space blast pipe

The objective of this study is to prove the feasibility of the suggested technical concept and validate the elementary performance calculations. Besides gas- and thermodynamic analyses, this includes basic examinations on some options for the supporting structure; the piston and the outlet mechanisms as well as the constructional constraints of the tube itself. The unsteady flow and the time-dependent pressure distribution inside the blast pipe will be modelled, computed and simulated. This is necessary to predict the required power and to define the different phases of the blasting process.

Here it is assumed that the pipe is inclined with an angle α against the horizon. The pressure variation bases on aerodynamic forces, expansion waves and convective influences depending on the aerostatic conditions inside this inclined pipe.

During the INITIALISATION PHASE in the beginning the chamber below the piston platform is pressurised until the reference pressure is reached. The pressure over the platform has to decrease on a minimum to reduce the drag during the later acceleration phase. For the de-pressurizing this upper volume during this initialization phase the upper outlet of the pipe has to be closed.

In the ACCELARATION PHASE the piston platform is unlocked and accelerated by the difference pressure. The local pressure change inside the blast pipe is predicted by the running shock waves and the aerostatic pressure distribution inside this very high tube. While the pressure “under” the platform decreases because of the expanding volume, hot gas is induced by local gaps in the side walls of the inner volume of the blast pipe. During this process the pressure in the upper chamber increases by the permanent volume reduction.

When the pressure in the upper chamber reaches the atmospheric pressure behind the still closed outlet at the top of the pipe, this shot is opened and the ATMOSPHERIC PHASE starts. During this time interval the gas of the upper chamber is pushed into the atmosphere until the platform reaches the outlet. After this point the phase outside the blast pipe starts only with drag and gravitation forces while payload is shot into space.