Velocity Characteristics of Air-mist Jet during Secondary Cooling of Continuous Casting Using PIV and LDV

Hydropower is a sustainable and clean renewable energy source. The Pelton turbine is an impulse type of hydraulic turbine and operates under high head and low discharge. It comprises an injector, which converts high-pressure water into kinetic energy as a high-speed free surface water jet that impinges on the runner generating power coupled with an electric generator. The water is highly accelerated in the nozzle, which produces turbulent kinetic energy in the jet flow. Before impinging on the runner, the surrounding air is entrained into the jet, which causes the jet dispersion. The effective conversion of water energy into mechanical energy and the quality of a jet depend significantly on the uniformity of the jet. However, the jet encounters instabilities and non-uniformity caused by secondary flow and turbulence. Jet surface and velocity distribution do not remain symmetric. Investigation of the jet's velocity profile and turbulence intensities is important to understand the flow behavior and improvements in the design of injector. In this study, the experimental investigation of the jet has been performed using the laser Doppler velocimetry (LDV) system. The turbulent intensity and instantaneous velocity of the jet are analyzed at different locations along the jet flow. The velocity wake zone occurs around the center of the jet, which diminishes in the axial direction of the jet, with non-dimensional jet velocities values 0.91, 0.92, and 0.94 at x/Do of 0.5, 1, and 2 for ∼98% nozzle opening. The secondary flow velocity magnitude is larger for 90°–60° injector jet flow than for 90°–50°. The jet velocity profile obtained from the LDV has been compared with computational fluid dynamics analysis.

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LDV measurements and analysis of pulsating velocity characteristics in a flat plate turbulent boundary layer

郭,

闫,

周

et al. 2024

First Aerospace Frontiers Conference (AFC 2024)

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The study of the characteristics of the pulsating velocity distribution in a flat plate turbulent boundary layer is important for the development of pulsating velocity turbulence models. In this paper, high temporal and spatial resolution measurements of velocity pulsations within the boundary layer of a flat plate turbulence are carried out in a wind tunnel using a laser Doppler velocimeter (LDV). By analyzing the measurement results, a mean velocity distribution curve is obtained, which is consistent with the turbulent velocity distribution curve given by other studies, confirming that the experimental setup of measuring the velocity in the flat plate boundary layer using LDV is reliable in this experiment. The analysis of the statistical results of the pulsation velocity reveals that the root mean square distribution of the pulsation velocity has a distinct inner peak and a small outer peak within the boundary layer, which is consistent with the results of recent studies and further characterizes the distribution of the pulsation velocity within the boundary layer. At the same time, the spectral analysis of the pulsation velocity reveals that the pulsation characteristics in different regions of the boundary layer are different, the pulsation amplitude in the logarithmic law region fluctuates from high to low, and the pulsation in the outer layer of the boundary layer appears to be intermittent.

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Velocity Characteristics of Air-mist Jet during Secondary Cooling of Continuous Casting Using PIV and LDV

Cited by 5 publications

References 18 publications

Effect of droplet characteristics on liquid-phase distribution in spray zone of internal mixing air-mist nozzle

Effect of droplet characteristics on liquid-phase distribution in spray zone of internal mixing air-mist nozzle

Pelton turbine jet flow investigations using laser Doppler velocimetry

LDV measurements and analysis of pulsating velocity characteristics in a flat plate turbulent boundary layer

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