Devising a method for improving the efficiency of artillery shooting based on the Markov model

This paper reports a method for improving the firing efficiency of an artillery unit that results in enhanced effectiveness. Given the modern use of artillery for counter-battery warfare, the effectiveness of shooting is not enough assessed by accuracy only. It is also necessary to take into consideration and minimize the time spent by the unit in the firing position and the consumption of shells to hit the target. It has been shown that in order to assess the effectiveness of an artillery shot due to the initial velocity of the projectile, the most rapid and simple means is to classify the quality of the shot by the acoustic field. A procedure for categorizing the shot has been improved by applying an automatic classifier with training based on a machine of support vectors with the least squares. It is established that the error in the classification of the effectiveness of the second shot does not exceed 0.05. The concept of the effectiveness of a single artillery shot was introduced. Under the conditions of intense shooting, there may be accidental disturbances in each shot due to the wear of the charging chamber of the gun, its barrel, and incomplete information about the powder charge. When firing involves disturbances, the firing of an artillery unit can be described by a model of a discrete Markov chain. Based on the Markov model, a method for improving the efficiency of artillery fire has been devised. The method is based on the identification of guns that produce ineffective shots. The fire control phase of the unit has been introduced. In the process of controlling the fire of the unit, such guns are excluded from further firing. A generalized criterion for the effectiveness of artillery firing of a unit, based on the convolution of criteria, has been introduced. It is shown that the devised method significantly improves the effectiveness of shooting according to the generalized criterion.

Identification of Shortcomings in the Method of Application of Probes and Improvement of the Parachute-Jet System

The article deals with the issues of improvement of the parachute-jet system (ORS) with the use of modern radio altimeters in order to increase the percentage of soft landings and to allow adjusting the position of the landing object in the horizontal plane depending on the angle of inclination of the surface of the intersection. The experience gained in heavy-duty aircraft landing illuminates the problem of calculating the probe length required for successful lan­ding. The main disadvantage of the method of using probes is that their length is rigidly fixed long before the landing (before loading), which does not allow to adjust it to account for changes in para­meters. The main disadvantages of the technique of using OPS probes are the inability to accurately predict the temperature of the landing site, the high probability of error in determining the full mass of the object before the landing, the inability to account for the pre­sence, power of upward airflows and does not allow to adjust it to account for changes in parameters. Therefore, there is the question of improving the method of determining the optimum height for the inclusion of the powder bra­king system, which would at least improve the consideration of the above parameters to ensure a minimum landing speed of heavy machinery. This is especially true of the real rate of descent of the ORS, which mainly depends on the flight mass of the object, the tempe­rature and pressure of the atmospheric air, the temperature of the powder charge of the ORS engine, the presence and power of upward airflows that are difficult to predict accurately, and the wind speeds near the landing site, which in general Improvement of the parachute-jet system in the direction of increasing the reliability, accuracy and safety of the landing of the object by the use of radar system will allow casting safely carry heavy objects dropping from airplanes.

SIMULATION OF FILTRATION AND CONVECTIVE BURNING IN BLOCK CHARGES OF POWDER GRAINS INHIBITED BY POLYVINYL BUTYRAL AT CONSTANT VOLUME

Increase of loading density could be considered as one of the ways of increasing muzzle velocity in guns. At the same time, reduction of maximum pressure requires increase in burning progressivity of the powder charge, which can be reached at the expense of coating of powder grains with polymer film and further compression to high density into block charge. Multidimensional numerical simulation of ignition and combustion of such charges is a relevant issue. Two-dimensional axisymmetric generalization of one-dimensional semianalytical model of convective burning of block charges is introduced. The gas-powder mixture is modeled by a two-phase nonequilibrium heterogeneous medium consisting of a multicomponent gas phase of the combustion products and a polydisperse condensed phase of the charge elements. Mathematical model and computational algorithm were validated through numerical simulation of the following problems: powder gas filtration in the dense charge, combustion of bulk and dense charges, consisting of 7-perforated grains, covered with film, in a closed vessel. Comparison of obtained results with experimental data demonstrates satisfactory predictive qualities of the model.

NUMERICAL STUDY OF THE DYNAMICS OF INTRA-CHAMBER PROCESSES IN A ROCKET ENGINE FOR MOBILE COMPLEXES WITH A MULTI-TURRET POWDER CHARGE

A solid-fuel rocket engine is a complex technical system in which a number of interrelated non – stationary and substantially nonlinear physical and chemical processes simultaneously occur. The type of SFRE under consideration has its own problems and design features. To optimize the parameters of a rocket engine, we study the dynamics of its internal processes. The research method is to set up a computational experiment. We consider the conjugate statement of the problem, which includes: triggering of the ignition device; – heating, ignition and subsequent unsteady and turbulent combustion of the powder charge; – unsteady threedimensional shock wave and a vortex of homogeneous-heterogeneous flow of air and products of combustion in the combustion chamber, nozzle block and launchers unit; – depressurization of the combustion chamber and the subsequent departure of the stub nozzle block. Each of the subtasks is considered in a relationship and resolved simultaneously - at a single time step. As a result of researches it is established that when triggered, the solid-propellant in the combustion chamber is implemented by an abnormal process associated with the segregation of the combustion mode of multi-turret powder charge. The results of numerical calculations are presented, on the basis of which constructive measures are developed to eliminate this undesirable effect.

