scholarly journals Investigation on Dynamic Stresses of Pump-Turbine Runner during Start Up in Turbine Mode

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 499
Author(s):  
Funan Chen ◽  
Huili Bi ◽  
Soo-Hwang Ahn ◽  
Zhongyu Mao ◽  
Yongyao Luo ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Unsteady Flow ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Leading Edge ◽  
Complex Flow ◽  
Dynamic Stresses ◽  
Start Up ◽  
Pumped Storage ◽  
Turbine Mode

The startup process occurs frequently for pumped storage units. During this process, the rotating rate that changes rapidly and unsteady flow in runner cause the complex dynamic response of runner, sometimes even resonance. The sharp rise of stress and the large-amplitude dynamic stresses of runner will greatly shorten the fatigue life. Thus, the study of start-up process in turbine mode is critical to the safety operation. This paper introduced a method of coupling one dimensional (1D) pipeline calculation and three-dimensional computational dynamics (3D CFD) simulation to analyze transient unsteady flow in units and to obtain more accurate and reliable dynamic stresses results during start up process. According to the results, stress of the ring near fixed support increased quickly as rotating rate rose and became larger than at fillets of leading edge and band in the later stages of start-up. In addition, it was found that dynamic response can be caused by rotor stator interaction (RSI), but also could even be generated by the severe pressure fluctuation in clearance, which can also be a leading factor of dynamic stresses. This study will facilitate further estimation of dynamic stresses in complex flow and changing rotating rate cases, as well as fatigue analysis of runner during transient operation.

Research Analysis and Experiment Study on Flow Field of Hydrodynamic Coupling

2011 ◽  
Vol 418-420 ◽  
pp. 2006-2011
Author(s):  
Rui Zhang ◽  
Cheng Jian Sun ◽  
Yue Wang
Keyword(s):  
Flow Field ◽  
Cfd Simulation ◽  
Two Phase Flow ◽  
Three Dimensional ◽  
Internal Flow ◽  
Phase Flow ◽  
Complex Flow ◽  
Two Phase ◽  
Operation Conditions ◽  
Hydrodynamic Coupling

CFD simulation and PIV test technology provide effective solution for revealing the complex flow of hydrodynamic coupling’s internal flow field. Some articles reported that the combination of CFD simulation and PIV test can be used for analyzing the internal flow field of coupling, and such analysis focuses on one-phase flow. However, most internal flow field of coupling are gas-fluid two-phase flow under the real operation conditions. In order to reflect the gas-fluid two-phase flow of coupling objectively, CFD three-dimensional numerical simulation is conducted under two typical operation conditions. In addition, modern two-dimensional PIV technology is used to test the two-phase flow. This method of combining experiments and simulation presents the characteristics of the flow field when charging ratios 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.

Detailed Three-Dimensional Velocity Field Measurements of a Complex Internal Cooling Flow Within a Gas Turbine Vane

2019 ◽  
Author(s):  
Michael J. Benson ◽  
David Helmer ◽  
Bret P. Van Poppel ◽  
Benjamin Duhaime ◽  
David Bindon ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Three Dimensional ◽  
Leading Edge ◽  
Scale Model ◽  
Internal Cooling ◽  
Complex Flow ◽  
Copper Sulfate Solution ◽  
Flow Rates ◽  
Experimental Apparatus ◽  
Turbine Vane

Abstract A 6.67 scale model of the Advanced Recirculation Total Impingement Cooling (ARTIC) gas turbine vane insert’s leading edge was designed, built using stereolithography (SLA) fabrication methods, and tested using Magnetic Resonance Velocimetry (MRV), a non-invasive data acquisition technique that captures three-dimensional, three-component velocity fields of a copper sulfate solution over the course of several hours. The experimental apparatus supplied constant flow rates through a test section placed within a 3.0 Tesla MRI magnet. Tests were run at two fully turbulent flow rates corresponding to Reynolds numbers based on hydraulic diameter of 10,000 and 20,000 with the higher flow rate case achieving dynamic similarity with the full-scale ARTIC device. The experimental results elucidated key details and intricacies of the complex flow within the insert. Analysis of flow distribution between each of the three independent impingement zones revealed a degree of measurable jet to jet variability. Stagnation and recirculation zones were detected, informing design modifications and enabling assessment of inlet effects on impingement. Measurement uncertainty was assessed and estimated to be approximately 7.5% of the peak velocity at the inlet to the central feed cavity.

