Numerical study of the transition to a steady-state operating mode of a nozzleless propulsion system with a viscoelastic cylindrical charge

Source abstract

This article presents the results of numerical modeling in a two-dimensional axisymmetric approximation of the interaction between solid propellant (SP) combustion products and a deformable viscoelastic charge during the transition to a steady-state operating mode of a nozzleless propulsion system. The turbulent flow of a viscous compressible gas in the combustion chamber is described by the Navier-Stokes equations using the k-» SST turbulence model. The viscoelastic behavior of the charge is described using the relaxation moduli of elasticity, which are approximated by the Prony series, and the Williams-Landel-Ferry time-temperature shift function. Displacements of the points on the charge surface are obtained as functions of time for three values of the initial shear modulus. The influence of the viscoelastic behavior of the charge on the time variation of maximum pressure in the combustion chamber and on the position of the sonic line in the charge channel is determined. It is shown that the time dependence of the maximum pressure in the combustion chamber has a characteristic maximum that coincides with the characteristic relaxation time of the relative shear modulus. A decrease of the initial shear modulus of the SP leads to an elongation of the sonic line into the channel.