Finite-volume modelling of system with compressible flow propelled and actuated body motion

Abstract

A finite-volume model for the gas flow in a compressible flow driven system with two moving components is developed and applied. In this system, high pressure and temperature compressible flow propels one body along a main flow channel. When this body passes an opening in the main flow channel, some of the high pressure gas bleeds off, entering a secondary, telescoping, flow channel that empties into a plenum. The bleed-off flow causes the pressure in the plenum to increase, actuating the motion of a secondary (actuated) body that forms a bounding surface of the plenum, causing the plenum to expand and the secondary channel to lengthen. This model is used to characterize the basic flow effects in the system and to investigate the significance of the system parameters. For the parameters studied, the flow in the system consists of a series of pressure pulses rather than a continuous flow, with reflected pressure waves playing a significant role in the flow field development. For a given initial pressure, changing the size of the opening and secondary flow channel had a minimal effect on the motion of the propelled body. The size of the opening and the initial high pressure were found to have the greatest impact on the velocity of the secondary, actuated moving body.