Swirling flow in a hydraulic turbine discharge cone at different speeds and discharge conditions

Skripkin, Sergey; Куйбин, П. А.; Шторк, С. И.

doi:10.1016/j.expthermflusci.2018.09.015

Cited by 41 publications

(17 citation statements)

References 39 publications

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“…When shifting the operation conditions of the hydro turbine apart from the nominal regime, the flow passing the impeller acquires a swirl. The swirling level of the flow is commonly represented by the swirl parameter S determined in turn as the ratio of the axial flux of the angular momentum M to the product of the axial flux of the axial momentum G and the characteristic radius R [12]: The momenta M and G in equation ( 1) can be calculated based on the measured velocity distributions (V is the axial component and U is the tangential component; 𝐷 0 is the channel diameter in the measured cross-section):…”

Section: Resultsmentioning

confidence: 99%

“…In the first case, the flow swirl number exceeds the critical value of 0.5 at which the vortex breakdown normally takes place [8]. This means the development of a central recirculation zone, shifting the flow towards the cone wall, and the emergence of unsteady large-scale vortical structures in the form of precessing vortex core (PVC) [12]. In the second case, the swirl number remains below the threshold level.…”

Section: Resultsmentioning

confidence: 99%

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The swirl number as a method for determining the optimal operating mode of the micro hydro turbine

Суслов

Litvinov

Gorelikov

et al. 2021

J. Phys.: Conf. Ser.

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The paper presents the data of a detailed study of the flow characteristics behind the runner of an air model of a propeller-type micro hydro turbine with varying operating modes from partial load to severe overload. Detailed measurements of the flow field distributions were carried out using an automated system for contactless optical diagnostics (LDA). The obtained data made it possible to link the identified features of the development of the flow structure when changing the operating mode of the installation with the nature of the evolution of the integral swirl number that determines the state of the swirled flow. Eventually, the work results can be used in the elaboration of recommendations for extending the regulation range of the operating regimes of hydraulic microturbines and providing their high efficiency.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

The swirl number as a method for determining the optimal operating mode of the micro hydro turbine

Суслов

Litvinov

Gorelikov

et al. 2021

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

show abstract

“…To model the conditions for PVC formation, we did not simulate the entire hydroturbine channel, including the spiral case, the guide vanes and the runner, but we used a simplified geometry consisting of two swirlers, one stationary and one rotating, arranged in series. This makes it possible to simulate the velocity distribution at the inlet of the draft tube model that coincides with the velocity distribution at the inlet of the full-scale turbine draft tube [24][25][26]. The blades were designed so as to provide optimum performance of Francis hydraulic turbines [27] (Best Efficiency Point, BEP), which for the scale of the given test section, corresponds to a volumetric flow rate Q c = 0.049 m 3 /s and a speed of the clockwise rotating runner n c = 2432 rpm.…”

Section: Methodsmentioning

confidence: 99%

Experimental Study of Transient Flow Regimes in a Model Hydroturbine Draft Tube

et al. 2021

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Swirling flow with the formation of a precessing vortex core (PVC) in the draft tube model of a hydroturbine was studied. Experiments were performed on an aerodynamic setup under transient operating conditions of the hydroturbine. The turbine operating conditions were varied by continuously changing the flow rate at a constant runner speed. The transition from the partial load regime, when a precessing vortex core is formed, to the best efficiency point without a core is considered. Applied to this task, a comparison of the windowed Fourier transform with wavelet analysis is given. The dependence of the PVC lifetime in the transient regime correlates with the transient time. It is shown that the velocity profiles and the spectrum of pressure pulsations in transient regimes change quasistatically between part-load operation and the best efficiency point of the turbine. The phase-averaged velocity distributions in the transient regimes show that a transient regime is a sequence of quasisteady regimes.

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“…The benchmark problem called "Timisoara Swirl Generator" which includes the computational domains with mesh and experimental data are available as OpenFOAM test case [67]. This benchmark problem has been used by other groups [65,68] to investigate the behavior of the swirling flow similar to Francis turbine.…”

Section: Experimental Setup 21 Test Rig Experimental Setupmentioning

confidence: 99%

Influence of the Reshaped Elbow on the Unsteady Pressure Field in a Simplified Geometry of the Draft Tube

2021

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The paper focuses on the influence of the reshaped elbow geometry of the draft tube on the unsteady pressure field under different operating conditions. The experimental investigations are conducted considering two simplified geometrical configurations of the draft tubes with sharp heel elbow and modified/reshaped elbow, respectively. The discriminated power spectra (rotating and plunging components) of the acquired pressure signals on the wall are determined on five levels for seven operating conditions to quantify the influence of the reshaped elbow. The influence of the reshaped elbow on the fundamental frequencies of both rotating and plunging components and on the amplitude of the rotating component is negligible. In contrast, the equivalent amplitude associated with the root mean square of the plunging power spectrum that propagates along the hydraulic passage is mitigated up to 25% by the reshaped geometry of the elbow. The equivalent amplitude on the narrow band around the fundamental frequency of the plunging component is diminished with 40–50% by reshaping the elbow geometry of the simplified draft tube.

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Swirling flow in a hydraulic turbine discharge cone at different speeds and discharge conditions

Cited by 41 publications

References 39 publications

The swirl number as a method for determining the optimal operating mode of the micro hydro turbine

The swirl number as a method for determining the optimal operating mode of the micro hydro turbine

Experimental Study of Transient Flow Regimes in a Model Hydroturbine Draft Tube

Influence of the Reshaped Elbow on the Unsteady Pressure Field in a Simplified Geometry of the Draft Tube

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