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The Dynamics and Acoustics of Travelling Bubble Cavitation
Pages 331-348

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From page 331... ... These results are compared to the observed bubble dynamics and numerical solutions of the Rayleigh- Plesset equation. Finally, the cavitation nuclei flux was measured and predicted cavitation event rates and bubble maximum size distributions are compared with the measurements of these quantities. Read the entire page →
From page 332... ... maximum bubble volume distribution PA acoustic pressure PO freestream pressure Pv water vapor pressure r acoustic path length R (t) calculated bubble radius Rc critical nuclei radius RB headform radius at CPM RH headform radius RL bubble radius along trajectory RM cavitation bubble maximum radius RMR cavitation bubble maximum reduced radius RO nuclei radius Re Reynolds number, UD/u S water surface tension SP acoustic pressure spectral coefficients t time integration limits for experimental impulse acoustic pulse duration calculated dimensionless pulse duration free stream velocity calculated bubble volume Weber number, pU2RH/S constant, pulse width relationship constant, nuclei stability relationship headform radius of curvature at CPM water viscosity water density cavitation number, (P-Pv) Read the entire page →
From page 333... ... Any definition of the bubble cavitation inception index must therefore be associated with a particular free stream nuclei number distribution. The attached cavitation formation index for the Schiebe body was aaC = 0.40 and for the I.T.T.C. Read the entire page →
From page 335... ... Increasing the amount of residual gas reduces the violence of the bubble collapse making coherent rebounds possible. On the other hand, the nuclei populations of the present study were quite small, and the cavitation bubbles observed were almost entirely vaporous. Read the entire page →
From page 338... ... 5. MEASUREMENT OF THE ACOUSTIC EMISSION OF SINGLE CAVITATION BUBBLES The detailed relationship between the collapse mechanism of hydrodynamic cavitation bubbles and the resulting noise generation is not completely clear but some features are suggested by the present work. Read the entire page →
From page 339... ... Series of photographs detailing typical bubble collapse mechanism on the Schiebe headform, U-9m/s and <:r 0.45. Read the entire page →
From page 340... ... ~ ~ - ~ ~ ~ ` l - ~ ~ ~ ~ ~:~; ~:: ~1 ~`~ ~ 1 ~ ~_ - ~A:: - ~ -: ~:: :~ - ~:: -- ~- ~~ - ~ - - ~ - - ~ - ~ ~: ~ : : ~I: ::::: :: : :: i::: ::::: :~ ~ :::::::: : :~T~ i: :~ ~ _I : - ~ - - .~ - it ~ - ~ - ~ ~ ~ - Am - ~ ::~: ~ ~ #a ;:: 3~ _ ~....11.1 : ~- ~ : - ~ - ~ma a~a, ~ma= ~- - Figure 10. Series of photographs detailing typical bubble collapse mechanism on the I.T.T.C. Read the entire page →
From page 341... ... Acoustic impulse plotted against the maximum bubble volume for the Schiebe body at U = 9m/s and a = 0.42. Read the entire page →
From page 342... ... Consequently the maximum size achieved will be approximately independent of the nucleus size. This accounts for the uniformity of cavitation bubbles observed experimentally. Read the entire page →
From page 343... ... Comparison of theoretically predicted and experimentally measured acoustic impulse as a function of the maximum bubble volume for bubbles generated on the Schiebe body and I.T.T.C. body. Read the entire page →
From page 344... ... 7. OBSERVATIONS OF CAVITATION EVENT RATES AND BUBBLE MAXIMUM SIZE DISTRIBUTIONS Experiments were performed to measure the cavitation event rate and bubble maximum size distribution on both headforms along with the freestream nuclei number distribution. Read the entire page →
From page 345... ... We shall now compare the measured cavitation event rates and bubble maximum size distributions with the predicted quantities based on holographicallydetermined free stream nuclei number distributions. The nuclei populations were measured at the same time tliat the cavitation statistics were recorded, and the smallest nucleus which could be detected with certainty was approximately 20,um in diameter. Read the entire page →
From page 346... ... Analysis of cavitation event statistics and size distributions can relate the freestream nuclei distribution to the cavitation process. And, once the number and size of the cavitation events are known, the total noise emission may be estimated based on the single bubble measurements. Read the entire page →
From page 347... ... 1987. Free Stream Microbubble Effects on Travelling Bubble Cavitation Inception on the Schiebe Headform. Read the entire page →
From page 348... ... In fact, a listener standing near the tunnel could easily detect the difference in the acoustic emission between the two headforms. Consequently, the authors have concluded that different acoustic impulses generated by bubbles of equal maximum volume result from the significant difference in the bubble collapse mechanisms, in turn influences the radiated noise. Read the entire page →

From page 331...

... These results are compared to the observed bubble dynamics and numerical solutions of the Rayleigh- Plesset equation. Finally, the cavitation nuclei flux was measured and predicted cavitation event rates and bubble maximum size distributions are compared with the measurements of these quantities.

The Dynamics and Acoustics of Travelling Bubble Cavitation Pages 331-348

The Dynamics and Acoustics of Travelling Bubble Cavitation
Pages 331-348