The Space Engineering and Technology magazine
¹ 4 (15), 2016
FLYING VEHICLES AERODYNAMICS AND HEAT EXCHANGE PROCESSES
Aksenov A.A., Dyadkin A.A., Rybak S.P.
Numerical simulation of shock-wave efects on the return capsule of the manned transport vehicle during the emergency rescue system operation
The paper presents the results of numerical simulation of shock-wave processes accompanying the start of solid-propellant engines of the emergency rescue system of the new manned transport vehicle (MTV) at the launch vehicle failure in the injection phase.
The adaptation data of FlowVission software package is given for solving this class of tasks and verifying this software package based on the results of numerical simulation of testing the gas-dynamic model at a scale of 1:10 of the separable payload module of MTV emergency rescue system.
During the study the following is made: estimates of the amplitudes of the shock-wave effects on MTV return capsule in different operation modes of the engines of the emergency rescue rocket block in different flight phases of the integrated launch vehicle with MTV. The analysis of the calculation results showed that the maximum values of the shock-wave pressure on the return capsule are implemented during operation of MTV emergency rescue system in the initial flight phase of the launch-vehicle.
Key words: return capsule, propulsion system start, manned vehicle, FlowVision software package, launch vehicle, emergency rescue system, shock-wave pressure, numerical simulation.
FLYING VEHICLES ENGINEERING, DESIGN AND MANUFACTURING
RSC «Energia»’s experience of spacecraft development shows that the main critical loading events occur on ascent flight together with launch vehicle. The validity of internal loads for spacecraft structural elements during ascent flight (which are determined by coupled load analysis) to a large extent depends on the accuracy of spacecraft dynamic finite element models. Updating of dynamic model parameters is implemented after getting the modal test results. It is presented the analysis of two the most frequently used experimental methods of spacecraft structure modal testing: under oscillations been creating by local force of shaker rod and under base driven kinematic excitation by stationary vibro-shaker. It have been stated the advantages and deficiencies of both methods mentioned above and given the recommendations of their applicability for spacecraft development stages.
Key words: spacecraft, launch vehicle, finite element model, couple loads analysis, modal survey tests, verification method, local force excitation, kinematic excitation.
Shachnev S.Yu., Paschenko V.A., Makhin I.D., Bazeskin A.V., Dubovitskiy A.D.
Developing technology of friction stir welding of heavy gauge aluminum alloys 1570S, AMg6 for use in RSC Energia advanced designs
The paper provides a review of the friction stir welding method, its pros and cons. It presents the results of friction stir welding technology development at ZAO ZEM of RSC Energia as applied to products made of heavy-gauge aluminum alloys. It describes an in-house built tool for friction stir welding of various-gauge aluminum alloys. It describes friction stir welding of aluminum alloys Amg6 and 1570S and results of mechanical tests of the welds. Feasibility was established of using friction stir welding to build nearly space-rated structures with the use of production tools developed and built by ZAO ZEM specialists.
Key words: friction stir welding, aluminum alloy AMg6, aluminum ally 1570S, production tooling for friction stir welding, mechanical tests of the welds, friction stir welding modes.
FLYING VEHICLES THERMAL, ELECTRIC PROPULSION ENGINES AND POWER GENERATING SYSTEMS
In the context of the combined power and propulsion unit of the Martian Expeditionary Vehicle, design studies reviewed five options for modular lithium-niobium thermionic Nuclear Power Generating System (NPGS) with 5–10 MW electric output. The first option was designed to meet specifications of the planned NPGS for the orbital transfer vehicle Hercules, while the other options had higher specific output performances, which, to a significant degree, were validated in experiments, including reactor tests. The paper provides design parameters for thermionic power-generating channels, packages and a thermionic fast neutron converter/reactor, five-layered biological protection against radiation, lithium cooling system, as well as specifications of the NPGS as a whole. The paper points out the need to develop a new, as compared to the Hercules NPGS, reactor control and protection system. It provides NPGS layouts for the transportation configuration (when launched in a cargo transportation container of an Energia-type launch vehicle) and the operational configuration. It discusses the issues involved in further improvement of power and mass properties.
Key words: design studies, nuclear power generating system, thermionic converter/reactor, lithium-niobium cooling system, shady biological shielding, reactor control and protection system, NPGS configuration.
CHECKING AND TESTING FLYING VEHICLES AND THEIR SYSTEMS
Arkhipov A.B., Bryukhanov N.A., Dementyev V.K., Dyadkin A.A., Komarov V.V., Ponomarev N.B., Ponomarev A.A.
Experimental studies of performance of the manned transportation spaceship’s landing propulsion system and its jets’ gasdynamic efects on the landing surface
The paper presents the results of model experimental studies of discharge coefficient and the coefficient of the specific impulse of thrust produced by the nozzle of the braking solid-rocket motor for the future crew transportation spacecraft, flow patterns in this nozzle and distribution of pressure over the landing surface in the area where the jet impinges on the surface.
