Ramjet Combustion

B.Tech Final Year Project

Description

In this project we investigate the combustion phenomena inside the ramjet engine. Here the work on an already developed experimental ramjet combustor facility (at University of Michigan, Ann Arbor) is taken into account and then the three dimensional CAD geometry based on the experimental facility are made and then the complete Computational Fluid Dynamic analysis is done on ANSYS FLUENT package. The present work focuses on the CFD analysis of a three dimensional lab scale model of a ramjet engine. The prime focus of this work is to investigate the non-premixed mixing of fuel (hydrogen H₂) and oxidizer (air) and the combustion phenomenon using steady laminar flamelet model (SLFM). The models associated with the detailed 9 species and 21 reversible chemical reaction mechanism to predict the combustion process inside the engine. The SLFM uses two additional equation for mixture fraction and variance to determine the reaction flow field. The results obtained are compared with the data of the experiment performed and are in close agreement. The simulation is done for subsonic combustion, simulation for will also be performed for supersonic combustion. The analysis in this study also includes the comparison of data such as heat release rates at various locations, variation of temperature and pressure along the length of combustor obtained from the CFD analysis with the experimental data. Below is the experimental test facility (at Michigan Ann Arbor)

CAD Model and Simulation

Mesh Geometry

The meshed regions include the combustion and diverging area sections of the experimental apparatus only. The mesh is more densely clustered near the fuel injector to capture the physics of the fuel air mixing as accurately possible. The mesh is also denser near the leading edge and trailing edge of the stabilization cavity to capture their influence on downstream choke point created by heat addition to the subsonic flow.

Simulation

The heat release distribution in figure below shows the comparative results obtained from the experiments and Fluent simulation. In the experiment, heat release intensity is measured by the OH fluorescence image that shows the estimated intensity of heat release, in ANSYS Fluent the heat release is calculated by the positive part of the rate of change of sensible enthalpy not due to convection or diffusion.

Heat release contour along the length of combustor

Heat release contour along different cross sectional area of combustor

Graphs

Variation of Macho no. along the length of combustor

Variation of pressure ratios along the length of combustor

Variation of temperature ratios along the length of combustor

References

Micka, D. J., and Driscoll, J. F., “Combustion Characteristics of a Dual-Mode Scramjet Combustor with Cavity Flameholder,” Proceedings of the Combustion Institute, Vol. 32, Combustion Inst., Pittsburgh, PA, 2009, pp. 2397–2404.
Dalle, D. J., Fotia, M. L., Ihme, M., and Driscoll, J. F., “Reduced-Order Modeling of Turbulent Reacting Flows with Application to Ramjets and Scramjets,” Journal of Propulsion and Power, Vol. 27, No. 2, 2011, pp. 371–382.

Google Sites

Report abuse