In Response to “Comparison of Particle Image Velocimetry and Laser Doppler Velocimetry Measurements in Turbulent Fluid Flow” by Wernet et al.

2000 ◽  
Vol 28 (11) ◽  
pp. 1395-1396
Author(s):  
Rahul Saxena ◽  
Agnes Ramuzat ◽  
Ajit Yoganathan
Keyword(s):  
Particle Image Velocimetry ◽  
Fluid Flow ◽  
Laser Doppler Velocimetry ◽  
Particle Image ◽  
Laser Doppler ◽  
Doppler Velocimetry ◽  
Turbulent Fluid Flow ◽  
Turbulent Fluid ◽  
Image Velocimetry

Flow in a Centrifugal Pump Impeller at Design and Off-Design Conditions—Part I: Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV) Measurements

2003 ◽  
Vol 125 (1) ◽  
pp. 61-72 ◽  
Author(s):  
Nicholas Pedersen ◽  
Poul S. Larsen ◽  
Christian B. Jacobsen
Keyword(s):  
Particle Image Velocimetry ◽  
Centrifugal Pump ◽  
Laser Doppler Velocimetry ◽  
Particle Image ◽  
Laser Doppler ◽  
Doppler Velocimetry ◽  
Pump Impeller ◽  
Design Load ◽  
Image Velocimetry ◽  
Centrifugal Pump Impeller

Detailed optical measurements of the flow inside the rotating passages of a six-bladed shrouded centrifugal pump impeller of industrial design have been performed using particle image velocimetry (PIV) and laser Doppler velocimetry (LDV). Results include instantaneous and ensemble averaged PIV velocity vector maps as well as bin-resolved LDV data acquired in the midplane between hub and shroud of the impeller. The flow is surveyed at both design load and at severe off-design conditions. At design load, Q=Qd, the mean field of relative velocity is predominantly vane congruent, showing well-behaved flow with no separation. At quarter-load, Q=0.25Qd, a previously unreported “two-channel” phenomenon consisting of alternate stalled and unstalled passages was observed, with distinct flow congruence between every second of the six passages. A large recirculation cell blocked the inlet to the stalled passage while a strong relative eddy dominated the remaining parts of the passage. The stall phenomenon was steady, nonrotating and not initiated via the interaction with stationary components. The study demonstrates that the PIV technique is efficient in providing reliable and detailed velocity data over a full impeller passage, also in the close vicinity of walls due to the use of fluorescent seeding. A quantitative comparison of blade-to-blade distributions of mean fields obtained by PIV and LDV showed a satisfactory agreement.

Numerical Investigation of Flow in a Runner of Low-Head Bulb Turbine and Correlation With Particle Image Velocimetry and Laser Doppler Velocimetry Measurements

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
David Štefan ◽  
Sébastien Houde ◽  
Claire Deschênes
Keyword(s):  
Particle Image Velocimetry ◽  
Velocity Field ◽  
Laser Doppler Velocimetry ◽  
Particle Image ◽  
Draft Tube ◽  
Laser Doppler ◽  
Doppler Velocimetry ◽  
Image Velocimetry ◽  
Low Head ◽  
Bulb Turbine

It is a well-known fact and a much studied problematic that the performance of low-head hydraulic turbines is highly dependent on the runner–draft tube coupling. Around the optimal operating conditions, the efficiency of the turbine follows closely the performance of the draft tube that in turn depends on the velocity field exiting the runner. Hence, in order to predict correctly the performance of the draft tube using numerical simulations, the flow inside the runner must be simulated accurately. Using results from unique and detailed particle image velocimetry (PIV) and laser Doppler velocimetry (LDV) measurements inside the runner channel of a bulb turbine, this paper presents an extensive study of the predictive capability of a widely used simulation methodology based on unsteady Reynolds-averaged Navier–Stokes equations with a k-epsilon closure model. The main objective was to identify the main parameters influencing the numerical predictions of the velocity field at the draft tube entrance in order to increase the accuracy of the simulated performance of the turbine. This paper relies on a comparison of simulations results with already published LDV measurements in the draft tube cone, interblade LDV, and stereoscopic PIV measurements within the runner. This paper presents a detailed discussion of numerical–experimental data correlation inside the runner channel and at the drat tube entrance. It shows that, contrary to widely circulated ideas, the near-wall predictions at the draft tube entrance is surprisingly good while the simulation accuracy inside the runner channels deteriorates from the leading to the trailing edges.

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