This paper addresses the physiochemical mechanisms involved in transcritical and supercritical vaporization, mixing, and combustion processes in contemporary liquid-fueled propulsion and power-generation systems. Fundamental investigation into these phenomena poses an array of challenges due to the obstacles in conducting experimental measurements and numerical simulations at scales sufficient to resolve the underlying processes. In addition to all of the classical problems for multiphase chemically reacting flows, a unique set of problems arises from the introduction of thermodynamic nonidealities and transport anomalies. The situation becomes even more complex with increasing pressure because of an inherent increase in the flow Reynolds number and difficulties that arise when fluid states approach the critical mixing condition. The paper attempts to provide an overview of recent advances in theoretical modeling and numerical simulation of this subject. A variety of liquid propellants, including hydrocarbon and cryogenic fluids, under both steady and oscillatory conditions, are treated systematically. Emphasis is placed on the development of a hierarchical approach and its associated difficulties. Results from representative studies are presented to lend insight into the intricate nature of the problem.

http://www.yang.gatech.edu/publications/Journal/P%26C(2000,%20ref19,%20Yang).pdf

Modeling of supercritical vaporization, mixing, and combustion processes in liquid-fueled propulsion systems

Supercritical (and subcritical) fluid behavior and modeling: drops, streams, shear and mixing layers, jets and sprays

Modeling high-pressure mixing and combustion processes in liquid rocket engines involves a variety of challenges that include all of the classical closure problems and a unique set of problems imposed by the introduction of thermodynamic nonidealities and transport anomalies. The complicating factors of chemical kinetics, highly nonlinear source terms, and subgrid-scale velocity and scalar-mixing interactions must all be considered. The situation becomes more complex with increasing pressure because of an inherent increase in the  ow Reynolds number and dif culties that arise when  uid states approach the critical condition. This paper 1) outlines the fundamental dif culties associated with modeling mixing and combustion processes at near-critical conditions, 2) outlines the theoretical and numerical framework developed to handle these dif culties, and 3) presents the results of simulations that lend insight into the intricate nature of the problem. Case studies focus on model performance and accuracy requirements, Lagrangian –Eulerian treatments of transcritical spray dynamics, and pure Eulerian treatments of transcritical and supercritical mixing and combustion processes.

Modeling High-Pressure Mixing and Combustion Processes in Liquid Rocket Engines

Fundamental challenges and opportunities for preparative supercritical fluid chromatography.

This paper provides an overview of recent advances in the theoretical modeling and numerical simulation of cryogenic fluid injection and mixing in transcritical and supercritical environments. The basis of the analysis is a general theoretical and numerical framework that accommodates full conservation laws and real-fluid thermodynamic and transport phenomena. All of the thermophysical properties are determined directly from fundamental thermodynamics theories, along with the use of corresponding-state principles. Turbulence closure is achieved using a large-eddy-simulation technique, in which large-scale motions are calculated explicitly and the effects of unresolved small-scale turbulence are modeled either analytically or empirically. The analysis has been applied to study: (1) fluid jet dynamics, (2) swirl injection of liquid oxygen through a simplex swirl injector, and (3) shear co-axial injection and mixing of liquid oxygen and methane. Various effects, including density stratification, she...

Cryogenic fluid jets and mixing layers in transcritical and supercritical environments

A new generalized chart analogous to that of Slattery and Bird (SB chart) was prepared from the observed values of the self- and binary-diffusion coefficients of gases at high pressures. The deviation of the values produced by the new chart from those observed is 4.1% on the average, whereas that of the values produced by the SB chart is 7.9%. In addition the new chart gives the average of the values observed, whereas the SB chart gives lower values for most of the systems.

/pdf/preparation-of-a-generalized-chart-for-the-diffusion-9fccszltxb.pdf

Preparation of a generalized chart for the diffusion coefficients of gases at high pressures

normal ethylene) at atmospheric pressure, which could not be found in the literature, were obtained from Figs. 1 to 4 by extrapolation and correction for molecular weights. As can be seen from Table 2, the values obtained from the 14CO2 (trace)-C2H4 system are in good agreement with those obtained from the 14C2H4 (trace)-CO2 system. This agreement is experimental support for the first approximation derived from theories that binary diffusion coefficients do not depend on the proportion of mixtures2}. Diffusion coefficients at high pressures were calculated using T9) and SB3) charts. As can be seen from Figs. 1 and 2, the T chart is in better agreement than the SB chart in the lower-pressure (P<100x 105 Pa) region, and the SB chart is better in the higherpressure region. Diffusion coefficients calculated using the modified Enskog-Thorne theory are shown in Figs. 3 and 4. The compressibility factors and the second and third virial Received June 4, 1981. Correspondence concerning this article should be addressed to S. Takahashi. Shinji TAKAHASHIand Masaru HONGO Chemical Research Institute of Non-aqueous Solutions, Tohoku University, Sendai 980

https://www.jstage.jst.go.jp/article/jcej1968/15/1/15_1_57/_pdf

Diffusion coefficients of gases at high pressures in the c02-c2h4 system

The diffusion coefficient of 14C-labelIed ethylene in normal ethylene was measured at temperatures of 25, 50, and 75°C in the range up to 10 × 10-3 mol/cm-sp3 density and 197 atm pressure. The measurements were made through a plug of porous bronze in a diffusion cell of two-chamber type by using the radioactive tracer technique. The diffusion coefficient-density products decreased slightly with increasing density, and could be predicted by a modified Enskog-Thorne theory. The values obtained in this study agreed fairly well with those calculated from a generalized chart which was prepared from correlation of experimental data.

Shinji Takahashi

Papers

Preparation of a generalized chart for the diffusion coefficients of gases at high pressures

Diffusion coefficients of gases at high pressures in the c02-c2h4 system

The diffusion coefficient of 14C-labelled ethylene in normal ethylene at high pressure.

Viscosity of chlorodifluoromethane (R22) at high pressures.

The diffusion coefficients of 14co2, in the c02-n2 system at high pressure