TY - JOUR

T1 - Statistical structure of the velocity field in cavitating flow around a 2D hydrofoil

AU - Timoshevskiy, Mikhail V.

AU - Ilyushin, Boris B.

AU - Pervunin, Konstantin S.

PY - 2020/10/1

Y1 - 2020/10/1

N2 - Transformation of flow turbulence structure with cavitation occurrence, determination of the flow conditions favorable for nucleation of cavitation bubbles, influence of the statistical structure of turbulence on this process and the inverse effect of cavitation on the flow dynamics are challenging problems in modern fluid mechanics. The paper reports on the results of statistical processing of the velocity fields measured by a PIV technique in cavitating flow over a 2D symmetric hydrofoil for four flow conditions, starting from a cavitation-free regime and finishing by unsteady cloud cavitation. We analyze basic information on the statistical structure of velocity fluctuations in the form of histograms and Q-Q diagrams along with profiles of the mean velocity and turbulent kinetic energy. The research reveals that the flow turbulence pattern and distributions of turbulent fluctuations change significantly with the cavitation development. Under unsteady cloud cavitation conditions, the probability density function of the fluctuating velocity has a two-mode distribution, which indicates switching of two alternating flow conditions in a region above the hydrofoil aft part due to periodic passing of cavitation clouds. Behaviors of the mean and most probable velocities unexpectedly appear to be different with a monotonous increase of the incoming flow velocity. This finding must be caused by modification of the skewness coefficient of the fluctuating velocity.

AB - Transformation of flow turbulence structure with cavitation occurrence, determination of the flow conditions favorable for nucleation of cavitation bubbles, influence of the statistical structure of turbulence on this process and the inverse effect of cavitation on the flow dynamics are challenging problems in modern fluid mechanics. The paper reports on the results of statistical processing of the velocity fields measured by a PIV technique in cavitating flow over a 2D symmetric hydrofoil for four flow conditions, starting from a cavitation-free regime and finishing by unsteady cloud cavitation. We analyze basic information on the statistical structure of velocity fluctuations in the form of histograms and Q-Q diagrams along with profiles of the mean velocity and turbulent kinetic energy. The research reveals that the flow turbulence pattern and distributions of turbulent fluctuations change significantly with the cavitation development. Under unsteady cloud cavitation conditions, the probability density function of the fluctuating velocity has a two-mode distribution, which indicates switching of two alternating flow conditions in a region above the hydrofoil aft part due to periodic passing of cavitation clouds. Behaviors of the mean and most probable velocities unexpectedly appear to be different with a monotonous increase of the incoming flow velocity. This finding must be caused by modification of the skewness coefficient of the fluctuating velocity.

KW - Flow separation

KW - Hydrofoil

KW - PIV measurements

KW - Probability density function (PDF)

KW - Recirculation zone

KW - Sheet/cloud cavities

KW - Skewness and excess

KW - Turbulence structure

KW - Turbulent kinetic energy

KW - Two-mode statistical distribution

KW - Unsteady cloud cavitation

KW - Velocity fields

KW - PRESSURE-FLUCTUATIONS

KW - LEADING-EDGE

UR - http://www.scopus.com/inward/record.url?scp=85087403180&partnerID=8YFLogxK

U2 - 10.1016/j.ijheatfluidflow.2020.108646

DO - 10.1016/j.ijheatfluidflow.2020.108646

M3 - Article

AN - SCOPUS:85087403180

VL - 85

JO - International Journal of Heat and Fluid Flow

JF - International Journal of Heat and Fluid Flow

SN - 0142-727X

M1 - 108646

ER -