Tham khảo tài liệu 'cavitation and bubble dynamics part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 1 - Cavitation and Bubble Dynamics - Christopher E. Brennen latent heat and critical temperature the tensile strength is determined by weaknesses at points within the liquid. Such weaknesses are probably ephemeral and difficult to quantify since they could be caused by minute impurities. This difficulty and the dependence on the time of application of the tension greatly complicate any theoretical evaluation of the tensile strength. CAVITATION AND BOILING As we discussed in section the tensile strength of a liquid can be manifest in at least two ways 1. A liquid at constant temperature could be subjected to a decreasing pressure p which falls below the saturated vapor pressure pv. The value of pv -p is called the tension Ap and the magnitude at which rupture occurs is the tensile strength of the liquid Apc. The process of rupturing a liquid by decrease in pressure at roughly constant liquid temperature is often called cavitation. 2. A liquid at constant pressure may be subjected to a temperature T in excess of the normal saturation temperature Ts. The value of AT T-TS is the superheat and the point at which vapor is formed ATC is called the critical superheat. The process of rupturing a liquid by increasing the temperature at roughly constant pressure is often called boiling. Though the basic mechanics of cavitation and boiling must clearly be similar it is important to differentiate between the thermodynamic paths that precede the formation of vapor. There are differences in the practical manifestations of the two paths because although it is fairly easy to cause uniform changes in pressure in a body of liquid it is very difficult to uniformly change the temperature. Note that the critical values of the tension and superheat may be related when the magnitudes of these quantities are small. By the Clausius-Clapeyron relation where Pl pV are the saturated liquid and vapor densities and L is the latent heat of evaporation. Except close to the .
