Liquid-Propellant Droplet Dynamics and Combustion in Supercritical Forced-Convective Environments


Book Description

A focused research has been conducted to investigate the dynamic behavior of liquid propellant droplets in supercritical forced convective environments. The purpose is to establish a solid theoretical basis for enhancing the understanding of liquid propellant droplet vaporization, combustion, and dynamics at supercritical conditions, with emphasis placed on the effect of forced convection. A variety of liquid propellants and propellant simulants, including hydrocarbon and cryogenic fluids, at both steady and oscillatory conditions were treated systematically. The formulation is based on the full conservation equations for both gas and liquid phases, and accommodates variable properties and finite rate chemical kinetics. Full account is taken of thermodynamic non-idealities and transport anomalies at high pressures, as well as liquid vapor phase equilibria for multi-component mixtures. Because the model allows for solutions from first principles, a systematic examination of droplet behavior over wide ranges of temperature and pressure is made possible. Results have not only enhanced the basic understanding of the problem, but also served as a basis for establishing droplet vaporization and combustion correlations for the study of liquid rocket engine combustion, performance, and stability.




Liquid-Propellant Droplet Combustion and Cluster-Behavior at Supercritical Conditions


Book Description

A systematic investigation of superoritical droplet vaporization and cluster behavior has been conducted based on the complete conservation equations in both the gas and liquid phases. The research work addresses a variety of fundamental issues related to droplet vaporization and dynamics at realistic conditions typical of liquid-propellant rocket combustion devices. A unified treatment of real-fluid thermodynamics has been developed based on fundamental theories. Special attention was given to the thermodynamic non-ideality and transport anomaly in the transcritical regime. A series of calculations has been performed to examine the cluster behavior of liquid oxygen (LOX) droplets in both sub- and super-critical hydrogen environments. Results show that pressure has strong effect on droplet interactions, while the temperature effect is relatively minor at high pressures. The hydrogen density plays a decisive role in determining droplet interactions through its influence on the temperature and mass fraction gradients at the LOX droplet surface. The characteristics of LOX droplet vaporization in forced-convective environments has also been studied. A dimensionless parameter We/Oh 1/2, which represents the ratio of aerodynamic and viscous forces, is found to be the major factor determining the droplet deformation under supercritical conditions. Results of droplet lifetime are well correlated as a function of the initial droplet Reynolds number and pressure. Finally, the interactions between two droplets moving in tandem in supercritical convective environments were investigated in detail.







ARO and AFOSR Contractors Meeting in Chemical Propulsion, Held in Virginia Beach, Virginia on 3-6 June 1996


Book Description

Partial contents: Supercritical droplet behavior; Fundamentals of acoustic instabilities in liquid-propellant rockets; Modeling liquid jet atomization proceses; Liquid-propellant droplets dynamics and combustions in supercritical forced convective environments; Contributions of shear coaxial injectors to liquid rocket motor combustion instabilities; High pressure combustion studies under combustion driven oscillatory flow conditions; Droplet collision on liquid propellant combustion; Combustion and plumes; Development of a collisional radiative emission model for strongly nonequilibrium flows; Energy transfer processes in the production of excited states in reacting rocket flows; modeling nonequilibrium radiation in high altitude plumes; kinetics of plume radiation, and of HEDMs and metallic fuels combustion; Nonsteady combustion mechanisms of advanced solid propellants; Chemical mechanisms at the burning surface. p15










Liquid Rocket Engine Combustion Instability


Book Description

Annotation Since the invention of the V-2 rocket during World War II, combustion instabilities have been recognized as one of the most difficult problems in the development of liquid propellant rocket engines. This book is the first published in the United States on the subject since NASA's Liquid Rocket Combustion Instability (NASA SP-194) in 1972. In this book, experts cover four major subject areas: engine phenomenology and case studies, fundamental mechanisms of combustion instability, combustion instability analysis, and engine and component testing. Especially noteworthy is the inclusion of technical information from Russia and China--a first.










Study of the Sub- and Supercritical Behavior of Fuel Droplets


Book Description

A study of the droplet gasification and combustion characteristics of hydrocarbon fuel droplets was conducted at sub- and supercritical. The experimental setup provided quiescent and convective environments under supercritical pressure and temperature conditions. The droplet combustion experiment hardware consisted of: a liquid pressurizing and transfer system; a high pressure and temperature combustion chamber; a droplet formation, deployment and ignition system; and a high speed CCD imaging system. The gasification and combustion characteristics of droplets of several hydrocarbons under quiescent environments were studied. Specifically, the mass emission rates and combustion characteristics of 1.5-mm-diameter suspended droplets of a series of hydrocarbons ranging from hexane (C6) to tetradecane (Cl4) were measured at sub- and supercritical pressures and temperatures using the high-speed image system. The images of droplet gasification and combustion revealed interesting phenomena and provided better understanding of the droplet behavior in sub- and supercritical pressure and temperature environments.