scholarly journals An Indirect Measurement Methodology to Identify Load Fluctuations on Axial Turbine Runner Blades

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7220
Author(s):  
Arash Soltani Dehkharqani ◽  
Fredrik Engström ◽  
Jan-Olov Aidanpää ◽  
Michel J. Cervantes

Smooth integration of intermittent energy sources, such as solar and wind power, into the electrical grid induces new operating conditions of the hydraulic turbine by increasing the off-design operations, start/stops, and load variations. Therefore, hydraulic turbines are subject to unstable flow conditions and unfavorable load fluctuations. Predicting load fluctuations on the runner using indirect measurements can allow for optimized operations of the turbine units, increase turbine refurbishment time intervals, and avoid structural failures in extreme cases. This paper investigates an experimental methodology to assess and predict the flow condition and load fluctuations on a Kaplan turbine runner at several steady-state operations by performing measurements on the shaft in the rotating and stationary frame of references. This unit is instrumented with several transducers such as miniature pressure transducers, strain gages, and proximity probes. The results show that for any propeller curve of a Kaplan turbine, the guide vane opening corresponding to the minimum pressure and strain fluctuations on the runner blade can be obtained by axial, torsion, and bending measurements on the shaft. Torsion measurements on the shaft could support index-testing in Kaplan turbines particularly for updating the cam-curve during the unit operation. Furthermore, a signature of every phenomenon observed on the runner blade signals, e.g., runner frequency, rotating vortex rope components, and rotor-stator interaction, is found in the data obtained from the shaft.

2009 ◽  
Vol 2009 ◽  
pp. 1-7 ◽  
Author(s):  
Martin Karlsson ◽  
Håkan Nilsson ◽  
Jan-Olov Aidanpää

The rotordynamic behavior of a hydraulic turbine is influenced by fluid-rotor interactions at the turbine runner. In this paper computational fluid dynamics (CFDs) are used to numerically predict the torsional dynamic coefficients due to added polar inertia, damping, and stiffness of a Kaplan turbine runner. The simulations are carried out for three operating conditions, one at about 35% load, one at about 60% load (near best efficiency), and one at about 70% load. The runner rotational speed is perturbed with a sinusoidal function with different frequencies in order to estimate the coefficients of added polar inertia and damping. It is shown that the added coefficients are dependent of the load and the oscillation frequency of the runner. This affect the system's eigenfrequencies and damping. The eigenfrequency is reduced with up to 65% compared to the eigenfrequency of the mechanical system without the fluid interaction. The contribution to the damping ratio varies between 30–80% depending on the load. Hence, it is important to consider these added coefficients while carrying out dynamic analysis of the mechanical system.


Author(s):  
Nobuhiko Fukuda ◽  
Satoshi Someya ◽  
Koji Okamoto

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.


Author(s):  
Tânia S. Cação Ferreira ◽  
Tony Arts

An investigation of thermal effects on bypass transition was conducted on the highly-loaded turbine guide vane LS89 in the short-duration isentropic Compression Tube (CT-2) facility at the von Karman Institute for Fluid Dynamics (VKI). Measurements from high response surface-mounted thin films coupled with analog circuits provided the time-resolved wall heat flux history whereas pneumatic probes, differential pressure transducers and thermocouples allowed the accurate definition of the inlet and outlet flow conditions. The gas-to-wall temperature ratio, ranging from 1.11 to 1.55, was varied by changing the inlet total temperature. The isentropic exit Mach number ranged from 0.90 to 1.00 and the global freestream turbulence intensity value was set at 0.8, 3.9 and 5.3%. The isentropic exit Reynolds number was kept at 106. The onset of transition was tracked through the wall heat flux signal fluctuations. Within the present operating conditions, no significant effect of the gas/wall temperature ratio was put in evidence. At the present (design) transonic exit conditions, the local free-stream pressure gradient appears to remain the main driver of the onset of transition. A wider range of operating conditions must be considered to draw final conclusions.


