Valeriy Trushlyakov’s research while affiliated with Omsk State Technical University and other places

The concept, schematic solution, and methodology for liquid residue passivation using additional acoustic impact based on a gas jet emitter when introducing gas into a closed vessel (CV) containing liquid residue have been developed. A methodology for numerical modeling of the process of liquid droplet entrainment from the CV using the Ansys Fluent software package has been developed, based on gas supply into the tank. The method consists of two interrelated physical-mathematical models (PMM): 1) PMM of gas introduction into CV taking into account additional acoustic impact and creation of two-phase flow structure with subsequent entrainment of liquid droplets through the drain valve into the environment; 2) PMM of acoustic cavitation occurrence in the liquid volume taking into account the assessment of vapor occurrence inside the liquid with subsequent use of these results as initial conditions in PMM on formation of two-phase gas flow. The influence of additional acoustic impact during gas introduction into the CV on the ejection of liquid residue was evaluated. The results showed that accounting for acoustic cavitation increases the entrainment of liquid droplets by approximately 40 %.

It is proposed to descent from orbit large objects of space debris such as the spent stage of a launch vehicle (LV), hereinafter referred to as a target, using a rotating tethered space system (RTSS), the parameters of which are determined during the ballistic design of interception schemes. The Angara-1.2 LV, the Aggregate Module (AM) – an analogue of the space tug, and the Autonomous Docking Module (ADM) are included in the rocket space complex for target interception. The “AM + ADM” payload is launched by the Angara-1.2 LV into an elliptical target intercept orbit in the vicinity of the intended intercept point with a relative velocity of up to 300 m/s. When the tether is stretched, the motions of the AM and the bundle “ADM + target” are exchanged and the RTSS “AM + tether + ADM + target” is formed. The angular velocity of the rotation is determined by the length of the tether and the relative velocity of the AM and the “ADM + target”. For different values of the transversal and radial projection of the relative velocity, the minimum tether length is determined based on the condition of its integrity.

To reduce the risk of explosion of propellant tanks of expended spacecraft and launch vehicles with liquid rocket engines in orbit, as well as in case of emergency situation, for example, loss of orientation, the Inter-Agency Space Debris Coordination Committee recommends passivation measures, including the discharge of residual liquid propellant and pressurant gas. In ANSYS-Fluent program complex possible initial positions of liquid propellant residues in a spherical tank at its rotation under conditions of low gravitational fields are determined. The values of liquid propellant residues depending on their initial position in the spherical tank at opening of the drain line for discharge of gas–liquid mixture into the ambient space are determined. The concept of formation of two-phase flows of liquid propellant on the example of the spherical tank at tangential entry of compressed gas is offered. The relationship between the number of gas inlet points and the effectiveness of the developed method (expressed as the ratio of the mass of expelled liquid propellant to the mass of gas expended) is demonstrated. For instance, the use of 2 gas inlet points achieves an efficiency of up to 30 %, while employing 3 gas inlet points increases it to 89 %.

The active deorbiting and passivation of launch vehicles has become key for the implementation of modern space debris mitigation guidelines. Appropriate engine restart conditions must be provided as part of this process. Ullage motors have been traditionally employed to induce active settling and ensure a gas-free propellant supply to the engines. Although robust and reliable, ullage rockets are also heavy, which motivates the study of alternative approaches to the problem. Classic propellant management devices could potentially be employed in this context, but they are hardly applicable to high flow rate cryogenic liquid systems. This paper explores several novel propellant settling strategies that are particularly well suited for cryogenic propellants. In particular, three distinct Magnetic Positive Positioning concepts, a hydrogen-peroxide-based Propellant Gasification System, and a hybrid device that combines both approaches are introduced. The preliminary technical analysis indicates that the successful development of these technologies could lead to mass savings of hundreds of kilograms and economic gains of several hundred thousand dollars per launch.

The paper considers the problem of capturing an uncooperative space debris object (target) such as an orbital stage for further active debris removal from orbit with a tether using a space tug. The autonomous docking module performs capture of the target by a probe-cone type device, using the nozzle of the target as a docking port. The paper analyzes the risks of two phases of space debris capture. The first phase considers the mechanical interaction of the probe with the target nozzle during the formation of the mechanical linkage. The second phase considers the stabilization of the bundle with a rotation along the tether direction to reduce the amplitude of oscillations of the bundle of the autonomous module with the target after the formation of tethered system.

The motion of a rotating tethered system for active debris removal is considered. The system consists of the space tug and space debris object connected by the tether. The influence of the relative tug-debris orbital motion on the longitudinal oscillations of the tether is investigated. Linearized equations of the tether oscillations are derived, and the estimation of maximum tether deformation is obtained as a function of initial conditions of tug-debris relative motion. An algorithm for the formation of an interception orbit is proposed to minimize the maximum deformation of the tether after the formation of the rotating tether system. The linearized model of longitudinal oscillations is validated by comparing its results with the results of the model of the motion of two bodies connected by a tether in a gravitational field. A numerical example illustrates the obtained results.

The active deorbiting and passivation of launch vehicles has become key for the implementation of modern space debris mitigation guidelines. Appropriate engine restart conditions must be provided as part of this process. Ullage motors have been traditionally employed to induce active settling and ensure a gas-free propellant supply to the engines. Although robust and reliable, ullage rockets are also heavy, which motivates the study of alternative approaches to the problem. This paper explores for the first time several high-risk-high-return propellant settling strategies that may result in significant benefits for future space systems. In particular, three distinct Magnetic Positive Positioning concepts, a hydrogen-peroxide-based Propellant Gasification System, and a hybrid device that combines both approaches are introduced. The preliminary feasibility analysis indicates that the successful development of these technologies may lead to mass savings of hundreds of kilograms and economic gains of several hundred thousand dollars per launch. However, the robustness of some of these methods may be compromised by complex fluid-structure interactions that require a careful numerical and/or experimental analysis.