Visualizations of the Unsteady Flow Field Near the Endwall of a Compressor Cascade

2001 ◽  
Author(s):  
Hongwei Ma ◽  
Haokang Jiang ◽  
Lin Yang
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Cross Sections ◽  
Leading Edge ◽  
Light Sheet ◽  
Horseshoe Vortex ◽  
Radial Clearance ◽  
Compressor Cascade ◽  
Complex Flow ◽  
Suction Surface

This paper presents flow visualizations of the unsteady flow field near the endwall of a compressor cascade. The experiments were performed in a water tunnel using the hydrogen bubble technique. A Pt wire was positioned parallel to the endwall and ahead of the cascade at 2% span from the endwall. The traces of hydrogen bubbles generated by the wire were visualized within a light sheet arranged at various cross-sections around the cascade. The unsteady flow field was visualized at different incidences without a radial clearance. A periodically fluctuating horseshoe vortex system of varying number of vortices is observed near the leading edge of the cascade, which plays a leading role in the flow field near the endwall. The interaction and the flow mixing among the counter-rotating horseshoe legs, the endwall boundary layer and the main flow, periodically occur in the passage. Breakdown of the horseshoe vortex is clearly observed in the cascade while the unsteady and complex flow field is shown at the corner of the suction surface.

Unsteady Separation on Lifting Surfaces

1987 ◽  
Vol 40 (4) ◽  
pp. 441-453 ◽  
Author(s):  
Mohamed Gad-el-Hak
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Subject Area ◽  
Complex Flow ◽  
Vast Number ◽  
Freestream Velocity ◽  
Unsteady Separation ◽  
Aspect Ratios ◽  
Local Shear ◽  
Lifting Surfaces

This article presents a review of some recent work that deals with the phenomenon of unsteady separation on two- and three-dimensional lifting surfaces. The presently available experimental data are interpreted in light of the recent idea advanced by Ho (1986), in which unsteady separation is associated with a spatially developing local shear layer. No attempt is made to give a complete account of the vast number of papers written in the subject area. Instead, reference is made to a few excellent review articles available in the open literature. The unsteady motions considered include change of angle of attack, impulsive start from rest, and change of freestream velocity. The lifting surfaces studied are bodies of revolution and wings of different aspect ratios, planforms, and leading edge bluntness. Other, nonlifting surfaces are briefly considered. Velocity probe measurements in such complex flow fields are sparse. However, flow visualization results are ample and are extensively reviewed in this paper.

scholarly journals Investigation of the Unsteady Flow Generated by an Axial Fan: Experimental Testing and Simulations

2005 ◽  
Vol 2005 (3) ◽  
pp. 256-263 ◽  
Author(s):  
R. S. Amano ◽  
E. K. Lee ◽  
C. Xu ◽  
Jianhui Xie
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Flow Measurement ◽  
Cfd Simulation ◽  
Experimental Testing ◽  
Strain Analysis ◽  
Test Facility ◽  
Axial Fan ◽  
Complex Flow ◽  
Fea Simulation

The unsteady flow measurement of a large axial fan with diameter 1.829m (6 ft) has been carried out. The complex flow field generated by the fan is investigated through experimental testing and CFD/FEA simulation. The results presented in this paper can be divided into three parts. The first part consists of the experimental description of the test facility, velocity measurement, flow-field visualization, and stress/strain analysis of the fan blades. The second part consists of the CFD simulation of the flow field. Simulation is carried out to analyze the flow pattern with and without a radiator attached to the fan casing. The results presented in this paper can be used as a reference for axial fan performance improvement in the future.

scholarly journals Analysis of flow characteristics in pumped storage unit during start-up in turbine mode

2021 ◽  
Vol 1985 (1) ◽  
pp. 012051
Author(s):  
Tao Liu ◽  
Chao Wang ◽  
Zhiming Chen ◽  
Funan Chen ◽  
Huili Bi ◽  
...  
Keyword(s):  
Flow Characteristics ◽  
Storage Unit ◽  
Start Up ◽  
Pumped Storage ◽  
Turbine Mode

Three Dimensional Measurements of a Turbine Blade Using Magnetic Resonance Thermometry and Magnetic Resonance Velocimetry

2017 ◽  
Author(s):  
Elliott T. Williams ◽  
Daniel C. Caniano ◽  
Gregory Davis ◽  
Angus M. Ferrell ◽  
Michael J. Benson ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Turbulent Flows ◽  
Turbine Blade ◽  
Three Dimensional ◽  
Leading Edge ◽  
Optical Measurements ◽  
Internal Cooling ◽  
Complex Flow ◽  
Full Field ◽  
Magnetic Resonance Velocimetry

