Vol 20, No 1 (2021)

Full Issue


Mathematical model of turbofan engine weight estimation taking into account the engine configuration and size

Avdeev S.V.


The paper presents a new correlation-regression model of estimating the turbofan engine weight considering the effect of the engine’s design schemes and dimensions. The purpose of this study was to improve the efficiency of the conceptual design process for aircraft gas turbine engines. Information on 183 modern turbofan engines was gathered using the available sources: publications, official websites, reference books etc. The statistic information included the values of the total engine air flow, the total turbine inlet gas temperature, the overall pressure ratio and the bypass ratio, as well as information on the structural layout of each engine. The engines and the related statistics were classified according to their structural layout and size. Size classification was based on the value of the compressor outlet air flow through the gas generator given by the parameters behind the compressor. Depending on the value of this criterion, the engines were divided into three groups: small-sized, medium-sized gas turbine engines, and large gas turbine engines. In terms of the structural layout, all engines were divided into three groups: turbofan engines without a mixing chamber, engines with a mixing chamber and afterburning turbofan engines. Statistical factors of the improved weight model were found for the respective groups of engines, considering their design and size. The coefficients of the developed model were determined by minimizing the standard deviations. Regression analysis was carried out to assess the quality of the developed model. The relative average error of approximation of the developed model was 8%, the correlation coefficient was 0,99, and the standard deviation was 10,2%. The model was found to be relevant and reliable according to Fisher's test. The obtained model can be used to assess the engine weight at the stage of conceptual design and for its optimization as part of an aircraft.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(1):5-13
pages 5-13 views

Methodological support for the training of UAV designers and operators

Lukyanov O.E., Zolotov D.V.


In this paper, we presented the developed concept for end-to-end training of designers and operators of UAVs on the basis of the use of specialized aircraft-type trainers.  The educational possibilities of the concept in terms of various training programs are discussed. A methodology for the selection of the main parameters of UAV taking into account the mutual effect of aerodynamics and weight was developed. It provided a wide range of specific requirements for UAVs for acquiring initial control skills in manual and automatic modes. The developed methodology is based on the takeoff-weight buildup equation modified with regard to the specific requirements for small-sized vehicles. This methodology also includes the process of choosing the most advantageous combination of geometric and kinematic parameters of an aircraft propeller using the isolated blade element theory. The methodology is implemented in PascalABC.NET language. A demonstrative example of selecting the main parameters of a training UAV for specific requirements is presented. The obtained basic technical characteristics of the UAV are given. A three-dimensional geometric model of the UAV was developed on the basis of the calculated data, and a prototype was manufactured. The flight parameters recorded through a series of test flights of the prototype are presented. The ways of using the described methodology for the development of training-and-research UAVs are discussed.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(1):14-28
pages 14-28 views

Influence of deviations in manufacturing of electrothermal propulsion system on nanosatellite maneuvering accuracy

Sinitsin L.I., Belokonov I.V.


A method is proposed for assessing the results of adjustment maneuvers for a nanosatellite (NS) with an electrothermal propulsion system (ETPS). Using the example of the SamSat-M nanosatellite under development, common causes of maneuvering errors associated with deviations in the manufacturing of the propulsion system are revealed. Probabalistic analysis of the NS maneuvering process was carried out. The design parameters of the ETPS are considered as random factors. Statistical models of the distributions of all random factors are assumed to be equally probable, which is the worst-case scenario, since the true distributions of the design parameters of the ETPS are unknown. The methodological basis of the study is the method of statistical modeling (Monte Carlo method) followed by the use of regression and factor analysis, on the basis of which the influence of the scatter of each of the design parameters on the controlled parameters is determined. Requirements for the design parameters of the ETPS that affect the spread of the projections of the velocity growth vector of the NS and the arising angular motion have been formulated. The presented results can be used to assess the influence of production deviations in the design parameters of propulsion systems on the nature of spacecraft motion, as well as to state requirements for the spread of design parameters to ensure the achievement of the objective.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(1):29-45
pages 29-45 views

Algorithm for solving optimal open-loop terminal control problem for spacecraft rendezvous with account of constraints on the state

Shorikov A.F., Goranov A.Y.


