A Limited Role of Separation Bubble in Desinent Cavitation

1985 ◽  
Vol 107 (1) ◽  
pp. 121-125 ◽  
Author(s):  
Y. Ito ◽  
R. Oba
Keyword(s):  
Separation Bubble ◽  
Marked Change ◽  
Cavitation Number ◽  
Hydrodynamic Conditions ◽  
Internal Flows ◽  
Backward Facing Step ◽  
Bubble Cloud ◽  
Limited Role ◽  
Cavitation Nuclei

In order to clarify whether a separation bubble always plays an important role, the desinence of streamer-cavitation, a kind of attached-cavitation, was carefully investigated in typical internal flows through venturies with and without a 40 μm thin backward facing step under a prescribed cavitation nuclei as well as various hydrodynamic conditions. The following facts have been found: (i) the separation bubble can play an important role in the desinence only when the separation bubble thickness H is larger than the diameter of nucleus dnp that may grow up to a critical one [18], (ii) a marked change takes place in the desinent cavitation number σd due to the step, i.e., σd ≅ |Cps| for H > dnp but σd < |Cps| for H ≦ dnp, (iii) for the cavitation there are two geneses, i.e., the nuclei floating within the separation bubble and the bubble-cloud occurring in the reattachment-region.

Cavitation in an Extremely Limited Flow Through Very Small Orifices

1982 ◽  
Vol 104 (1) ◽  
pp. 94-98 ◽  
Author(s):  
R. Oba ◽  
T. Ikohagi ◽  
K. T. Kim
Keyword(s):  
Turbulent Flows ◽  
Water Flow ◽  
Cavitation Number ◽  
Orifice Diameter ◽  
Flow Through ◽  
Cavitation Nuclei ◽  
Technical Interest

In order to clarify the role of cavitation nuclei upon inception, the behavior of inception was carefully investigated in an extremely limited water flow through very small orifices less than 1.0 mm in diameter under a prescribed nuclei condition. The following facts of technical interest were determined: a) The desinent cavitation number (σd) decreased rapidly and exponentially with the orifice diameter d, up to one hundredth in magnitude; and b) the cavitation appearance in such limited flows was quite different from that in fully turbulent flows through larger orifices.

The Effect of Nuclei on the Inception of Bubble and Sheet Cavitation on Axisymmetric Bodies

1981 ◽  
Vol 103 (4) ◽  
pp. 557-563 ◽  
Author(s):  
Y. Kodama ◽  
N. Take ◽  
S. Tamiya ◽  
H. Kato
Keyword(s):  
Size Distribution ◽  
Cavitation Number ◽  
Experimental Results ◽  
Sheet Cavitation ◽  
Upper Limit ◽  
Hydrogen Bubbles ◽  
Cavitation Nuclei ◽  
Axisymmetric Bodies ◽  
Measured Size Distribution

Hydrogen bubbles were generated as cavitation nuclei and their distributions were measured. The number and size distribution of bubble cavities generated on axisymmetric bodies was calculated and compared with experimental results. The measured size distribution of bubble cavities agreed qualitatively with the calculated value, but the total number of cavities was about one half of the calculation. The role of stream nuclei on the inception of sheet cavity was investigated experimentally. Without added nuclei, the value of the incipient cavitation number σi showed a large scattering, whereas with added nuclei the scattering became fairly small and σi converged to the upper limit of that when no nuclei were added. σi with added nuclei also coincided with the desinent cavitation number σd, and σd remained unchanged by adding nuclei.

scholarly journals Cavitation Bubble Cloud Break-Off Mechanisms at Micro-Channels

Fluids ◽  
2021 ◽  
Vol 6 (6) ◽  
pp. 215
Author(s):  
Paul McGinn ◽  
Daniel Pearce ◽  
Yannis Hardalupas ◽  
Alex Taylor ◽  
Konstantina Vogiatzaki
Keyword(s):  
Cavitation Bubble ◽  
Cavitation Inception ◽  
Wave Dynamics ◽  
Bubble Cloud ◽  
Cloud Dynamics ◽  
Micro Channels ◽  
Physical Insight ◽  
Cloud Process ◽  
Good Agreement

This paper provides new physical insight into the coupling between flow dynamics and cavitation bubble cloud behaviour at conditions relevant to both cavitation inception and the more complex phenomenon of flow “choking” using a multiphase compressible framework. Understanding the cavitation bubble cloud process and the parameters that determine its break-off frequency is important for control of phenomena such as structure vibration and erosion. Initially, the role of the pressure waves in the flow development is investigated. We highlight the differences between “physical” and “artificial” numerical waves by comparing cases with different boundary and differencing schemes. We analyse in detail the prediction of the coupling of flow and cavitation dynamics in a micro-channel 20 m high containing Diesel at pressure differences 7 MPa and 8.5 MPa, corresponding to cavitation inception and "choking" conditions respectively. The results have a very good agreement with experimental data and demonstrate that pressure wave dynamics, rather than the “re-entrant jet dynamics” suggested by previous studies, determine the characteristics of the bubble cloud dynamics under “choking” conditions.

scholarly journals The Limited Role of Formal Statistical Inference in Scientific Inference

2019 ◽  
Vol 73 (sup1) ◽  
pp. 91-98 ◽  
Author(s):  
Raymond Hubbard ◽  
Brian D. Haig ◽  
Rahul A. Parsa
Keyword(s):  
Statistical Inference ◽  
Scientific Inference ◽  
Limited Role

scholarly journals Correlation Analyses Reveal a Limited Role of Transcription in Genome-Wide Differential MicroRNA Expression in Mammals

2018 ◽  
Vol 9 ◽  
Author(s):  
Xiaoxiao Zhang ◽  
Siling Hu ◽  
Jia Su ◽  
Zixuan Xie ◽  
Wenjing Li ◽  
...  
Keyword(s):  
Microrna Expression ◽  
Limited Role ◽  
Correlation Analyses ◽  
Genome Wide

Limited role of entropy in information economics

1974 ◽  
Vol 5 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Jacob Marschak
Keyword(s):  
Information Economics ◽  
Limited Role
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