On the behavior of the flow field components from the momentum equation for a functioning model of rocket motors

In this study, a fluid is expelled by the suction process from the intermediate space between to porous plates in transverse movement in order to model the functioning of a compartment of a rocket motor. This transverse motion of the plates can reduce or increase the flow domain in order to enhance the performance of the motor. From a theoretical point of view which is the present contribution, the problem is described by the velocity and the pressure gradient known as the flow field components which are determined under different values of the Reynolds number and the expansion or contraction ratio representing the control parameters of the problem. It is found that, the decrease of the magnitude of the axial pressure gradient by expanding the space occupied by the fluid causes flow reversal in the case of low suction Reynolds numbers. The reduction of the flow domain increases the magnitude of the axial pressure gradient and destroys the backward flow for all the suction Reynolds numbers. This reduction or contraction of the flow field causes a linear profile of the radial velocity and a linear behavior of the axial pressure gradient.