Method for passivation of propellant residues in orbital stage tank of launch vehicle

The problem of removing unused liquid propellant residues from the tanks of spent spacecraft and orbital stages of Launch Vehicles (LV) leads to their explosion and the formation of space debris in orbits. To provide a solution to this problem, a method for removing liquid propellant residues from the LV tanks after the mission completion is proposed. The method is based on the gasification of liquid propellant residues in the tanks under acoustic-vacuum exposure and the discharge of the gasification products into the surrounding outer space. Experimental investigations were carried out on a Ground-based Experimental Installation (GEI) to determine the coefficient of heat transfer from the surface of an acoustic radiator to a liquid. The obtained coefficient was then used to calculate the energy costs for the gasification of kerosene. Numerical estimates are given on the example of the tank with kerosene residues from a spent second stage of the LV “Soyuz-2.1 v”. The optimal discharge rate at which kerosene does not freeze is 0.14 m³/s. Moreover, the acoustic exposure leads to an increase in the mass of evaporated kerosene over a given time by 96.1%, and the energy costs are 1756.7 kJ (approximately 50% of the remaining electrical energy).