Analysis And Comparison Of Analytical And Numerical Solution Of Flow Field In Rocket Motors

The research on the flow field in rocket motors is taken into account increasingly. The flow field in solid and liquid rocket motors is studied with both analytical method and numerical method in present paper.In the aspect of solid rocket motors, the flow field in fore combustion chamber of solid rocket motors with grain regression is mainly studied. Based on incompressible N-S equation of two-dimensional axisymmetric flow, the analytical method, which includes not only simplifying N-S equation by spatial similarity and temporal similarity but also solving the high order equation by the method of variation of parameters and the method of perturbation, is introduced firstly. Then the internal flow field is numerically simulated with the technology of dynamic mesh in FLUENT software. The velocity field, pressure field and shear stress distribution are studied for different dimensionless regression ratioαand injection Reynolds number Re. The results indicate that the influence of grain regression should be considered whenα/Re is large and can be ignored only whenα/Re is very small. In addition, the fact that numerical results are well in agreement with the analytical solutions gains confidence in the analytical approximation.In the aspect of liquid rocket motors, the flow field in the whole combustion chamber of liquid rocket motors with bidirectional coaxial vortex is mainly studied. The analytical method, which includes not only solving simplified Euler equations by separation of variables but also solving the tangential momentum equation with viscous term by matched asymptotic expansion method, is introduced firstly. Then the internal flow field is numerically simulated with Reynolds Stress equation Model (RSM) in FLUENT software. The velocity field, pressure field and vorticity field are studied for different effective Reynolds number and chamber aspect ratio. The results not only validate the existence of outer free vortex and inner forced vortex and confirm the location of the zero-axial-velocity mantle which is the interface of outer vortex and inner vortex, but also validate some other property of the flow field. In addition, numerical results are well in agreement with the analytical solutions except at some places where there is a little difference because of the existence of viscosity.