The paper proposes an algorithm for solving the optimal open-loop terminal control problem of two spacecraft rendezvous with constraints on their states. A system of nonlinear differential equations that describes the dynamics of the active (maneuvering) spacecraft relative to the passive spacecraft (station) in the central gravitational field of the Earth in the orbital coordinate system of coordinates related to the passive spacecraft center-of-mass is considered as an initial model. The obtained nonlinear model of the active spacecraft dynamics is linearized relative to the specified reference state trajectory of the passive spacecraft, and then it is discretized and reduced to linear recurrence relations. Mathematical formalization of the spacecraft rendezvous problem under consideration is carried out at a specified final moment of time for the obtained discrete-time controlled dynamical system. The quality of solving the problem is estimated by a convex functional taking into account the geometric constraints on the active spacecraft states and the associated control actions in the form of convex polyhedral-compacts in the appropriate finite dimensional vector space. We propose a solution of the problem of optimal terminal control over the approach of the active spacecraft relative to the passive spacecraft in the form of a constructive algorithm on the basis of the general recursive algebraic method for constructing the availability domains of linear discrete controlled dynamic systems, taking into account specified conditions and constraints, as well as using the methods of direct and inverse constructions. In the final part of the paper, the computer modeling results are presented and conclusions about the effectiveness of the proposed algorithm are made.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(1):46-64
pages 46-64 views


Research of restrained bending of aircraft parts with curved sides

Gromova E.G., Moiseev V.K., Sharov A.A., Lomovskoi O.V., Mantusov М.N., Plotnikov A.N.


In the article the authors present a method of restrained elastomer bending of aircraft sheet parts with curved sides. Manufacturing of a part is carried out in two transitions; as a result of the first transition a part with thinning in the radial part is obtained, the second transition is carried out on the mold block of reduced height, as a result of which the resulting wave of excess material deforms along the radius of the bending mandrel. In the finished part, we can observe an increase in the thickness of the workpiece in the zone of the bend radius. Numerical studies of the process were conducted using the ANSYS/LS-DYNA software complex. As part of the study, the process flow model was worked out, the distribution of thickness of the material of the part over the entire surface under consideration was obtained, and graphs were plotted showing the elastomer pressure distributions and the deformation of the material of the part at characteristic points.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(1):65-74
pages 65-74 views

Digital design of heat-resistant dimensionally stable carbon laminate (CFRP) structures

Komarov V.A., Kishov E.A., Laikova O.G., Pavlov A.A.


Special features of designing heat-resistant dimensionally stable structures are considered. A new design procedure is proposed, in which finite elements are used as a language for describing the load-bearing structure of a construction and the distribution of material in it considering the possibility of setting the desired structure of a composite material. The design task is formulated in terms of nonlinear mathematical programming. A sequence of digital models is used for its approximate solution in the interactive mode. The specific features of finite element modeling of thin-walled structures made of laminated composite material are discussed. The technique is demonstrated using the example of the development of a large-size space telescope body.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(1):75-86
pages 75-86 views

Analysis of contact interaction of polymer honeycomb core and CFRP base layers in sandwich-core constructions

Pavlova S.A.


The article considers the challenge of studying the mechanical properties of composite sandwich constructions at the interface between the base layers and the lightweight core. The results of strength tests are presented for specimens of sandwich-core panels with coats made of high-strength carbon fiber-reinforced plastics (CFRP) and polymer honeycomb core considering various loading conditions. It is noted that a discrepancy in the values of shear stresses occurs in four-point bending and shear tests due to the complex stress-strain state of the specimens during bending. In order to interpret the experimental data, numerical analysis of the area of contact interaction between the coats and the filler of the sandwich-core composite structures is carried out. It is noted that in the presence of significant normal stresses in the adhesive coat the base layers separate from the core during shear tests and there is underestimation of the values of shear stresses by about 20%. Recommendations for the assignment of ultimate shear stresses for the use in practical design of sandwich-core composite constructions are put forward.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(1):87-96
pages 87-96 views

Experimental investigation of CFRP fracture toughness by delamination type

Chernyakin S.A.


The results of analyzing fracture toughness in carbon fiber-reinforced plastics by the type of delamination are presented in the article. The goal of this paper is investigation of delamination propagation process and fracture mechanics parameters in modern CFRPs. This type of composite materials is extensively used in high load aerospace structures. Modern polymer composite materials are the subject of our research. A technique of manufacturing specimens for testing by the vacuum infusion process is presented in the paper. Experimental investigation of delamination propagation process by mode I and II was performed with the aid of up-to-date testing equipment using a special type of specimens such as a double cantilever beam. Researchers usually use this type of specimen for the validation of their numerical models. Critical values of energy release rate and load-displacement curves were obtained for two types of material – unidirectional and woven. Examination of microscopic sections of the tested specimens using an optical microscope allowed us to identify the specific fracture mechanisms of material structure.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(1):97-108
pages 97-108 views

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