Problems of Providing Completeness of the Methane-Containing Block-Jet Combustion in a Rocket Ramjet Engine’s Combustion Chamber

Paper number

IAC-07-C4.5.04

Author

Prof. Valeriy Tymoshenko, Institute of Technical Mechanics NASU NSAU, Ukraine

Coauthor

Dr. Igor S. Belotserkovets, Institute of Technical Mechanics NASU NSAU, Ukraine

Coauthor

Dr. Vjacheslav Gusinin, Ukraine

Year

2007

Abstract

Problems of methane-containing hydrocarbon fuel preparation on board a launch vehicle, organization of combustion, control of a burn-out zone length and a combustion effect on thermogasdynamic parameters in the combustion chamber of a rocket-ramjet engine are discussed in the paper. A problem of kinetic combustion of the block of two-dimensional (planar) supersonic methane-containing jets flowing out into a wake subsonic airflow in the two-dimensional channel is considered. To calculate the non-equilibrium flow of a chemically reacting gas mixture in a two-dimensional channel with accounting the viscosity influence, a model is used which includes “narrow” channel equations supplemented with equations of turbulence characteristics transfer in the boundary layer closeness. To describe the methane combustion kinetics, a system of multistage gross-reaction is used. The method of splitting by physical processes was taken as a basis of the algorithm. The conducted research resulted in the establishment of a number of factors, which are necessary to take into account in guaranteeing the reduction of the burn-out zone of a supersonic methane-containing jet in the wake subsonic flow in the combustion chamber of a rocket ramjet engine. The list of the main factors is the following:

• 1. At the interaction of a high-speed supersonic methane-containing jet with the wake subsonic air flow in the region of mixing a significant increase of a static temperature can be observed at certain parameter combinations due to the supersonic flow deceleration. It creates conditions for the gas mixture self-energized ignition in the case when the initial flow static temperatures are lower than the temperature of ignition.
• 2. The main parameter characterizing the process of methane combustion in oxygen of air is the degree of oxidant excess in the initial section of interaction. It is established that the value of the oxidant excess degree can be optimized by a rational combination of the initial methane concentration in a jet and a relative half width of an air jet.
• 3. Combustion effects at the subsonic, on the average, gas flow at the channel inlet the energy release as a result of combustion leads to the flow acceleration, decrease of the static pressure level and increase of its static temperature at its outlet; combustion leads to the decrease of flow turbulence that results in the increase of the length of the flows mixing zone;
• 4. Increase of the initial temperature of the injected jet results in the decrease of the static pressure level at the end of the zone of the flows turbulent mixing and chemical interaction; increase of the initial temperature of the injected jet or the initial temperature of the wake air flow results in the increase of the zone length of the flow turbulent mixing and chemical interaction;

Abstract document

IAC-07-C4.5.04.pdf

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