The Researching of Dynamic Electricity Distribution Along with the Renovation of Automobile Details by the Contact Covering Welding

The goal of completed research is determination of common factors of dynamic electricity distribution in the area of simple welding spot forming due to contact welding-on compact and powdered materials. Due to contact welding-on of compact (rod, belt) and powdered materials there is the dissimilarity of an electric field, which determines the unequal distribution of temperature field in the area of the moulded core creating and influence on the welded on covering quality. By the contact welding-on of compact materials, there is an occurrence of central core zone unheating, which is coming as a result of geometrical, temperature and magnetic-electric factors. During contact welding of metal powders, considering high speed of heating and a small-time of dynamic electricity passage through powder, it is possible to make a conclusion, that the stability of heat generation in a powder surface will be determined by starting electricity resistance value. High-quality plating can be reached if the powder charge will have low and stable electricity resistance in a cross-section and good compactness under the condition of low compress pressure, which is used for welding. (40 ... 70 MPa). Electrical field dissimilarity with contact welding-on powdered materials leads to unequal heating of powdered materials and covering defects, which is taking place due to the features of powder compression. As a result of current lines concoction in the central area is observed at a local temperature increase. Besides, interstices are dielectrical phase and increase electrical resistance in the peripheral areas. To increase the quality of coverings, got by contact welding-on is able due to providing high-quality powder material compression on the whole covering cut.

STUDY OF THE PASTE-LIKE PROPELLANT COMBUSTION AT VARIOUS LOADING SCHEMES

The experimental and theoretical studies of the paste-like propellant combustion in a model ballistic installation are implemented. The research is carried out using three masses of projectile assemblies and three types of the propellant charge. The paper presents two versions of the law of dispersion for paste-like propellants which allow accounting for the pressure on the front and acceleration of the projectile assembly with a traveling charge. The coefficients in the laws of dispersion are obtained. Using the mathematical model presented in this work, the gas-dynamic pictures of the shots when the propellants are applied as traveling charges are obtained for each dispersion law. Based on the results, a detailed study of the processes occurring with the traveling charge consisting of a model paste-like propellant is implemented for various shot arrangements. The discrepancy between theoretical results and the results obtained in the set of experiments is no more than 2% for the maximum pressure and no more than 1% for the muzzle velocity. The dispersion law accounting for the projectile assembly acceleration and traveling charge makes it possible to describe accurately the processes in the space behind the projectile for projectile assemblies of various masses and different types of granulated powder charge in terms of the model ballistic installation in the considered pressure range.

Complex stress-strain behaviour of a cylindrical shell with a dynamically breaking internal elastic base

During the operation of a solid-propellant rocket engine, the combustion products of a powder charge create increased pressure in the combustion chamber. Besides, the combustion of gunpowder is accompanied by a large release of heat, which, despite the thermal insulation, causes the appearance of deformations in the engine cowling. This leads to the need to investigate the durability of the shell under the influence of internal pressure and temperature fields. The aim of the paper is to determine the complex dynamic deformed state and vibrations of the engine cowling under the action of force and temperature loads. The problem of a complex axisymmetric stress-strain state and vibrations of a thin cylindrical shell with a dynamically breaking internal elastic foundation, obeying Winkler's hypothesis, is approximately solved. The shell is under the action of internal pressure and temperature fields on a part of its length free from an elastic base. The resolving equation of the problem of the shell deflection is solved by the Bubnov-Galerkin method, reducing the problem to a system of linear algebraic equations. The examples are considered, in which the basic frequencies of natural vibrations of the structure are determined depending on the conditions of shell fastening. Parametric studies are carried out.

Study of the effect of synthesized high voltage electric charge of a powder mixture on the physical and mechanical properties of epoxy composites for the transport industry

For the formation of composite materials and protective coatings for the transport industry, ED-20 epoxy yanoic oligomer, the polyethylene polyamine PEPA and microfine fractions of high-voltage synthesized powder charge were used. The dependence of the content of microdispersed powder on the adhesive, physical and mechanical properties, and residual stresses of epoxy composites has been investigated. It has been proved that for the formation of a composite material or protective coating with improved adhesive and cohesive properties, the optimal particle content is 0.05–0.50 parts by weight per 100 parts by weight of the ED-20 epoxy oligomer. Such materials are characterized by increased mechanical strength and the ability to resist static and dynamic loads, since their properties are significantly increased compared with the matrix. The obtained results of experimental studies of physical and mechanical properties of composite materials are consistent with the test results of samples with adhesive characteristics, indicating their reliability.

Dynamics of a cylindrical shell with a collapsing elastic base under the action of a pressure wave

In the dynamic and quasi-static statements, the issue of non-stationary deformation and stability of the solid propellant rocket engine (SPRE) was approximately solved. It is modeled by a thin, smooth cylindrical shell, inside of which, on a part of its length, there is an elastic base corresponding to a gradually burning powder charge. A pressure wave is moving along the outer surface of the body, simulated by the running load. The deformed state of the shell is considered axisymmetric and is determined on the basis of the moment theory of the shells. For diverse variants of mounting the ends of the shell in a closed form, expressions were obtained for the critical velocity of the load. Examples were considered.

Study of porosity and structure of wearresistant powder coatings with modifying additives

Researches of open porosity and structure of the electroarc metallization coatings received from powder wire with the modifying additives in the form of the complex concentrator of Tomtorsky field rare-earth elements are conducted. It is established that open porosity depend on features of formation of layers which the sizes of refractory components of powder charge of wire significantly affect. It is shown that the porosity of layer on smooth substrate is close to zero, with removal from substrate the average porosity of coating layers increases. Keywords: electroarc metallization coating, rare-earth metals, open porosity, hydrostatic weighing, microstructure, Markov process.