2018 ◽  
Vol 8 (12) ◽  
pp. 2505 ◽  
Author(s):  
Jean Decaix ◽  
Vlad Hasmatuchi ◽  
Maximilian Titzschkau ◽  
Cécile Münch-Alligné

Due to the integration of new renewable energies, the electrical grid undergoes instabilities. Hydroelectric power plants are key players for grid control thanks to pumped storage power plants. However, this objective requires extending the operating range of the machines and increasing the number of start-up, stand-by, and shut-down procedures, which reduces the lifespan of the machines. CFD based on standard URANS turbulence modeling is currently able to predict accurately the performances of the hydraulic turbines for operating points close to the Best Efficiency Point (BEP). However, far from the BEP, the standard URANS approach is less efficient to capture the dynamics of 3D flows. The current study focuses on a hydraulic turbine, which has been investigated at the BEP and at the Speed-No-Load (SNL) operating conditions. Several “advanced” URANS models such as the Scale-Adaptive Simulation (SAS) SST k - ω and the BSL- EARSM have been considered and compared with the SST k - ω model. The main conclusion of this study is that, at the SNL operating condition, the prediction of the topology and the dynamics of the flow on the suction side of the runner blade channels close to the trailing edge are influenced by the turbulence model.


Author(s):  
Marco Tulio C. Faria ◽  
Fernando R. Queiroz ◽  
Eduardo B. Medeiros ◽  
Carlos B. Martinez

This work presents an experimental study about the application of acoustic emission (AE) techniques in the monitoring of cavitation erosion mass loss in small Francis turbines. A vertical Francis turbine test bench is specially devised to perform some experiments designed to evaluate the influence of small surface mass losses on turbine blades in the acoustic emission signals. An AE wideband transducer is employed in the test bench instrumentation system. In order to evaluate the AE levels associated with the turbine erosion stages, a small defect is introduced into the turbine runner. This defect is intended to simulate a small mass loss in the turbine runner. The measurements of the AE signals are performed in the Turbine Francis model at two situations: 1) turbine without defect, which means that the runner blades are free of apparent geometric imperfections; 2) turbine with defect, which is represented by a small hole drilled into a runner blade. The AE transducer is installed on the turbine draft tube and the AE measurements are performed at several operating conditions. The preliminary results obtained for the AE amplitude in this investigation show that the small defect introduced into a runner blade causes variations in the AE levels measured in the experiments, confirming that there is a large potential for the application of AE monitoring techniques in the accurate evaluation of cavitation wear on hydraulic turbines in field.


2012 ◽  
Vol 15 (6) ◽  
pp. 062042 ◽  
Author(s):  
J Arpin-Pont ◽  
M Gagnon ◽  
S A Tahan ◽  
A Coutu ◽  
D Thibault

2013 ◽  
Vol 456 ◽  
pp. 207-210
Author(s):  
Fang He

This paper presents a vibration prediction method for Francis turbine: Provided with advanced CFX software, Numerical simulation of movable guide vane and Turbine runner’s internal flow state. From the source of hydraulic vibration, Focus on numerical analysis, numerical simulation for the cutting thickness of the runner blade. After analysis of the influence of the blade of hydraulic vibration. To explore new ways for the hydro turbine control hydraulic vibration.


2011 ◽  
Vol 354-355 ◽  
pp. 631-635
Author(s):  
Ling Hua Wang ◽  
Pan Hua Ning ◽  
Chao Gan

This paper analyses quantitatively mechanism that hydraulic turbine runner blade tail produces Carmen vortex column, and the blade hydraulic elastic vibration which is produced by Carmen vortex column, also analyses the harms of blade hydraulic resonance, puts forward corresponding preventative measures. For the stable operation of large Francis hydraulic turbine, these measures have reference meaning.


2022 ◽  
Vol 2150 (1) ◽  
pp. 012001
Author(s):  
S G Skripkin ◽  
D A Suslov ◽  
I V Litvinov ◽  
E U Gorelikov ◽  
M A Tsoy ◽  
...  

Abstract This article presents a comparative analysis of flow characteristics behind a hydraulic turbine runner in air and water. Swirling flow with a precessing vortex core (PVC) was investigated using a laser Doppler anemometer and pressure pulsation sensors. The experiments were conducted on aerodynamic and hydrodynamic test rigs over a wide range of hydraulic turbine operating conditions. Part-load modes of hydraulic turbine operation were investigated using the Fourier transform of pressure pulsations obtained from acoustic sensors. The features of the swirling flow were shown for the range of operating conditions from deep partl-load to overload.


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