Experimental Investigation of the Interblade Flow in a Kaplan Runner at Several Operating Points Using Laser Doppler Anemometry

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Kaveh Amiri ◽  
Berhanu Mulu ◽  
Michel J. Cervantes
Keyword(s):  
Vortex Breakdown ◽  
Laser Doppler Anemometry ◽  
Secondary Flows ◽  
Laser Doppler ◽  
Asymmetric Flow ◽  
Vortex Rope ◽  
Runner Blade ◽  
Kaplan Turbine ◽  
Flow Through ◽  
Operating Points

This paper presents laser Doppler anemometry (LDA) measurements within the runner blade channels and at the runner outlet of a Kaplan turbine model. The model was investigated at six operating points located on two propeller curves of the turbine to study the flow condition during on-cam and off-cam operations. Main and secondary flows within and after the runner were analyzed, and the effects of the hub and tip clearances on the velocity fields within and after the runner were evaluated. Operation of the turbine at flow rates that are lower than the designed rate for the corresponding propeller curve resulted in vortex breakdown and the formation of a rotating vortex rope (RVR). The RVR formation produced an asymmetrical velocity distribution within and after the runner. The results demonstrated the occurrence of an oscillating flow with the same frequency as the vortex rope within the blade channels located upstream of the RVR. This results in an asymmetric flow through the runner and oscillating forces on the runner blades. The measured velocities indicated that the geometrical asymmetries in the runner manufacturing process resulted in various flow asymmetries at the measured sections. The asymmetries were up to 3% within the runner and 7% at the runner outlet.

scholarly journals A Rotating Laser-Doppler Anemometry System for Unsteady Relative Flow Measurements in Model Centrifugal Impellers

1993 ◽  
Author(s):  
M. Abramian ◽  
J. H. G. Howard
Keyword(s):  
Laser Doppler Anemometry ◽  
Fluid Dynamic ◽  
Rotating Stall ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Laser Doppler ◽  
Low Flow ◽  
Centrifugal Impeller ◽  
Flow Measurements ◽  
Relative Flow

The behaviour of the relative flow in centrifugal turbomachines is extremely complex due to the existence of various fluid dynamic phenomena and their interaction. At design and off-design operating conditions, the relative flow is subject to stationary unsteadiness which includes the flow separation and wakes associated with passage pressure gradients, secondary flows, and boundary layer stability. It is also subject to periodic unsteadiness from the rotating stall and the cyclic flow phenomena induced by the casing. This paper describes the mechanical and optical design of a rotating laser-Doppler anemometry system which allows direct measurement of the relative flow by means of an optical de-rotator. By isolating the impeller rotational frequency from the sampling frequency, it allows direct time-average measurements of the stationary behaviour of the relative flow along with the ensemble (phase)-average measurements of its periodic behaviour. Its success is demonstrated with measurements conducted in a low specific speed centrifugal impeller fitted with a single volute. Sample results of the time-averaged blade-to-blade variation of total relative velocities along with their associated turbulence intensities are reported. The (periodic) cyclic variations of the impeller exit flow, induced by the volute at low flow rates, are also presented for the suction and pressure sides.

A Rotating Laser-Doppler Anemometry System for Unsteady Relative Flow Measurements in Model Centrifugal Impellers

1994 ◽  
Vol 116 (2) ◽  
pp. 260-268 ◽  
Author(s):  
M. Abramian ◽  
J. H. G. Howard
Keyword(s):  
Laser Doppler Anemometry ◽  
Fluid Dynamic ◽  
Rotating Stall ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Laser Doppler ◽  
Low Flow ◽  
Centrifugal Impeller ◽  
Flow Measurements ◽  
Relative Flow

The behavior of the relative flow in centrifugal turbomachines is extremely complex due to the existence of various fluid dynamic phenomena and their interaction. At design and off-design operating conditions, the relative flow is subject to stationary unsteadiness, which includes the flow separation and wakes associated with passage pressure gradients, secondary flows, and boundary layer stability. It is also subject to periodic unsteadiness from the rotating stall and the cyclic flow phenomena induced by the casing. This paper describes the mechanical and optical design of a rotating laser-Doppler anemometry system, which allows direct measurement of the relative flow by means of an optical derotator. By isolating the impeller rotational frequency from the sampling frequency, it allows direct time-averaged measurements of the stationary behavior of the relative flow along with the ensemble (phase)-averaged measurements of its periodic behavior. Its success is demonstrated with measurements conducted in a low specific speed centrifugal impeller fitted with a single volute. Sample results of the time-averaged blade-to-blade variation of total relative velocities along with their associated turbulence intensities are reported. The (periodic) cyclic variations of the impeller exit flow, induced by the volute at low flow rates, are also presented for the suction and pressure sides.

Experimental Analysis of Cavitation Phenomena on Kaplan Turbine Blades Using Flow Visualization

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Andrej Podnar ◽  
Matevž Dular ◽  
Brane Širok ◽  
Marko Hočevar
Keyword(s):  
Turbine Blades ◽  
Suction Side ◽  
Cavitation Inception ◽  
Runner Blade ◽  
Kaplan Turbine ◽  
Turbine Performance ◽  
Blade Shape ◽  
The Right ◽  
Operating Points ◽  
Acceptance Tests

In this study, a comparison of two different Kaplan turbine runners with differently shaped turbine blades was performed. The two turbines differed in the selection of the hydrofoil, the main hydrofoil parameters of which had been modified including, the position of maximum thickness and curvature and the inlet edge radius. Both turbines (unmodified and modified hydrofoils) were tested on a rig designed for low pressure model turbine acceptance tests. The effect of blade shape on cavitation inception, development, and intensity was demonstrated using computer aided visualization. Visualization was performed on the suction side of Kaplan runner blade where the shape of the blade determines cavitation inception and development. The modified Kaplan turbine reduced the cavitation phenomena, and as a result, both turbine performance and output increased for the selected operating points. This demonstrates that choosing the right turbine blade shape is key for optimal turbine performance.

scholarly journals Laser Doppler anemometry measurements of steady flow through two bi-leaflet prosthetic heart valves

2013 ◽  
Vol 28 (4) ◽  
Author(s):  
Ovandir Bazan ◽  
Jayme Pinto Ortiz ◽  
Francisco Ubaldo Vieira Junior ◽  
Reinaldo Wilson Vieira ◽  
Nilson Antunes ◽  
...  
Keyword(s):  
Steady Flow ◽  
Heart Valves ◽  
Laser Doppler Anemometry ◽  
Laser Doppler ◽  
Prosthetic Heart Valves ◽  
Flow Through

Acoustic power flow measurement in a thermoacoustic resonator by means of laser Doppler anemometry (L.D.A.) and microphonic measurement

2000 ◽  
Vol 60 (1) ◽  
pp. 1-11 ◽  
Author(s):  
H. Bailliet ◽  
P. Lotton ◽  
M. Bruneau ◽  
V. Gusev ◽  
J.C. Valière ◽  
...  
Keyword(s):  
Flow Measurement ◽  
Power Flow ◽  
Laser Doppler Anemometry ◽  
Acoustic Power ◽  
Laser Doppler
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