Hi Bavan

• Cavitation is the process of rupturing a liquid by decrease in pressure at roughly constant liquid temperature. If the liquid at constant temperature undergoes to a decreasing pressure, p, which falls below the saturated vapor pressure, pv. The value of (pv -p) is called the tension, and the pressure you mean will be the pressure of the liquid which is compared with saturated vapor pressure. The cavitation phenomenon to occur the pressure must be raised again to high value than the vapor pressure to lead cavity collapsing.
• Flashing is the process of rupturing a liquid by decrease in pressure at roughly constant liquid temperature but differ from cavitation that the decreased pressure eventually remains lower than the vapor pressure and doesn't  recover again.
• Boiling is a rupturing of the  liquid by increasing the temperature at roughly constant pressure. A liquid at constant pressure may be subjected to a temperature, T, in excess of the normal saturation temperature, Ts. The value of dT=T-Ts is the superheat, and the point at which vapor is formed, DTC, is called the critical superheat.

For more information I suggest

CAVITATION AND BUBBLE DYNAMICS book by Christopher Earls Brennen

http://caltechbook.library.caltech.edu/archive/00000001/00/bubble.htm7/8/2003 3:53:57 AM

With regards

Thanks

This is already covered in RG in the form of an earlier question by Belkacem Abderrezzak.

https://www.researchgate.net/post/what_is_the_difference_between_hydrodynamic_cavitation_and_flash_boiling

 Thanks, can you please clarify the rest 2 doubts 

Hi Bavan

• Cavitation is the process of rupturing a liquid by decrease in pressure at roughly constant liquid temperature. If the liquid at constant temperature undergoes to a decreasing pressure, p, which falls below the saturated vapor pressure, pv. The value of (pv -p) is called the tension, and the pressure you mean will be the pressure of the liquid which is compared with saturated vapor pressure. The cavitation phenomenon to occur the pressure must be raised again to high value than the vapor pressure to lead cavity collapsing.
• Flashing is the process of rupturing a liquid by decrease in pressure at roughly constant liquid temperature but differ from cavitation that the decreased pressure eventually remains lower than the vapor pressure and doesn't  recover again.
• Boiling is a rupturing of the  liquid by increasing the temperature at roughly constant pressure. A liquid at constant pressure may be subjected to a temperature, T, in excess of the normal saturation temperature, Ts. The value of dT=T-Ts is the superheat, and the point at which vapor is formed, DTC, is called the critical superheat.

For more information I suggest

CAVITATION AND BUBBLE DYNAMICS book by Christopher Earls Brennen

http://caltechbook.library.caltech.edu/archive/00000001/00/bubble.htm7/8/2003 3:53:57 AM

With regards

Thanks

Within the context of two-phase flows, two bubble-dynamic phenomena, boiling (or heterogeneous boiling) and flashing or cavitation (homogeneous boiling) with bubble collapse, are technologically very important. The main difference between boiling and flashing is that bubble growth (and collapse) in boiling is inhibited by limitations on the heat transfer at the interface, whereas bubble growth (and collapse) in flashing is limited primarily by inertial effects in the surrounding liquid. The flashing process tends to be far more explosive (or implosive), and is more violent and damaging (at least in the near term) than the bubble dynamics of boiling.  However, other problematic phenomena, such as departure from nucleate boiling (DNB) and CRUD deposition, are intimately connected with the boiling process.

For a vapor to be formed from the liquid phase (vaporization), energy must be added to the liquid to produce vapor at nucleation sites; whether the liquid is heated directly or decompressed below its saturation pressure.  A liquid-to-vapor phase change may occur based on two main mechanisms.  The first is related to vaporization induced by external heating or heat transfer in a nearly constant pressure environment which is called heterogeneous boiling or simple boiling.  This heat input can occur through a solid/liquid interface with the solid typically hotter than the liquid, or through a liquid/gas interface with the gas being hotter than the liquid. The second case corresponds to flashing vaporization such as aviation induced by strong and rapid depressurization of the liquid phase (sometimes referred to as homogeneous boiling).   In this relaxation process no extra energy is needed for the phase change; the necessary energy is already contained in the liquid phase in the form of internal energy.

I suggest the following for more information:

F.J. Moody, Introduction to Unsteady Thermofluid Mechanics, Wiley Interscience, 1990.

R.A. Berry, et al., RELAP-7 Theory Manual, Idaho National Laboratory report INL/EXT-14-31366 (Revision 2), March 2016 (available on Research Gate).

Thanks Ray, Please clarify this if water @ 150 C is flash evaporating at at 1bar what will be the temp and pressure state of vapor forming? will that be same as water or it will be at equilibrium values?