The experimental studies were run on a 1:1.5 scaled model of the nozzle for vertical braking, which has an adjustable rectangular throat section, together with a mockup of a fragment of the aft section of the reentry vehicle and a simulator of the landing surface at the differential nozzle test facility of the Keldysh Reserch Center. Full propellant pressure upstream the nozzles varied within the range of 60 to 120 kgf/cm2. The tests were run on high-temperature combustion products of the air-ethanol propellant and on cold air. The obtained experimental data were recalculated to full-scale conditions.
Key words: reentry vehicle, landing solid-rocket motor, landing surface, nozzle with adjustable throat section, nozzle discharge coefficient, specific impulse coefficient of a nozzle, gasdynamic effects of a supersonic jet impinging on a surface.
FLYING VEHICLES DYNAMICS, TRAJECTORY AND MOTION CONTROL
Shangareev A.T., Timakov S.N., Platonov V.N.
The Kalman filter application to the problems of spacecraft berthing control
The capability of using the adaptive observer with Kalman filtering to control berthing of a large-sized spacecraft with elastic structural elements to the orbital station is considered. Making the state vector estimates of the approaching spacecraft is based on the use of modal decomposition of its dynamic behavior. The indicated estimates minimize the effect of the increasing intensity of non-stationary noise in signals from sensors, caused by rereflection of radio signals from structural elements of the orbital station, the growing parallax distortions during the rendezvous and elastic vibrations of the approaching spacecraft structure. The algorithm of the spacecraft motion control in the berthing and docking mode is presented. A comparative analysis of the results of mathematical simulation of the control object dynamics in the berthing mode both with the use of Kalman filtering and without it is given.
Key words: berthing, control algorithm, adaptive observer, Kalman filter.
A review of new methods for continuous thrust spacecraft trajectory optimization is presented. The methods are based on a trajectory discretization by small segments and on a near-uniform discrete approximation of thrust directions by a set of pseudoimpulses with an inequality constraint for each segment. The optimization problem is to minimize the total characteristic velocity. The optimal impulse in each segment can be presented by the sum of non-zero pseudoimpulses with a constraint on the total characteristic velocities of the pseudoimpulses. The terminal conditions are presented as a linear matrix equation. A matrix inequality on the sums of the pseudo-impulses is used to transform the problem into a large-scale linear programming form. The continuous burns include a number of adjacent segments and a post-processing of the linear programming solutions is needed to form a sequence of the burns. An optimal number of the burns is automatically determined. The methods provide flexible opportunities for the trajectory computation in complex missions with various requirements and constraints. Summary of application examples of trajectory optimization for different spacecraft types is presented. Advantages of the methods are discussed.
Key words: spacecraft trajectory optimization, linear programming application, review.
The paper provides an analysis of how the trajectory plan of a manned mission to Mars affects the trajectory performance indicators such as the initial mass of the Martian vehicle and the mission duration. The reviewed trajectory plans for one-vehicle manned mission to Mars using a nuclear-powered electric propulsion system are characterized by the non-uniqueness of solutions to the problem of optimizing the Earth–Mars–Earth transit trajectory with time-constrained stay of the vehicle in the vicinity of Mars. In addition, a trajectory plan was also reviewed, which put no constraints on the time spent in the vicinity of Mars. For the trajectory plan with time-constrained stay in the vicinity of Mars the following properties were demonstrated: the ability to support two launch dates within one synodic period; in case of using direct atmospheric re-entry of the return vehicle, at moderate launch masses it is possible to reduce the duration of the transit down to that of high-thrust missions (with propulsion systems based on liquid-propellant engines or nuclear rocket engines) with similar trajectory plan.
Key words: manned mission to Mars, interplanetary transfer trajectory, nuclear-powered electrical propulsion system, optimization, non-uniqueness of solutions, initial mass of the Mars expedition vehicle, mission duration.
SYSTEMS ANALYSIS, CONTROL AND DATA PROCESSING (BY INDUSTRY SECTORS)
The paper identifies methods of variable analysis and synthesis of complex processes occurring onboard spacecraft providing their system-wide analytical representation. Discussed as an example of the methods application is the controlling of a system of electric thrusters on Yamal spacecraft. Analysis and synthesis in the said system were performed for subsequently optimizing the propellant consumption during maneuvers by selecting a system control option with minimal mass flow rate in the thrusters. Additionally, the said methods made it possible to resolve anomalies in the system, which otherwise would have resulted in reduced life expectancy of its elements and system failures.
The paper presents validation of the newly identified methods for variable analysis and synthesis of complex processes during control of one of the onboard systems in an actual mission of a Yamal spacecraft.The use of the methods made it possible to significantly reduce propellant requirements for the communication satellites geostationary mission and prevent the propagation of a hidden anomalous situation which actually occurred and would have resulted in the failure of one of the system’s elements.
An axiom and a hypothesis were defined, which are the newly introduced methodological foundations for variable flight control of a SC. The proposed hypothesis was confirmed based on the results of its verification during a SC maneuvering using a system of electric thrusters.
Key words: variable control method, variable analysis method, variable synthesis method, axiom, hypothesis, decomposition, complex control process, stratification, process cluster, complex process aggregate, system of electric thrusters, stationary plasma thrusters, thrust module, discharge current, discharge voltage, propellant.
¹ 4 (15) october-december 2016