A hollowed NACA-0012 airfoil with removable inserts was developed to study the complex flow through two interior chambers. The geometry represented an internally cooled gas turbine blade with internal impingement in several locations. A fully turbulent water flow passed the airfoil. Within the airfoil, a second fluid at a different temperature was mixed through the insert nearest the leading edge and recirculated to the aft chamber for additional internal cooling before exiting the airfoil as film cooling on the suction side and at the trailing edge. Time-averaged, three-dimensional temperature and three-component velocity measurements were collected using Magnetic Resonance Imagery (MRI) based techniques. Magnetic Resonance Velocimetry (MRV) and Thermometry (MRT) are techniques for measuring the velocity and temperature of fully turbulent flows at sub-millimeter-scale resolution. The benefits of these techniques over similar measuring techniques include the ability to collect full-field, three-dimensional, nonintrusive, non-optical measurements for conjugate heat transfer simulation validation in complex, turbulent flows. Multiple MRI-based techniques can be combined within the same experiment to explore the interaction between the mean fields of multiple quantities. The experimental setup employed in this work produced time-averaged velocity and temperature data illustrating flow details through the airfoil’s interior chambers and heat flux through the entire airfoil and at specific locations.

scholarly journals Numerical Research on the Vortex Center on the Forward-Swept 3-D Wind Turbine Blades at Low Rotational Speed

2018 ◽  
Vol 12 (12) ◽  
pp. 80
Author(s):  
Sutrisno . ◽  
Setyawan Bekti Wibowo ◽  
Sigit Iswahyudi
Keyword(s):  
Wind Turbine ◽  
Rotational Speed ◽  
Cfd Simulation ◽  
Velocity Ratio ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Leading Edge ◽  
Vortex Center ◽  
Wind Turbine Blades ◽  
Horizontal Axis Wind Turbine

This paper studies the CFD simulation of forward three-dimensional (3-D) horizontal axis wind turbine (HAWT) blades. Using logarithmic grid and Q-criterion to learn the vortex dynamics around the blades at low rotational speed. The computational fluid dynamics (CFD) simulation uses Q-criterion to probe vortices and logarithmic grid to emphasize the micro-gridding effect of the turbulent boundary layer. The visualization & measurement of the simulation results give the coefficient of pressure (Cp). For forward 3-D wind turbine blade, at low rotational speed, the strongly accelerated laminar region surrounds the lower blade, and the decelerated tip blade region coalesce each other give rise to a reverse limiting streamline, eroding the laminar region further until a little is left on the tip of the blade. The "reverse limiting streamline" grows inward radially, the area is narrowing closing to the leading edge of the blade tip. The second side of the rolled-up vortex appears the velocity ratio (Uc/Ulocal) of the second vortices are higher than the main vortex cores. For radius R=1.547 m, U=12 m/s, at 210 RPM, CL and CD values reach a maximum with fully laminar tip conditions. While at 120 RPM, the CL and CD values reach a minimum in the absence of laminar tips. The results show the detailed vortex dynamic pattern surround the blades, give more understanding to design laminar 3-D blade toward a noiseless wind turbine system.

Investigation of Periodically Unsteady Flow in a Radial Pump by CFD Simulations and LDV Measurements

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Jianjun Feng ◽  
Friedrich-Karl Benra ◽  
Hans Josef Dohmen
Keyword(s):  
Unsteady Flow ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Measurement Data ◽  
Load Condition ◽  
Navier Stokes ◽  
Complex Flow ◽  
Data Set ◽  
Vaned Diffuser ◽  
Radial Pump

The periodically unsteady flow fields in a low specific speed radial diffuser pump have been investigated both numerically and experimentally for the design condition (Qdes) and also one part-load condition (0.5Qdes). Three-dimensional, unsteady Reynolds-averaged Navier–Stokes equations are solved on high-quality structured grids with the shear stress transport turbulence model by using the CFD (computational fluid dynamics) code CFX-10. Furthermore, two-dimensional laser Doppler velocimetry (LDV) measurements are successfully conducted in the interaction region between the impeller and the vaned diffuser, in order to capture the complex flow with abundant measurement data and to validate the CFD results. The analysis of the obtained results has been focused on the behavior of the periodic velocity field and the turbulence field, as well as the associated unsteady phenomena due to the unsteady interaction. In addition, the comparison between CFD and LDV results has also been addressed. The blade orientation effects caused by the impeller rotation are quantitatively examined and detailedly compared with the turbulence effect. This work offers a good data set to develop the comprehension of the impeller-diffuser interaction and how the flow varies with relative impeller position to the diffuser in radial diffuser pumps.

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