Nucleation Characteristics of Static Liquid Nitrogen and Liquid Hydrogen

Abstract

Characteristics which control the existence of metastable (superheated) liquid states and the nucleation of the vapor phase have been studied; knowledge of these characteristics will assist in the prediction of cavitation in hydraulic equipment. The liquids were superheated by reducing the ullage pressure in a vessel of liquid which was initially in thermodynamic equilibrium. Experimental superheat limit curves for liquid nitrogen and liquid hydrogen, statically contained in a nearly ideal (acid cleaned, smooth glass) system, are presented and compared with theoretical limit curves. The effects of some nonideal liquid-solid interfaces on the nucleation characteristics have been studied and are also included. The theory developed in the text is in fair agreement with the experimental data for the nearly ideal system. Persistence of the metastable state is shown to be dependent upon the rate of pressure decay, the initial equilibrium pressure, fluid environment, and the nucleation pressure. Appreciable superheat persisted for long times with liquid nitrogen (e.g., 44.2 psi superheat persisted for 4.3 sec at 90 deg K) while the persistence times for liquid hydrogen were much shorter (e.g., 48.7 psi superheat persisted for only 0.030 sec at 26.7 deg K).

Cavitation in Liquid Cryogens

“…3, and p = 0. 5 ( see data set T [1][2][3][4][5][6][7][8][9][10][11][12][13][14] were least affected by reference cavity length; note that these exponents produce a low standard deviation. In general, the 2.0 in.…”

“…While the non-cavitating performance of hydraulic equipment may be predicted from established similarity laws, cavitating performance can seldom be predicted from fluid to fluid. The effects of fluid properties on cavitation performance are well recognized [5][6][7][8][9][10][11][12][13][14] and require more understanding to develop improved similarity relations [ 151 for equipment design. NASA has undertaken a program [ 161 to determine the thermodynamic behavior of different fluids in an effort to obtain improved design criteria to aid in the prediction of cavitating pump performance.…”

Studies of nucleation and heat transfer in liquid helium isotopes 3 and 4

“…The classical theory of kinetics involved in the nucleation of one phase from another has received much attention since its original formulation by Volmer and Weber (1926), Becker and Doring (1935), and others (Blander and Katz 1975). helium-4 (Sinha 1982b, Nishigaki 1983, Hord 1964 (Beams 1956, 1959, Marston 1976.…”

Incipient and developed cavitation in liquid cryogens

“…While the non-cavitating performance of hydraulic equipment may be predicted from established similarity laws, cavitating performance can seldom be predicted from fluid to fluid. The effects of fluid properties on cavitation performance are well recognized [5][6][7][8][9][10][11][12][13][14] and require more understanding to develop improved similarity relations [ 151 for equipment design. NASA has undertaken a program [ 16] to determine the thermodynamic behavior of different fluids in an effort to obtain improved design criteria to aid in the prediction of cavitating pump performance.…”