Block-sparse compressive localization for incipient tip vortex cavitation noise

2019 ◽  
Vol 145 (3) ◽  
pp. 1936-1936
Author(s):  
MinSeuk Park ◽  
Woojae Seong ◽  
Youngmin Choo ◽  
Yongsung Park
Keyword(s):  
Tip Vortex ◽  
Cavitation Noise ◽  
Tip Vortex Cavitation

scholarly journals Numerical Investigation of Tip-Vortex Cavitation Noise of an Elliptic Wing Using Coupled Eulerian-Lagrangian Approaches

2020 ◽  
Vol 10 (17) ◽  
pp. 5897 ◽  
Author(s):  
Garam Ku ◽  
Cheolung Cheong ◽  
Hanshin Seol
Keyword(s):  
Flow Field ◽  
Numerical Method ◽  
Vortex Flow ◽  
Acoustic Pressure ◽  
Tip Vortex ◽  
Experimental Result ◽  
Cavitation Noise ◽  
Navier Stokes Equation ◽  
Tip Vortex Cavitation ◽  
Cavitation Inception

In this study, a numerical methodology is developed to investigate the tip-vortex cavitation of NACA16-020 wings and their flow noise. The numerical method consists of a sequential one-way coupled application of Eulerian and Lagrangian approaches. First, the Eulerian method based on Reynolds-averaged Navier–Stokes equation is applied to predict the single-phase flow field around the wing, with particular emphasis on capturing high-resolution tip-vortex flow structures. Subsequently, the tip-vortex flow field is regenerated by applying the Scully vortex model. Secondly, the Lagrangian approach is applied to predict the tip-vortex cavitation inception and noise of the wing. The initial nuclei are distributed upstream of the wing. The subsequent time-varying size and position of each nucleus are traced by solving spherically symmetric bubble dynamics equations for the nuclei in combination with the flow field predicted from the Eulerian approach. The acoustic pressure at the observer position is computed by modelling each bubble as a point source. The numerical results of the acoustic pressure spectrum are best matched to the measured results when the nuclei number density of freshwater is used. Finally, the current numerical method is applied to the flows of various cavitation numbers. The results reveal that the cavitation inception determined by the predicted acoustic pressure spectrum well matched the experimental result.

Experimental Study of Scale Effects on the Scaling Law for Tip Vortex Cavitation Noise

2014 ◽  
Author(s):  
Jisoo Park ◽  
Cheolsoo Park ◽  
Youngmin Choo ◽  
Woojae Seong
Keyword(s):  
High Speed ◽  
Scale Effects ◽  
Scaling Law ◽  
Size Variation ◽  
Tip Vortex ◽  
Cavitation Noise ◽  
Scaling Exponents ◽  
Tip Vortex Cavitation ◽  
Cavitation Inception ◽  
Vortex Model

Novel scaling law for the tip vortex cavitation (TVC) noise is derived from the physical basis of TVC, employing the Rankine vortex model, the Rayleigh-Plesset equation, the lifting surface theory, and the number of bubbles generated per unit time (N0). All terms appearing in the scaling law have physical or mathematical grounds except for N0. Therefore, to experimentally validate the N0 term, experiments are designed to keep the same TVC patterns as velocities and dimensions vary. Optimal shooting conditions with a velocity and size variation are determined from the scaling exponents, cavitation numbers and Reynolds numbers at each condition. To avoid wall effects and flow field interaction, two hydrofoils are optimally arranged by using computational fluid dynamics (CFD) for size variation. Images taken by a high speed camera are used to count N0, considering similitude of the spectra of nuclei. Scaling exponents curve fitted from five velocities and cavitation inception numbers have an exponent value of 0.371, which is closely placed on scaling exponents curve deduced from Schlichting’s friction coefficients fitting with Reynolds number. The tendency that N0 is proportional to a velocity and inversely proportional to a size can be confirmed by this study.

Numerical investigation into effects of gas concentration and bubble collapse on tip vortex cavitation noise of NACA16-020 wing

2021 ◽  
Vol 263 (5) ◽  
pp. 1813-1817
Author(s):  
Garam Ku ◽  
Cheolung Cheong ◽  
Hanshin Seol ◽  
Hongseok Jeong
Keyword(s):  
Bubble Dynamics ◽  
Lagrangian Method ◽  
Tip Vortex ◽  
Bubble Collapse ◽  
Acoustic Analogy ◽  
Dynamics Model ◽  
Cavitation Noise ◽  
Tip Vortex Cavitation ◽  
Gas Concentration ◽  
Vortex Pattern

In this study, the effects of gas concentration and bubble collapse on tip vortex cavitation noise of NACA16-020 wings are investigated using coupled Eulerian-Lagrangian method based on sequential application of Reynolds averaged Navier-Stokes (RANS) solver, bubble dynamics model and acoustic analogy. The bubble dynamics model used in the preceding study (Ku et al., 2020) is modified by including the gas pressure terms and the bubble collapse model, which depends on the timing and threshold of bubble collapse, the number, initial radius and location of divided bubbles. The validity of the modified bubble dynamics model is confirmed through its application to a benchmark problem where single bubble is triggered by laser. Then, the coupled Eulerian-Lagrangian method based on the modified bubble dynamic model is applied for the prediction of tip-vortex cavitation noise of NACA16-020 wing. The predicted results of the tip vortex pattern and acoustic pressure spectrum are compared with the measured results, which shows closer agreements between two results than those in the previous study.

Characteristics of Tip Vortex Cavitation Noise

1989 ◽  
Vol 111 (4) ◽  
pp. 495-501 ◽  
Author(s):  
H. Higuchi ◽  
R. E. A. Arndt ◽  
M. F. Rogers
Keyword(s):  
Noise Source ◽  
Tip Vortex ◽  
Source Distribution ◽  
Cavitation Noise ◽  
Tip Vortex Cavitation ◽  
Cavitation Inception

Tip vortex cavitation noise was experimentally investigated utilizing hydrofoils with an elliptic planform. The noise was monitored by an array of hydrophones. A variety of cavitating conditions were studied, including inception, fully developed vortex cavitation, and surface cavitation. An analysis of noise source distribution indicated that sound at cavitation inception is radiated from either just downstream of the vortex roll-up region or right at the tip of the hydrofoil where the vortex cavity intially develops.

Sign in / Sign up

Export Citation Format

Share Document