Atomization and Breakup of Cryogenic Propellants Under High-Pressure Subcritical and Supercritical Conditions

1998 ◽  
Vol 14 (5) ◽  
pp. 835-842 ◽  
Author(s):  
Wolfgang O. H. Mayer ◽  
Axel H. A. Schik ◽  
Bruno Vielle ◽  
Christian Chauveau ◽  
Iskender Gokalp ◽  
...  
Keyword(s):  
High Pressure ◽  
Supercritical Conditions ◽  
Cryogenic Propellants

scholarly journals Migration and Evaporation Characteristics of Kerosene Droplet in Supercritical Environment

2019 ◽  
Vol 257 ◽  
pp. 01002
Author(s):  
Hailong Wu ◽  
Wansheng Nie ◽  
Zhi Zheng ◽  
Yu Liu
Keyword(s):  
High Pressure ◽  
Mass Fraction ◽  
Physical Property ◽  
Droplet Surface ◽  
Supercritical Conditions ◽  
One Dimensional ◽  
Liquid Phases ◽  
Rise Rate ◽  
Volume Method ◽  
Surrogate Fuel

A one-dimensional full transient droplet evaporation model was established under consideration of factors such as high pressure vapour-liquid equilibrium, high-pressure physical property corrections, gas phase dissolution, and shift of interface. The finite volume method was used for discretization to study the migration and evaporation characteristics of the surrogate fuel for kerosene, which was constituting of (mass fraction)80% n-decane and 20%1,2,4-trimethylbenzene, under supercritical conditions. The results show that, under supercritical conditions, the higher the temperature and the pressure, the easier and the sooner the supercritical migration occurs. Before the supercritical migration occurring, there was obvious boundary between the gas and liquid phases. The mass fraction of component was discontinuous, and the gradient of temperature near the interface was large. After the supercritical migration occurring, the surface of the droplet disappeared, there was no obvious boundary between the gas and liquid phases, and the distribution of the components mass fraction and temperature were continuously. With the increase of the initial temperature of the droplet, the time of the supercritical migration was greatly advanced, the rise rate of the droplet surface temperature increased, and the phenomenon of endothermic expansion no longer appeared.

Onset of Combustion Instabilities During Transition to Supercritical Fuel Injection in High Pressure Combustor

2005 ◽  
Author(s):  
E. Lubarsky ◽  
D. Shcherbik ◽  
D. Scarborough ◽  
O. Bibik ◽  
B. T. Zinn
Keyword(s):  
High Pressure ◽  
High Performance ◽  
High Pressures ◽  
Fuel Injection ◽  
Frequency Instability ◽  
Critical Conditions ◽  
Inlet Temperature ◽  
Combustion Instabilities ◽  
Fuel Temperature ◽  
Supercritical Conditions

This paper describes a study of the onset of severe combustion instabilities (i.e., with peak to peak amplitudes of up to 0.97MPa) in a high pressure (PC>500psia or 3.45MPa) air breathing combustor as the inlet temperature of the injected liquid fuel (n-heptane - C7H16) was varied over the 20–335°C range, achieving supercritical conditions when the temperature exceeded 300°C. The attainment of supercritical operation was determined by a specially developed probe that illuminated the liquid spray with a laser beam and collected the light scattered off the spray. As the temperature of the fuel was increased, the spray disappeared when the fuel attained a supercritical state and the scattered signal could be no longer detected. Two different unstable modes (i.e., ∼100 and ∼400Hz) were excited in the combustor as the fuel temperature was increased from low to supercritical conditions and then cooled again. The lower frequency instability (∼100Hz) was excited and then disappeared when the fuel temperature was well below supercritical values (i.e., TFUEL<200°C) whereas the higher frequency mode (∼400Hz) was typically excited at sub- and super- critical conditions (i.e., TFUEL>250°C). It’s shown that the dynamics of the excitation and disappearance of these modes as well as their limit cycle amplitudes strongly depend upon the direction in which fuel temperature varies and also upon the temperature of the combustion air. Significantly, the results of this study strongly suggest that combustion instabilities may be excited in future high performance aircraft combustor that will operate at very high-pressures and with supercritical fuel injection.

A new approach to describe high-pressure adsorption isotherms in subcritical and supercritical conditions

AIChE Journal ◽  
2009 ◽  
Vol 55 (7) ◽  
pp. 1793-1802 ◽  
Author(s):  
Ch. Chilev ◽  
B. Weinberger ◽  
J. Ph. Passarello ◽  
F. Darkrim Lamari ◽  
I. Pentchev
Keyword(s):  
High Pressure ◽  
Adsorption Isotherms ◽  
Supercritical Conditions ◽  
New Approach ◽  
High Pressure Adsorption

High-pressure freezing of cells in suspension for low-voltage scanning electron microscopy (LVSEM)

1991 ◽  
Vol 49 ◽  
pp. 64-65
Author(s):  
Marek Malecki ◽  
James Pawley ◽  
Hans Ris
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Low Voltage ◽  
Culture Media ◽  
Cell Structure ◽  
Freeze Substitution ◽  
Ice Crystal ◽  
High Pressure Freezing ◽  
Cell Culture Media ◽  
Voltage Scanning

The ultrastructure of cells suspended in physiological fluids or cell culture media can only be studied if the living processes are stopped while the cells remain in suspension. Attachment of living cells to carrier surfaces to facilitate further processing for electron microscopy produces a rapid reorganization of cell structure eradicating most traces of the structures present when the cells were in suspension. The structure of cells in suspension can be immobilized by either chemical fixation or, much faster, by rapid freezing (cryo-immobilization). The fixation speed is particularly important in studies of cell surface reorganization over time. High pressure freezing provides conditions where specimens up to 500μm thick can be frozen in milliseconds without ice crystal damage. This volume is sufficient for cells to remain in suspension until frozen. However, special procedures are needed to assure that the unattached cells are not lost during subsequent processing for LVSEM or HVEM using freeze-substitution or freeze drying. We recently developed such a procedure.

Sign in / Sign up

Export Citation Format

Share Document