsteady Simulation ◽  
Unsteady Characteristics ◽  
Cooling Air

Abstract Secondary sealing flow is of great importance in the turbine disk cooling and sealing system. The amount of cooling air extracted from the compressor is crucial to engine efficiency. To determine a minimum amount of cooling air, the flow characteristic of the rim seal should be investigated. Numerical simulation is carried out to investigate the flow field near the rim seal region. Both RANS and URANS numerical simulation methods are used in the commercial CFD code ANSYS CFX to analyze axial and radial rim seals. In the simulation, a 1/33 sector is selected as computing region to simulate the flow field and the SST turbulent model is used. The steady and unsteady simulation results of pressure distribution and seal efficiency are analyzed and compared. The computed results show that due to the different geometry configuration, the pressure distribution also shows inconsistency. Unsteady phenomena are observed in both axial and radial type of rim seals. Radial sealing lip can suppress the inherent unsteadiness and interaction between main flow and sealing flow, thus showing higher sealing efficiency. Comparing to steady results using the RANS method; unsteady simulation, using the URANS method, can capture the pressure difference and seal efficiency fluctuation at the disk rim more efficiently. Also, the interaction between the rotor and stator is considered in unsteady simulation, so the unsteady simulation is recommended. The results obtained in the current paper are useful to the investigation and design of turbine rim seals.

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